Intramyocardial and Intra-atrial courses in the Right Coronary Artery: Prevalence and characteristics

Intramyocardial and Intra-atrial courses in the Right Coronary Artery: Prevalence and characteristics | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Intramyocardial and Intra-atrial courses in the Right Coronary Artery: Prevalence and characteristics Yeliz Akturk, Rasime Pelin Kavak, Nimet Akin, Omer Koray Hekimoglu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4356019/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Oct, 2024 Read the published version in The International Journal of Cardiovascular Imaging → Version 1 posted 12 You are reading this latest preprint version Abstract Purpose We aimed to determine the prevalence and radiological characteristics of myocardial bridging (MB) and intra-atrial course anomaly (IARCA), which are rare course variations of the right coronary artery (RCA), in the adult patient population. Methods Radiological images of cases over the age of 18 who underwent coronary CT angiography (CTA) examination in our clinic were scanned from the archives retrospectively, and cases with MB of the RCA and IARCA detection were included in the study. The number, age and gender distribution of the cases, whether there were any other accompanying vascular anomalies, whether there was atherosclerosis in the coronary arteries (calculation of Agatston total calcium score, calculation of atherosclerotic stenosis as a percentage, if any) were evaluated. Results The prevalence of MB in the RCA was 2.06%, and the prevalence of IARCA was 0.44%. In one case, both anomalies were detected together. The average MB segment length in RCA was 21.9mm, and the average IARCA segment length was 37.9mm. There was no atherosclerotic disease in the RCA segment where anomaly was detected. Conclusion Recognition of rare course anomalies of RCA before treatment procedures such as ablation and surgery is important to prevent complications that may have potentially fatal consequences. RCA miyocardial bridging intra-atrial course Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The epicardial arteries, encompassing the right and left coronary arteries and their principal branches, traverse the cardiac surface. Occasionally, segments of these vessels may be embedded within the myocardium, leading to the phenomenon termed myocardial bridging (MB), wherein the artery appears to traverse beneath a myocardial bridge [ 1 ]. MB, a congenital anatomical variant, is predominantly associated with the left anterior descending artery (LAD) and is characterized by an intramural passage of the epicardial coronary artery through the myocardium [ 1 , 2 , 3 ]. The clinical relevance of MB is a subject of ongoing research. While certain studies classify MB as benign or asymptomatic, others have documented associated complications, including arrhythmias, ischemia, acute coronary syndromes, and even sudden death [ 1 , 2 , 4 ]. MB exhibits a reported incidence rate ranging from 5.4–85.7% in autopsy studies, with a notably higher prevalence in autopsy compared to angiography (5–12%), demonstrating considerable variability across different investigations [ 5 , 6 ]. The predilection site for MB is predominantly the proximal half of the LAD (60%), with a lower incidence observed in other coronary branches [ 6 ]. Rare occurrences have also been documented in the left circumflex artery (LCx) or the right coronary artery (RCA) main body or branches, with instances of multiple artery involvement reported [ 7 ]. MB in RCA branches is less common and exhibits greater variability in location (2.8–11.4%) [ 5 ]. The intra-atrial right coronary artery (IARCA) refers to the segment of the RCA that is intracavitary within the right atrium, lacking a myocardial interface between the blood pool and the vessel adventitia. An atrialized coronary artery denotes a segment of the RCA coursing superiorly to its typical epicardial position within the atrioventricular groove, representing a rare and atypical condition for the RCA [ 8 ]. Radiologically, IARCA is characterized as an RCA segment entirely encompassed by intra-atrial contrast throughout the cardiac cycle, in contrast to MB, where the coronary artery segment appears entirely surrounded by myocardial muscle [ 9 ]. Recognition of IARCA prior to cardiac surgery or endocavitary procedures is imperative, given its potential for vascular injury leading to catastrophic consequences [ 10 ]. Initially identified in postmortem specimens and during cardiac surgeries, the prevalence of IARCA ranges from approximately 0.1–1.8% [ 8 ]. Despite being considered a benign and incidental anomaly, the importance of IARCA lies in its identification prior to ablative procedures for arrhythmias, catheterization of the right-sided chambers, and pacemaker implantation [ 11 ]. The literature contains a limited array of studies concerning the RCA exhibiting an intramyocardial course and IARCA, a rare anatomical variant. This investigation aims to ascertain the prevalence and characteristics of RCA demonstrating incidental MB and IARCA in an adult cohort subjected to coronary computed tomography angiography (CTA), drawing upon the experience of a singular medical center. Methods Study Population Subsequent to obtaining approval from the ethics committee, this retrospective study re-assessed the radiological images of individuals aged 18 years and older who underwent CTA at our institution between February 2023 and March 2023. The inclusion criteria encompassed cases presenting with a RCA exhibiting an intramyocardial or inter-atrial trajectory. Exclusion criteria were individuals younger than 18 years and cases with suboptimal CTA examinations due to factors such as unsuitable examination phases or motion artifacts. CTA Assessment CTA imaging was conducted using either a dual-energy 128-slice (GE Revolution Frontier, Milwaukee, USA) or a 1024 (512x2) slice CT (GE Revolution Apex Pxtream, Milwaukee, USA). The procedures were ECG-gated and involved the administration of an intravenous non-ionic contrast agent at a flow rate of 5ml/sec, followed by bolus tracking. The scanning protocol was adapted based on the initial heart rate (BPM) of the patient, employing a prospective gated method for individuals with a BPM of 80 or lower, and a retrospective gated method for those with a BPM above 80. Evaluation of all CTA images was performed independently and retrospectively by two cardiothoracic radiology experts (with 10 and 25 years of experience, respectively) using multiplanar and curved planar reconstructions on a specialized workstation (AWS 4.6, GE, Milwaukee, USA). Cases exhibiting MB and inter-atrial courses in the RCA were identified. Recorded data included the patient's age and sex, as well as the characteristics of the affected RCA segment (length, location, depth), presence of atherosclerotic disease, and coronary dominance (right, left, codominant). Additional evaluations were conducted to ascertain the presence of other vascular anomalies associated with the course anomaly, the existence of atherosclerosis in other segments of the RCA and left coronary arteries (using Agatston total calcium scoring and percentage calculation of atherosclerotic narrowing, if present). The presence of pulmonary hypertension (PHT), left ventricular hypertrophy, and chronic obstructive pulmonary disease (COPD) were also documented in the patient cohort. Among the 1600 patients included in our study, we obtained a random group of 110 patients who did not have any abnormalities in the course of RCA and compared them with our special groups to see if there was a difference in our variables. Statistical Analysis While evaluating the findings obtained in the study, SPSS 26 (Statistical Package for the Social Sciences) program was used for statistical analysis. While evaluating the study data, quantitative variables were shown with mean, standard deviation, median, min and max values, and qualitative variables were shown with descriptive statistical methods such as frequency and percentage. ShapiroWilks test and Box Plot graphics were used to evaluate the suitability of the data for normal distribution. Mann Whitney-U test was used to evaluate variables that do not show normal distribution according to two groups; Kruskal Wallis test was used for comparisons of three groups or more. Relationships between variables were evaluated with Spearman's correlation analysis. Fisher Freeman Halton test was used to compare qualitative data. Significance was accepted at p < 0.05 level. Results A total of 1600 coronary CTAs were assessed, with participant ages spanning from 18 to 86 years. No discrepancies were noted between radiologists in the diagnosis of MB in the RCA and IARCA. The prevalence of MB in the RCA was identified in 33 cases (2.06%), while IARCA was detected in 7 cases (0.44%), with one case exhibiting both anomalies. The age range for cases with MB in the RCA was 29 to 84 years (mean 56.5), and for those with IARCA, it was 48 to 68 years (mean 59.7). All cases with identified MB in the RCA and IARCA demonstrated right coronary artery dominance, except for one case exhibiting left coronary dominance with MB in the RCA. The segment length displaying MB in the RCA varied from 6 to 70 mm (mean 21.9 mm), while the IARCA segment length ranged from 15 to 55 mm (mean 37.9 mm). No cases exhibited atherosclerotic involvement in the RCA segment with MB and/or inter-atrial course. Among the cases with MB in the RCA, 16 (48.5%) showed no atherosclerotic disease in other RCA segments, while 17 cases (51.5%) had atherosclerotic plaque. Additionally, 8 patients (24.2%) had varying degrees of calcified plaque in other RCA segments. In the cases with detected IARCA, only one case (14.3%) demonstrated atherosclerotic involvement in the remaining segment of the RCA. In assessing other coronary arteries, no atherosclerotic involvement was identified in 5 cases (15.2%) with MB in the RCA and in 3 cases (42.8%) IARCA, while the remaining cases exhibited atherosclerotic plaques leading to varying degrees of stenosis. The bridged segment's in the RCA depth varied between 1 and 4.7 mm (mean 1.7 mm), with 26 patients (78.8%) having a bridged segment depth of less than 2 mm. The depth of the IARCA segment ranged from 3.3 to 8.3 mm (mean 5.1 mm). Regarding the location of MB in the RCA, 10 segments (30.3%) were proximal, 20 (60.6%) were middle, and 3 (9.1%) were distal. MB presented an intramyocardial course in the right atrium wall in 22 cases (66.7%) and in the right ventricle wall in 11 cases (33.3%). The IARCA segment was located in the middle section in 3 patients (42.9%) and in the distal section in 4 patients (57.1%), with no cases of IARCA detected in the proximal segment. In cases with MB in the RCA, 13 (39.4%) exhibited no accompanying anomalies or variations. However, 8 cases had superficial MB in the LAD (24.2%), and 12 cases had deep MB in the LAD. One case simultaneously presented with MB in the RCA, an RCA origin anomaly (malignant course), deep MB in the LAD, and IARCA. Another case displayed MB in the RCA, dual RCA variation, an origin anomaly in the LCx (originating from the right coronary sinus), and deep MB in the LAD. Among the cases with an identified IARCA, the anomaly was isolated in only one case. In contrast, 2 cases (28.6%) exhibited superficial MB in the LAD, and 3 cases (42.8%) demonstrated deep MB in the LAD. Additionally, dual RCA variation was observed in 3 cases (42.8%) alongside IARCA. The demographic characteristics and findings of the cases with MB in the RCA are presented in Table 1, whereas those of the cases with IARCA are detailed in Table 2. Table 1. Demographic characteristics of cases showing myocardial bridging in the right coronary artery Prevalence rate, n (%) 33 (%2.06) Sex ratio (male/female), n ( %) 20 (%60.6) / 13 (%39.4) Age (year), mean (range) 29-84 (56.5) Segment of RCA involved, n (%) Proximal Mid Distal 10 (%30.3) 20 (%60.6) 3 (%9.1) Location, n (%) Right atrium Right ventricle 22 (66.7) 11 (33.3) Length of MB in the RCA (mm), mean (range) 21.9 (6-70) Depth of MB in the RCA (mm), mean (range) Superficial MB, n (%) Deep MB, n (%) 1.7 (1-4.7) 26 (78.8) 7 (21.2) Atherosclerotic disease in the MB segment of the RCA, n (%) 0 (0) Atherosclerotic evaluation in other segments of the RCA, n (%) CAD-RADS 1 CAD-RADS 2 CAD-RADS 3 CAD-RADS 4a CAD-RADS 4b CAD-RADS 5 10 (30.3) 5 (15.2) 2 (6.1) 0 (0) 0 (0) 0 (0) Atherosclerosis in other arteries, n (%) CAD-RADS 1 CAD-RADS 2 CAD-RADS 3 CAD-RADS 4a CAD-RADS 4b CAD-RADS 5 8 (24.2) 9 (27.3) 8 (24.2) 2 (6.1) 1 (3) 0 (0) Presence of calcific plaque in RCA (Agatston score), n (%) 1-100 101-300 301-999 >1000 7 (21.2) 1 (3.0) 0 (0) 0 (0) Presence of calcific plaque in other coronary arteries (Agatston score), n (%) 1-100 101-300 301-999 >1000 4 (12.1) 3 (9.1) 3 (9.1) 1 (3.0) Dominance (Right/Left), n 32/1 Other accompanying variations-anomalies * Superficial MB in LAD Deep MB in LAD Origin anomaly in RCA Origin anomaly in LCx IARCA Dual RCA 8 (24.3) 12 (36.4) 1 (3) 1 (3) 1 (3) 1 (3) Concomitant diseases, n (%) Pulmonary hypertension Left ventricular hypertrophy COPD 1 (3) 4 (12.1) 1 (3) RCA, right coronary artery; MB, myocardial bridging; LAD, left anterior descending artery; LCx, left circumflex artery; IARCA, intra-atrial right coronary artery; COPD, and chronic obstructive pulmonary disease; *, in some cases, there is more than one variation-anomaly. Table 2. Demographic characteristics of intra-atrial right coronary artery cases Prevalence rate, n (%) 7 (%0.44) Sex ratio (male/female), n ( %) 4 (%57.1)/3 (%42.9) Age (year), mean (range) 48-68 (59.7) Segment of RCA involved, n (%) Proximal Mid Distal 0 (0) 3 (42.9) 4 (57.1) Length of IARCA segment (mm), mean (range) 37.9 (15-55) Depth of IARCA segment (mm), mean (range) 5.1 (3.3-8.3) Atherosclerotic disease in the IARCA segment, n (%) 0 (0) Atherosclerotic evaluation in other segments of the RCA, n (%) CAD-RADS 1 CAD-RADS 2 CAD-RADS 3 CAD-RADS 4a-b CAD-RADS 5 0 (0) 1 (14.3) 0 (0) 0 (0) 0 (0) Atherosclerosis in other arteries, n (%) CAD-RADS 1 CAD-RADS 2 CAD-RADS 3 CAD-RADS 4a CAD-RADS 4b CAD-RADS 5 1(14.3) 0 (0) 2 (28.6) 1 (14.3) 0 (0) 0 (0) Presence of calcific plaque in RCA (Agatston score), n (%) 1-100 101-300 301-999 >1000 0 (0) 0 (0) 0 (0) 0 (0) Presence of calcific plaque in other coronary arteries (Agatston score), n (%) 1-100 101-300 301-999 >1000 1 (14.3) 0 (0) 0 (0) 0 (0) Dominance (Right/Left), n 7/0 Other accompanying variations-anomalies * Superficial MB in LAD Deep MB in LAD MB in the RCA Origin anomaly in RCA Dual RCA 2 (28.6) 3 (42.8) 1 (3) 1 (3) 3 (42.8) Concomitant diseases, n (%) Pulmonary hypertension Left ventricular hypertrophy COPD 0 (0) 0 (0) 0 (0) RCA, right coronary artery; IARCA, intra-atrial right coronary artery; MB, myocardial bridging; LAD, left anterior descending artery; COPD, and chronic obstructive pulmonary disease; *, in some cases, there is more than one variation-anomaly. According to gender; No statistically significant relationship was found between the depth, localization, coronary dominance, atherosclerotic disease in the RCA and other coronary arteries, and the occurrence of other coronary anomalies of IARCA and MB in the RCA (p>0.05). When compared with 110 randomly selected cases without course anomalies in the RCA, no statistically significant difference was observed between the groups according to coronary dominance, the presence of atherosclerotic stenosis in the RCA and other coronary arteries, and the presence of other coronary anomalies (p>0,05) (table 3). Table 3. Comparative evaluations of randomly selected control group and IARCA\MB in the RCA groups IARCA (n=7) MB in the RCA (n=33) Control (n=110) p Gender Male 4 (57.1) 20 (60.6) 75 (68.2) a 0.655 Female 3 (42.9) 13 (39.4) 35 (31.8) Age Mean±Ss 59.71±7.27 56.52±12.48 54.38±10.09 b 0.061 Median (Min-Max) 58 (48-68) 58 (29-84) 51.5 (22-80) Dominance Right dominance 7 (100) 32 (97) 98 (89.1) a 0.764 Left dominance 0 (0) 1 (3) 8 (7.3) Codominance 0 (0) 0 (0) 4 (3.6) Atherosclerotic disease in the RCA None 6 (85.7) 16 (48.5) 59 (53.6) a 0.192 Present 1 (14.3) 17 (51.5) 51 (46.4) Atherosclerotic disease in other coronary arteries None 3 (42.9) 5 (15.2) 21 (19.1) a 0.241 Present 4 (57.1) 28 (84.8) 89 (80.9) Other anomalies None 0 (0) 12 (37.5) 50 (45.5) a 0.073 Present 6 (100) 20 (62.5) 60 (54.5) IARCA, intra-atrial right coronary artery; MB, myocardial bridging; RCA, right coronary artery. a FisherFreemanHalton Test b Kruskal Wallis Test &Dunn- Bonferroni Test Example cases are shown in figures 1, 2, 3 and 4. Discussion MB constitutes a band of myocardial fibers enveloping a subepicardial segment of the coronary artery [ 8 ]. The inaugural anatomical delineation of myocardial bridges was provided by Reyman in 1737, followed by Black in 1805, with subsequent autopsy examination by Geiringer in 1951 and radiological identification by Portsmann and Iwig in 1960 [ 2 ]. The angiographic manifestation of MB is contingent upon a multitude of factors, including the myocardial bridge's thickness and length, the presence of loose connective or adipose tissue surrounding the bridged segment, myocardial contractility status, the tissue composition between the coronary artery and the myocardium, and the observer's proficiency. Consequently, numerous bridging instances, encompassing the involvement of the LCx and RCA, may remain undetected [ 6 ]. The reported prevalence of MB exhibits considerable variation depending on the employed diagnostic modality. Traditional imaging techniques, such as conventional angiography, demonstrate lower detection rates relative to advanced imaging modalities like CTA, which afford comprehensive anatomical visualization. The incidence of MB identified through CTA ranges from 3.5–100% [ 12 ]. Myocardial bridges predominantly occur in the middle segment of the LAD, yet they may also manifest in any epicardial coronary artery, such as the diagonal branches, the posterior descending branch of the RCA, or the marginal branches of the LCx [ 2 ]. The presence of myocardial bridges in the right coronary system is comparatively rare. Corban et al. reported the prevalence of MK in the LAD to be between 67% and 98%, while Möhlenkamp et al. documented incidences of 18% and 40% for diagonal and marginal branches, respectively [ 13 , 14 ]. In the literature, reports concerning MB in the RCA and its branches are primarily documented as case reports. Nguyen et al. described a rare instance of MB in two posterolateral branches of the RCA. Tiryakioğlu et al. illustrated significant bridging in the middle segment of the posterior interventricular branch of the RCA [ 15 ]. Kulkarni et al. reported a case of isolated MB in the RCA [ 16 ]. Riezzo et al. presented a case of superficial bridging approximately 1 cm from the starting point in the descending branch of the RCA [ 6 ]. Studies encompassing case series are limited in number. While the reported prevalence of MB segments in the RCA is 2.9%, the rate in the branches of the RCA ranges between 3.7% and 5.9% [ 12 ]. In our study, we determined the prevalence of MB in the RCA to be 2.06%. However, this finding is inconsistent with the high incidence of 41.4% of MB in the RCA and its branches detected by Polacek in autopsies [ 5 ]. The existence of multiple myocardial bridges spanning various areas within both the left and right coronary arteries has been infrequently documented [ 17 ]. Richter et al. have detailed three instances in which MB was concurrently present in the RCA and the LAD [ 18 ]. In our study, isolated MB in the RCA was observed in 39.4% of cases. In addition to this, in the remaining 60.6% of the cases, we encounted superficial and/or deep MB in the LAD. Moreover, among patients with MB in the RCA, anomalies such as dual RCA, IARCA, and RCA origin anomalies were identified. The relationship between coronary dominance and the prevalence of MB in the RCA has not been explored in the literature's case series; however, our research found right coronary dominance in all but one patient. Our findings also indicated a higher incidence of MB in the RCA among male participants. MB is delineated as either superficial or deep, contingent upon its depth within the myocardium, and it is possible for a vessel to harbor several bridged segments [ 2 , 19 ]. Gould et al. have categorized myocardial bridges as superficial if the depth ranges from 1 to 2 mm, and as deep if the bridge extends beyond 2 mm within the myocardium [ 20 ]. Superficial MB, reported at 75% in the literature, predominates over deep bridges, which account for 25% of reports [ 2 ]. In our analysis, the mean MB depth in the RCA was established at 1.7 mm, with superficial MB constituting 78.8% of instances. The literature posits the average MB length at 20.2 mm and the depth at 3.1 mm. Studies utilizing angiography and autopsy reveal only marginal disparities in average MB length and thickness. The mean length is documented as 21.0 mm in investigations employing computed CTA and conventional angiography, and 19.3 mm in those utilizing autopsy/cadaver dissection. The average MB thickness or depth stands at 3 mm for both CTA and conventional angiography, and at 3.2 mm for autopsy/cadaver dissection, indicating minimal variance between examination methods. Employing imaging techniques such as CTA for MB dimension assessment yields findings congruent with autopsy outcomes. A correlation between artery compression and its depth has been established [ 12 ]. Our research found the MB segment length in the RCA to average 21.9 mm, with a prevalent location in the middle segment at 60.6%. Furthermore, our study contributes to the literature by detailing the localization of MB segments; 66.7% demonstrated an intramyocardial course within the right atrium, while the rest were within the right ventricle. The impact of MB on coronary physiology has sparked considerable debate. Although MB is predominantly perceived as benign, it has been frequently linked to myocardial ischemia, infarction, ventricular arrhythmias, and sudden death, especially in the context of hypertrophic cardiomyopathy and coronary atherosclerosis [ 6 ]. The involvement of myocardial bridges in atherosclerosis represents an additional area of contention, as highlighted by Soran et al. [ 1 ]. Loukas et al. have posited the potential for "protective effects" of myocardial bridges [ 21 ]. Conversely, Ishii et al., Lee and Chen, and Zeina et al. have noted that while the proximal segment to the bridged area exhibits atherosclerotic changes, the segment under the bridge appears to be shielded from atherosclerosis [ 4 , 22 , 23 ]. Schar, however, contests the notion of the bridged segment being safeguarded against atherosclerotic alterations [ 24 ]. In our observations, none of the segments with bridging presented atherosclerotic involvement, yet about half (51.5%) demonstrated atherosclerotic presence in other segments of the RCA not affected by bridging. In alignment with this, no calcified atherosclerotic plaques were identified within the bridged segment of the RCA, yet 24.2% of the instances revealed calcified plaque in varying quantities in other segments of the RCA. In the majority of instances involving MB in the RCA, clinical or radiographic indications of PHT, left ventricular hypertrophy, cardiomyopathy, and COPD have been documented [ 18 ]. Contrarily, our investigation identified PHT and COPD in only one distinct case each, with left ventricular hypertrophy observed at a comparatively low prevalence of 12.1%. These findings deviate from established literature. Nonetheless, to facilitate statistical analyses, further research with more extensive cohorts is warranted. The intra-atrial or intracavitary trajectory of the RCA is characterized by the RCA's passage through the right atrial cavity [ 10 ]. Radiographically, this manifests as an RCA segment that is consistently enveloped by intracavitary contrast throughout all phases of the cardiac cycle. Although the literature includes case reports detailing IARCA instances, research series quantifying its prevalence remain scarce. Initially detected solely in post-mortem specimens and during heart surgeries, its observed frequency ranges from 0.1–1.8% [ 10 , 11 , 25 ]. IARCA's prevalence, as reported in autopsy or surgical cohorts is notably minimal [ 11 ]. MacAlpine et al. quantified a 0.1% prevalence in a thousand autopsy evaluations, and Ochsner et al. indicated a surgical prevalence of 0.09% [ 26 , 27 ]. Krishnan et al. uncovered IARCA in six out of 331 autopsy dissections, noting a 1.8% occurrence rate [ 8 ], without finding any RCA origin anomalies. Opolski et al. elucidated the efficacy of CTA in recognizing IARCA within an extensive cohort of 9284 subjects, marking a 0.15% prevalence rate [ 28 ]. Hossain et al., with a 464 patient cohort, reported a 0.4% prevalence, while Ganga et al. found a 0.29% prevalence in a 7114 CTA case series [ 9 , 11 ]. Buckley et al., across a 7847 CTA case series, identified IARCA in 17 individuals, documenting a 0.22% prevalence [ 29 ]. Given the escalating application of sophisticated cardiac imaging like CTA, an increase in the actual prevalence is anticipated. Our study also revealed an IARCA prevalence of 0.44%. Consistent with the broader scholarly discourse, where sex disparities are generally not emphasized, Hossain et al. identified a predilection for IARCA occurrences in males [ 9 ]. Although a higher prevalence among males is noted in our cohort, with males constituting 4 of the 7 cases, the sample size is limited. Frey et al. documented the case featuring a concurrent dual RCA and IARCA, a rarity in medical literature [ 25 ]. Despite a small sample size in our investigation, we observed a relatively elevated incidence of dual RCA and IARCA coexistence at 42.8%. This suggests that the simultaneous presence of these rare anatomical variations may not be as infrequent as previously assumed. Regarding the predominantly affected segment, while most literature cites the distal RCA as the frequent site, Ganga et al. highlighted the mid RCA. Our findings similarly emphasize the distal segment in 4 patients but also identified the mid-segment in 3 patients, without any instances affecting the proximal segment, underscoring the need for further investigation despite the absence of statistical analysis due to the small sample size. Ganga et al. delineated the average depth and length of IARCA as 2.57 mm and 14.85 mm, respectively. Contrastingly, our findings revealed an average depth of 5.1 mm and length of 37.9 mm, suggesting a significant deviation towards more pronounced anatomical manifestations. Literature scantily suggests a higher observation of right coronary dominance in IARCA cases [ 11 ]. Consistently, our study confirmed right coronary dominance across all instances, aligning with the extant observations on coronary dominance dynamics in IARCA presentations. Kolodziej et al. delineated mild atherosclerosis affecting the intra-atrial segment in a subset of three individuals diagnosed with IARCA [ 30 ]. This contrasts with the broader literature, where no atherosclerotic conditions in IARCA segments are typically reported. Studies by Opolski et al., Krishnan et al., and Ganga et al. likewise indicated an absence of noteworthy atherosclerosis in the IARCA segments [ 8 , 11 , 28 ]. Our findings are similar to the literature in this respect. A singular case in our cohort showed mild coronary artery disease in segments of the RCA apart from the IARCA, with no instances of calcified atherosclerotic plaques within the RCA. In our review of English-language literature, no investigations were found addressing comorbidities associated with IARCA. Our analysis extended to the exploration of concurrent conditions such as PHT, left ventricular hypertrophy, and COPD, none of which were detected across our patient cohort. While IARCA manifestations are predominantly asymptomatic and considered benign, unrecognized presence prior to conducting invasive cardiac interventions can precipitate adverse outcomes. Challenges in pinpointing vessel localization arise during cardiovascular surgical revascularization and bypass graft operations. Furthermore, right heart catheterization procedures bear a risk of inflicting potential harm to the vessel. In electrophysiological interventions such as catheter ablation or lead device placements within the right atrium wall or right ventricular apex, there exists a direct risk to intracavitary coronary arteries, potentially culminating in inadvertent vessel damage [ 25 ]. The proximity between the electrode and artery during ablation, where thermal damage to tissues approximately 3–5 mm in proximity is a known risk, underscores a heightened injury risk post-ablation when IARCA is present [ 31 ]. Even though the RCA in scenarios of left-dominant circulation might influence a lesser extent of the myocardium, it remains susceptible to damage during the aforementioned procedures. Ganga et al. reported a predominance of right-sided dominance in 81% of their patient cohort [ 11 ]. While the literature largely omits discussions on coronary dominance, our analysis similarly observed right coronary dominance across all cases. Conclusions In summation, MB in the RCA and IARCA within are chiefly incidental and nonpathogenic anatomical variants detected in the adult demographic. The detection of such features is paramount owing to the conceivable correlations with additional anatomical aberrations, variations, and clinical pathologies. Moreover, the antecedent identification of IARCA is essential prior to the initiation of electrophysiological interventions, right heart catheterization procedures, and selected surgical operations, thereby accentuating the necessity for scrupulous surveillance. In the realm of diagnostic imaging, CTA emerges as a robust and proficient imaging technique for the articulation of these anomalies, mandating comprehensive radiological evaluations to attenuate the risk of vascular complications. Limitations Our study was a single-center study and our number of patients was limited to 1600. Therefore, there is a limitation in representing the general population. Since the number of cases with MB in the RCA and IARCA was low, statistical analysis could not be performed for some parameters. Additionally, since CTA was performed on patients with low or moderate risk of coronary heart disease, our study is inadequately representative of the rest of the population. Asymptomatic cases were not included in the study group because there was no indication for coronary CTA. All cases were from our own country population and we could not compare the incidence of defined variations in different races. There is a need for larger series of studies on this subject. Declarations Conflict of Interest: The authors declare that they have no conflict of interest. Consent to participate: All participants provided written informed consent and could at all times choose to withdraw consent Author Contribution Author contributionsConceptualization, Y.A. and O.K.H.; method¬ology, Y.A. and R.P.K.; formal analysis and data curation, Y.A.; writing—original draft preparation, R.P.K and O.K.H.; writing—review and editing, Y.A. and N.A; visualization, Y.A., R.P.K., N.A. and O.K.H.; supervision and project administration, V.H. and D.B. All authors have read and agreed to the published version of the manuscript. 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Int J Cardiol 14;115(3):99–101. https://doi.org/10.1016/j.ijcard.2006.07.060 Kumar B, Wardhan H, Nath RK, Sharma A (2012) A rare case of myocardial bridge involving left main, left circumflex, and left anterior descending coronary arteries. J Am Coll Cardiol 59(10):965 Krishnan B, Cross C, Dykoski R, Benditt DG, Mbai M, McFalls E, Li JM, Bertog S, Tholakanahalli VN (2017) Intra-Atrial Right Coronary Artery and its Ablation Implications. JACC Clin Electrophysiol 3(9):1037–1045. https://doi.org/10.1016/j.jacep.2017.02.025 Hossain R, Chelala L, Amin SB, Bergquist PJ, Vairavamurthy J, Jeudy J, White CS (2019) Intracavitary Coronary Artery: An Unusual Coronary Anomaly. J Thorac Imaging 34:121–124. https://doi.org/10.1097/RTI.0000000000000418 Barbiero G, Maiolino G, Argiolas A, Testolin L, De Conti G (2022) Intra-atrial course of right coronary artery: A case report. World J Cardiol 26(9):514–521. https://doi.org/10.4330/wjc.v14.i9.514 Ganga KP, Ojha V, Goyal A, Deepti S, Kumar S (2021) Intra-atrial right coronary artery on dual-source CT: prevalence and characteristics. Diagn Interv Radiol 27:595–598. https://doi.org/10.5152/dir.2021.20340 Roberts W, Charles SM, Ang C, Holda MK, Walocha J, Lachman N, Tubbs RS, Loukas M (2021) Myocardial bridges: A meta-analysis. Clin Anat 34(5):685–709. https://doi.org/10.1002/ca.23697 Corban MT, Hung OY, Eshtehardi P, Rasoul-Arzrumly E, McDaniel M, Mekonnen G, Timmins LH, Lutz J, Guyton RA, Samady H (2014) Myocardial bridging: contemporary understanding of pathophysiology with implications for diagnostic and therapeutic strategies. J Am Coll Cardiol 63(22):2346–2355. https://doi.org/10.1016/j. jacc.2014.01.049 Möhlenkamp S, Hort W, Ge J, Erbel R (2002) Update on myocardial bridging. Circulation 106(20):2616–2622. https://doi.org/10.1161/01.cir.0000038420.14867.7a Nguyen TH, Burnside PR, Dieter RS, Nanjundappa A (2007) Right coronary artery distribution of myocardial bridging: an unusual case presenting with ST-elevation myocardial infarction. Tex Heart Inst J 34(4):489–491 Kulkarni M, Sodani A, Rosita, Puranik C, Sullere S, Saha BJ (2004) Right myocardial bridge on CT coronary angiography. Assoc Physicians India 52:661–662 Mazzu A, Di Tano G, Cogode R, Lo Presti G (1995) Myocardial bridging involving more than one site of the left anterior descending coronary artery: an uncommon cause of acute ischemia syndrome. Cathet Cardiovasc Diagn 34:329–332 Rychter K, Salanitri J, Edelman RR (2006) Multifocal coronary artery myocardial bridging involving the right coronary and left anterior descending arteries detected by ECG-gated 64 slice multidetector CT coronary angiography. Int J Cardiovasc Imaging 22(5):713–717. https://doi.org/10.1007/s10554-006-9086-7 Rogers IS, Tremmel JA, Schnittger I (2017) Myocardial bridges: Overview of diagnosis and management. Congenit Heart Dis 12(5):619–623. https://doi.org/10.1111/chd.12499 Gould KL, Johnson NP (2015) Myocardial bridges: lessons in clinical coronary pathophysiology. JACC Cardiovasc Imaging 8(6):705–709. https://doi.org/10.1016/j.jcmg.2015.02.013 Loukas M, Curry B, Bowers M, Louis RG Jr, Bartczak A, Kiedrowski M, Kamionek M, Fudalej M, Wagner T (2006) The relationship of myocardial bridges to coronary artery dominance in the adult human heart. J Anat 209(1):43–50. https://doi.org/10.1111/j.1469- 7580.2006.00590.x Ishii T, Asuwa N, Masuda S, Ishikawa Y (1998) The effects of a myocardial bridge on coronary atherosclerosis and ischaemia. J Pathol 185(1):4–9. https://doi.org/10.1002/(SICI)1096-9896(199805)185:13.0.CO;2-3 Lee MS, Chen CH (2015) Myocardial bridging: an up-to-date review. J Invasive Cardiol 27(11):521–528 Schar B (2000) Myocardial bridging: Symptoms of coronary disease that sometimes is not (German). Schweiz Rundsch Med Prax 67:206–209 Frey SM, Brantner P, Gehweiler J, Madaffari A, Zellweger MJ, Haaf P (2022) 3D-printed visualization of a double right coronary artery with intra-atrial course. Int J Cardiovasc Imaging 38(3):709–710. https://doi.org/10.1007/s10554-021-02451-5 McAlpine W (1975) Heart and coronary arteries. Anatomical atlas for clinical diagnosis, radiological investigation and surgical treatment. New York: Springer, 1975;186–187 Ochsner JL, Mills NL (1984) Surgical management of diseased intracavitary coronary arteries. Ann Thorac Surg 38:356–362 Opolski MP, Pregowski J, Kruk M, Staruch AD, Witkowski A, Demkow M, Hryniewiecki T, Michalek P, Ruzyllo W, Kepka C (2014) The prevalence and characteristics of intra-atrial right coronary artery anomaly in 9,284 patients referred for coronary computed tomography angiography. Eur J Radiol 83:1129–1134 Buckley CM, Rosamond T, Hegde SR, Wetzel L (2017) The intracavitary coronary artery: a rare anomaly with implications for invasive cardiac procedures - demonstration by coronary computed tomography angiography. JACC 69:11:1437 Kolodziej AW, Lobo FV, Walley VM (1994) Intra-atrial course of the right coronary artery and its branches. Can J Cardiol 10:263–267 Yan S, Gu K, Wu X, Wang W (2020) Computer simulation study on the effect of electrode-tissue contact force on thermal lesion size in cardiac radiofrequency ablation. Int J Hyperth 37:37–48 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 03 Oct, 2024 Read the published version in The International Journal of Cardiovascular Imaging → Version 1 posted Editorial decision: Revision requested 16 Sep, 2024 Reviews received at journal 09 Sep, 2024 Reviews received at journal 06 Sep, 2024 Reviewers agreed at journal 21 Aug, 2024 Reviewers agreed at journal 21 Aug, 2024 Reviews received at journal 10 May, 2024 Reviewers agreed at journal 08 May, 2024 Reviewers agreed at journal 07 May, 2024 Reviewers invited by journal 07 May, 2024 Submission checks completed at journal 05 May, 2024 Editor assigned by journal 05 May, 2024 First submitted to journal 01 May, 2024 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. 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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-4356019","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":300087812,"identity":"5be40153-afe8-4ade-bf6e-f4cb10f11429","order_by":0,"name":"Yeliz Akturk","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7klEQVRIiWNgGAWjYFAC5oYDDAwJQAYb4wMGhgPEaGEEa5EAamE2IFoLA1QLmwRRWgyONzYe/FGTVmdw+1haNU/NHTl+BuaHj27g03LmYMMBiWM5Egbn0o7d5jn2zFiygc3YOAeflhuJDQcM2CokDM6wt93mYTucuOEAD5s0Xi33HzYcSPgH0VLM848YLTeAIXawDeiwM2zHmHnbiNAieSax4WBjX5rkzDNsyZJz+w4bSzYT8Avf8cOHP/74lszPd4bN8MObb4fl+NmbHz7Gp0XhABKHiQdEMuNRDgLyDUgcxh8EVI+CUTAKRsHIBAC95VXiKP6e3gAAAABJRU5ErkJggg==","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Yeliz","middleName":"","lastName":"Akturk","suffix":""},{"id":300087814,"identity":"ed2b9420-133c-4302-96f1-896483592847","order_by":1,"name":"Rasime Pelin Kavak","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Rasime","middleName":"Pelin","lastName":"Kavak","suffix":""},{"id":300087816,"identity":"622e6d03-b644-4d6e-9f56-93cd83f8ad03","order_by":2,"name":"Nimet Akin","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Nimet","middleName":"","lastName":"Akin","suffix":""},{"id":300087818,"identity":"f11f9cd6-8dd4-4a3c-bc64-8e97e68bff04","order_by":3,"name":"Omer Koray Hekimoglu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Omer","middleName":"Koray","lastName":"Hekimoglu","suffix":""}],"badges":[],"createdAt":"2024-05-01 21:38:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4356019/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4356019/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10554-024-03255-z","type":"published","date":"2024-10-03T15:57:28+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":56411909,"identity":"a68887e0-6d8c-4dcc-8c4c-aa89fff62067","added_by":"auto","created_at":"2024-05-13 20:31:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":188673,"visible":true,"origin":"","legend":"\u003cp\u003eRight coronary artery (white arrow) showing an intramyocardial course in the right atrium wall (A) and right ventricular wall (B)\u003c/p\u003e","description":"","filename":"Figure1..png","url":"https://assets-eu.researchsquare.com/files/rs-4356019/v1/a0e98424ac65e5b5718cc17d.png"},{"id":56411906,"identity":"958ce197-8b91-4c53-b5a7-19d857392689","added_by":"auto","created_at":"2024-05-13 20:31:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":180428,"visible":true,"origin":"","legend":"\u003cp\u003eRCA with intramyocardial course (white arrow)\u003c/p\u003e","description":"","filename":"Figure2..png","url":"https://assets-eu.researchsquare.com/files/rs-4356019/v1/19c491d6e3c110fb9edcf439.png"},{"id":56411905,"identity":"65d2a85a-e445-441a-a61c-990f797b03e3","added_by":"auto","created_at":"2024-05-13 20:31:24","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":145038,"visible":true,"origin":"","legend":"\u003cp\u003eA and B Dual RCA in the middle segment, one with an intra-atrial course (white arrow) and the other with a normal course\u003c/p\u003e","description":"","filename":"figure3..png","url":"https://assets-eu.researchsquare.com/files/rs-4356019/v1/5bd68225231f18685f6cdd5f.png"},{"id":56411908,"identity":"5f160fec-af60-46db-a692-7de75394243f","added_by":"auto","created_at":"2024-05-13 20:31:26","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":158105,"visible":true,"origin":"","legend":"\u003cp\u003e3D image of dual RCA in the middle segment, one with an intra-atrial course (white arrow) and the other with a normal course\u003c/p\u003e","description":"","filename":"Figure4..png","url":"https://assets-eu.researchsquare.com/files/rs-4356019/v1/52712e2ce8bb3f09d308af22.png"},{"id":66096821,"identity":"3d26a81b-2b61-4bb9-bdce-40ad6019dec8","added_by":"auto","created_at":"2024-10-07 16:10:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1355028,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4356019/v1/6d490fac-15da-4027-8bc0-1e012b917e2f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Intramyocardial and Intra-atrial courses in the Right Coronary Artery: Prevalence and characteristics","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe epicardial arteries, encompassing the right and left coronary arteries and their principal branches, traverse the cardiac surface. Occasionally, segments of these vessels may be embedded within the myocardium, leading to the phenomenon termed myocardial bridging (MB), wherein the artery appears to traverse beneath a myocardial bridge [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. MB, a congenital anatomical variant, is predominantly associated with the left anterior descending artery (LAD) and is characterized by an intramural passage of the epicardial coronary artery through the myocardium [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe clinical relevance of MB is a subject of ongoing research. While certain studies classify MB as benign or asymptomatic, others have documented associated complications, including arrhythmias, ischemia, acute coronary syndromes, and even sudden death [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMB exhibits a reported incidence rate ranging from 5.4–85.7% in autopsy studies, with a notably higher prevalence in autopsy compared to angiography (5–12%), demonstrating considerable variability across different investigations [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The predilection site for MB is predominantly the proximal half of the LAD (60%), with a lower incidence observed in other coronary branches [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Rare occurrences have also been documented in the left circumflex artery (LCx) or the right coronary artery (RCA) main body or branches, with instances of multiple artery involvement reported [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. MB in RCA branches is less common and exhibits greater variability in location (2.8–11.4%) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe intra-atrial right coronary artery (IARCA) refers to the segment of the RCA that is intracavitary within the right atrium, lacking a myocardial interface between the blood pool and the vessel adventitia. An atrialized coronary artery denotes a segment of the RCA coursing superiorly to its typical epicardial position within the atrioventricular groove, representing a rare and atypical condition for the RCA [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Radiologically, IARCA is characterized as an RCA segment entirely encompassed by intra-atrial contrast throughout the cardiac cycle, in contrast to MB, where the coronary artery segment appears entirely surrounded by myocardial muscle [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Recognition of IARCA prior to cardiac surgery or endocavitary procedures is imperative, given its potential for vascular injury leading to catastrophic consequences [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Initially identified in postmortem specimens and during cardiac surgeries, the prevalence of IARCA ranges from approximately 0.1–1.8% [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Despite being considered a benign and incidental anomaly, the importance of IARCA lies in its identification prior to ablative procedures for arrhythmias, catheterization of the right-sided chambers, and pacemaker implantation [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe literature contains a limited array of studies concerning the RCA exhibiting an intramyocardial course and IARCA, a rare anatomical variant. This investigation aims to ascertain the prevalence and characteristics of RCA demonstrating incidental MB and IARCA in an adult cohort subjected to coronary computed tomography angiography (CTA), drawing upon the experience of a singular medical center.\u003c/p\u003e "},{"header":"Methods","content":"\u003cp\u003eStudy Population\u003c/p\u003e\u003cp\u003eSubsequent to obtaining approval from the ethics committee, this retrospective study re-assessed the radiological images of individuals aged 18 years and older who underwent CTA at our institution between February 2023 and March 2023. The inclusion criteria encompassed cases presenting with a RCA exhibiting an intramyocardial or inter-atrial trajectory. Exclusion criteria were individuals younger than 18 years and cases with suboptimal CTA examinations due to factors such as unsuitable examination phases or motion artifacts.\u003c/p\u003e\u003cp\u003eCTA Assessment\u003c/p\u003e\u003cp\u003eCTA imaging was conducted using either a dual-energy 128-slice (GE Revolution Frontier, Milwaukee, USA) or a 1024 (512x2) slice CT (GE Revolution Apex Pxtream, Milwaukee, USA). The procedures were ECG-gated and involved the administration of an intravenous non-ionic contrast agent at a flow rate of 5ml/sec, followed by bolus tracking.\u003c/p\u003e\u003cp\u003eThe scanning protocol was adapted based on the initial heart rate (BPM) of the patient, employing a prospective gated method for individuals with a BPM of 80 or lower, and a retrospective gated method for those with a BPM above 80.\u003c/p\u003e\u003cp\u003eEvaluation of all CTA images was performed independently and retrospectively by two cardiothoracic radiology experts (with 10 and 25 years of experience, respectively) using multiplanar and curved planar reconstructions on a specialized workstation (AWS 4.6, GE, Milwaukee, USA). Cases exhibiting MB and inter-atrial courses in the RCA were identified. Recorded data included the patient's age and sex, as well as the characteristics of the affected RCA segment (length, location, depth), presence of atherosclerotic disease, and coronary dominance (right, left, codominant). Additional evaluations were conducted to ascertain the presence of other vascular anomalies associated with the course anomaly, the existence of atherosclerosis in other segments of the RCA and left coronary arteries (using Agatston total calcium scoring and percentage calculation of atherosclerotic narrowing, if present). The presence of pulmonary hypertension (PHT), left ventricular hypertrophy, and chronic obstructive pulmonary disease (COPD) were also documented in the patient cohort.\u003c/p\u003e\u003cp\u003eAmong the 1600 patients included in our study, we obtained a random group of 110 patients who did not have any abnormalities in the course of RCA and compared them with our special groups to see if there was a difference in our variables.\u003c/p\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eWhile evaluating the findings obtained in the study, SPSS 26 (Statistical Package for the Social Sciences) program was used for statistical analysis. While evaluating the study data, quantitative variables were shown with mean, standard deviation, median, min and max values, and qualitative variables were shown with descriptive statistical methods such as frequency and percentage. ShapiroWilks test and Box Plot graphics were used to evaluate the suitability of the data for normal distribution. Mann Whitney-U test was used to evaluate variables that do not show normal distribution according to two groups; Kruskal Wallis test was used for comparisons of three groups or more. Relationships between variables were evaluated with Spearman's correlation analysis. Fisher Freeman Halton test was used to compare qualitative data. Significance was accepted at p \u0026lt; 0.05 level.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 1600 coronary CTAs were assessed, with participant ages spanning from 18 to 86 years. No discrepancies were noted between radiologists in the diagnosis of MB in the RCA and IARCA. The prevalence of MB in the RCA was identified in 33 cases (2.06%), while IARCA was detected in 7 cases (0.44%), with one case exhibiting both anomalies. The age range for cases with MB in the RCA was 29 to 84 years (mean 56.5), and for those with IARCA, it was 48 to 68 years (mean 59.7).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll cases with identified MB in the RCA and IARCA demonstrated right coronary artery dominance, except for one case exhibiting left coronary dominance with MB in the RCA.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe segment length displaying MB in the RCA varied from 6 to 70 mm (mean 21.9 mm), while the IARCA segment length ranged from 15 to 55 mm (mean 37.9 mm). No cases exhibited atherosclerotic involvement in the RCA segment with MB and/or inter-atrial course. Among the cases with MB in the RCA, 16 (48.5%) showed no atherosclerotic disease in other RCA segments, while 17 cases (51.5%) had atherosclerotic plaque. Additionally, 8 patients (24.2%) had varying degrees of calcified plaque in other RCA segments. In the cases with detected IARCA, only one case (14.3%) demonstrated atherosclerotic involvement in the remaining segment of the RCA.\u003c/p\u003e\n\u003cp\u003eIn assessing other coronary arteries, no atherosclerotic involvement was identified in 5 cases (15.2%) with MB in the RCA and in 3 cases (42.8%) IARCA, while the remaining cases exhibited atherosclerotic plaques leading to varying degrees of stenosis. The bridged segment\u0026apos;s in the RCA depth varied between 1 and 4.7 mm (mean 1.7 mm), with 26 patients (78.8%) having a bridged segment depth of less than 2 mm. The depth of the IARCA segment ranged from 3.3 to 8.3 mm (mean 5.1 mm).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRegarding the location of MB in the RCA, 10 segments (30.3%) were proximal, 20 (60.6%) were middle, and 3 (9.1%) were distal. MB presented an intramyocardial course in the right atrium wall in 22 cases (66.7%) and in the right ventricle wall in 11 cases (33.3%). The IARCA segment was located in the middle section in 3 patients (42.9%) and in the distal section in 4 patients (57.1%), with no cases of IARCA detected in the proximal segment.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn cases with MB in the RCA, 13 (39.4%) exhibited no accompanying anomalies or variations. However, 8 cases had superficial MB in the LAD (24.2%), and 12 cases had deep MB in the LAD. One case simultaneously presented with MB in the RCA, an RCA origin anomaly (malignant course), deep MB in the LAD, and IARCA. Another case displayed MB in the RCA, dual RCA variation, an origin anomaly in the LCx (originating from the right coronary sinus), and deep MB in the LAD.\u003c/p\u003e\n\u003cp\u003eAmong the cases with an identified IARCA, the anomaly was isolated in only one case. In contrast, 2 cases (28.6%) exhibited superficial MB in the LAD, and 3 cases (42.8%) demonstrated deep MB in the LAD. Additionally, dual RCA variation was observed in 3 cases (42.8%) alongside IARCA.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe demographic characteristics and findings of the cases with MB in the RCA are presented in Table 1, whereas those of the cases with IARCA are detailed in Table 2. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1. Demographic characteristics of cases showing myocardial bridging in the right coronary artery\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePrevalence rate, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e33 (%2.06)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSex ratio (male/female), n ( %)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e20 (%60.6) / 13 (%39.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAge (year), mean (range)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;29-84 (56.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSegment of RCA involved, n (%)\u003c/p\u003e\n \u003cp\u003eProximal\u003c/p\u003e\n \u003cp\u003eMid\u003c/p\u003e\n \u003cp\u003eDistal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e10 (%30.3)\u003c/p\u003e\n \u003cp\u003e20 (%60.6)\u003c/p\u003e\n \u003cp\u003e3 (%9.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eLocation, n (%)\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eRight atrium\u003c/p\u003e\n \u003cp\u003eRight ventricle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e22 (66.7)\u003c/p\u003e\n \u003cp\u003e11 (33.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eLength of MB in the RCA (mm), mean (range)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21.9 (6-70)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDepth of MB in the RCA (mm), mean (range)\u003c/p\u003e\n \u003cp\u003eSuperficial MB, n (%)\u003c/p\u003e\n \u003cp\u003eDeep MB, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.7 (1-4.7)\u003c/p\u003e\n \u003cp\u003e26 (78.8)\u003c/p\u003e\n \u003cp\u003e7 (21.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAtherosclerotic disease in the MB segment of the RCA, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAtherosclerotic evaluation in other segments of the RCA, n (%)\u003c/p\u003e\n \u003cp\u003eCAD-RADS 1\u003c/p\u003e\n \u003cp\u003eCAD-RADS 2\u003c/p\u003e\n \u003cp\u003eCAD-RADS 3\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4a\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4b\u003c/p\u003e\n \u003cp\u003eCAD-RADS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e10 (30.3)\u003c/p\u003e\n \u003cp\u003e5 (15.2)\u003c/p\u003e\n \u003cp\u003e2 (6.1)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAtherosclerosis in other arteries, n (%)\u003c/p\u003e\n \u003cp\u003eCAD-RADS 1\u003c/p\u003e\n \u003cp\u003eCAD-RADS 2\u003c/p\u003e\n \u003cp\u003eCAD-RADS 3\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4a\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4b\u003c/p\u003e\n \u003cp\u003eCAD-RADS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e8 (24.2)\u003c/p\u003e\n \u003cp\u003e9 (27.3)\u003c/p\u003e\n \u003cp\u003e8 (24.2)\u003c/p\u003e\n \u003cp\u003e2 (6.1)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePresence of calcific plaque in RCA (Agatston score), n (%)\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1-100\u003c/p\u003e\n \u003cp\u003e101-300\u003c/p\u003e\n \u003cp\u003e301-999\u003c/p\u003e\n \u003cp\u003e\u0026gt;1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e7 (21.2)\u003c/p\u003e\n \u003cp\u003e1 (3.0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePresence of calcific plaque in other coronary arteries (Agatston score), n (%)\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1-100\u003c/p\u003e\n \u003cp\u003e101-300\u003c/p\u003e\n \u003cp\u003e301-999\u003c/p\u003e\n \u003cp\u003e\u0026gt;1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e4 (12.1)\u003c/p\u003e\n \u003cp\u003e3 (9.1)\u003c/p\u003e\n \u003cp\u003e3 (9.1)\u003c/p\u003e\n \u003cp\u003e1 (3.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDominance (Right/Left), n\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e32/1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eOther accompanying variations-anomalies *\u003c/p\u003e\n \u003cp\u003eSuperficial MB in LAD\u003c/p\u003e\n \u003cp\u003eDeep MB in LAD\u003c/p\u003e\n \u003cp\u003eOrigin anomaly in RCA\u003c/p\u003e\n \u003cp\u003eOrigin anomaly in LCx\u003c/p\u003e\n \u003cp\u003eIARCA\u003c/p\u003e\n \u003cp\u003eDual RCA\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e8 (24.3)\u003c/p\u003e\n \u003cp\u003e12 (36.4)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eConcomitant diseases, n (%)\u003c/p\u003e\n \u003cp\u003ePulmonary hypertension\u003c/p\u003e\n \u003cp\u003eLeft ventricular hypertrophy\u003c/p\u003e\n \u003cp\u003eCOPD\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e4 (12.1)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eRCA, right coronary artery; MB, myocardial bridging; LAD, left anterior descending artery; LCx,\u0026nbsp;left circumflex artery; IARCA, intra-atrial right coronary artery; COPD, and chronic obstructive pulmonary disease;\u0026nbsp;*, in some cases, there is more than one variation-anomaly.\u003c/p\u003e\n\u003cp\u003eTable 2. Demographic characteristics of\u0026nbsp;intra-atrial right coronary artery cases\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003ePrevalence rate, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e7 (%0.44)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eSex ratio (male/female), n ( %)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e4 (%57.1)/3 (%42.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eAge (year), mean (range)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;48-68 (59.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eSegment of RCA involved, n (%)\u003c/p\u003e\n \u003cp\u003eProximal\u003c/p\u003e\n \u003cp\u003eMid\u003c/p\u003e\n \u003cp\u003eDistal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e3 (42.9)\u003c/p\u003e\n \u003cp\u003e4 (57.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eLength of IARCA segment (mm), mean (range)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e37.9 (15-55)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eDepth of IARCA segment (mm), mean (range)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e5.1 (3.3-8.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eAtherosclerotic disease in the IARCA segment, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eAtherosclerotic evaluation in other segments of the RCA, n (%)\u003c/p\u003e\n \u003cp\u003eCAD-RADS 1\u003c/p\u003e\n \u003cp\u003eCAD-RADS 2\u003c/p\u003e\n \u003cp\u003eCAD-RADS 3\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4a-b\u003c/p\u003e\n \u003cp\u003eCAD-RADS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e1 (14.3)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eAtherosclerosis in other arteries, n (%)\u003c/p\u003e\n \u003cp\u003eCAD-RADS 1\u003c/p\u003e\n \u003cp\u003eCAD-RADS 2\u003c/p\u003e\n \u003cp\u003eCAD-RADS 3\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4a\u003c/p\u003e\n \u003cp\u003eCAD-RADS 4b\u003c/p\u003e\n \u003cp\u003eCAD-RADS 5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1(14.3)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e2 (28.6)\u003c/p\u003e\n \u003cp\u003e1 (14.3)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003ePresence of calcific plaque in RCA (Agatston score), n (%)\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1-100\u003c/p\u003e\n \u003cp\u003e101-300\u003c/p\u003e\n \u003cp\u003e301-999\u003c/p\u003e\n \u003cp\u003e\u0026gt;1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003ePresence of calcific plaque in other coronary arteries (Agatston score), n (%)\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1-100\u003c/p\u003e\n \u003cp\u003e101-300\u003c/p\u003e\n \u003cp\u003e301-999\u003c/p\u003e\n \u003cp\u003e\u0026gt;1000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1 (14.3)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eDominance (Right/Left), n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e7/0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eOther accompanying variations-anomalies *\u003c/p\u003e\n \u003cp\u003eSuperficial MB in LAD\u003c/p\u003e\n \u003cp\u003eDeep MB in LAD\u003c/p\u003e\n \u003cp\u003eMB in the RCA\u003c/p\u003e\n \u003cp\u003eOrigin anomaly in RCA\u003c/p\u003e\n \u003cp\u003eDual RCA\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;2 (28.6)\u003c/p\u003e\n \u003cp\u003e3 (42.8)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e3 (42.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"51.954397394136805%\" valign=\"top\"\u003e\n \u003cp\u003eConcomitant diseases, n (%)\u003c/p\u003e\n \u003cp\u003ePulmonary hypertension\u003c/p\u003e\n \u003cp\u003eLeft ventricular hypertrophy\u003c/p\u003e\n \u003cp\u003eCOPD\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"48.045602605863195%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\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\u003cp\u003eRCA, right coronary artery; IARCA, intra-atrial right coronary artery; MB, myocardial bridging; LAD, left anterior descending artery; COPD, and chronic obstructive pulmonary disease; *, in some cases, there is more than one variation-anomaly.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to gender; No statistically significant relationship was found between the depth, localization, coronary dominance, atherosclerotic disease in the RCA and other coronary arteries, and the occurrence of other coronary anomalies of IARCA and MB in the RCA (p\u0026gt;0.05).\u003c/p\u003e\n\u003cp\u003eWhen compared with 110 randomly selected cases without course anomalies in the RCA, no statistically significant difference was observed between the groups according to coronary dominance, the presence of atherosclerotic stenosis in the RCA and other coronary arteries, and the presence of other coronary anomalies (p\u0026gt;0,05) (table 3). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3. Comparative evaluations of randomly selected control group and IARCA\\MB in the RCA groups\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"top\"\u003e\n \u003cp\u003eIARCA\u003c/p\u003e\n \u003cp\u003e(n=7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"top\"\u003e\n \u003cp\u003eMB in the RCA (n=33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"top\"\u003e\n \u003cp\u003eControl (n=110)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eGender\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e4 (57.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e20 (60.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e75 (68.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e0.655\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e3 (42.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e13 (39.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e35 (31.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eAge\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003eMean\u0026plusmn;Ss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e59.71\u0026plusmn;7.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e56.52\u0026plusmn;12.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e54.38\u0026plusmn;10.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003e\u003csup\u003eb\u003c/sup\u003e0.061\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003eMedian (Min-Max)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e58 (48-68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e58 (29-84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e51.5 (22-80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003eDominance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003eRight dominance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e7 (100)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e32 (97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e98 (89.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e0.764\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003eLeft dominance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e8 (7.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003eCodominance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e4 (3.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eAtherosclerotic disease in the RCA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e6 (85.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e16 (48.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e59 (53.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e0.192\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e1 (14.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e17 (51.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e51 (46.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eAtherosclerotic disease in other coronary arteries\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e3 (42.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e5 (15.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e21 (19.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e0.241\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e4 (57.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e28 (84.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e89 (80.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.903225806451612%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eOther anomalies\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.838709677419356%\" valign=\"top\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e12 (37.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.93548387096774%\" valign=\"bottom\"\u003e\n \u003cp\u003e50 (45.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.451612903225806%\" valign=\"top\"\u003e\n \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e0.073\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"24.165029469548134%\" valign=\"top\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e6 (100)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e20 (62.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.6286836935167%\" valign=\"bottom\"\u003e\n \u003cp\u003e60 (54.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.948919449901767%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIARCA, intra-atrial right coronary artery;\u0026nbsp;MB, myocardial bridging; RCA, right coronary artery.\u003cem\u003e\u003csup\u003e\u0026nbsp;a\u003c/sup\u003e\u003c/em\u003e\u003cem\u003eFisherFreemanHalton Test\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/em\u003e\u003cem\u003eKruskal Wallis Test \u0026amp;Dunn- Bonferroni Test\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eExample cases are shown in figures 1, 2, 3 and 4.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eMB constitutes a band of myocardial fibers enveloping a subepicardial segment of the coronary artery [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The inaugural anatomical delineation of myocardial bridges was provided by Reyman in 1737, followed by Black in 1805, with subsequent autopsy examination by Geiringer in 1951 and radiological identification by Portsmann and Iwig in 1960 [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe angiographic manifestation of MB is contingent upon a multitude of factors, including the myocardial bridge's thickness and length, the presence of loose connective or adipose tissue surrounding the bridged segment, myocardial contractility status, the tissue composition between the coronary artery and the myocardium, and the observer's proficiency. Consequently, numerous bridging instances, encompassing the involvement of the LCx and RCA, may remain undetected [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The reported prevalence of MB exhibits considerable variation depending on the employed diagnostic modality. Traditional imaging techniques, such as conventional angiography, demonstrate lower detection rates relative to advanced imaging modalities like CTA, which afford comprehensive anatomical visualization. The incidence of MB identified through CTA ranges from 3.5\u0026ndash;100% [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMyocardial bridges predominantly occur in the middle segment of the LAD, yet they may also manifest in any epicardial coronary artery, such as the diagonal branches, the posterior descending branch of the RCA, or the marginal branches of the LCx [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The presence of myocardial bridges in the right coronary system is comparatively rare. Corban et al. reported the prevalence of MK in the LAD to be between 67% and 98%, while M\u0026ouml;hlenkamp et al. documented incidences of 18% and 40% for diagonal and marginal branches, respectively [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the literature, reports concerning MB in the RCA and its branches are primarily documented as case reports. Nguyen et al. described a rare instance of MB in two posterolateral branches of the RCA. Tiryakioğlu et al. illustrated significant bridging in the middle segment of the posterior interventricular branch of the RCA [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Kulkarni et al. reported a case of isolated MB in the RCA [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Riezzo et al. presented a case of superficial bridging approximately 1 cm from the starting point in the descending branch of the RCA [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Studies encompassing case series are limited in number. While the reported prevalence of MB segments in the RCA is 2.9%, the rate in the branches of the RCA ranges between 3.7% and 5.9% [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In our study, we determined the prevalence of MB in the RCA to be 2.06%. However, this finding is inconsistent with the high incidence of 41.4% of MB in the RCA and its branches detected by Polacek in autopsies [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe existence of multiple myocardial bridges spanning various areas within both the left and right coronary arteries has been infrequently documented [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Richter et al. have detailed three instances in which MB was concurrently present in the RCA and the LAD [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In our study, isolated MB in the RCA was observed in 39.4% of cases. In addition to this, in the remaining 60.6% of the cases, we encounted superficial and/or deep MB in the LAD. Moreover, among patients with MB in the RCA, anomalies such as dual RCA, IARCA, and RCA origin anomalies were identified.\u003c/p\u003e \u003cp\u003eThe relationship between coronary dominance and the prevalence of MB in the RCA has not been explored in the literature's case series; however, our research found right coronary dominance in all but one patient. Our findings also indicated a higher incidence of MB in the RCA among male participants.\u003c/p\u003e \u003cp\u003eMB is delineated as either superficial or deep, contingent upon its depth within the myocardium, and it is possible for a vessel to harbor several bridged segments [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Gould et al. have categorized myocardial bridges as superficial if the depth ranges from 1 to 2 mm, and as deep if the bridge extends beyond 2 mm within the myocardium [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Superficial MB, reported at 75% in the literature, predominates over deep bridges, which account for 25% of reports [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In our analysis, the mean MB depth in the RCA was established at 1.7 mm, with superficial MB constituting 78.8% of instances.\u003c/p\u003e \u003cp\u003eThe literature posits the average MB length at 20.2 mm and the depth at 3.1 mm. Studies utilizing angiography and autopsy reveal only marginal disparities in average MB length and thickness. The mean length is documented as 21.0 mm in investigations employing computed CTA and conventional angiography, and 19.3 mm in those utilizing autopsy/cadaver dissection. The average MB thickness or depth stands at 3 mm for both CTA and conventional angiography, and at 3.2 mm for autopsy/cadaver dissection, indicating minimal variance between examination methods. Employing imaging techniques such as CTA for MB dimension assessment yields findings congruent with autopsy outcomes. A correlation between artery compression and its depth has been established [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Our research found the MB segment length in the RCA to average 21.9 mm, with a prevalent location in the middle segment at 60.6%. Furthermore, our study contributes to the literature by detailing the localization of MB segments; 66.7% demonstrated an intramyocardial course within the right atrium, while the rest were within the right ventricle.\u003c/p\u003e \u003cp\u003eThe impact of MB on coronary physiology has sparked considerable debate. Although MB is predominantly perceived as benign, it has been frequently linked to myocardial ischemia, infarction, ventricular arrhythmias, and sudden death, especially in the context of hypertrophic cardiomyopathy and coronary atherosclerosis [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The involvement of myocardial bridges in atherosclerosis represents an additional area of contention, as highlighted by Soran et al. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Loukas et al. have posited the potential for \"protective effects\" of myocardial bridges [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Conversely, Ishii et al., Lee and Chen, and Zeina et al. have noted that while the proximal segment to the bridged area exhibits atherosclerotic changes, the segment under the bridge appears to be shielded from atherosclerosis [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Schar, however, contests the notion of the bridged segment being safeguarded against atherosclerotic alterations [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In our observations, none of the segments with bridging presented atherosclerotic involvement, yet about half (51.5%) demonstrated atherosclerotic presence in other segments of the RCA not affected by bridging. In alignment with this, no calcified atherosclerotic plaques were identified within the bridged segment of the RCA, yet 24.2% of the instances revealed calcified plaque in varying quantities in other segments of the RCA.\u003c/p\u003e \u003cp\u003eIn the majority of instances involving MB in the RCA, clinical or radiographic indications of PHT, left ventricular hypertrophy, cardiomyopathy, and COPD have been documented [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Contrarily, our investigation identified PHT and COPD in only one distinct case each, with left ventricular hypertrophy observed at a comparatively low prevalence of 12.1%. These findings deviate from established literature. Nonetheless, to facilitate statistical analyses, further research with more extensive cohorts is warranted.\u003c/p\u003e \u003cp\u003eThe intra-atrial or intracavitary trajectory of the RCA is characterized by the RCA's passage through the right atrial cavity [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Radiographically, this manifests as an RCA segment that is consistently enveloped by intracavitary contrast throughout all phases of the cardiac cycle. Although the literature includes case reports detailing IARCA instances, research series quantifying its prevalence remain scarce. Initially detected solely in post-mortem specimens and during heart surgeries, its observed frequency ranges from 0.1\u0026ndash;1.8% [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. IARCA's prevalence, as reported in autopsy or surgical cohorts is notably minimal [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. MacAlpine et al. quantified a 0.1% prevalence in a thousand autopsy evaluations, and Ochsner et al. indicated a surgical prevalence of 0.09% [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Krishnan et al. uncovered IARCA in six out of 331 autopsy dissections, noting a 1.8% occurrence rate [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], without finding any RCA origin anomalies. Opolski et al. elucidated the efficacy of CTA in recognizing IARCA within an extensive cohort of 9284 subjects, marking a 0.15% prevalence rate [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Hossain et al., with a 464 patient cohort, reported a 0.4% prevalence, while Ganga et al. found a 0.29% prevalence in a 7114 CTA case series [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Buckley et al., across a 7847 CTA case series, identified IARCA in 17 individuals, documenting a 0.22% prevalence [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Given the escalating application of sophisticated cardiac imaging like CTA, an increase in the actual prevalence is anticipated. Our study also revealed an IARCA prevalence of 0.44%.\u003c/p\u003e \u003cp\u003eConsistent with the broader scholarly discourse, where sex disparities are generally not emphasized, Hossain et al. identified a predilection for IARCA occurrences in males [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Although a higher prevalence among males is noted in our cohort, with males constituting 4 of the 7 cases, the sample size is limited. Frey et al. documented the case featuring a concurrent dual RCA and IARCA, a rarity in medical literature [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Despite a small sample size in our investigation, we observed a relatively elevated incidence of dual RCA and IARCA coexistence at 42.8%. This suggests that the simultaneous presence of these rare anatomical variations may not be as infrequent as previously assumed.\u003c/p\u003e \u003cp\u003eRegarding the predominantly affected segment, while most literature cites the distal RCA as the frequent site, Ganga et al. highlighted the mid RCA. Our findings similarly emphasize the distal segment in 4 patients but also identified the mid-segment in 3 patients, without any instances affecting the proximal segment, underscoring the need for further investigation despite the absence of statistical analysis due to the small sample size. Ganga et al. delineated the average depth and length of IARCA as 2.57 mm and 14.85 mm, respectively. Contrastingly, our findings revealed an average depth of 5.1 mm and length of 37.9 mm, suggesting a significant deviation towards more pronounced anatomical manifestations. Literature scantily suggests a higher observation of right coronary dominance in IARCA cases [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Consistently, our study confirmed right coronary dominance across all instances, aligning with the extant observations on coronary dominance dynamics in IARCA presentations.\u003c/p\u003e \u003cp\u003eKolodziej et al. delineated mild atherosclerosis affecting the intra-atrial segment in a subset of three individuals diagnosed with IARCA [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. This contrasts with the broader literature, where no atherosclerotic conditions in IARCA segments are typically reported. Studies by Opolski et al., Krishnan et al., and Ganga et al. likewise indicated an absence of noteworthy atherosclerosis in the IARCA segments [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Our findings are similar to the literature in this respect. A singular case in our cohort showed mild coronary artery disease in segments of the RCA apart from the IARCA, with no instances of calcified atherosclerotic plaques within the RCA.\u003c/p\u003e \u003cp\u003eIn our review of English-language literature, no investigations were found addressing comorbidities associated with IARCA. Our analysis extended to the exploration of concurrent conditions such as PHT, left ventricular hypertrophy, and COPD, none of which were detected across our patient cohort.\u003c/p\u003e \u003cp\u003eWhile IARCA manifestations are predominantly asymptomatic and considered benign, unrecognized presence prior to conducting invasive cardiac interventions can precipitate adverse outcomes. Challenges in pinpointing vessel localization arise during cardiovascular surgical revascularization and bypass graft operations. Furthermore, right heart catheterization procedures bear a risk of inflicting potential harm to the vessel. In electrophysiological interventions such as catheter ablation or lead device placements within the right atrium wall or right ventricular apex, there exists a direct risk to intracavitary coronary arteries, potentially culminating in inadvertent vessel damage [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The proximity between the electrode and artery during ablation, where thermal damage to tissues approximately 3\u0026ndash;5 mm in proximity is a known risk, underscores a heightened injury risk post-ablation when IARCA is present [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Even though the RCA in scenarios of left-dominant circulation might influence a lesser extent of the myocardium, it remains susceptible to damage during the aforementioned procedures. Ganga et al. reported a predominance of right-sided dominance in 81% of their patient cohort [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. While the literature largely omits discussions on coronary dominance, our analysis similarly observed right coronary dominance across all cases.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summation, MB in the RCA and IARCA within are chiefly incidental and nonpathogenic anatomical variants detected in the adult demographic. The detection of such features is paramount owing to the conceivable correlations with additional anatomical aberrations, variations, and clinical pathologies. Moreover, the antecedent identification of IARCA is essential prior to the initiation of electrophysiological interventions, right heart catheterization procedures, and selected surgical operations, thereby accentuating the necessity for scrupulous surveillance. In the realm of diagnostic imaging, CTA emerges as a robust and proficient imaging technique for the articulation of these anomalies, mandating comprehensive radiological evaluations to attenuate the risk of vascular complications.\u003c/p\u003e \u003cp\u003eLimitations\u003c/p\u003e \u003cp\u003eOur study was a single-center study and our number of patients was limited to 1600. Therefore, there is a limitation in representing the general population. Since the number of cases with MB in the RCA and IARCA was low, statistical analysis could not be performed for some parameters. Additionally, since CTA was performed on patients with low or moderate risk of coronary heart disease, our study is inadequately representative of the rest of the population. Asymptomatic cases were not included in the study group because there was no indication for coronary CTA. All cases were from our own country population and we could not compare the incidence of defined variations in different races. There is a need for larger series of studies on this subject.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eConflict of Interest:\u003c/strong\u003e \u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to participate:\u003c/strong\u003e \u003cp\u003e All participants provided written informed consent and could at all times choose to withdraw consent\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor contributionsConceptualization, Y.A. and O.K.H.; method\u0026not;ology, Y.A. and R.P.K.; formal analysis and data curation, Y.A.; writing\u0026mdash;original draft preparation, R.P.K and O.K.H.; writing\u0026mdash;review and editing, Y.A. and N.A; visualization, Y.A., R.P.K., N.A. and O.K.H.; supervision and project administration, V.H. and D.B. 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Ann Thorac Surg 38:356\u0026ndash;362\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOpolski MP, Pregowski J, Kruk M, Staruch AD, Witkowski A, Demkow M, Hryniewiecki T, Michalek P, Ruzyllo W, Kepka C (2014) The prevalence and characteristics of intra-atrial right coronary artery anomaly in 9,284 patients referred for coronary computed tomography angiography. Eur J Radiol 83:1129\u0026ndash;1134\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBuckley CM, Rosamond T, Hegde SR, Wetzel L (2017) The intracavitary coronary artery: a rare anomaly with implications for invasive cardiac procedures - demonstration by coronary computed tomography angiography. JACC 69:11:1437\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKolodziej AW, Lobo FV, Walley VM (1994) Intra-atrial course of the right coronary artery and its branches. 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Int J Hyperth 37:37\u0026ndash;48\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-cardiovascular-imaging","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"caim","sideBox":"Learn more about [The International Journal of Cardiovascular Imaging](https://www.springer.com/journal/10554)","snPcode":"10554","submissionUrl":"https://submission.nature.com/new-submission/10554/3","title":"The International Journal of Cardiovascular Imaging","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"RCA, miyocardial bridging, intra-atrial course","lastPublishedDoi":"10.21203/rs.3.rs-4356019/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4356019/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eWe aimed to determine the prevalence and radiological characteristics of myocardial bridging (MB) and intra-atrial course anomaly (IARCA), which are rare course variations of the right coronary artery (RCA), in the adult patient population.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eRadiological images of cases over the age of 18 who underwent coronary CT angiography (CTA) examination in our clinic were scanned from the archives retrospectively, and cases with MB of the RCA and IARCA detection were included in the study. The number, age and gender distribution of the cases, whether there were any other accompanying vascular anomalies, whether there was atherosclerosis in the coronary arteries (calculation of Agatston total calcium score, calculation of atherosclerotic stenosis as a percentage, if any) were evaluated.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe prevalence of MB in the RCA was 2.06%, and the prevalence of IARCA was 0.44%. In one case, both anomalies were detected together. The average MB segment length in RCA was 21.9mm, and the average IARCA segment length was 37.9mm. There was no atherosclerotic disease in the RCA segment where anomaly was detected.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eRecognition of rare course anomalies of RCA before treatment procedures such as ablation and surgery is important to prevent complications that may have potentially fatal consequences.\u003c/p\u003e","manuscriptTitle":"Intramyocardial and Intra-atrial courses in the Right Coronary Artery: Prevalence and characteristics","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-13 20:30:47","doi":"10.21203/rs.3.rs-4356019/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-16T12:36:54+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T19:58:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-06T07:27:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"51808856388391560275480379799781778536","date":"2024-08-21T18:55:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"302057652997838131532408445407097328881","date":"2024-08-21T17:52:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-10T09:21:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"172503978005909382278741068087538157905","date":"2024-05-08T08:50:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"209907890375665149564924466368699760888","date":"2024-05-07T07:37:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-05-07T07:33:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-06T03:54:41+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-06T03:54:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"The International Journal of Cardiovascular Imaging","date":"2024-05-01T21:28:15+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-international-journal-of-cardiovascular-imaging","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"caim","sideBox":"Learn more about [The International Journal of Cardiovascular Imaging](https://www.springer.com/journal/10554)","snPcode":"10554","submissionUrl":"https://submission.nature.com/new-submission/10554/3","title":"The International Journal of Cardiovascular Imaging","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"078e93e4-5867-4c3a-ae48-8096ddad7c90","owner":[],"postedDate":"May 13th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-07T16:01:19+00:00","versionOfRecord":{"articleIdentity":"rs-4356019","link":"https://doi.org/10.1007/s10554-024-03255-z","journal":{"identity":"the-international-journal-of-cardiovascular-imaging","isVorOnly":false,"title":"The International Journal of Cardiovascular Imaging"},"publishedOn":"2024-10-03 15:57:28","publishedOnDateReadable":"October 3rd, 2024"},"versionCreatedAt":"2024-05-13 20:30:47","video":"","vorDoi":"10.1007/s10554-024-03255-z","vorDoiUrl":"https://doi.org/10.1007/s10554-024-03255-z","workflowStages":[]},"version":"v1","identity":"rs-4356019","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4356019","identity":"rs-4356019","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}