Electrocardiographic Profiles by Sex in a Cohort of Healthy Vietnamese University Students

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Methods: In this cross-sectional study, 5,127 first-year Vietnamese university students (58.6% female; age 17–29) underwent resting 12-lead ECG recordings as part of a routine health screening. Participants were asymptomatic and free of known cardiovascular or metabolic disease. Standard ECG parameters—including heart rate (HR), PR interval, QRS duration (QRSd), QTc (Bazett’s correction), and QRST angle—were automatically extracted and manually verified. J-point (JV1–V6), ST-segment (ST60V1–V6), and T-wave amplitudes (TV1–V6) in precordial leads were evaluated to identify sex-based patterns. Data were summarized as medians with interquartile ranges and compared using non-parametric Wilcoxon rank-sum tests. Results: Significant sex differences were observed across all ECG parameters (p < 0.001). Females exhibited higher HR (83 vs. 80 bpm), shorter PR intervals (138 vs. 140 ms), and longer QTc intervals (423 vs. 406 ms), while males had longer QRS durations (90 vs. 80 ms) and narrower QRST angles. In the precordial leads, males demonstrated greater J-point and ST60 amplitudes, particularly in V2–V3, where the 98th percentile of ST60V2 reached 0.40 mV in males—surpassing international reference thresholds. Females more frequently exhibited anterior T-wave inversion (TWI), with 71.3% showing TWI in V1 and 2.5% in V2, compared to 48.1% and 0.9% in males, respectively. TWI beyond V2 was rare in both sexes. These patterns closely mirrored sex-specific repolarization profiles described in Western and athletic cohorts. Conclusion: This study provides the first comprehensive sex-stratified ECG reference data for healthy Vietnamese adults. Distinct sex-specific patterns in precordial leads—including elevated ST segments in males and higher prevalence of anterior TWI in females—underscore the need for ethnically tailored ECG interpretation criteria. These findings have clinical implications for improving diagnostic precision and avoiding overinterpretation of repolarization variants in Southeast Asian populations. Electrocardiogram sex differences Vietnamese population precordial leads early repolarization T-wave inversion ST-segment elevation ECG reference values Figures Figure 1 I. Introduction Cardiovascular disease (CVD) remains the world’s leading cause of death, underscoring the importance of early detection through accessible, cost-effective tools like the electrocardiogram (ECG). Despite its widespread use, accurate ECG interpretation demands consideration of individual physiological factors, particularly sex- and ethnicity-specific variations in cardiac electrophysiology. Decades of research have shown that males and females exhibit distinct ECG profiles. Women typically present with faster heart rates, shorter PR and QRS durations, and longer QT intervals, while men more commonly show features like J-point elevation, sometimes associated with arrhythmic syndromes such as Brugada syndrome. Ethnic background also plays a critical role, influencing parameters like ST-segment elevation, ventricular voltage patterns, and T-wave morphology. Yet, current ECG reference ranges are largely derived from Western populations, leaving groups such as Southeast Asians—particularly Vietnamese individuals—underrepresented. This study addresses this gap by examining sex-based ECG differences in a large cohort of healthy Vietnamese adults. By establishing baseline reference values for key ECG parameters, this study aims to establish ECG reference values tailored to the Vietnamese population, supporting ethnically attuned diagnostic accuracy and risk stratification. II. Method 2.1 Study design and participant This cross-sectional study enrolled first-year Vietnamese university students as part of the annual pre-semester health screening program conducted by Phenikaa University, in collaboration with Phenikaa University Hospital in Hanoi, Vietnam. Inclusion Criteria Participants were eligible for inclusion if they met all of the following criteria: Vietnamese ethnicity Aged 17 to 29 years, a range chosen to capture the emergence of sex-related differences in ECG parameters during adolescence and early adulthood Asymptomatic at the time of evaluation with a previously normal physical examination No personal or family history of cardiovascular disease, genetic disorders, or metabolic conditions such as diabetes mellitus or insulin resistance Body mass index (BMI) within the standard reference range (18–25 kg/m²) Not currently taking cardiovascular medications or any hormonal agents known to influence cardiac electrophysiology, including oral contraceptives or exogenous testosterone Participants who fulfilled all inclusion criteria underwent a standard 12-lead resting ECG. ECGs showing normal sinus rhythm, as defined by accepted diagnostic standards, were included for further analysis. In line with current clinical and research guidelines, ECGs demonstrating sinus arrhythmia, premature atrial contractions (PACs), or premature ventricular contractions (PVCs) were also retained. These findings are well-recognized as benign and physiologically normal in healthy young individuals. 2.2 ECG measurement and data collection: ECGs were recorded in the supine position using standardized 12-lead placement and the MAC 5 Resting ECG system (GE Healthcare, USA; 500 Hz sampling rate). Trained nurses performed all recordings. ECGs were saved as anonymized PDFs and coded using the Minnesota system. Of 5,391 recordings, 264 were excluded for technical issues; 5,127 met quality criteria and were included in the analysis. Core parameters—heart rate, PR interval, QRS duration, QTcB, and QRST angle—were automatically extracted via the GE Marquette™ 12SL™ algorithm. Additional features, including precordial QRS amplitude, J-point elevation, ST60, and T-wave amplitude (V1–V6), were manually measured relative to the PR segment. Ambiguous J-points were estimated using standard tangential methods. All ECGs were reviewed independently by four trained physicians; discrepancies were adjudicated by a fifth cardiologist. Reviewers were blinded to the sex of the participants. Measurements were standardized and rounded to the nearest 0.5 mm (0.05 mV) to ensure consistency. 2.3 Statistical analysis Statistical analyses were performed using STATA version 14. Normality of continuous variables was assessed using the Kolmogorov–Smirnov test. Due to non-normal distributions, continuous ECG parameters were summarized as medians with interquartile ranges (25th–75th percentiles); means ± SD were also reported for comparison across studies. Between-group differences were evaluated using the Wilcoxon rank-sum test or independent t-test, as appropriate. Categorical variables were compared using the Pearson chi-square test. A two-sided p-value < 0.05 was considered statistically significant. Reference ranges were defined by the 2nd and 98th percentiles. III. Results Baseline demographic: Of 5127 final ECGs that satisfied the study’s criteria, 58,55% were female (n=3002), 41,45% were male (n=2125) (see Figure 1). The mean age of the population was 17.8 ± 0.6 years (range: 16–29 years) (see Table 1). Basic ECG parameters Age showed minimal variability, with a median and interquartile range (IQR) of 18 years. The median HR–related variables, including the PR interval (138 ms), QRSd (84 ms), and QTcB (416 ms), fall within recognized physiological ranges. The QRSd and QTcB demonstrated modest dispersion, with interquartile ranges of 78–92 ms and 401–430 ms, respectively (see Table 1 below). Table 1 position Frontal plane electrical axes also showed predictable variability: the median R axis was 75°, while the T axis was 41°, with wider spreads across the IQRs.. The QRST angle, which represents the spatial difference between depolarization and repolarization vectors, had a median of 32°. Sex-Based Differences in Core ECG Parameters Statistical comparison of ECG parameters between males and females using the Wilcoxon rank-sum test. Females had a higher resting HR than males, with a median of 83 bpm (IQR 75–93) versus 80 bpm (IQR 70–91), respectively ( p < 0.001; z = 8.259). PR intervals were shorter in females [138 ms (IQR 128–150)] than in males [140 ms (IQR 130–152), p < 0.001; z = –6.010]. In contrast, males exhibited significantly longer QRSd [90 ms (IQR 84–96)] compared to females [80 ms (IQR 76–86); p < 0.001; z = –37.509]. The QTcB was notably prolonged in females [423 ms (IQR 409–437)] compared to males [406 ms (IQR 391–420)] ( p < 0.001; z = 27.730). Similarly, the QRST angle was significantly wider in females [35° (IQR 23–50)] than in males [28° (IQR 18–41); p < 0.001; z = 12.209]. (See Table 2 below) Table 2 Position Sex-specific ECG pattern in precordial leads: Statistically significant sex differences were observed in the J-point (JV1-JV6) and ST60 elevation (ST60V1-ST60V6) amplitude measurements across all leads. These results indicate that both J-point elevation and ST-segment elevation are significantly greater in males across all precordial leads. The largest absolute differences were observed in leads V2 and V3. (see Table 3 and Table 4 below) . Table 3 and Table 4 Position Precordial T wave pattern between Vietnamese females and males: In V1, PTWI were observed in 71.3% of females (n=2,539/3,002) and 28.7% of males (n=1,021/2,125) (see Table 5 below). Table 5 Position In V2, negative T waves were present in 2.5% of females and only 0.9% of males, with 80.4% of all V2-negative cases being female. In V3, the prevalence of PTWI further declined but remained more frequent among females (3.7% vs. 0.1% in males), representing 98.2% of all individuals with V3 PTWI. Progressing further laterally, PTWI became exceedingly rare. In V4, only 19 females (0.6%) and 1 male (0.05%) exhibited PTWI. In V5, PTWI was seen exclusively in females (n=3, 0.1%). Notably, no subject of either sex exhibited PTWI in V6. IV. DISCUSSION Ethnicity-specific core ECG parameter: In our study, we observed a mean heart rate of 82.8 bpm, notably higher than the values reported in several other ethnic cohorts. For instance, the Singaporean SAFE study by Sia et al . reported lower mean heart rates among Southeast Asian males, while Palhares et al. found a median of 65 bpm in Brazilian males aged 16 years and older, and Ahmadi et al. reported a mean of 70.6 bpm in the Tehran adult population [1 - 3] (see Table 6 below) Table 6 Position The mean PR interval in our study was 139.9 ms, which is shorter than the median values reported in Chinese (149 ms, Wu et al.), Thai (148–164 ms, Khumrin et al.), and Brazilian (150–164 ms, Palhares et al.) studies. [3 - 5] This finding aligns more closely with the SAFE study, which found shorter PR intervals in young Southeast Asian males. [1] Regarding QRSd, the mean value of 84.8 ms in our sample is comparable to the findings from Wu et al. and Palhares et al. (median 94 ms) and falls within the range reported by Khumrin et al. (76–142 ms). [2, 4, 5] It is slightly lower than the mean of 87.9 ms reported in Nigerian males (Katibi et al.) but consistent with other global populations [6]. Our QTcB interval averaged 415.5 ms, slightly higher than values reported in Mason et al. (403 ms), Palhares et al. (406 ms), and notably higher than the 394 ms found in a Swiss conscript study. [2,7,8] Additionally, frontal plane axis measurements, such as mean R axis (70.7°), T axis (39.2°), and QRST angle (35.1°), are relatively understudied in other populations but appear to follow similar patterns of variation. Palhares et al. and Ahmadi et al. documented shifts in QRS and T axes with age and sex, suggesting our findings may contribute valuable normative data for regional diagnostic criteria in Southeast Asia. [2,3] Sex - specific core ECG parameters: The higher resting heart rate in females, observed in our study (84.1 vs. 80.9 bpm), aligns with findings from the Tehran Cohort (Ahmadi et al.) and Brazilian studies (Palhares et al.), reinforcing the influence of autonomic regulation and hormonal differences. [2,3] The shorter PR interval in Vietnamese females (138.7 ms vs. 141.6 ms in males) echoes similar sex gaps reported in Thai (Khumrin et al.) and Chinese (Wu et al.) populations, with Southeast Asian groups tending toward shorter overall PR durations. [4,5] Males in our cohort had longer QRS durations (90.7 ms vs. 80.7 ms), a pattern universally observed across studies in Nigeria, Iran, and Latin America, likely reflecting greater myocardial mass and conduction path length in males. [2,3,6] Similarly, QTc intervals were significantly prolonged in females (422.8 ms vs. 405.2 ms), a well-established finding with implications for sex-specific arrhythmia risk thresholds. Notably, the QRST angle, a less commonly reported parameter, was also significantly higher in Vietnamese females, while Palhares et al. suggested wider QRS-T angle variability in males. [2] Vietnamese adults' precordial ECG pattern: Gender-related differences in J-point amplitude and ST-segment morphology have been consistently reported across numerous studies. These distinctions form the basis of what is commonly referred to as the “male” and “female” repolarization patterns on the ECG, particularly in the precordial leads. [9 - 11] The male ECG pattern—characterized by higher J-point elevations, steeper ST segments, and greater early repolarization—is largely influenced by testosterone and emerges during puberty, peaking in young men aged 17–24 (up to 91%), before declining with age to around 14% in older men. In contrast, the female pattern—defined by lower J-point and ST amplitudes with flatter repolarization—remains consistent across the lifespan, with a stable prevalence of ~80% from adolescence through old age. [10,12] These findings in our cohort were evaluated against established international norms, particularly data from White and Black American populations. [13,14] 3.1 J point and ST-Segment pattern in Precordial Leads: In our cohort, the 98th percentile ST60 in V2 reached 0.40 mV in males, exceeding the commonly cited 0.30 mV threshold for White males, and aligning more closely with values reported in Black male populations. [13,14] Among females, the ST60 amplitude peaked at 0.20 mV, consistent with the ULN for White women. In both sexes, lead V2 consistently demonstrated the highest ST elevations. Our findings parallel those of Surawicz and Parikh. In their cohort of young adults (ages 17–24), this pattern was observed in 91% of males but only 13% of females.[13] Similarly, Vietnamese males in our study showed mean J-point elevations ≥0.10 mV and ST60 values up to 0.40 mV in V2–V3, while females displayed significantly lower values—the mean ST60 in V2 was just 0.072 mV. [13,14] (see Table 7 below) Table 7 position A large study by Hiss et al. found that 91% of 6,014 healthy U.S. Air Force men (aged 16–58) exhibited 1–3 mm ST-segment elevation in at least one precordial lead, most commonly in V2. [15] The 0.40 mV (4 mm) ST60 amplitude observed in Vietnamese males at the 98th percentile in V2 is comparable in magnitude and lead distribution. 3.2 Precordial T-Wave Inversion (PTWI): In our Vietnamese cohort, PTWI was most prevalent in lead V1, particularly among females (71.3% vs. 48.1% in males). The frequency declined sharply in lateral leads: in V2, PTWI was present in 2.5% of females and 0.9% of males, and in V3, 3.7% and 0.1%, respectively. Beyond V3, PTWI was rare (≤0.6% in V4–V5) and absent in V6 in both sexes. (see Table 5). These patterns closely parallel findings from Malhotra et al., who reported that PTWI in healthy White individuals aged 16–35 was largely confined to V1–V2 and more common in females.[10] Our findings align with AHA/ACCF/HRS guidelines that consider TWI in V1–V2 normal in young adults, especially females. [16] TWI beyond V2 was rare in our cohort, supporting its benign nature when confined to early precordial leads. T-wave amplitudes followed expected sex-specific norms, with males reaching up to 1.3 mV in V2–V3, and most inverted T waves remained shallow. [16] 4. Limitations This study has several limitations. First, the sample was limited to first-year university students aged 17–29, restricting the generalizability of findings to older adults or non-academic populations. Second, although strict inclusion criteria were applied, lifestyle factors such as diet, smoking, alcohol use, stress, and sleep—known to affect autonomic tone and ECG parameters—were not systematically assessed. Third, we did not account for body composition or physical fitness levels, which may confound ECG indices like heart rate and QT interval, especially in sex comparisons. Fourth, while hormonal therapies were excluded, serum hormone levels were not measured, limiting insights into endogenous hormonal effects on repolarization. Lastly, the cross-sectional design and lack of follow-up prevent evaluation of temporal changes or the prognostic significance of ECG variants such as early repolarization and T-wave inversion. V. Conclusion This study represents the largest investigation to date of sex-specific electrocardiographic reference values in a healthy Vietnamese population aged 17–29 years. Our findings underscore clear and consistent sex-based differences across multiple ECG parameters, including HR, PR interval, QRSd, QTcB, and QRST angle, supporting the need for sex-specific interpretation in routine clinical practice. Notably, the mean QTc interval in Vietnamese females (423 ms) and the median QRS duration in males (90 ms) are higher than values commonly reported in Western cohorts, signaling the importance of regionally appropriate diagnostic thresholds. Furthermore, this study provides the first detailed characterization of anterior repolarization patterns in Southeast Asian youth. The high prevalence of physiological ST-segment elevation in V2 among Vietnamese males—reaching a 98th percentile of 0.40 mV—mirrors early repolarization patterns traditionally reported in athletic or African-descent populations, yet has not been previously documented in this ethnic group. Conversely, T-wave inversion beyond lead V2 remains exceedingly rare and highly sex-specific, with a strong female predominance. Taken together, these results emphasize the clinical relevance of incorporating population-specific ECG norms into cardiovascular risk stratification and screening protocols. By establishing robust reference values and highlighting ethnic and sex-specific variants, our study lays the foundation for more accurate and equitable ECG interpretation in Vietnamese and broader Southeast Asian populations. Declarations Clinical trial number: not applicable. Ethics approval and consent to participate This study was conducted in accordance with the ethical standards of the institutional and national research committees. All participants provided informed consent as part of the university's routine health screening program. Ethical approval was granted by the Phenikaa University Institutional Review Board. Consent for publication Yes. This manuscript does not contain any individual personal data. All data have been fully anonymized, and participants consented to the use of their information for research and publication purposes. Availability of data and materials Data is provided within supplementary information files Competing interests The authors declare that they have no competing interests. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Authors' Contributions TNN conceived and designed the study, conducted statistical analysis, and was the major contributor in drafting and revising the manuscript. LNTN , APV , SHT , NNM , and TVT were involved in data collection, clinical validation, and interpretation of ECG findings. HLTB , HTV , PTTH , DPN , TTTL , and LDP assisted in data management, quality control, and visualization. DDC provided methodological oversight, contributed to data interpretation, and reviewed the manuscript for important intellectual content. LN , NNM , DTKC , NTH , and NTTH supported data cleaning, reviewed ECG recordings, and contributed to the literature review. All authors read and approved the final manuscript. Acknowledgments The authors would like to express their sincere gratitude to the students of Phenikaa University who generously participated in this study. We are also deeply appreciative of the dedicated nursing team and medical personnel at Phenikaa University Hospital for their consistent efforts in conducting the ECG screenings with precision and care. Special thanks to the university administrative staff for facilitating data collection logistics. Lastly, heartfelt thanks to our families for their unwavering support and encouragement throughout this research. References Sia CH, Dalakoti M, Tan BYQ, Lee ECY, Shen X, Wang K, et al. A population-wide study of electrocardiographic (ECG) norms and the effect of demographic and anthropometric factors on selected ECG characteristics in young, Southeast Asian males—results from the Singapore Armed Forces ECG (SAFE) study. Ann Noninvasive Electrocardiol. 2019;24(3):e12634. 10.1111/anec.12634 . Palhares DMF, Marcolino MS, Santos TMM, Ribeiro ALP, Nascimento BR, Melo MDT, et al. Normal limits of the electrocardiogram derived from a large database of Brazilian primary care patients. BMC Cardiovasc Disord. 2017;17:152. 10.1186/s12872-017-0572-8 . Ahmadi P, Afzalian A, Jalali A, Haghjoo M, Khosravi A, Maleki M, et al. Age and gender differences of basic electrocardiographic values and abnormalities in the general adult population; Tehran Cohort Study. BMC Cardiovasc Disord. 2023;23:303. 10.1186/s12872-023-03339-z . Wu J, Kors JA, Rijnbeek PR, van Herpen G, Lu Z, Xu C. Normal limits of the electrocardiogram in Chinese subjects. Int J Cardiol. 2003;87(1):37–51. 10.1016/S0167-5273(02)00248-6 . Khumrin P, Srisuwan P, Lertprayoonmit W, et al. Effective ECG reference ranges for Northern Thai people. Heart Asia. 2015;7:32–40. 10.1136/heartasia-2014-010584 . Katibi I, Clark EN, Devine B, Lloyd SM, Macfarlane PW. Normal limits of the electrocardiogram in Nigerians. J Electrocardiol. 2013;46(4):289–95. 10.1016/j.jelectrocard.2013.04.002 . Mason JW, Ramseth DJ, Chanter DO, Moon TE, Goodman DB, Mendzelevski B. Electrocardiographic reference ranges derived from 79,743 ambulatory subjects. J Electrocardiol. 2007;40(3):228–e2348. 10.1016/j.jelectrocard.2006.09.003 . Kobza R, Roos M, Niggli B, Abächerli R, Linde C, Erne P. Prevalence of long and short QT in a young population of 41,767 predominantly male Swiss conscripts. Heart Rhythm. 2009;6(5):652–7. 10.1016/j.hrthm.2009.01.017 . Wang K, Asinger RW, Marriott HJL. ST-segment elevation in conditions other than acute myocardial infarction. N Engl J Med. 2003;349(22):2128–35. 10.1056/NEJMra022580 . Malhotra A, Dhutia H, Gati S, Yeo TJ, Dores H, Bastiaenen R, et al. Anterior T-wave inversion in young White athletes and nonathletes: prevalence and significance. J Am Coll Cardiol. 2017;69(1):1–9. 10.1016/j.jacc.2016.10.044 . Carbone V, Guarnaccia F, Carbone G, Zito GB, Oliviero U, Soreca S, et al. Gender differences in the 12-lead electrocardiogram: clinical implications and prospects. Ital J Gender-Specific Med. 2020;6(3):126–31. 10.1723/3432.34217 . Prajapati C, Koivumäki J, Pekkanen-Mattila M, Tuomainen T, Koivisto AP, Tavi P, et al. Sex differences in heart: from basics to clinics. Eur J Med Res. 2022;27:241. 10.1186/s40001-022-00880-z . Surawicz B, Parikh SR. Prevalence of male and female patterns of early ventricular repolarization in the normal ECG of males and females from childhood to old age. J Am Coll Cardiol. 2002;40(10):1870–6. 10.1016/S0735-1097(02)02492-0 . Walsh B, Macfarlane PW, Prutkin JM, Smith SW. Distinctive ECG patterns in healthy Black adults. J Electrocardiol. 2019;56:15–23. 10.1016/j.jelectrocard.2019.06.007 . Hiss RG, Lamb LE, Allen MF. Electrocardiographic findings in 67,375 asymptomatic subjects. X. Normal values. Am J Cardiol. 1960;6(1):200–31. 10.1016/0002-9149(60)90047-3 . Rautaharju PM, Surawicz B, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval. J Am Coll Cardiol. 2009;53(11):982–91. 10.1016/j.jacc.2008.12.014 . Tables Table 1 . Median and Interquartile Ranges (25th–75th Percentiles) with 95% Confidence Intervals for Selected Demographic and ECG Parameters (N = 5,127) Variable N Mean ± SD 25th Percentile Median (50th) 75th Percentile 95% CI (25th) 95% CI (Median) 95% CI (75th) Age (years) 5,127 17.8 ± 0.6 18 18 18 18–18 18–18 18–18 Heart Rate 5,127 82.8 ± 13.8 73 82 92 72-73 81-82 91-92 PR Interval (ms) 5,127 139.9 ± 17.1 128 138 150 128–130 138–140 150–150 QRS Duration (ms) 5,127 84.8 ± 9.6 78 84 92 78–78 84–84 90–92 QTcB Interval (ms) 5,127 414.5 ± 22.4 401 416 430 400–402 415–417 430–432 R Axis (°) 5,127 70.7 ± 22.8 62 75 84 61–63 75–76 83–84 T Axis (°) 5,127 39.2 ± 18.5 28 41 52 27–29 40–42 52–53 QRST Angle (°) 5,127 35.1 ±20.9 21 32 46 20–21 32–33 46–47 Table 2 presents sex-specific basic electrocardiographic characteristics for healthy Vietnamese adults. Statistically significant differences were found across all measured parameters. Heart Rate (bpm) PR interval (ms) QRS duration (ms) QTcB (ms) QRST angle (°) Female Male Female Male Female Male Female Male Female Male Median (25th–75th Percentile) 83 (75–93) 80 (70–91) 138 (128–150) 140 (130–152) 80 (76–86) 90 (84–96) 423 (409–437) 406 (391–420) 35 (23–50) 28 (18–41) Combined Median 82 (73-92) 138 (128-150) 84 (78-92) 416 (410-430) 32 (21-46) Mean ± SD 84.1 ± 13.3 80.9 ± 14.3 138.7 ± 17.0 141.6 ± 17.1 80.7 ± 7.8 90.7 ± 8.8 422.8 ± 20.6 405.2 ± 20.8 37.9 ± 21.4 31.0 ± 19.4 Combined Mean 82.8 139.9 84.8 415.5 35.1 Maximum 135 132 208 204 112 126 540 470 209 195 Minimum 52 44 84 82 60 64 352 335 0 0 Centiles 2nd 60 57 106 110 66 74 378 362 3 2 98th 115 115 178 181 100 110 464 445.5 90 78 p-value < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 z Value 8.259 -6.010 -37.509 27.730 12.209 Table 3 Sex-specific differences in J-point (JV) and ST-segment (ST60) amplitudes across precordial leads (V1–V6). Values are presented as mean ± standard deviation (SD) in millimeters (mm) and median (25th–75th Percentile) for female and male participants. Z-scores and p-values are from Wilcoxon rank-sum tests comparing sexes. Lead Parameter Vietnamese Female Vietnamese Male Z-score p-value Mean ± SD (mm) Median (25th–75th Percentile) (mm) Male Mean ± SD (mm) Median (25th–75th Percentile) (mm) V1 J 0.07 ± 0.22 0.0 (0.0-0.0) 0.31 ± 0.44 0.0 (0.0-0.5) -22.774 <0.0001 ST60 0.15 ± 0.34 0.0 (0.0-0.0) 0.52 ± 0.60 0.0 (0.5-1.0) -25.673 <0.0001 V2 J 0.29 ± 0.43 0.0 (0.0-0.5) 1.00 ± 0.72 0.5 (1.0-1.5) -37.131 <0.0001 ST60 0.72 ± 0.64 1.0 (0.0-1.0) 1.87 ± 0.98 2.0 (1.0-2.5) -41.738 <0.0001 V3 J 0.16 ± 0.35 0.0 (0.0-0.0) 0.77 ± 0.69 1.0 (0.0-1.0) -35.872 <0.0001 ST60 0.50 ± 0.57 0.5 (0.0-1.0) 1.77 ± 0.98 2.0 (1.0-2.0) -45.874 <0.0001 V4 J 0.11 ± 0.28 0.0 (0.0-0.0) 0.42 ± 0.53 0.0 (0.0-1.0) -24.502 <0.0001 ST60 0.35 ± 0.49 0.0 (0.0-0.5) 1.20 ± 0.82 1.0 (0.5-2.0) -38.655 <0.0001 V5 J 0.06 ± 0.21 0.0 (0.0-0.0) 0.19 ± 0.37 0.0 (0.0-0.0) -15.384 <0.0001 ST60 0.19 ± 0.37 0.0 (0.0-0.0) 0.71 ± 0.69 1.0 (0.0-1.0) -31.848 <0.0001 V6 J 0.03 ± 0.15 0.0 (0.0-0.0) 0.10 ± 0.26 0.0 (0.0-0.0) -10.838 <0.0001 ST60 0.09 ± 0.26 0.0 (0.0-0.0) 0.37 ± 0.50 0.0 (0.0-1.0) -23.791 <0.0001 Table 4: Sex-specific 2nd and 98th percentile values for key electrocardiographic amplitude parameters across precordial leads (V1–V6). All amplitudes are expressed in millimeters (mm). Percentile values provide reference thresholds for normal limits in the study. Lead Parameter Female 2nd Female 98th Male 2nd Male 98th V1 Total QRS (mm) 4 24 5 32 R (mm) 0.5 9 0.5 11 S (mm) 2 17 3 23 J (mm) 0 1 0 1 ST60 (mm) 0 1 0 2 T (mm) -3 2 -3 4.74 V2 Total QRS (mm) 8 33 12 46 R (mm) 2 15 2 19 S (mm) 2 22.97 4 34 J (mm) 0 1 0 2.5 ST60 (mm) 0 2 0 4 T (mm) -1 7 1 12 V3 Total QRS (mm) 7 28 10 44 R (mm) 3 18 4 26.24 S (mm) 0 17.94 1 30 J (mm) 0 1 0 2 ST60 (mm) 0 2 0 4 T (mm) -1 8 3 13 V4 Total QRS (mm) 9 28 11.5 41 R (mm) 5 23 7 31.48 S (mm) 0 12 0 19 J (mm) 0 1 0 2 ST60 (mm) 0 1.5 0 3 T (mm) 1 8 2 12 V5 Total QRS (mm) 9 25 10 36 R (mm) 6 21.97 7 30 S (mm) 0 9 0 12.48 J (mm) 0 1 0 1 ST60 (mm) 0 1 0 2 T (mm) 1 6.5 2 10 V6 Total QRS (mm) 7.5 22 8 28 R (mm) 6 19.97 6 25 S (mm) 0 6 0 8 J (mm) 0 0.5 0 1 ST60 (mm) 0 1 0 1.74 T (mm) 1 6 2 8 Table 5: PTWI = Precordial T-wave inversion; T-wave considered inverted if amplitude < 0 mV. The Pearson chi-square test was used to assess the association between sex and the presence of T-wave inversion in each lead. V6 was excluded from chi-square testing as there were no instances of T-wave inversion (TWI). Lead Sex PTWI (n) Total (n) % with ATWI Pearson χ² (df = 1) p -value V1 Female 2,539 3,002 84.6% 782.37 <0.001 Male 1,021 2,125 48.1% V2 Female 74 3,002 2.5% 18.48 <0.001 Male 18 2,125 0.9% V3 Female 110 3,002 3.7% 74.22 <0.001 Male 2 2,125 0.1% V4 Female 19 3,002 0.6% 10.99 0.001 Male 1 2,125 0.05% V5 Female 3 3,002 0.1% 2.12 0.145 Male 0 2,125 0.0% V6 Female 0 3,002 0.0% — — Male 0 2,125 0.0% Table 6. Comparison of Mean ECG Parameters Between Vietnamese Cohort and Other Ethnic Populations Parameter Vietnamese (This Study) Chinese (Wu et al. 2003) Thai (Khumrin et al. 2015) White (Mason et al. 2007) Brazilian (Palhares et al. 2017) (16–19 yo) Tehran Cohort (adults aged ≥ 35 ) SAFE study Chinese Malay Indian Heart Rate (bpm) M: 80.9 F: 84.1 ~75 M: 72.3 F: 77.4 ~75 M: 65 F: 73 M: 68.4 F: 72.4 M: 80.4 M: 79.3 M: 77.3 PR Interval (ms) M: 141.6 F: 138.7 M: 149 M: 148 F: 156 141 (10–19 yo, both sexes) M: 142 Not reported M: 146.7 M: 145.2 M: 141.2 QRS Duration (ms) M: 90.7 F: 80.7 94 M: 94 F: 86 M: 89 M: 94 M: 86.8 F: 81.3 M: 94.5 M: 92.6 M: 92.5 QTcB (ms) M: 405.2 F: 422.8 ~409 M: 427 F: 432–443 M: 403 (10–19 yo) M: 406 (16–19 yo) Not reported M: 408.3 M: 403.5 M: 401.2 Table 7. Comparison of Corrected ST-Segment Amplitudes (mV) in Leads V1–V3 Between Vietnamese Adults and Western Reference Standards. Parameter Vietnamese Male 98th %ile Vietnamese Female 98th %ile White Male ULN White Female ULN Black Male ULN Black Female ULN JV1 (mV) 0.10 0.10 0.10 0.10 0.15 0.15 ST60V1(mV) 0.20 0.10 0.30 0.20 0.35 0.25 JV2(mV) 0.25 0.10 0.25–0.33 0.15 0.35–0.40 0.15 ST60V2(mV) 0.40 0.20 0.30 0.20 0.35 0.25 JV3(mV) 0.20 0.10 ~0.25 ~0.15 ~0.30 ~0.20 ST60V3(mV) 0.40 0.20 0.30 0.20 0.35 0.25 ULN: Upper Limit of Normal; Source: Surawicz et al., 2009. Derived from racial stratification in American and European ECG studies. Additional Declarations No competing interests reported. Supplementary Files ECGDATAFINAL.dta Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7099961","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":500046221,"identity":"df4314dd-c892-47a1-8fda-77448757c73d","order_by":0,"name":"Thang Nguyen 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Van","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"An","middleName":"Pham","lastName":"Van","suffix":""},{"id":500046224,"identity":"54657129-76bd-46d9-996f-f4425cc2f45d","order_by":3,"name":"Soan Hoang Thu","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Soan","middleName":"Hoang","lastName":"Thu","suffix":""},{"id":500046225,"identity":"b6ab30d0-b577-435d-b7b1-895123f35eee","order_by":4,"name":"Nghia Nguyen Minh","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Nghia","middleName":"Nguyen","lastName":"Minh","suffix":""},{"id":500046226,"identity":"18aadc5f-8484-4921-a1b6-dc568cf291d3","order_by":5,"name":"Thang Vu Tien","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Thang","middleName":"Vu","lastName":"Tien","suffix":""},{"id":500046227,"identity":"2b7da1ca-0991-4094-ab1b-b6bf4bce815d","order_by":6,"name":"Hong Le Thi Bich","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hong","middleName":"Le Thi","lastName":"Bich","suffix":""},{"id":500046228,"identity":"a5bfa285-e6d7-44c0-9a1e-78aeaffa1213","order_by":7,"name":"Hung Tran Viet","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hung","middleName":"Tran","lastName":"Viet","suffix":""},{"id":500046229,"identity":"db786a07-6fc1-4ebc-b73c-212273c3f361","order_by":8,"name":"Huyen Pham Thi Thu","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Huyen","middleName":"Pham Thi","lastName":"Thu","suffix":""},{"id":500046230,"identity":"7f132960-92f4-4eaa-9be8-e5d63f342223","order_by":9,"name":"Nhung Do","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Nhung","middleName":"","lastName":"Do","suffix":""},{"id":500046231,"identity":"e22bd293-c733-49ff-8f50-7457e9f13311","order_by":10,"name":"Linh Tran","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Linh","middleName":"","lastName":"Tran","suffix":""},{"id":500046232,"identity":"5bff640e-d755-4256-b564-12b72428d033","order_by":11,"name":"Le Dao Phuong","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Le","middleName":"Dao","lastName":"Phuong","suffix":""},{"id":500046233,"identity":"f78bae1f-ff65-45c7-bbd8-0ca33ceac1f1","order_by":12,"name":"Cuong Duong 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Thi","lastName":"Kim","suffix":""},{"id":500046238,"identity":"620869e3-f739-4a35-928a-a9bcece56ca8","order_by":16,"name":"Hien Nguyen Thu","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hien","middleName":"Nguyen","lastName":"Thu","suffix":""},{"id":500046240,"identity":"8702d040-2c94-4d54-8e17-474b66e4f969","order_by":17,"name":"Huyen Nguyen","email":"","orcid":"","institution":"¹Phenikaa University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Huyen","middleName":"","lastName":"Nguyen","suffix":""}],"badges":[],"createdAt":"2025-07-11 09:23:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7099961/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7099961/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89386108,"identity":"bb8f544c-8446-4849-975a-6b597586c1ca","added_by":"auto","created_at":"2025-08-19 12:34:16","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":223839,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eillustrates the sex distribution of 5127 ECGs included for analysis in the study\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7099961/v1/8a5a8043182e6fc2e2143d41.jpeg"},{"id":97670582,"identity":"2644d65e-08d4-45f0-9191-9360824aa0bb","added_by":"auto","created_at":"2025-12-08 09:30:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1979484,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7099961/v1/9c04e1d3-95db-4346-a476-b273b57ca817.pdf"},{"id":89384605,"identity":"e5976d85-1888-419f-96a0-50efea90fa53","added_by":"auto","created_at":"2025-08-19 12:26:16","extension":"dta","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":1731695,"visible":true,"origin":"","legend":"","description":"","filename":"ECGDATAFINAL.dta","url":"https://assets-eu.researchsquare.com/files/rs-7099961/v1/ed3eafc0a5577854baf5b8a7.dta"}],"financialInterests":"No competing interests reported.","formattedTitle":"Electrocardiographic Profiles by Sex in a Cohort of Healthy Vietnamese University Students","fulltext":[{"header":"I. Introduction","content":"\u003cp\u003eCardiovascular disease (CVD) remains the world\u0026rsquo;s leading cause of death, underscoring the importance of early detection through accessible, cost-effective tools like the electrocardiogram (ECG). Despite its widespread use, accurate ECG interpretation demands consideration of individual physiological factors, particularly sex- and ethnicity-specific variations in cardiac electrophysiology.\u003c/p\u003e\n\u003cp\u003eDecades of research have shown that males and females exhibit distinct ECG profiles. Women typically present with faster heart rates, shorter PR and QRS durations, and longer QT intervals, while men more commonly show features like J-point elevation, sometimes associated with arrhythmic syndromes such as Brugada syndrome. Ethnic background also plays a critical role, influencing parameters like ST-segment elevation, ventricular voltage patterns, and T-wave morphology.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eYet, current ECG reference ranges are largely derived from Western populations, leaving groups such as Southeast Asians\u0026mdash;particularly Vietnamese individuals\u0026mdash;underrepresented. \u0026nbsp;This study addresses this gap by examining sex-based ECG differences in a large cohort of healthy Vietnamese adults. By establishing baseline reference values for key ECG parameters, this study aims to establish ECG reference values tailored to the Vietnamese population, supporting ethnically attuned diagnostic accuracy and risk stratification.\u003c/p\u003e"},{"header":"II. Method","content":"\u003cp\u003e\u003cstrong\u003e2.1 Study design and participant\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis cross-sectional study enrolled first-year Vietnamese university students as part of the annual pre-semester health screening program conducted by Phenikaa University, in collaboration with Phenikaa University Hospital in Hanoi, Vietnam.\u003c/p\u003e\n\u003ch4\u003e\u003cstrong\u003eInclusion Criteria\u003c/strong\u003e\u003c/h4\u003e\n\u003cp\u003eParticipants were eligible for inclusion if they met all of the following criteria:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eVietnamese ethnicity\u003c/li\u003e\n \u003cli\u003eAged 17 to 29 years, a range chosen to capture the emergence of sex-related differences in ECG parameters during adolescence and early adulthood\u003c/li\u003e\n \u003cli\u003eAsymptomatic at the time of evaluation with a previously normal physical examination\u003c/li\u003e\n \u003cli\u003eNo personal or family history of cardiovascular disease, genetic disorders, or metabolic conditions such as diabetes mellitus or insulin resistance\u003c/li\u003e\n \u003cli\u003eBody mass index (BMI) within the standard reference range (18\u0026ndash;25 kg/m\u0026sup2;)\u003c/li\u003e\n \u003cli\u003eNot currently taking cardiovascular medications or any hormonal agents known to influence cardiac electrophysiology, including oral contraceptives or exogenous testosterone\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eParticipants who fulfilled all inclusion criteria underwent a standard 12-lead resting ECG. ECGs showing normal sinus rhythm, as defined by accepted diagnostic standards, were included for further analysis. In line with current clinical and research guidelines, ECGs demonstrating sinus arrhythmia, premature atrial contractions (PACs), or premature ventricular contractions (PVCs) were also retained. These findings are well-recognized as benign and physiologically normal in healthy young individuals.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 ECG measurement and data collection:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eECGs were recorded in the supine position using standardized 12-lead placement and the MAC 5 Resting ECG system (GE Healthcare, USA; 500 Hz sampling rate). Trained nurses performed all recordings. ECGs were saved as anonymized PDFs and coded using the Minnesota system. Of 5,391 recordings, 264 were excluded for technical issues; 5,127 met quality criteria and were included in the analysis.\u003c/p\u003e\n\u003cp\u003eCore parameters\u0026mdash;heart rate, PR interval, QRS duration, QTcB, and QRST angle\u0026mdash;were automatically extracted via the GE Marquette\u0026trade; 12SL\u0026trade; algorithm. Additional features, including precordial QRS amplitude, J-point elevation, ST60, and T-wave amplitude (V1\u0026ndash;V6), were manually measured relative to the PR segment. Ambiguous J-points were estimated using standard tangential methods.\u003c/p\u003e\n\u003cp\u003eAll ECGs were reviewed independently by four trained physicians; discrepancies were adjudicated by a fifth cardiologist. Reviewers were blinded to the sex of the participants. Measurements were standardized and rounded to the nearest 0.5 mm (0.05 mV) to ensure consistency.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Statistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using STATA version 14. Normality of continuous variables was assessed using the Kolmogorov\u0026ndash;Smirnov test. Due to non-normal distributions, continuous ECG parameters were summarized as medians with interquartile ranges (25th\u0026ndash;75th percentiles); means \u0026plusmn; SD were also reported for comparison across studies. Between-group differences were evaluated using the Wilcoxon rank-sum test or independent t-test, as appropriate. Categorical variables were compared using the Pearson chi-square test. A two-sided p-value \u0026lt; 0.05 was considered statistically significant. Reference ranges were defined by the 2nd and 98th percentiles.\u003c/p\u003e"},{"header":"III. Results","content":"\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eBaseline demographic:\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eOf \u0026nbsp; 5127 final ECGs that satisfied the study\u0026rsquo;s criteria, 58,55% were female (n=3002), 41,45% were male (n=2125) (see Figure 1).\u003c/p\u003e\n\u003cp\u003eThe mean age of the population was 17.8 \u0026plusmn; 0.6 years (range: 16\u0026ndash;29 years) (see Table 1).\u0026nbsp;\u003c/p\u003e\n\u003col start=\"2\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eBasic ECG parameters\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eAge showed minimal variability, with a median and interquartile range (IQR) of 18 years. The median HR\u0026ndash;related variables, including the PR interval (138 ms), QRSd (84 ms), and QTcB (416 ms), fall within recognized physiological ranges. The QRSd and QTcB demonstrated modest dispersion, with interquartile ranges of 78\u0026ndash;92 ms and 401\u0026ndash;430 ms, respectively (see Table 1 below).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 1 position\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFrontal plane electrical axes also showed predictable variability: the median R axis was 75\u0026deg;, while the T axis was 41\u0026deg;, with wider spreads across the IQRs.. The QRST angle, which represents the spatial difference between depolarization and repolarization vectors, had a median of 32\u0026deg;.\u0026nbsp;\u003c/p\u003e\n\u003col start=\"3\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eSex-Based Differences in Core ECG Parameters\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eStatistical comparison of ECG parameters between males and females using the Wilcoxon rank-sum test. Females had a higher resting HR than males, with a median of 83 bpm (IQR 75\u0026ndash;93) versus 80 bpm (IQR 70\u0026ndash;91), respectively (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; \u003cem\u003ez\u003c/em\u003e = 8.259). PR intervals were shorter in females [138 ms (IQR 128\u0026ndash;150)] than in males [140 ms (IQR 130\u0026ndash;152), \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; \u003cem\u003ez\u003c/em\u003e = \u0026ndash;6.010]. In contrast, males exhibited significantly longer QRSd [90 ms (IQR 84\u0026ndash;96)] compared to females [80 ms (IQR 76\u0026ndash;86); \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; \u003cem\u003ez\u003c/em\u003e = \u0026ndash;37.509].\u003c/p\u003e\n\u003cp\u003eThe QTcB was notably prolonged in females [423 ms (IQR 409\u0026ndash;437)] compared to males [406 ms (IQR 391\u0026ndash;420)] (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; \u003cem\u003ez\u003c/em\u003e = 27.730). Similarly, the QRST angle was significantly wider in females [35\u0026deg; (IQR 23\u0026ndash;50)] than in males [28\u0026deg; (IQR 18\u0026ndash;41); \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001; \u003cem\u003ez\u003c/em\u003e = 12.209]. \u0026nbsp;(See Table 2 below)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 2 Position\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003col start=\"4\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eSex-specific ECG pattern in precordial leads:\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eStatistically significant sex differences were observed in the J-point (JV1-JV6) and ST60 elevation (ST60V1-ST60V6) amplitude measurements across all leads. These results indicate that both J-point elevation and ST-segment elevation are significantly greater in males across all precordial leads. The largest absolute differences were observed in leads V2 and V3. (see Table 3 and Table 4 below) .\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 3 and Table 4 Position\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003col start=\"5\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003ePrecordial T wave pattern between Vietnamese females and males: \u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eIn V1, PTWI \u0026nbsp;were observed in 71.3% of females (n=2,539/3,002) and 28.7% of males (n=1,021/2,125) (see Table 5 below).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 5 Position\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn V2, negative T waves were present in 2.5% of females and only 0.9% of males, with 80.4% of all V2-negative cases being female. In V3, the prevalence of \u0026nbsp; PTWI further declined but remained more frequent among females (3.7% vs. 0.1% in males), representing 98.2% of all individuals with V3 PTWI.\u003c/p\u003e\n\u003cp\u003eProgressing further laterally, PTWI \u0026nbsp;became exceedingly rare. In V4, only 19 females (0.6%) and 1 male (0.05%) exhibited PTWI. In V5, PTWI was seen exclusively in females (n=3, 0.1%). Notably, no subject of either sex exhibited PTWI \u0026nbsp;in V6.\u003c/p\u003e"},{"header":"IV. DISCUSSION","content":"\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eEthnicity-specific core ECG parameter:\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eIn our study, \u0026nbsp;we observed a mean heart rate of 82.8 bpm, notably higher than the values reported in several other ethnic cohorts. For instance, the Singaporean SAFE study by Sia et al . reported lower mean heart rates among Southeast Asian males, while Palhares et al. found a median of 65 bpm in Brazilian males aged 16 years and older, and Ahmadi et al. reported a mean of 70.6 bpm in the Tehran adult population [1 - 3]\u0026nbsp; (see Table 6 below)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 6 Position\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe mean PR interval in our study was 139.9 ms, which is shorter than the median values reported in Chinese (149 ms, Wu et al.), Thai (148\u0026ndash;164 ms, Khumrin et al.), and Brazilian (150\u0026ndash;164 ms, Palhares et al.) studies. [3 - 5]\u0026nbsp; This finding aligns more closely with the SAFE study, which found shorter PR intervals in young Southeast Asian males. [1]\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRegarding QRSd, the mean value of 84.8 ms in our sample is comparable to the findings from Wu et al. and Palhares et al. (median 94 ms) and falls within the range reported by Khumrin et al. (76\u0026ndash;142 ms). [2, 4, 5] It is slightly lower than the mean of 87.9 ms reported in Nigerian males (Katibi et al.) but consistent with other global populations [6].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur QTcB interval averaged 415.5 ms, slightly higher than values reported in Mason et al. (403 ms), Palhares et al. (406 ms), and notably higher than the 394 ms found in a Swiss conscript study. [2,7,8]\u003c/p\u003e\n\u003cp\u003eAdditionally, frontal plane axis measurements, such as mean R axis (70.7\u0026deg;), T axis (39.2\u0026deg;), and QRST angle (35.1\u0026deg;), are relatively understudied in other populations but appear to follow similar patterns of variation. Palhares et al. and Ahmadi et al. documented shifts in QRS and T axes with age and sex, suggesting our findings may contribute valuable normative data for regional diagnostic criteria in Southeast Asia. [2,3]\u003c/p\u003e\n\u003col start=\"2\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eSex - \u0026nbsp;specific core ECG parameters:\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eThe higher resting heart rate in females, observed in our study (84.1 vs. 80.9 bpm), aligns with findings from the Tehran Cohort (Ahmadi et al.) and Brazilian studies (Palhares et al.), reinforcing the influence of autonomic regulation and hormonal differences. [2,3] The shorter PR interval in Vietnamese females (138.7 ms vs. 141.6 ms in males) echoes similar sex gaps reported in Thai (Khumrin et al.) and Chinese (Wu et al.) populations, with Southeast Asian groups tending toward shorter overall PR durations. [4,5]\u003c/p\u003e\n\u003cp\u003eMales in our cohort had longer QRS durations (90.7 ms vs. 80.7 ms), a pattern universally observed across studies in Nigeria, Iran, and Latin America, likely reflecting greater myocardial mass and conduction path length in males. [2,3,6] Similarly, QTc intervals were significantly prolonged in females (422.8 ms vs. 405.2 ms), a well-established finding with implications for sex-specific arrhythmia risk thresholds. Notably, the QRST angle, a less commonly reported parameter, was also significantly higher in Vietnamese females, while Palhares et al. suggested wider QRS-T angle variability in males. [2]\u003c/p\u003e\n\u003col start=\"3\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eVietnamese adults\u0026apos; precordial ECG pattern:\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eGender-related differences in J-point amplitude and ST-segment morphology have been consistently reported across numerous studies. These distinctions form the basis of what is commonly referred to as the \u0026ldquo;male\u0026rdquo; and \u0026ldquo;female\u0026rdquo; repolarization patterns on the ECG, particularly in the precordial leads. [9 - 11]\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe male ECG pattern\u0026mdash;characterized by higher J-point elevations, steeper ST segments, and greater early repolarization\u0026mdash;is largely influenced by testosterone and emerges during puberty, peaking in young men aged 17\u0026ndash;24 (up to 91%), before declining with age to around 14% in older men. In contrast, the female pattern\u0026mdash;defined by lower J-point and ST amplitudes with flatter repolarization\u0026mdash;remains consistent across the lifespan, with a stable prevalence of ~80% from adolescence through old age. [10,12]\u003c/p\u003e\n\u003cp\u003eThese findings in our cohort were evaluated against established international norms, particularly data from White and Black American populations. [13,14]\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1 J point and ST-Segment pattern in Precordial Leads:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn our cohort, the 98th percentile ST60 in V2 reached 0.40 mV in males, exceeding the commonly cited 0.30 mV threshold for White males, and aligning more closely with values reported in Black male populations. [13,14] Among females, the ST60 amplitude peaked at 0.20 mV, consistent with the ULN for White women. In both sexes, lead V2 consistently demonstrated the highest ST elevations.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur findings parallel those of Surawicz and Parikh. In their cohort of young adults (ages 17\u0026ndash;24), this pattern was observed in 91% of males but only 13% of females.[13]\u0026nbsp; Similarly, Vietnamese males in our study showed mean J-point elevations \u0026ge;0.10 mV and ST60 values up to 0.40 mV in V2\u0026ndash;V3, while females displayed significantly lower values\u0026mdash;the mean ST60 in V2 was just 0.072 mV.\u0026nbsp;[13,14] (see Table 7 below)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 7 position\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA large study by Hiss et al. found that 91% of 6,014 healthy U.S. Air Force men (aged 16\u0026ndash;58) exhibited 1\u0026ndash;3 mm ST-segment elevation in at least one precordial lead, most commonly in V2. [15] The 0.40 mV (4 mm) ST60 amplitude observed in Vietnamese males at the 98th percentile in V2 is comparable in magnitude and lead distribution.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Precordial T-Wave Inversion (PTWI):\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn our Vietnamese cohort, PTWI was most prevalent in lead V1, particularly among females (71.3% vs. 48.1% in males). The frequency declined sharply in lateral leads: in V2, PTWI was present in 2.5% of females and 0.9% of males, and in V3, 3.7% and 0.1%, respectively. Beyond V3, PTWI was rare (\u0026le;0.6% in V4\u0026ndash;V5) and absent in V6 in both sexes. (see Table 5).\u003c/p\u003e\n\u003cp\u003eThese patterns closely parallel findings from Malhotra et al., who reported that PTWI in healthy White individuals aged 16\u0026ndash;35 was largely confined to V1\u0026ndash;V2 and more common in females.[10]\u003c/p\u003e\n\u003cp\u003eOur findings align with AHA/ACCF/HRS guidelines that consider TWI in V1\u0026ndash;V2 normal in young adults, especially females. [16] TWI beyond V2 was rare in our cohort, supporting its benign nature when confined to early precordial leads. T-wave amplitudes followed expected sex-specific norms, with males reaching up to 1.3 mV in V2\u0026ndash;V3, and most inverted T waves remained shallow. [16]\u003c/p\u003e\u003cp\u003e\u003cstrong\u003e4. Limitations\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study has several limitations. First, the sample was limited to first-year university students aged 17\u0026ndash;29, restricting the generalizability of findings to older adults or non-academic populations. Second, although strict inclusion criteria were applied, lifestyle factors such as diet, smoking, alcohol use, stress, and sleep\u0026mdash;known to affect autonomic tone and ECG parameters\u0026mdash;were not systematically assessed. Third, we did not account for body composition or physical fitness levels, which may confound ECG indices like heart rate and QT interval, especially in sex comparisons. Fourth, while hormonal therapies were excluded, serum hormone levels were not measured, limiting insights into endogenous hormonal effects on repolarization. Lastly, the cross-sectional design and lack of follow-up prevent evaluation of temporal changes or the prognostic significance of ECG variants such as early repolarization and T-wave inversion.\u003c/p\u003e"},{"header":"V. Conclusion","content":"\u003cp\u003eThis study represents the largest investigation to date of sex-specific electrocardiographic reference values in a healthy Vietnamese population aged 17–29 years. Our findings underscore clear and consistent sex-based differences across multiple ECG parameters, including HR, PR interval, QRSd, QTcB, and QRST angle, supporting the need for sex-specific interpretation in routine clinical practice. Notably, the mean QTc interval in Vietnamese females (423 ms) and the median QRS duration in males (90 ms) are higher than values commonly reported in Western cohorts, signaling the importance of regionally appropriate diagnostic thresholds.\u003c/p\u003e\u003cp\u003eFurthermore, this study provides the first detailed characterization of anterior repolarization patterns in Southeast Asian youth. The high prevalence of physiological ST-segment elevation in V2 among Vietnamese males—reaching a 98th percentile of 0.40 mV—mirrors early repolarization patterns traditionally reported in athletic or African-descent populations, yet has not been previously documented in this ethnic group. Conversely, T-wave inversion beyond lead V2 remains exceedingly rare and highly sex-specific, with a strong female predominance.\u003c/p\u003e\u003cp\u003eTaken together, these results emphasize the clinical relevance of incorporating population-specific ECG norms into cardiovascular risk stratification and screening protocols. By establishing robust reference values and highlighting ethnic and sex-specific variants, our study lays the foundation for more accurate and equitable ECG interpretation in Vietnamese and broader Southeast Asian populations.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eClinical trial number:\u003c/strong\u003e not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003cbr\u003e\u003c/strong\u003e This study was conducted in accordance with the ethical standards of the institutional and national research committees. All participants provided informed consent as part of the university\u0026apos;s routine health screening program. Ethical approval was granted by the Phenikaa University Institutional Review Board.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003cbr\u003e\u003c/strong\u003e Yes. This manuscript does not contain any individual personal data. All data have been fully anonymized, and participants consented to the use of their information for research and publication purposes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003cbr\u003e\u003c/strong\u003eData is provided within supplementary information files\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003cbr\u003e\u003c/strong\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003cbr\u003e\u003c/strong\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003ch3\u003e\u003cstrong\u003eAuthors\u0026apos; Contributions\u003c/strong\u003e\u003c/h3\u003e\n\u003cp\u003e\u003cstrong\u003eTNN\u003c/strong\u003e conceived and designed the study, conducted statistical analysis, and was the major contributor in drafting and revising the manuscript.\u003cbr\u003e\u003cstrong\u003eLNTN\u003c/strong\u003e, \u003cstrong\u003eAPV\u003c/strong\u003e, \u003cstrong\u003eSHT\u003c/strong\u003e, \u003cstrong\u003eNNM\u003c/strong\u003e, and\u0026nbsp;\u003cstrong\u003eTVT\u003c/strong\u003e were involved in data collection, clinical validation, and interpretation of ECG findings.\u003cbr\u003e\u003cstrong\u003eHLTB\u003c/strong\u003e, \u003cstrong\u003eHTV\u003c/strong\u003e, \u003cstrong\u003ePTTH\u003c/strong\u003e, \u003cstrong\u003eDPN\u003c/strong\u003e, \u003cstrong\u003eTTTL\u003c/strong\u003e, and\u0026nbsp;\u003cstrong\u003eLDP\u003c/strong\u003e assisted in data management, quality control, and visualization.\u003cbr\u003e\u0026nbsp;\u003cstrong\u003eDDC\u003c/strong\u003e provided methodological oversight, contributed to data interpretation, and reviewed the manuscript for important intellectual content.\u003cbr\u003e\u003cstrong\u003eLN\u003c/strong\u003e, \u003cstrong\u003eNNM\u003c/strong\u003e, \u003cstrong\u003eDTKC\u003c/strong\u003e, \u003cstrong\u003eNTH\u003c/strong\u003e, and \u003cstrong\u003eNTTH\u003c/strong\u003e supported data cleaning, reviewed ECG recordings, and contributed to the literature review.\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to express their sincere gratitude to the students of Phenikaa University who generously participated in this study. We are also deeply appreciative of the dedicated nursing team and medical personnel at Phenikaa University Hospital for their consistent efforts in conducting the ECG screenings with precision and care. Special thanks to the university administrative staff for facilitating data collection logistics. Lastly, heartfelt thanks to our families for their unwavering support and encouragement throughout this research.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSia CH, Dalakoti M, Tan BYQ, Lee ECY, Shen X, Wang K, et al. A population-wide study of electrocardiographic (ECG) norms and the effect of demographic and anthropometric factors on selected ECG characteristics in young, Southeast Asian males\u0026mdash;results from the Singapore Armed Forces ECG (SAFE) study. 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AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval. J Am Coll Cardiol. 2009;53(11):982\u0026ndash;91. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jacc.2008.12.014\u003c/span\u003e\u003cspan address=\"10.1016/j.jacc.2008.12.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cem\u003eTable 1\u003cstrong\u003e.\u0026nbsp;\u003c/strong\u003eMedian and Interquartile Ranges (25th\u0026ndash;75th Percentiles) with 95% Confidence Intervals for Selected Demographic and ECG Parameters (N = 5,127)\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"697\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean \u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e25th Percentile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian (50th)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e75th Percentile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI (25th)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI (Median)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI (75th)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;17.8 \u0026plusmn; 0.6\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e18\u0026ndash;18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e18\u0026ndash;18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e18\u0026ndash;18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHeart Rate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;82.8 \u0026plusmn; 13.8\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e72-73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e81-82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e91-92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePR Interval (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e139.9 \u0026plusmn; 17.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e128\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e128\u0026ndash;130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e138\u0026ndash;140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e150\u0026ndash;150\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQRS Duration (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e84.8 \u0026plusmn; 9.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e78\u0026ndash;78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e84\u0026ndash;84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e90\u0026ndash;92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQTcB Interval (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e414.5 \u0026plusmn; 22.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e401\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e416\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e430\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e400\u0026ndash;402\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e415\u0026ndash;417\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e430\u0026ndash;432\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eR Axis (\u0026deg;)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e70.7 \u0026plusmn; 22.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e61\u0026ndash;63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e75\u0026ndash;76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e83\u0026ndash;84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eT Axis (\u0026deg;)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e39.2 \u0026plusmn; 18.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e27\u0026ndash;29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e40\u0026ndash;42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e52\u0026ndash;53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQRST Angle (\u0026deg;)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 45px;\"\u003e\n \u003cp\u003e5,127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e35.1 \u0026plusmn;20.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e20\u0026ndash;21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e32\u0026ndash;33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 69px;\"\u003e\n \u003cp\u003e46\u0026ndash;47\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eTable 2\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e\u0026nbsp;presents sex-specific basic electrocardiographic characteristics for healthy Vietnamese adults. Statistically significant differences were found across all measured parameters.\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"743\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" rowspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHeart Rate (bpm)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePR interval (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQRS duration (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQTcB (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQRST angle (\u0026deg;)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian (25th\u0026ndash;75th Percentile)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e83 (75\u0026ndash;93)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;80 (70\u0026ndash;91)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e138\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(128\u0026ndash;150)\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\u003cbr\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e140 (130\u0026ndash;152)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e80 (76\u0026ndash;86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e90 (84\u0026ndash;96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\u003cbr\u003e\n \u003cp\u003e423 (409\u0026ndash;437)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e406 (391\u0026ndash;420)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e35 (23\u0026ndash;50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e28 (18\u0026ndash;41)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCombined Median\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e82 (73-92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e138 (128-150)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e84 (78-92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e416 (410-430)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e32 (21-46)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean \u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e84.1 \u0026plusmn; 13.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e80.9 \u0026plusmn; 14.3\u003c/p\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e138.7 \u0026plusmn; 17.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e141.6 \u0026plusmn; 17.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e80.7 \u0026plusmn; 7.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e90.7 \u0026plusmn; 8.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e422.8 \u0026plusmn; 20.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e405.2 \u0026plusmn; 20.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e37.9 \u0026plusmn; 21.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e31.0 \u0026plusmn; 19.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCombined Mean\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e82.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e139.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e84.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e415.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e35.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMaximum\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e135\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;208\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;204\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e126\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u0026nbsp;540\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e470\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e209\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e195\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMinimum\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e352\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e335\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCentiles\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e2nd\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e106\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e378\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e362\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e98th\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e178\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e181\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e464\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e445.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep-value\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e\u0026lt; 0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ez Value\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e8.259\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e-6.010\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e-37.509\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e27.730\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 124px;\"\u003e\n \u003cp\u003e12.209\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e \u003cem\u003eSex-specific differences in J-point (JV) and ST-segment (ST60) amplitudes across precordial leads (V1\u0026ndash;V6). Values are presented as mean \u0026plusmn; standard deviation (SD) in millimeters (mm) and median (25th\u0026ndash;75th Percentile) \u0026nbsp;for female and male participants. Z-scores and p-values are from Wilcoxon rank-sum tests comparing sexes.\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"697\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLead\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 261px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVietnamese Female\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 240px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVietnamese Male\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eZ-score\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;Mean \u0026plusmn; SD (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian (25th\u0026ndash;75th Percentile) (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale Mean \u0026plusmn; SD (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian (25th\u0026ndash;75th Percentile) (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.07 \u0026plusmn; 0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.31 \u0026plusmn; 0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-22.774\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.15 \u0026plusmn; 0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.52 \u0026plusmn; 0.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.0 (0.5-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-25.673\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.29 \u0026plusmn; 0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.00 \u0026plusmn; 0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.5 (1.0-1.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-37.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.72 \u0026plusmn; 0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e1.0 (0.0-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.87 \u0026plusmn; 0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e2.0 (1.0-2.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-41.738\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.16 \u0026plusmn; 0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.77 \u0026plusmn; 0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.0 (0.0-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-35.872\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.50 \u0026plusmn; 0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.5 (0.0-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.77 \u0026plusmn; 0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e2.0 (1.0-2.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-45.874\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.11 \u0026plusmn; 0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.42 \u0026plusmn; 0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.0 (0.0-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-24.502\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.35 \u0026plusmn; 0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.20 \u0026plusmn; 0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.0 (0.5-2.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-38.655\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.06 \u0026plusmn; 0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.19 \u0026plusmn; 0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-15.384\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.19 \u0026plusmn; 0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.71 \u0026plusmn; 0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e1.0 (0.0-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-31.848\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 36px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.03 \u0026plusmn; 0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.10 \u0026plusmn; 0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-10.838\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.09 \u0026plusmn; 0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 131px;\"\u003e\n \u003cp\u003e0.0 (0.0-0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.37 \u0026plusmn; 0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 120px;\"\u003e\n \u003cp\u003e0.0 (0.0-1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e-23.791\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eTable 4: \u003cem\u003eSex-specific 2nd and 98th percentile values for key electrocardiographic amplitude parameters across precordial leads (V1\u0026ndash;V6). All amplitudes are expressed in millimeters (mm). Percentile values provide reference thresholds for normal limits in the study.\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"606\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLead\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale 2nd\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale 98th\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale 2nd\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale 98th\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eTotal QRS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eR (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eJ (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eST60 (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eT (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e-3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e4.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eTotal QRS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eR (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e22.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eJ (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eST60 (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eT (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eTotal QRS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eR (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e26.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e17.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eJ (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eST60 (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eT (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eTotal QRS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e11.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eR (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e31.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eJ (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eST60 (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eT (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eTotal QRS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eR (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e21.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e12.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eJ (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eST60 (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eT (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eTotal QRS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e7.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eR (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e19.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eS (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eJ (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eST60 (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e1.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eT (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 116px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cem\u003eTable 5: PTWI = Precordial T-wave inversion; T-wave considered inverted if amplitude \u0026lt; 0 mV. The Pearson chi-square test was used to assess the association between sex and the presence of T-wave inversion in each lead. V6 was excluded from chi-square testing as there were no instances of T-wave inversion (TWI).\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"656\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLead\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePTWI \u0026nbsp;(n)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal (n)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e% with ATWI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePearson \u0026chi;\u0026sup2; (df = 1)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003ep\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e2,539\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e3,002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e84.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e782.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e1,021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e2,125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e48.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e3,002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e2.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e18.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e2,125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.9%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e3,002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e3.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e74.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e2,125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e3,002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e10.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e2,125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.05%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e3,002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e2.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e0.145\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e2,125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e3,002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 141px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 65px;\"\u003e\n \u003cp\u003e\u0026mdash;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 160px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 74px;\"\u003e\n \u003cp\u003e2,125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e0.0%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eTable 6. Comparison of Mean ECG Parameters Between Vietnamese Cohort and Other Ethnic Populations\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"696\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVietnamese (This Study)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eChinese (Wu et al. 2003)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eThai (Khumrin et al. 2015)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWhite (Mason et al. 2007)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBrazilian (Palhares et al. 2017) (16\u0026ndash;19 yo)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTehran Cohort\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(adults aged\u0026thinsp;\u0026ge;\u0026thinsp;35 )\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 216px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSAFE study\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eChinese\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMalay\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIndian\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHeart Rate (bpm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003eM: 80.9\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 84.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e~75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eM: 72.3\u003c/p\u003e\n \u003cp\u003eF: 77.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e~75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 65\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 68.4\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eF: 72.4\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 80.4\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 79.3\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 77.3\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePR Interval (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003eM: 141.6\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 138.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003eM: 149\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eM: 148\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e141 (10\u0026ndash;19 yo, both sexes)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 142\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eNot reported\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 146.7\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 145.2\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 141.2\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQRS Duration (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003eM: 90.7\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 80.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eM: 94\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003eM: 89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 94\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 86.8\u003c/p\u003e\n \u003cp\u003eF: 81.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 94.5\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 92.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 92.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eQTcB (ms)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003eM: 405.2\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 422.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e~409\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eM: 427\u0026emsp;\u003c/p\u003e\n \u003cp\u003eF: 432\u0026ndash;443\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003eM: 403 (10\u0026ndash;19 yo)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 406 (16\u0026ndash;19 yo)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eNot reported\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 408.3\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 403.5\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003eM: 401.2\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e\u0026nbsp;\u003cem\u003eTable 7. Comparison of Corrected ST-Segment Amplitudes (mV) in Leads V1\u0026ndash;V3 Between Vietnamese Adults and Western Reference Standards.\u003c/em\u003e\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"699\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVietnamese Male 98th %ile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVietnamese Female 98th %ile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWhite Male ULN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWhite Female ULN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBlack Male ULN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBlack Female ULN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJV1 (mV)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60V1(mV)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJV2(mV)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.25\u0026ndash;0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.35\u0026ndash;0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60V2(mV)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eJV3(mV)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e~0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e~0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e~0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e~0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eST60V3(mV)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 119px;\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eULN: Upper Limit of Normal; Source: Surawicz et al., 2009.\u003cbr\u003e\u0026nbsp; Derived from racial stratification in American and European ECG studies.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Electrocardiogram, sex differences, Vietnamese population, precordial leads, early repolarization, T-wave inversion, ST-segment elevation, ECG reference values","lastPublishedDoi":"10.21203/rs.3.rs-7099961/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7099961/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective:\u003cbr\u003e\n \u003c/strong\u003e\u0026nbsp;To establish sex-specific electrocardiographic (ECG) reference values among healthy young Vietnamese adults and to characterize sex-based differences in precordial lead patterns, with particular attention to early repolarization and T-wave morphology.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003cbr\u003e\n \u003c/strong\u003e\u0026nbsp;In this cross-sectional study, 5,127 first-year Vietnamese university students (58.6% female; age 17–29) underwent resting 12-lead ECG recordings as part of a routine health screening. Participants were asymptomatic and free of known cardiovascular or metabolic disease. Standard ECG parameters—including heart rate (HR), PR interval, QRS duration (QRSd), QTc (Bazett’s correction), and QRST angle—were automatically extracted and manually verified. J-point (JV1–V6), ST-segment (ST60V1–V6), and T-wave amplitudes (TV1–V6) in precordial leads were evaluated to identify sex-based patterns. Data were summarized as medians with interquartile ranges and compared using non-parametric Wilcoxon rank-sum tests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003cbr\u003e\n \u003c/strong\u003e\u0026nbsp;Significant sex differences were observed across all ECG parameters (p \u0026lt; 0.001). Females exhibited higher HR (83 vs. 80 bpm), shorter PR intervals (138 vs. 140 ms), and longer QTc intervals (423 vs. 406 ms), while males had longer QRS durations (90 vs. 80 ms) and narrower QRST angles. In the precordial leads, males demonstrated greater J-point and ST60 amplitudes, particularly in V2–V3, where the 98th percentile of ST60V2 reached 0.40 mV in males—surpassing international reference thresholds. Females more frequently exhibited anterior T-wave inversion (TWI), with 71.3% showing TWI in V1 and 2.5% in V2, compared to 48.1% and 0.9% in males, respectively. TWI beyond V2 was rare in both sexes. These patterns closely mirrored sex-specific repolarization profiles described in Western and athletic cohorts.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003cbr\u003e\n \u0026nbsp;\u003c/strong\u003eThis study provides the first comprehensive sex-stratified ECG reference data for healthy Vietnamese adults. Distinct sex-specific patterns in precordial leads—including elevated ST segments in males and higher prevalence of anterior TWI in females—underscore the need for ethnically tailored ECG interpretation criteria. These findings have clinical implications for improving diagnostic precision and avoiding overinterpretation of repolarization variants in Southeast Asian populations.\u003c/p\u003e","manuscriptTitle":"Electrocardiographic Profiles by Sex in a Cohort of Healthy Vietnamese University Students","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-19 12:26:11","doi":"10.21203/rs.3.rs-7099961/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e111cee7-c05f-454b-a0dd-9fb7a0e672a8","owner":[],"postedDate":"August 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-05T16:08:46+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-19 12:26:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7099961","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7099961","identity":"rs-7099961","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}