Averaged Impedance Drop as an Indicator of Lesion Formation Dynamics During Radiofrequency Catheter Ablation

Averaged Impedance Drop as an Indicator of Lesion Formation Dynamics During Radiofrequency Catheter Ablation | 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 Averaged Impedance Drop as an Indicator of Lesion Formation Dynamics During Radiofrequency Catheter Ablation Nobuhiro Nakamura, Satoshi Oka, Akinori Wakamiya, Nobuhiko Ueda, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9473730/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Real-time monitoring of myocardial tissue response during radiofrequency applications using a mesh-shaped flexible irrigation tip ablation catheter (TactiFlex) is currently limited by the lack of lesion size index guidance. This study assessed the dynamics of averaged impedance drop percentage (AID%), a novel ablation parameter, and the association with lesion formation characteristics through clinical and experimental analyses. Methods: We retrospectively analyzed 1,423 radiofrequency applications in 30 patients undergoing initial pulmonary vein (PV) isolation using TactiFlex to examine relationships between AID% and conduction-gap formation. Mechanistic validation was performed using an ex vivo porcine myocardial model (152 lesions). AID%-guided ablation protocol (n = 23) was compared with the conventional protocol. Results: AID% values were modestly lower in conduction-gap segments compared with non-gap segments (10% vs. 11%, p = 0.002). Overall discrimination was limited [area under the curve (AUC) 0.58, 95% confidence interval (CI) 0.53–0.63; optimal cutoff 13%], whereas impedance behavior varied with power settings. The highest correlation was observed within the 41–45 W range (AUC 0.78, 95% CI 0.70–0.85). Ex vivo experiments demonstrated that lesion geometry depended strongly on both power and AID% targets. Compared with a 10% target, a 13% target produced deeper and larger lesions without steam pops. The first-pass PV isolation percentage was numerically higher in the AID 11–13%-targeted protocol (left, 78% vs. 67%; right, 87% vs. 73%). Conclusion: AID% is associated with lesion formation characteristics and may serve as an indicator of lesion formation dynamics, reflecting real-time tissue response during RF applications using TactiFlex. atrial fibrillation averaged impedance drop generator impedance drop catheter ablation radiofrequency ablation Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. INTRODUCTION Electrical pulmonary vein (PV) isolation is an established treatment for atrial fibrillation (AF), as arrhythmogenic triggers often arise from the PVs [ 1 ]. In procedures using ipsilateral circumferential radiofrequency (RF) applications to isolate the left and right PVs, achieving first-pass isolation is associated with durable PV isolation [ 2 – 4 ]. A contact force (CF)-sensing catheter with a mesh-shaped flexible irrigation tip, TactiFlex™, Sensor Enabled™ (TFSE, Abbott, Abbott Park, IL, USA) enables high-power, short-duration RF applications [ 5 ]. Previous studies have demonstrated the efficacy and safety of PV isolation using TFSE compared with conventional ablation catheters [ 6 – 8 ]. However, real-time assessment of tissue response and lesion formation during RF delivery remains challenging, and optimized ablation strategies using this catheter have not been fully established, partly due to the lack of lesion size index [ 9 , 10 ] guidance. Even in the era of pulsed-field ablation, RF application is expected to continue with novel technologies, such as a next-generation dual-energy ablation catheter (TactiFlex™ Duo, Sensor Enabled™, Abbott), underscoring the need for a deeper understanding of tissue responses during RF delivery. Ablation lesion formation is influenced by multiple factors, including CF, RF power, application duration, inter-lesion distance, catheter orientation, electrode tip size, and catheter stability. Although generator impedance drop (GID) has been explored as a potential lesion monitoring parameter, its accuracy is often compromised by heartbeat-induced oscillations. The EnSite™ X version 3 (Abbott) three-dimensional mapping system incorporates a novel parameter, averaged impedance drop (AID), which filters out these oscillations. This study focuses on analyzing AID dynamics during pulmonary vein isolation, integrating formed lesion-level clinical observations with controlled ex vivo experiments. 2. METHODS 2.1 Study 1: Clinical retrospective analysis from the conventional protocol cohort 2.1.1 Patients We identified 243 consecutive patients who underwent catheter ablation for AF between December 2023 and April 2024 at the National Cerebral and Cardiovascular Center, Suita, Japan. The exclusion criteria were: (1) ablation procedures other than RF applications (n = 58), (2) repeat ablation or prior Cox maze procedure (n = 55), and (3) PV isolation using an RF catheter other than TFSE (n = 100). After applying these criteria, 30 patients with AF treated with initial PV isolation using TFSE were included and retrospectively evaluated. 2.1.2 Baseline characteristics Baseline data on age, sex, height, body weight, and comorbidities were collected upon admission for ablation. Preoperative transthoracic echocardiography was performed by cardiac ultrasonographers using standard protocols, according to the American Society of Echocardiography/European Association of Cardiovascular Imaging [ 11 ]. 2.1.3 Electroanatomical mapping and ablation procedure All patients were sedated with propofol and dexmedetomidine and monitored, maintaining a bispectral index of 40–60 throughout the procedure. After vascular access, intravenous heparin was administered to maintain an activated clotting time of > 300 s. Electrophysiological studies were performed using the EnSite X™ version 3 three-dimensional electroanatomical mapping system. Left atrial electroanatomical mapping was conducted with a multipolar Advisor HD Grid™ (Abbott) catheter. High-density left atrial omnipolar voltage mapping was performed during sinus rhythm or atrial pacing before the ablation procedures, if possible [ 12 ]. Ipsilateral circumferential PV isolation was performed using TFSE. RF energy was delivered point-by-point at 25–50 W for 5–30 s, and the saline irrigation rate was 13 mL/min. A CF ≥ 5–10 g was maintained during ablation. An AF provocation test was performed in all patients after complete routine PV isolation, confirming a bidirectional block. 2.1.4 Primary objective The primary objective of Study 1 was to (1) characterize the relationship between AID% and lesion formation patterns, assessed by the presence or absence of conduction gaps at each pulmonary vein segment; (2) describe ablation parameter distributions in relation to lesion formation patterns. To explore impedance behavior under different ablation conditions, AID% values were analyzed according to RF power categories (≤ 40 W, 41–45 W, and 46–50 W). The encirclement of the superior and inferior PVs was divided into six segments to evaluate conduction gaps [ 13 ]. PV segments with shortened RF duration due to esophageal temperature elevation were excluded from the analysis to minimize confounding effects on impedance behavior. ‘‘First-pass isolation’’ was defined as anatomically continuous PV encirclement without conduction gaps. Lesion formation parameters at each ablation point were obtained from the EnSite Aid Module (Abbott). 2.1.5 Secondary objective The secondary objective of this analysis was to further explore factors associated with variability in AID% behavior. RF applications that did not reach the reference AID% values identified in the primary analysis were descriptively evaluated. Procedural factors (including contact force, RF power, application duration, and inter-lesion distance) and patient-related factors (including local atrial voltage at ablation sites) were examined for their association with AID% behavior. 2.2 Study 2: Ex vivo analysis for evaluating the lesion characteristics associated with AID% behavior 2.2.1 Experimental setup An ex vivo experimental model was used to evaluate the relationship between averaged impedance drop percentage (AID%) and lesion characteristics under controlled conditions. A section of porcine left ventricular myocardium was placed on a ground plate submerged in a circulating saline bath containing 5.0 L of saline maintained at 37°C. A flow pump with a velocity of 0.2 m/s was used to simulate intracardiac flow conditions (Fig. 1 A). The TFSE was positioned either perpendicularly or obliquely at 45° from the tissue surface using a custom-made plastic pipe (Fig. 1 B). To replicate clinical conditions, salinity was carefully controlled to maintain an impedance of 100 ± 5 Ω, measured by the catheter above the myocardial slab, based on typical clinical values. 2.2.2 Ablation protocol Ablations were performed under the following conditions: Power settings : 30, 35, and 40 W targeting AID% 10%; 45 W targeting both AID 10% and 13%; and 50 W targeting AID 13%. CF : Two levels—10 g and 15 g—were applied. Irrigation flow : This was set at 13 mL/min in accordance with the clinical TFSE protocol. RF duration : The RF energy delivery was continued until the targeted AID% value (10% or 13%) was achieved. At least three lesions were created for each combination of settings, and ablation parameters were recorded for analysis. 2.2.3 Lesion assessment After RF delivery, lesion surface and cross-sectional areas were measured (Fig. 1 C). Each lesion was evaluated using a digital caliper with 0.1 mm resolution by a single observer blinded to the ablation conditions. Lesion surface area and volume were calculated using the following formulas: Lesion surface area = 𝜋 × a / 2 × b / 2 Lesion volume = (1 / 6) × 𝜋 × (e2 × d + c × a2 ∕ 2) 2.3 Study 3: Exploratory analysis of AID%-guided ablation workflow Among 1,223 patients treated with AF ablation, we identified 23 consecutive patients who subsequently underwent AID%-guided initial PV isolation, based on the findings from Studies 1 and 2, between May 2024 and September 2025 at the National Cerebral and Cardiovascular Center, Suita, Japan (AID%-guided protocol cohort). The exclusion criteria were: (1) ablation procedures other than RF applications (n = 489), (2) repeat ablation or prior Cox maze procedure (n = 415), and (3) PV isolation using an RF catheter other than TFSE or conventional protocol (n = 297). These patients were compared with the conventional protocol cohort patients to descriptively compare procedural characteristics, including first-pass PV isolation rates. Electroanatomical mapping and ablation procedures were almost the same as those of Study 1, except for the optimal power setting and real-time monitoring of AID%. 2.4 Ethical consideration The ethics committee of the National Cerebral and Cardiovascular Center approved Studies 1 and 3, retrospective analyses of clinically acquired patient data (M26-148). All patients provided written informed consent before undergoing ablation. Study 2 was exempt from ethical approval because it did not involve clinical or animal experimentation. 2.5 Statistical analyses Continuous variables are expressed as mean ± standard deviation (or median [interquartile range]) based on the normality of their distribution, which was assessed using the Kolmogorov–Smirnov test. Depending on the distribution, either Student’s t-test or Mann–Whitney U test was used to compare differences between groups as appropriate. Categorical variables were compared using Fisher’s exact test. Receiver operating characteristic (ROC) curve analysis was performed to describe the discriminative properties of AID% under different RF power settings. Univariate and stepwise multivariate analyses were performed using a logistic regression model to identify factors associated with the outcome and to estimate their odds ratios (ORs) with 95% confidence intervals (CIs). Variables considered clinically relevant to lesion durability and energy delivery, including AID%, GID%, average RF power, contact force, ILD, and ablation duration, were included in the multivariable logistic regression model. All statistical tests were two-sided, and p < 0.05 was considered statistically significant. All statistical analyses were performed using R statistical software (R Foundation for Statistical Computing, Vienna, Austria). 3. RESULTS 3.1 Study 1 Clinical retrospective analysis from the conventional protocol cohort 3.1.1 Baseline characteristics Overall, 30 consecutive patients with AF undergoing initial PV isolation using TFSE were included in the clinical analysis. The mean age was 70 ± 8 years, and 57% were men. The average body mass index was 24 ± 3 kg/m². Paroxysmal AF was observed in 43% of the patients. The median CHADS2 and CHA2DS2-VA scores were 2 [1–3] and 3 [2–4], respectively. Common comorbidities included hypertension (83%), congestive heart failure (53%), and chronic kidney disease (50%). Structural heart disease was present in 30% of the patients. Echocardiography showed a left ventricular ejection fraction of 60 [49–63] %, left atrial diameter of 44 ± 7 mm, and left atrial volume index of 56 ± 19 mL/m². The mean estimated glomerular filtration rate was 58 ± 13 mL/min/1.73 m², and brain natriuretic peptide was 163 [83–271] pg/mL. Baseline characteristics are summarized in Table 1A. 3.1.2 Primary objective PV isolation was successfully achieved in all 30 patients. First-pass isolation was achieved in 20 left PVs (67%) and 22 right (73%). In total, 1,423 RF applications were analyzed, of which 138 (10%) were classified as gap-related lesions. To further clarify the anatomical distribution of conduction gaps, a schematic was created to illustrate the locations of the ablation points and conduction gaps around the PVs (Figure 2A). AID and AID% were significantly lower in the gap segments than in the non-gap segments (11 [8–12] Ω vs. 12 [9–14] Ω, p < 0.001, and 10 [8–12] % vs. 11 [9–13] %, p = 0.002). Significant differences were also in the maximum CF (28 [19–47] g vs. 25 [18–37] g, p = 0.042), average power (42 [39–48] W vs. 44 [39–48] W, p = 0.002), GID (12 [10–14] Ω vs. 13 [11–16] Ω, p = 0.002, and 12 [10–14] % vs. 13 [11–15], p = 0.014) between the gap and the non-gap segments (Table 1B). The overall discriminative performance of AID% for distinguishing gap and non-gap segments was modest (AUC: 0.58). Discriminative performance varied across RF power categories (AUC: 0.58 for ≤40 W, 0.78 for 41–45 W, and 0.53 for 46–50 W) (Figure 2B). In regression analysis, AID% <10% was associated with conduction-gap segments (OR: 1.62; 95% CI: 1.09–2.39; p = 0.016). Average RF power was also associated with conduction-gap formation (OR: 0.95; 95% CI: 0.91–0.98; p = 0.004). In contrast, GID% <10% was not associated with conduction-gap segments in either univariate or multivariate analyses (Table 2). 3.1.3 Secondary objective Of the 1,423 RF applications included in the main analysis, 1,224 with available pre-ablation omnipolar voltage data were included in the sub-analysis. The maximum omnipolar voltage at the ablation site was significantly higher in the conduction-gap segments compared to the non-gap segments (2.6 [1.2–5.1] mV vs. 2.0 [0.9–3.7] mV, p = 0.001). Using a power-specific targeted AID% threshold, 585 applications (48%) were categorized as having a lower AID%. These lesions showed slightly lower average power and average and minimum CF, but no significant differences in duration, temperature, total energy delivery, or omnipolar voltage (Table S1). Multivariate logistic regression analysis showed that average RF power (OR: 1.08; 95% CI: 1.05–1.11; p < 0.001), average CF (OR: 1.10; 95% CI: 1.07–1.14; p < 0.001), and RF duration (OR: 1.03; 95% CI: 1.00–1.05; p = 0.026) were associated with AID% behavior. In contrast, omnipolar voltage was not associated with AID% insufficiency in the multivariable model (OR: 1.00; 95% CI: 0.94–1.05; p = 0.94) (Table 3). 3.2 Study 2: Ex vivo analysis for evaluating the lesion characteristics associated with AID% behavior A total of 152 lesions were included in the ex vivo analysis. No steam pops were observed under any ablation conditions. 3.2.1 Lesion characteristics at AID% 10% Under the AID% 10% condition, lesion characteristics were compared across different RF power settings. Lesion volume decreased with increasing RF power (≤40 W vs. 45 W: 58.5 [36.2–83.1] mm³ vs. 45.4 [30.8–57.0] mm³, p = 0.047; 45 W vs. 50 W: 45.4 [30.8–57.0] mm³ vs. 25.5 [16.7–32.9] mm³, p = 0.001). In contrast, lesion surface area increased with higher RF power (≤40 W vs. 45 W: 10.5 [9.1–13.5] mm² vs. 12.9 [11.0–15.7] mm², p = 0.009; 45 W vs. 50 W: 12.9 [11.0–15.7] mm² vs. 19.2 [15.4–23.4] mm², p < 0.001). Surface diameter was also larger at higher power (≤40 W vs. 45 W: 4.2 [3.7–4.7] mm vs. 4.7 [4.2–5.0] mm, p = 0.018; 45 W vs. 50 W: 4.7 [4.2–5.0] mm vs. 5.3 [4.8–6.3] mm, p = 0.002). Lesion depth decreased with increasing RF power (≤40 W vs. 45 W: 2.8 [2.2–3.4] mm vs. 2.2 [1.8–2.5] mm, p = 0.001; 45 W vs. 50 W: 2.2 [1.8–2.5] mm vs. 1.6 [1.1–1.8] mm, p < 0.001) (Figure 3A). 3.2.2 Lesion characteristics at AID% 13% At the AID% 13% condition, lesion characteristics were compared between the 45 W and 50 W groups. No significant differences were observed in lesion volume (83.5 [57.7–117.8] mm³ vs. 85.6 [66.8–96.2] mm³, p = 0.89), surface area (17.9 [15.2–20.7] mm² vs. 16.9 [14.6–24.8] mm², p = 0.94), surface diameter (5.3 [5.0–6.2] mm vs. 5.5 [5.0–6.2] mm, p = 0.91), or lesion depth (2.8 [2.5–3.5] mm vs. 2.7 [2.2–3.2] mm, p = 0.47) (Figure 3B). 3.2.3 RF application duration The RF application duration required to reach the target AID% was also evaluated. At the AID% 10% condition, the duration was shorter at higher RF power (≤40 W vs. 45 W: 12 [8–16.5] s vs. 6 [4–7] s, p < 0.001; 45 W vs. 50 W: 6 [4–7] s vs. 4 [4–4] s, p < 0.001). At the AID% 13% condition, no significant difference was observed between the 45 W and 50 W groups (9.5 [6.8–12] s vs. 9.0 [6–13] s, p = 0.58). Within the 45 W setting, the duration was shorter at the AID% 10% target than at 13% (6 [4–7] s vs. 9.5 [6.8–12] s, p < 0.001) (Figure 4). 3.2.4 Comparison between AID% 10% and 13% at 45 W At 45 W, lesion characteristics were compared between AID% 10% and 13%. Lesion volume was larger at AID% 13% (83.5 [57.7–117.8] mm³ vs. 45.4 [30.8–57.0] mm³, p < 0.001). Surface area (17.9 [15.2–20.7] mm² vs. 12.9 [11.0–15.7] mm², p < 0.001), surface diameter (5.3 [5.0–6.2] mm vs. 4.7 [4.2–5.0] mm, p < 0.001), and lesion depth (2.8 [2.5–3.5] mm vs. 2.2 [1.8–2.5] mm, p < 0.001) were also greater at AID% 13% (Figure 5). 3.2.5 Effect of catheter orientation Lesion characteristics were compared between oblique (45°) and perpendicular (90°) catheter orientations. Lesion volume did not differ significantly between the two groups (49.3 [28.6–80.9] mm³ vs. 56.2 [35.2–91.9] mm³, p = 0.090). Surface area (17.3 [13.4–22.8] mm² vs. 14.3 [11.6–17.0] mm², p < 0.001) and surface diameter (5.2 [4.5–6.6] mm vs. 4.8 [4.3–5.3] mm, p = 0.002) were larger in oblique applications. Lesion depth was greater in perpendicular applications (2.2 [1.6–2.9] mm vs. 2.5 [2.0–3.2] mm, p = 0.042) (Figure S1). 3.3 Study 3 Exploratory analysis of AID%-guided ablation workflow 3.3.1 Baseline characteristics Overall, 23 consecutive patients with AF who initially underwent the AID%-guided PV isolation using TFSE were included. The mean age was 70 ± 11 years, and 61% were men. The average body mass index was 23 ± 4 kg/m². Paroxysmal AF was observed in 48% of the patients. No statistically significant differences in baseline clinical characteristics were observed between the two groups (Table 1A). 3.3.2 Ablation protocol Ablations were performed under the following conditions: Power settings: 45 W targeting AID 11–13% (RPV and the roof, supero-anterior, infero-anterior segments of LPV); 30, 35, and 40 W targeting AID% 10% (the bottom, supero-posterior, infero-posterior segments of LPV). CF: ≥5–10 g was maintained. Irrigation flow: This was set at 13 mL/min in accordance with the clinical TFSE protocol. RF duration: The point-by-point RF energy delivery was continued until 24 s or the targeted AID% value (11–13%) was achieved, with durations ranging from at least 16 s to a maximum of 24 s. When the esophageal temperature rose above 39℃, we immediately stopped the application. 3.3.3 First-pass isolation percentage PV isolation was successfully performed without any complications and steam pops in all the cases. Although not significant, the first-pass isolation percentages of both PVs were numerically higher in the AID%-guided protocol cohort patients than in the conventional protocol cohort patients (LPV, 78% vs. 67%, p = 0.54; RPV, 87% vs. 73%, p = 0.31, Figure S2). 4. DISCUSSION 4.1 Major findings In this study, we present a combined clinical and ex vivo evaluation of AID% behavior during PV isolation. The major findings are summarized as follows: i. AID% values differed between gap and non-gap segments, although overall discriminative performance was modest except for 41–45W RF power settings. ii. Lower AID% values were associated with conduction-gap segment formation. iii. The ex vivo analysis demonstrated differences in lesion characteristics under varying AID% targets and RF power settings. iv. First-pass isolation percentages were numerically higher in the AID%-guided cohort compared with the conventional cohort. 4.2 Clinical implications from the conventional protocol cohort Our findings suggest that AID% reflects real-time tissue response during RF delivery using a TFSE catheter rather than serves as a standalone predictor of lesion durability. Traditional surrogate indicators, such as the CF, force–time integral [14], or lesion size index, have been widely used. However, these parameters represent cumulative metrics based on input energy and may not accurately reflect the underlying tissue response. Notably, the clinical application of GID as a key lesion marker [15-17], has declined owing to limitations in specificity, sensitivity to physiological noise, and lack of standardization across mapping systems. In contrast, AID% reflects a filtered AID ratio rather than an absolute value and may offer a more robust and reproducible measure of tissue response during ablation. In our study, the overall discriminative performance of AID% was modest, and varied depending on RF power settings. These findings suggest that impedance behavior is influenced by multiple factors, including power delivery and catheter–tissue interaction, rather than any single parameter alone. In the sub-analysis, higher local omnipolar voltage was more frequently observed in conduction-gap segments, suggesting potential differences in underlying tissue properties. This observation is consistent with previous reports demonstrating that higher atrial voltage is associated with gap-related lesion formation, likely reflecting thicker atrial myocardium or preserved viable tissue requiring greater energy delivery. Takigawa et al. reported that higher bipolar voltage was associated with incomplete lesion formation despite high-power ablation [18]. However, in the present analysis, AID% behavior was more closely associated with procedural factors, including RF power, contact force, and application duration, while omnipolar voltage was not independently associated with AID% behavior in the multivariable analysis. These findings suggest that AID% behavior reflects not only intrinsic tissue characteristics but also energy-delivery conditions that are modifiable during ablation. 4.3 Additional ex vivo and clinical studies In the ex vivo analysis, lesion characteristics varied according to both RF power and AID% levels. At a lower AID% target, increasing RF power was associated with larger surface dimensions but reduced lesion depth, suggesting that lesion geometry is influenced by the energy delivery profile even when impedance changes are similar. In contrast, at a higher AID% level, lesion characteristics were more consistent across different power settings. A direct comparison under a fixed RF power setting demonstrated that higher AID% levels were associated with larger lesion dimensions. These findings are consistent with previous experimental studies showing that lesion geometry depends on both delivered power and duration, rather than a single parameter alone. In particular, Suga et al. reported that lesion formation during RF ablation is determined by the balance between resistive and conductive heating, with higher power favoring broader surface lesions and longer duration contributing to deeper tissue penetration [19]. Catheter orientation also influenced lesion characteristics, with oblique applications producing broader lesions and perpendicular applications resulting in deeper lesions. No steam pops were observed in this experimental setting. In the exploratory cohort, AID%-guided ablation was implemented without procedural complications, and first-pass isolation rates were numerically higher compared with the conventional cohort, although differences were not statistically significant. Given the small sample size and non-randomized design, these findings should be interpreted as hypothesis-generating. 5. Study limitations First, the clinical analysis was retrospective and conducted at a single center, which may limit generalizability. Second, AID% is a parameter specific to TFSE and cannot be measured using other ablation catheters or systems. Third, although omnipolar voltage data were included in the sub-analysis, not all RF applications had corresponding electroanatomical map data, potentially introducing selection bias. Fourth, all clinically relevant factors were included in the multivariable regression model, and despite the significant findings, the potential influence of collinearity among energy-delivery parameters (power, contact force, and duration) cannot be fully excluded. Fifth, ex vivo validation was performed on porcine myocardium under non-beating, temperature-controlled conditions, which might not fully replicate the clinical environment of a beating human heart. Finally, the comparison between the conventional and AID%-guided protocols was exploratory and based on a small retrospectively evaluated subgroup, which may limit the statistical power of the findings. Although numerically higher rates of PV isolation were observed without steam pops in a limited number of AID%-guided cases, further prospective studies are required to clarify the clinical implications of AID%-guided ablation. 6. CONCLUSION AID% is associated with lesion formation characteristics under both clinical and controlled experimental conditions, despite a variability in discriminative performance across RF power settings. These findings suggest that AID% may be useful as a physiological indicator of lesion formation dynamics, reflecting real-time tissue response during RF application using TFSE, rather than serving as a standalone predictor of lesion durability. Declarations Acknowledgments: The authors thank Editage for English-language editing, and Kim Sugi, Keisuke Hayashi, Taisuke Kanaoka, Masato Okamoto (Abbott Medical Japan), and Toru Yamaguchi (Nihon Kohden) for their technical assistance with the ex vivo validation study. Data availability: The data that support the findings of this study are not publicly available due to ethical and privacy restrictions, but are available from the corresponding author upon reasonable request. Funding statement: N/A. Conflict of interest disclosure: Kengo Kusano received speaker honoraria from Daiichi Sankyo Company and Medtronic, and research grants from Medtronic and JSR outside the submitted work. Koji Miyamoto received funding, grants, and speaker honoraria from Medtronic, Biosense Webster, Abbott, and Boston Scientific outside the submitted work. He is also affiliated with a department endowed by Medtronic outside the submitted work. Tsukasa Kamakura received honoraria from Biosense Webster, Medtronic, and Boston Scientific outside the submitted work. Nobuhiko Ueda and Satoshi Oka received honoraria for lectures from Medtronic outside the submitted work. Akinori Wakamiya received honoraria for lectures from Biosense Webster, Medtronic, and BIOTRONIK outside the submitted work. The other authors had no conflicts of interest to declare. Ethics approval statement: The ethics committee of the National Cerebral and Cardiovascular Center approved the clinical part of this study (Study 1 and 3, M26-148). Study 2 (the experimental part of this study) did not require ethics approval because it did not involve either clinical or animal experimentation. Patient consent statement: All patients provided written informed consent. Registry: Not applicable. Animal studies: No animal experimentation was performed in this study, while the non-flesh porcine left ventricular myocardium was used for ex vivo analysis. Capsule Summary: The averaged impedance drop was associated with conduction-gap formation and ex vivo lesion geometry during pulmonary vein isolation, supporting its role as a real-time indicator of lesion-formation dynamics. Author Contribution N.N. conceived and designed the study, collected and analyzed the data, and drafted the initial manuscript. S.O. supervised the study, contributed to study design and data interpretation, and critically revised the manuscript for important intellectual content. A.W., N.U., K.N., T.K., M.W., Y.I., K.M., H.M., and K.K. contributed to data acquisition and interpretation and provided important intellectual input. All authors reviewed and approved the final manuscript. References Haïssaguerre M, Jaïs P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998;339:659–66. https://doi.org/10.1056/NEJM199809033391003 . Ninomiya Y, Inoue K, Tanaka N, et al. Absence of first-pass isolation is associated with poor pulmonary vein isolation durability and atrial fibrillation ablation outcomes. J Arrhythm. 2021;37:1468–76. https://doi.org/10.1002/joa3.12629 . Osorio J, Hunter TD, Rajendra A, Zei P, Silverstein J, Morales G. Predictors of clinical success after paroxysmal atrial fibrillation catheter ablation. J Cardiovasc Electrophysiol. 2021;32:1814–21. https://doi.org/10.1111/jce.15028 . Okamatsu H, Okumura K, Onishi F, et al. Predictors of pulmonary vein non-reconnection in the second procedure after ablation index-guided pulmonary vein isolation for atrial fibrillation and its impact on the outcome. J Cardiovasc Electrophysiol. 2023;34:2452–60. https://doi.org/10.1111/jce.16084 . Matsumoto K, Tanaka N, Sasaki W, et al. Feasibility and efficacy of 50 W ablation with the TactiFlex catheter for the initial pulmonary vein isolation of atrial fibrillation. J Arrhythm. 2025;41:e13191. https://doi.org/10.1002/joa3.13191 . Yamaguchi J, Takigawa M, Goya M, et al. Safety verification of a novel irrigation catheter with flexible tip of laser-cut kerfs and contact force sensor. Pacing Clin Electrophysiol. 2023;46:1536–45. https://doi.org/10.1111/pace.14868 . Matsumoto K, Kawano D, Sasaki W, et al. Detailed investigation of the lesion formation with a novel contact force sensing catheter with a mesh-shaped irrigation tip. J Arrhythm. 2023;39:166–74. https://doi.org/10.1002/joa3.12835 . Dello Russo A, D'Angelo L, Compagnucci P, et al. High-power short-duration catheter ablation of atrial fibrillation: is it really a new era? Comparison between new and old radiofrequency contact force-sensing catheters. J Interv Card Electrophysiol. 2024;67:549–57. https://doi.org/10.1007/s10840-023-01612-x . Mattia L, Crosato M, Indiani S, et al. Prospective Evaluation of Lesion Index-Guided Pulmonary Vein Isolation Technique in Patients with Paroxysmal Atrial Fibrillation: 1-year Follow-Up. J Atr Fibrillation. 2018;10:1858. https://doi.org/10.4022/jafib.1858 . Kaneko Y, Naruse Y, Narumi T, Sano M, Urushida T, Maekawa Y. Evaluation and comparison of impedance and amplitude changes in lesion index-guided pulmonary vein isolation. J Arrhythmia. 2024;40:100–8. https://doi.org/10.1002/joa3.12966 . Lang RM, Badano LP, Mor-Avi V, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2015;16:233–70. https://doi.org/10.1093/ehjci/jev014 . Dittrich S, Scheurlen C, van den Bruck JH, et al. The omnipolar mapping technology—a new mapping tool to overcome bipolar blindness resulting in true high-density maps. J Interv Card Electrophysiol. 2024;67:399–408. https://doi.org/10.1007/s10840-023-01562-4 . Inoue K, Tanaka N, Ikada Y, et al. Characterizing clinical outcomes and factors associated with conduction gaps in VISITAG SURPOINT-guided catheter ablation for atrial fibrillation. J Arrhythm. 2021;37:574–83. https://doi.org/10.1002/joa3.12544 . Kautzner J, Neuzil P, Lambert H, et al. EFFICAS II: optimization of catheter contact force improves outcome of pulmonary vein isolation for paroxysmal atrial fibrillation. Europace. 2015;17:1229–35. https://doi.org/10.1093/europace/euv057 . Yokoyama K, Nakagawa H, Shah DC, et al. Novel contact force sensor incorporated in irrigated radiofrequency ablation catheter predicts lesion size and incidence of steam pop and thrombus. Circ Arrhythm Electrophysiol. 2008;1:354–62. https://doi.org/10.1161/CIRCEP.108.803650 . Ikeda A, Nakagawa H, Lambert H, et al. Relationship between catheter contact force and radiofrequency lesion size and incidence of steam pop in the beating canine heart: electrogram amplitude, impedance, and electrode temperature are poor predictors of electrode-tissue contact force and lesion size. Circ Arrhythm Electrophysiol. 2014;7:1174–80. https://doi.org/10.1161/CIRCEP.113.001094 . Reichlin T, Knecht S, Lane C, et al. Initial impedance decrease as an indicator of good catheter contact: insights from radiofrequency ablation with force sensing catheters. Heart Rhythm. 2014;11:194–201. https://doi.org/10.1016/j.hrthm.2013.10.048 . Takigawa M, Miyazaki S, Yamamoto T, et al. Significance of the local largest bipolar voltage for the optimized ablation strategy using very high-power short-duration mode. J Cardiovasc Electrophysiol. 2025;36:111–23. https://doi.org/10.1111/jce.16453 . Suga K, Yamazaki K, Sakurai T, et al. Evaluation of averaged impedance drop percent as a real-time parameter for safe and effective prolonged radiofrequency ablation using the TactiFlex SE catheter: an ex vivo study. J Interv Card Electrophysiol. 2025. https://doi.org/10.1007/s10840-025-02112-w . Tables Table 1. (A) Baseline clinical characteristics, echocardiographic findings, and laboratory data in the Conventional and AID%-guided protocols (B) Comparison of ablation parameters between gap and non-gap segments This table summarizes the baseline characteristics of the 53 enrolled patients (A) and parameters involved in ablation lesion formation (B). Data are presented as means ± standard deviations (normally distributed data), medians and interquartile ranges (non-normally distributed data), and n (%). All statistical tests were 2-tailed, and p<0.05 was considered significant (*). Abbreviations: eGFR, estimated glomerular filtration rate; BNP, brain natriuretic peptide ; CF, contact force; AID, averaged impedance drop; GID, generator impedance drop. Table 1A All (n = 53) Conventional protocol (n = 30) AID%-guided protocol (n = 23) p-value Clinical backgrounds Age [years] 70 ± 9 70 ± 8 70 ± 11 .78 Male sex [(%)] 31 (58) 17 (57) 14 (61) .79 Body mass index [kg/m 2 ] 24 ± 4 24 ± 3 23 ± 4 .35 Paroxysmal atrial fibrillation [(%)] 24 (45) 13 (43) 11 (48) .79 CHADS2 Score 2 [1-3] 2 [1-3] 2 [1-3] .61 CHA2DS2-VA Score 3 [2-4] 3 [2-4] 3 [2-4] .48 Congestive heart failure [(%)] 26 (49) 16 (53) 10 (43) .58 Hypertension [(%)] 42 (79) 25 (83) 17 (74) .50 Diabetes mellitus [(%)] 15 (28) 7 (23) 8 (35) .38 History of stroke [(%)] 3 (6) 2 (7) 1 (4) >0.99 Structural heart disease [(%)] 14 (26) 9 (30) 5 (22) .55 Chronic kidney disease [(%)] 22 (42) 15 (50) 7 (30) .17 Imaging variables Left ventricular ejection fraction [%] 60 [55-63] 60 [49-63] 60 [57-64] .25 Left atrial diameter [mm] 43 ± 7 44 ± 7 42 ± 8 .32 Left atrial volume index [mm/m 2 ] 55 ± 21 56 ± 19 55 ± 24 .87 Laboratory data eGFR [mL/min/1.73 m 2 ] 60 ± 14 58 ± 13 63 ± 16 .17 BNP [pg/mL] 111 [61-230] 163 [83-271] 71 [51-169] .066 Table 1B All (n=1423) Gap segment (n=138) Non-gap segment (n=1285) P-value Average CF (g) 11 [8-14] 11.5 [8-14] 11.0 [8-14] .96 Maximum CF (g) * 25 [18-38] 27.5 [19-46.8] 25.0 [18-38] .042 * Minimum CF (g) 2 [0-4] 2 [1-4] 2 [0-4] .47 Maximum temperature (℃) 34 [33-36] 34 [33-36] 34 [33-36] .79 Average power (W) * 44 [39-48] 42 [39-48] 44 [39-48] .002 * Duration (s) 21 [18-25] 21.5 [18-27] 21.0 [18-25] .14 Energy (W) 977 [824.5-1076.5] 953.5 [782-1099.5] 977.0 [834-1073] 1.00 ILD (mm) 3.7 [2.9-4.5] 3.6 [2.8-4.6] 3.7 [2.9-4.5] .88 GID (Ω) * 13 [11-16] 12 [10-14] 13 [11-16] .002 * GID (%) * 13 [11-15] 12 [10-14] 13 [11-15] .014 * AID(Ω) * 11 [9-14] 10 [8-12] 11 [9-14] <.001 * AID (%) * 11 [9-13] 10 [8-12] 11 [9-13] .002 * Table 2. Logistic regression analysis for predicting the formation of gap segments. All statistical tests were 2-tailed, and p<0.05 was considered significant (*). Abbreviations: CI, confidence interval; CF, contact force; AID, averaged impedance drop; GID, generator impedance drop Univariate Logistic analysis Multivariate Logistic analysis Odds Ratio 95% CI P-value Odds Ratio 95% CI P-value GID % <10% 0.97 0.55 – 1.70 .91 0.71 0.38 – 1.30 .26 AID % <10% * 1.50 1.05 – 2.13 .025 1.62 1.09 - 2.39 .016 * Average power (W) * 0.94 0.91 - 0.98 .002 0.95 0.91 - 0.98 .004 * Average CF (g) 0.99 0.95 - 1.04 .74 1.00 0.96 – 1.04 .96 ILD (mm) 0.97 0.86 - 1.10 .66 0.99 0.89 – 1.11 .90 Duration (s) 1.03 0.99 - 1.06 .14 1.02 0.98 – 1.05 .38 Table 3. Logistic regression analyses for factors associated with lower AID% attainment during PVI. All statistical tests were 2-tailed, and p<0.05 was considered significant (*). Abbreviations: CI, confidence interval; CF, contact force; PVI, pulmonary vein isolation. Univariate Logistic analysis Multivariate Logistic analysis Odds Ratio 95% CI P-value Odds Ratio 95% CI P-value Average power (W) * 1.06 1.04 - 1.09 <.001 1.08 1.05 - 1.11 <.001 * Average CF (g) * 1.09 1.06 - 1.12 <.001 1.10 1.07 - 1.14 <.001 * Duration (s) * 1.00 0.98 - 1.02 .79 1.03 1.00 - 1.05 .026 * Omnipolar voltage (mV) 0.98 0.93 - 1.03 .35 1.00 0.94 – 1.05 .94 Additional Declarations Competing interest reported. Kengo Kusano received speaker honoraria from Daiichi Sankyo Company and Medtronic, and research grants from Medtronic and JSR outside the submitted work. Koji Miyamoto received funding, grants, and speaker honoraria from Medtronic, Biosense Webster, Abbott, and Boston Scientific outside the submitted work. He is also affiliated with a department endowed by Medtronic outside the submitted work. Tsukasa Kamakura received honoraria from Biosense Webster, Medtronic, and Boston Scientific outside the submitted work. Nobuhiko Ueda and Satoshi Oka received honoraria for lectures from Medtronic outside the submitted work. Akinori Wakamiya received honoraria for lectures from Biosense Webster, Medtronic, and BIOTRONIK outside the submitted work. The other authors had no conflicts of interest to declare. Supplementary Files Supplementaryfile.docx TableS1.docx FigureS2.tif FigureS1.tif Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-9473730","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":634394620,"identity":"b531b91f-0760-4307-a3d3-999cece152fb","order_by":0,"name":"Nobuhiro Nakamura","email":"","orcid":"","institution":"National Cerebral and Cardiovascular Center","correspondingAuthor":false,"prefix":"","firstName":"Nobuhiro","middleName":"","lastName":"Nakamura","suffix":""},{"id":634394621,"identity":"425b841b-0b25-437e-9b83-7ae92487897a","order_by":1,"name":"Satoshi 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14:39:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9473730/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9473730/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108940121,"identity":"748004fc-2988-4bf8-83a1-c3e2121ac559","added_by":"auto","created_at":"2026-05-11 05:11:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":7244860,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eExperimental setup and lesion assessment method for \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eex vivo\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e RF ablation.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A) \u003c/strong\u003eOverview of the experimental setup using a circulating saline bath maintained at 37°C with a flow pump simulating left atrial blood flow. The TactiFlex™ Sensor Enabled™ catheter was used for \u003cem\u003eex vivo\u003c/em\u003eablation of porcine myocardium submerged in saline. An example of ablated porcine myocardium is also shown.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(B)\u003c/strong\u003e Adjustable catheter orientation with controlled ablation angles: perpendicular 90° (left) and oblique 45° (right) to the myocardial surface, fixed using a custom-made plastic support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(C)\u003c/strong\u003e Schematic illustrations for lesion dimension measurement.\u003c/p\u003e\n\u003cp\u003e· \u003cem\u003eSurface image\u003c/em\u003e: Horizontal (a) and vertical (b) diameters.\u003c/p\u003e\n\u003cp\u003e· \u003cem\u003eCross-sectional image\u003c/em\u003e: lesion width at the surface (a), maximum depth (d), depth at maximum surface width (c), and basal width (e).\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/823d2f537b457a216a0066ec.png"},{"id":108940171,"identity":"f36d31cb-2b1e-422c-9f93-db71211238be","added_by":"auto","created_at":"2026-05-11 05:11:40","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1778922,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eConduction gap segment analysis and receiver operating characteristic curves to determine a reference AID% value for predicting sufficient lesion formation.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A) \u003c/strong\u003eConduction gap segment analyses. Among the 30 patients of the conventional protocol cohort, first-pass isolation was achieved in 20 left (67%) and 22 right (73%) pulmonary veins. After excluding the supero-posterior, infero-posterior, and bottom segment of the left pulmonary vein, where radiofrequency applications potentially terminated due to the rise of esophageal temperature (blue circles), 1,423 radiofrequency applications were analyzed (red circles), including 138 (10%) applications classified as having gap-related lesions distributed at the conduction gap segment (star).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(B) \u003c/strong\u003eReceiver operating characteristic analyses were performed overall and stratified according to radiofrequency power. The diagnostic performance of AID% was highest in the 41–45 W group.\u003c/p\u003e\n\u003cp\u003eAbbreviations: AID, averaged impedance drop; ROC, receiver operating characteristic; AUC, area under the curve; CI, confidence interval; W, watts.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/c5ddbb9b5715276c02d886c7.png"},{"id":108939968,"identity":"5e8b85c8-8308-4144-a219-b9f3eb135bf9","added_by":"auto","created_at":"2026-05-11 05:10:53","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":761476,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLesion characteristics by power output under AID-guided ablation in \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eex vivo\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e ablation study.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eComparison of lesion volume, surface area, surface diameter, and depth (A) under averaged impedance drop (AID) 10% conditions between ≤40 W, 45 W, and 50 W groups, and (B) under AID 13% conditions between 45 W and 50 W groups.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/7225cc7354949a6e79ddf727.png"},{"id":108940110,"identity":"8a57583b-1385-441d-a5f1-3149c6ac8d4a","added_by":"auto","created_at":"2026-05-11 05:11:19","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":461867,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDuration to reach targeted AID% in \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eex vivo\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e ablation study\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eComparison of radiofrequency application durations required to reach the targeted averaged impedance drop (AID) under various conditions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003eComparison between ≤40 W, 45 W, and 50 W groups under the AID 10% target.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(B)\u003c/strong\u003e Comparison between 45 W and 50 W groups under the AID 13% target.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(C)\u003c/strong\u003e Comparison between AID 10% and AID 13% targets at 45 W output.\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/1db5985c837b7a2a658b031c.png"},{"id":108940112,"identity":"33187548-6d83-4620-a1bb-9e5729021af4","added_by":"auto","created_at":"2026-05-11 05:11:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":3173374,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLesion characteristics at 45 W comparing AID 10% vs. AID 13% targets in \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eex vivo\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e ablation study\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eComparison of lesion volume, surface area, surface diameter, and depth between averaged impedance drop 10% and 13% targets at 45 W output.\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/995b9b0debf65fe1be819436.png"},{"id":108940379,"identity":"99f9fbc5-c532-4008-8b55-625b46fb8e53","added_by":"auto","created_at":"2026-05-11 05:12:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":13304296,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/fc9d1a2a-2fe8-44b2-8870-673fbe114692.pdf"},{"id":108940111,"identity":"f537087f-08f0-4ba5-8cf3-55e5e81ec154","added_by":"auto","created_at":"2026-05-11 05:11:19","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":661947,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryfile.docx","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/d4912248651d1e5a369b7226.docx"},{"id":108940118,"identity":"a3007e6b-8fe4-4981-8fc3-009b5230d92c","added_by":"auto","created_at":"2026-05-11 05:11:21","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":18104,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1.docx","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/2d0ca5cdc5b20ad056cd1a0b.docx"},{"id":108940103,"identity":"356b9d93-5d4e-4bfe-8f5a-a1da16fbb130","added_by":"auto","created_at":"2026-05-11 05:11:15","extension":"tif","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":203024,"visible":true,"origin":"","legend":"","description":"","filename":"FigureS2.tif","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/08929158fa2454785d837f93.tif"},{"id":108940109,"identity":"97082cb1-5540-40ab-990a-d230c4ead1e0","added_by":"auto","created_at":"2026-05-11 05:11:18","extension":"tif","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":952892,"visible":true,"origin":"","legend":"","description":"","filename":"FigureS1.tif","url":"https://assets-eu.researchsquare.com/files/rs-9473730/v1/4ef08e1f4a615b0334cfdf85.tif"}],"financialInterests":"Competing interest reported. Kengo Kusano received speaker honoraria from Daiichi Sankyo Company and Medtronic, and research grants from Medtronic and JSR outside the submitted work. Koji Miyamoto received funding, grants, and speaker honoraria from Medtronic, Biosense Webster, Abbott, and Boston Scientific outside the submitted work. He is also affiliated with a department endowed by Medtronic outside the submitted work. Tsukasa Kamakura received honoraria from Biosense Webster, Medtronic, and Boston Scientific outside the submitted work. Nobuhiko Ueda and Satoshi Oka received honoraria for lectures from Medtronic outside the submitted work. Akinori Wakamiya received honoraria for lectures from Biosense Webster, Medtronic, and BIOTRONIK outside the submitted work. The other authors had no conflicts of interest to declare.","formattedTitle":"Averaged Impedance Drop as an Indicator of Lesion Formation Dynamics During Radiofrequency Catheter Ablation","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eElectrical pulmonary vein (PV) isolation is an established treatment for atrial fibrillation (AF), as arrhythmogenic triggers often arise from the PVs [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. In procedures using ipsilateral circumferential radiofrequency (RF) applications to isolate the left and right PVs, achieving first-pass isolation is associated with durable PV isolation [\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA contact force (CF)-sensing catheter with a mesh-shaped flexible irrigation tip, TactiFlex\u0026trade;, Sensor Enabled\u0026trade; (TFSE, Abbott, Abbott Park, IL, USA) enables high-power, short-duration RF applications [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Previous studies have demonstrated the efficacy and safety of PV isolation using TFSE compared with conventional ablation catheters [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, real-time assessment of tissue response and lesion formation during RF delivery remains challenging, and optimized ablation strategies using this catheter have not been fully established, partly due to the lack of lesion size index [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] guidance. Even in the era of pulsed-field ablation, RF application is expected to continue with novel technologies, such as a next-generation dual-energy ablation catheter (TactiFlex\u0026trade; Duo, Sensor Enabled\u0026trade;, Abbott), underscoring the need for a deeper understanding of tissue responses during RF delivery.\u003c/p\u003e \u003cp\u003eAblation lesion formation is influenced by multiple factors, including CF, RF power, application duration, inter-lesion distance, catheter orientation, electrode tip size, and catheter stability. Although generator impedance drop (GID) has been explored as a potential lesion monitoring parameter, its accuracy is often compromised by heartbeat-induced oscillations. The EnSite\u0026trade; X version 3 (Abbott) three-dimensional mapping system incorporates a novel parameter, averaged impedance drop (AID), which filters out these oscillations.\u003c/p\u003e \u003cp\u003eThis study focuses on analyzing AID dynamics during pulmonary vein isolation, integrating formed lesion-level clinical observations with controlled ex vivo experiments.\u003c/p\u003e"},{"header":"2. METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study 1: Clinical retrospective analysis from the conventional protocol cohort\u003c/h2\u003e \u003cdiv id=\"Sec4\" class=\"Section3\"\u003e \u003ch2\u003e2.1.1 Patients\u003c/h2\u003e \u003cp\u003eWe identified 243 consecutive patients who underwent catheter ablation for AF between December 2023 and April 2024 at the National Cerebral and Cardiovascular Center, Suita, Japan. The exclusion criteria were: (1) ablation procedures other than RF applications (n\u0026thinsp;=\u0026thinsp;58), (2) repeat ablation or prior Cox maze procedure (n\u0026thinsp;=\u0026thinsp;55), and (3) PV isolation using an RF catheter other than TFSE (n\u0026thinsp;=\u0026thinsp;100). After applying these criteria, 30 patients with AF treated with initial PV isolation using TFSE were included and retrospectively evaluated.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.1.2 Baseline characteristics\u003c/h2\u003e \u003cp\u003eBaseline data on age, sex, height, body weight, and comorbidities were collected upon admission for ablation. Preoperative transthoracic echocardiography was performed by cardiac ultrasonographers using standard protocols, according to the American Society of Echocardiography/European Association of Cardiovascular Imaging [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.1.3 Electroanatomical mapping and ablation procedure\u003c/h2\u003e \u003cp\u003eAll patients were sedated with propofol and dexmedetomidine and monitored, maintaining a bispectral index of 40\u0026ndash;60 throughout the procedure. After vascular access, intravenous heparin was administered to maintain an activated clotting time of \u0026gt;\u0026thinsp;300 s. Electrophysiological studies were performed using the EnSite X\u0026trade; version 3 three-dimensional electroanatomical mapping system. Left atrial electroanatomical mapping was conducted with a multipolar Advisor HD Grid\u0026trade; (Abbott) catheter. High-density left atrial omnipolar voltage mapping was performed during sinus rhythm or atrial pacing before the ablation procedures, if possible [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIpsilateral circumferential PV isolation was performed using TFSE. RF energy was delivered point-by-point at 25\u0026ndash;50 W for 5\u0026ndash;30 s, and the saline irrigation rate was 13 mL/min. A CF\u0026thinsp;\u0026ge;\u0026thinsp;5\u0026ndash;10 g was maintained during ablation. An AF provocation test was performed in all patients after complete routine PV isolation, confirming a bidirectional block.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.1.4 Primary objective\u003c/h2\u003e \u003cp\u003eThe primary objective of Study 1 was to (1) characterize the relationship between AID% and lesion formation patterns, assessed by the presence or absence of conduction gaps at each pulmonary vein segment; (2) describe ablation parameter distributions in relation to lesion formation patterns.\u003c/p\u003e \u003cp\u003eTo explore impedance behavior under different ablation conditions, AID% values were analyzed according to RF power categories (\u0026le;\u0026thinsp;40 W, 41\u0026ndash;45 W, and 46\u0026ndash;50 W).\u003c/p\u003e \u003cp\u003eThe encirclement of the superior and inferior PVs was divided into six segments to evaluate conduction gaps [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. PV segments with shortened RF duration due to esophageal temperature elevation were excluded from the analysis to minimize confounding effects on impedance behavior. \u0026lsquo;\u0026lsquo;First-pass isolation\u0026rsquo;\u0026rsquo; was defined as anatomically continuous PV encirclement without conduction gaps. Lesion formation parameters at each ablation point were obtained from the EnSite Aid Module (Abbott).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.1.5 Secondary objective\u003c/h2\u003e \u003cp\u003eThe secondary objective of this analysis was to further explore factors associated with variability in AID% behavior. RF applications that did not reach the reference AID% values identified in the primary analysis were descriptively evaluated.\u003c/p\u003e \u003cp\u003eProcedural factors (including contact force, RF power, application duration, and inter-lesion distance) and patient-related factors (including local atrial voltage at ablation sites) were examined for their association with AID% behavior.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Study 2: \u003cem\u003eEx vivo\u003c/em\u003e analysis for evaluating the lesion characteristics associated with AID% behavior\u003c/h2\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Experimental setup\u003c/h2\u003e \u003cp\u003eAn ex vivo experimental model was used to evaluate the relationship between averaged impedance drop percentage (AID%) and lesion characteristics under controlled conditions. A section of porcine left ventricular myocardium was placed on a ground plate submerged in a circulating saline bath containing 5.0 L of saline maintained at 37\u0026deg;C. A flow pump with a velocity of 0.2 m/s was used to simulate intracardiac flow conditions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). The TFSE was positioned either perpendicularly or obliquely at 45\u0026deg; from the tissue surface using a custom-made plastic pipe (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). To replicate clinical conditions, salinity was carefully controlled to maintain an impedance of 100\u0026thinsp;\u0026plusmn;\u0026thinsp;5 Ω, measured by the catheter above the myocardial slab, based on typical clinical values.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Ablation protocol\u003c/h2\u003e \u003cp\u003eAblations were performed under the following conditions:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003ePower settings\u003c/b\u003e: 30, 35, and 40 W targeting AID% 10%; 45 W targeting both AID 10% and 13%; and 50 W targeting AID 13%.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eCF\u003c/b\u003e: Two levels\u0026mdash;10 g and 15 g\u0026mdash;were applied.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eIrrigation flow\u003c/b\u003e: This was set at 13 mL/min in accordance with the clinical TFSE protocol.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eRF duration\u003c/b\u003e: The RF energy delivery was continued until the targeted AID% value (10% or 13%) was achieved.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eAt least three lesions were created for each combination of settings, and ablation parameters were recorded for analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Lesion assessment\u003c/h2\u003e \u003cp\u003eAfter RF delivery, lesion surface and cross-sectional areas were measured (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). Each lesion was evaluated using a digital caliper with 0.1 mm resolution by a single observer blinded to the ablation conditions. Lesion surface area and volume were calculated using the following formulas:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eLesion surface area = \u0026#120587; \u0026times; a / 2 \u0026times; b / 2\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eLesion volume = (1 / 6) \u0026times; \u0026#120587; \u0026times; (e2 \u0026times; d\u0026thinsp;+\u0026thinsp;c \u0026times; a2 ∕ 2)\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Study 3: Exploratory analysis of AID%-guided ablation workflow\u003c/h2\u003e \u003cp\u003e Among 1,223 patients treated with AF ablation, we identified 23 consecutive patients who subsequently underwent AID%-guided initial PV isolation, based on the findings from Studies 1 and 2, between May 2024 and September 2025 at the National Cerebral and Cardiovascular Center, Suita, Japan (AID%-guided protocol cohort). The exclusion criteria were: (1) ablation procedures other than RF applications (n\u0026thinsp;=\u0026thinsp;489), (2) repeat ablation or prior Cox maze procedure (n\u0026thinsp;=\u0026thinsp;415), and (3) PV isolation using an RF catheter other than TFSE or conventional protocol (n\u0026thinsp;=\u0026thinsp;297). These patients were compared with the conventional protocol cohort patients to descriptively compare procedural characteristics, including first-pass PV isolation rates. Electroanatomical mapping and ablation procedures were almost the same as those of Study 1, except for the optimal power setting and real-time monitoring of AID%.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Ethical consideration\u003c/h2\u003e \u003cp\u003e The ethics committee of the National Cerebral and Cardiovascular Center approved Studies 1 and 3, retrospective analyses of clinically acquired patient data (M26-148). All patients provided written informed consent before undergoing ablation. Study 2 was exempt from ethical approval because it did not involve clinical or animal experimentation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Statistical analyses\u003c/h2\u003e \u003cp\u003eContinuous variables are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (or median [interquartile range]) based on the normality of their distribution, which was assessed using the Kolmogorov\u0026ndash;Smirnov test. Depending on the distribution, either Student\u0026rsquo;s t-test or Mann\u0026ndash;Whitney U test was used to compare differences between groups as appropriate. Categorical variables were compared using Fisher\u0026rsquo;s exact test. Receiver operating characteristic (ROC) curve analysis was performed to describe the discriminative properties of AID% under different RF power settings. Univariate and stepwise multivariate analyses were performed using a logistic regression model to identify factors associated with the outcome and to estimate their odds ratios (ORs) with 95% confidence intervals (CIs). Variables considered clinically relevant to lesion durability and energy delivery, including AID%, GID%, average RF power, contact force, ILD, and ablation duration, were included in the multivariable logistic regression model. All statistical tests were two-sided, and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. All statistical analyses were performed using R statistical software (R Foundation for Statistical Computing, Vienna, Austria).\u003c/p\u003e \u003c/div\u003e"},{"header":"3. RESULTS","content":"\u003cp\u003e\u003cstrong\u003e3.1 Study 1 Clinical retrospective analysis from the conventional protocol cohort\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.1 Baseline characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOverall, 30 consecutive patients with AF undergoing initial PV isolation using TFSE were included in the clinical analysis. The mean age was 70 \u0026plusmn; 8 years, and 57% were men. The average body mass index was 24 \u0026plusmn; 3 kg/m\u0026sup2;. Paroxysmal AF was observed in 43% of the patients.\u003c/p\u003e\n\u003cp\u003eThe median CHADS2 and CHA2DS2-VA scores were 2 [1\u0026ndash;3] and 3 [2\u0026ndash;4], respectively. Common comorbidities included hypertension (83%), congestive heart failure (53%), and chronic kidney disease (50%). Structural heart disease was present in 30% of the patients.\u003c/p\u003e\n\u003cp\u003eEchocardiography showed a left ventricular ejection fraction of 60 [49\u0026ndash;63] %, left atrial diameter of 44 \u0026plusmn; 7 mm, and left atrial volume index of 56 \u0026plusmn; 19 mL/m\u0026sup2;. The mean estimated glomerular filtration rate was 58 \u0026plusmn; 13 mL/min/1.73 m\u0026sup2;, and brain natriuretic peptide was 163 [83\u0026ndash;271] pg/mL. Baseline characteristics are summarized in Table 1A.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.2 Primary objective\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePV isolation was successfully achieved in all 30 patients. First-pass isolation was achieved in 20 left PVs (67%) and 22 right (73%). In total, 1,423 RF applications were analyzed, of which 138 (10%) were classified as gap-related lesions. To further clarify the anatomical distribution of conduction gaps, a schematic was created to illustrate the locations of the ablation points and conduction gaps around the PVs (Figure 2A).\u003c/p\u003e\n\u003cp\u003eAID and AID% were significantly lower in the gap segments than in the non-gap segments (11 [8\u0026ndash;12] \u0026Omega; vs. 12 [9\u0026ndash;14] \u0026Omega;, p \u0026lt; 0.001, and 10 [8\u0026ndash;12] % vs. 11 [9\u0026ndash;13] %, p = 0.002). Significant differences were also in the maximum CF (28 [19\u0026ndash;47] g vs. 25 [18\u0026ndash;37] g, p = 0.042), average power (42 [39\u0026ndash;48] W vs. 44 [39\u0026ndash;48] W, p = 0.002), GID (12 [10\u0026ndash;14] \u0026Omega; vs. 13 [11\u0026ndash;16] \u0026Omega;, p = 0.002, and 12 [10\u0026ndash;14] % vs. 13 [11\u0026ndash;15], p = 0.014) between the gap and the non-gap segments (Table 1B).\u003c/p\u003e\n\u003cp\u003eThe overall discriminative performance of AID% for distinguishing gap and non-gap segments was modest (AUC: 0.58). Discriminative performance varied across RF power categories (AUC: 0.58 for \u0026le;40 W, 0.78 for 41\u0026ndash;45 W, and 0.53 for 46\u0026ndash;50 W) (Figure 2B).\u003c/p\u003e\n\u003cp\u003eIn regression analysis, AID% \u0026lt;10% was associated with conduction-gap segments (OR: 1.62; 95% CI: 1.09\u0026ndash;2.39; p = 0.016). Average RF power was also associated with conduction-gap formation (OR: 0.95; 95% CI: 0.91\u0026ndash;0.98; p = 0.004). In contrast, GID% \u0026lt;10% was not associated with conduction-gap segments in either univariate or multivariate analyses (Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.3 Secondary objective\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOf the 1,423 RF applications included in the main analysis, 1,224 with available pre-ablation omnipolar voltage data were included in the sub-analysis. The maximum omnipolar voltage at the ablation site was significantly higher in the conduction-gap segments compared to the non-gap segments (2.6 [1.2\u0026ndash;5.1] mV vs. 2.0 [0.9\u0026ndash;3.7] mV, p = 0.001).\u003c/p\u003e\n\u003cp\u003eUsing a power-specific targeted AID% threshold, 585 applications (48%) were categorized as having a lower AID%. These lesions showed slightly lower average power and average and minimum CF, but no significant differences in duration, temperature, total energy delivery, or omnipolar voltage (Table S1).\u003c/p\u003e\n\u003cp\u003e Multivariate logistic regression analysis showed that average RF power (OR: 1.08; 95% CI: 1.05\u0026ndash;1.11; p \u0026lt; 0.001), average CF (OR: 1.10; 95% CI: 1.07\u0026ndash;1.14; p \u0026lt; 0.001), and RF duration (OR: 1.03; 95% CI: 1.00\u0026ndash;1.05; p = 0.026) were associated with AID% behavior. In contrast, omnipolar voltage was not associated with AID% insufficiency in the multivariable model (OR: 1.00; 95% CI: 0.94\u0026ndash;1.05; p = 0.94) (Table 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Study 2: \u003cem\u003eEx vivo\u003c/em\u003e analysis for evaluating the lesion characteristics associated with AID% behavior\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 152 lesions were included in the ex vivo analysis. No steam pops were observed under any ablation conditions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.1 Lesion characteristics at AID% 10%\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUnder the AID% 10% condition, lesion characteristics were compared across different RF power settings.\u003c/p\u003e\n\u003cp\u003eLesion volume decreased with increasing RF power (\u0026le;40 W vs. 45 W: 58.5 [36.2\u0026ndash;83.1] mm\u0026sup3; vs. 45.4 [30.8\u0026ndash;57.0] mm\u0026sup3;, p = 0.047; 45 W vs. 50 W: 45.4 [30.8\u0026ndash;57.0] mm\u0026sup3; vs. 25.5 [16.7\u0026ndash;32.9] mm\u0026sup3;, p = 0.001). In contrast, lesion surface area increased with higher RF power (\u0026le;40 W vs. 45 W: 10.5 [9.1\u0026ndash;13.5] mm\u0026sup2; vs. 12.9 [11.0\u0026ndash;15.7] mm\u0026sup2;, p = 0.009; 45 W vs. 50 W: 12.9 [11.0\u0026ndash;15.7] mm\u0026sup2; vs. 19.2 [15.4\u0026ndash;23.4] mm\u0026sup2;, p \u0026lt; 0.001). Surface diameter was also larger at higher power (\u0026le;40 W vs. 45 W: 4.2 [3.7\u0026ndash;4.7] mm vs. 4.7 [4.2\u0026ndash;5.0] mm, p = 0.018; 45 W vs. 50 W: 4.7 [4.2\u0026ndash;5.0] mm vs. 5.3 [4.8\u0026ndash;6.3] mm, p = 0.002). Lesion depth decreased with increasing RF power (\u0026le;40 W vs. 45 W: 2.8 [2.2\u0026ndash;3.4] mm vs. 2.2 [1.8\u0026ndash;2.5] mm, p = 0.001; 45 W vs. 50 W: 2.2 [1.8\u0026ndash;2.5] mm vs. 1.6 [1.1\u0026ndash;1.8] mm, p \u0026lt; 0.001) (Figure 3A).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.2 Lesion characteristics at AID% 13%\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAt the AID% 13% condition, lesion characteristics were compared between the 45 W and 50 W groups. No significant differences were observed in lesion volume (83.5 [57.7\u0026ndash;117.8] mm\u0026sup3; vs. 85.6 [66.8\u0026ndash;96.2] mm\u0026sup3;, p = 0.89), surface area (17.9 [15.2\u0026ndash;20.7] mm\u0026sup2; vs. 16.9 [14.6\u0026ndash;24.8] mm\u0026sup2;, p = 0.94), surface diameter (5.3 [5.0\u0026ndash;6.2] mm vs. 5.5 [5.0\u0026ndash;6.2] mm, p = 0.91), or lesion depth (2.8 [2.5\u0026ndash;3.5] mm vs. 2.7 [2.2\u0026ndash;3.2] mm, p = 0.47) (Figure 3B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.3 RF application duration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe RF application duration required to reach the target AID% was also evaluated. At the AID% 10% condition, the duration was shorter at higher RF power (\u0026le;40 W vs. 45 W: 12 [8\u0026ndash;16.5] s vs. 6 [4\u0026ndash;7] s, p \u0026lt; 0.001; 45 W vs. 50 W: 6 [4\u0026ndash;7] s vs. 4 [4\u0026ndash;4] s, p \u0026lt; 0.001). At the AID% 13% condition, no significant difference was observed between the 45 W and 50 W groups (9.5 [6.8\u0026ndash;12] s vs. 9.0 [6\u0026ndash;13] s, p = 0.58). Within the 45 W setting, the duration was shorter at the AID% 10% target than at 13% (6 [4\u0026ndash;7] s vs. 9.5 [6.8\u0026ndash;12] s, p \u0026lt; 0.001) (Figure 4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.4 Comparison between AID% 10% and 13% at 45 W\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAt 45 W, lesion characteristics were compared between AID% 10% and 13%. Lesion volume was larger at AID% 13% (83.5 [57.7\u0026ndash;117.8] mm\u0026sup3; vs. 45.4 [30.8\u0026ndash;57.0] mm\u0026sup3;, p \u0026lt; 0.001). Surface area (17.9 [15.2\u0026ndash;20.7] mm\u0026sup2; vs. 12.9 [11.0\u0026ndash;15.7] mm\u0026sup2;, p \u0026lt; 0.001), surface diameter (5.3 [5.0\u0026ndash;6.2] mm vs. 4.7 [4.2\u0026ndash;5.0] mm, p \u0026lt; 0.001), and lesion depth (2.8 [2.5\u0026ndash;3.5] mm vs. 2.2 [1.8\u0026ndash;2.5] mm, p \u0026lt; 0.001) were also greater at AID% 13% (Figure 5).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.5 Effect of catheter orientation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLesion characteristics were compared between oblique (45\u0026deg;) and perpendicular (90\u0026deg;) catheter orientations. Lesion volume did not differ significantly between the two groups (49.3 [28.6\u0026ndash;80.9] mm\u0026sup3; vs. 56.2 [35.2\u0026ndash;91.9] mm\u0026sup3;, p = 0.090). Surface area (17.3 [13.4\u0026ndash;22.8] mm\u0026sup2; vs. 14.3 [11.6\u0026ndash;17.0] mm\u0026sup2;, p \u0026lt; 0.001) and surface diameter (5.2 [4.5\u0026ndash;6.6] mm vs. 4.8 [4.3\u0026ndash;5.3] mm, p = 0.002) were larger in oblique applications. Lesion depth was greater in perpendicular applications (2.2 [1.6\u0026ndash;2.9] mm vs. 2.5 [2.0\u0026ndash;3.2] mm, p = 0.042) (Figure S1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3 Study 3 Exploratory analysis of AID%-guided ablation workflow\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3.1 Baseline characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOverall, 23 consecutive patients with AF who initially underwent the AID%-guided PV isolation using TFSE were included. The mean age was 70 \u0026plusmn; 11 years, and 61% were men. The average body mass index was 23 \u0026plusmn; 4 kg/m\u0026sup2;. Paroxysmal AF was observed in 48% of the patients.\u003c/p\u003e\n\u003cp\u003eNo statistically significant differences in baseline clinical characteristics were observed between the two groups (Table 1A).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3.2 Ablation protocol\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAblations were performed under the following conditions:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePower settings:\u003c/strong\u003e 45 W targeting AID 11\u0026ndash;13% (RPV and the roof, supero-anterior, infero-anterior segments of LPV); 30, 35, and 40 W targeting AID% 10% (the bottom, supero-posterior, infero-posterior segments of LPV).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eCF:\u003c/strong\u003e \u0026ge;5\u0026ndash;10 g was maintained.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eIrrigation flow:\u003c/strong\u003e This was set at 13 mL/min in accordance with the clinical TFSE protocol.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eRF duration:\u003c/strong\u003e The point-by-point RF energy delivery was continued until 24 s or the targeted AID% value (11\u0026ndash;13%) was achieved, with durations ranging from at least 16 s to a maximum of 24 s. When the esophageal temperature rose above 39℃, we immediately stopped the application.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e3.3.3 First-pass isolation percentage\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePV isolation was successfully performed without any complications and steam pops in all the cases. Although not significant, the first-pass isolation percentages of both PVs were numerically higher in the AID%-guided protocol cohort patients than in the conventional protocol cohort patients (LPV, 78% vs. 67%, p = 0.54; RPV, 87% vs. 73%, p = 0.31, Figure S2).\u003c/p\u003e"},{"header":"4. DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003e4.1 Major findings\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, we present a combined clinical and ex vivo evaluation of AID% behavior during PV isolation. The major findings are summarized as follows:\u003c/p\u003e\n\u003cp\u003ei. AID% values differed between gap and non-gap segments, although overall discriminative performance was modest except for 41\u0026ndash;45W RF power settings.\u003c/p\u003e\n\u003cp\u003eii. Lower AID% values were associated with conduction-gap segment formation.\u003c/p\u003e\n\u003cp\u003eiii. The ex vivo analysis demonstrated differences in lesion characteristics under varying AID% targets and RF power settings.\u003c/p\u003e\n\u003cp\u003eiv. First-pass isolation percentages were numerically higher in the AID%-guided cohort compared with the conventional cohort.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.2 Clinical implications from the conventional protocol cohort\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOur findings suggest that AID% reflects real-time tissue response during RF delivery using a TFSE catheter rather than serves as a standalone predictor of lesion durability. Traditional surrogate indicators, such as the CF, force\u0026ndash;time integral [14], or lesion size index, have been widely used. However, these parameters represent cumulative metrics based on input energy and may not accurately reflect the underlying tissue response. Notably, the clinical application of GID as a key lesion marker [15-17], has declined owing to limitations in specificity, sensitivity to physiological noise, and lack of standardization across mapping systems. In contrast, AID% reflects a filtered AID ratio rather than an absolute value and may offer a more robust and reproducible measure of tissue response during ablation. In our study, the overall discriminative performance of AID% was modest, and varied depending on RF power settings. These findings suggest that impedance behavior is influenced by multiple factors, including power delivery and catheter\u0026ndash;tissue interaction, rather than any single parameter alone.\u003c/p\u003e\n\u003cp\u003eIn the sub-analysis, higher local omnipolar voltage was more frequently observed in conduction-gap segments, suggesting potential differences in underlying tissue properties.\u003c/p\u003e\n\u003cp\u003eThis observation is consistent with previous reports demonstrating that higher atrial voltage is associated with gap-related lesion formation, likely reflecting thicker atrial myocardium or preserved viable tissue requiring greater energy delivery. Takigawa et al. reported that higher bipolar voltage was associated with incomplete lesion formation despite high-power ablation [18].\u003c/p\u003e\n\u003cp\u003eHowever, in the present analysis, AID% behavior was more closely associated with procedural factors, including RF power, contact force, and application duration, while omnipolar voltage was not independently associated with AID% behavior in the multivariable analysis.\u003c/p\u003e\n\u003cp\u003eThese findings suggest that AID% behavior reflects not only intrinsic tissue characteristics but also energy-delivery conditions that are modifiable during ablation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.3 Additional \u003cem\u003eex vivo\u003c/em\u003e and clinical studies\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the ex vivo analysis, lesion characteristics varied according to both RF power and AID% levels. At a lower AID% target, increasing RF power was associated with larger surface dimensions but reduced lesion depth, suggesting that lesion geometry is influenced by the energy delivery profile even when impedance changes are similar. In contrast, at a higher AID% level, lesion characteristics were more consistent across different power settings. A direct comparison under a fixed RF power setting demonstrated that higher AID% levels were associated with larger lesion dimensions.\u003c/p\u003e\n\u003cp\u003eThese findings are consistent with previous experimental studies showing that lesion geometry depends on both delivered power and duration, rather than a single parameter alone. In particular, Suga et al. reported that lesion formation during RF ablation is determined by the balance between resistive and conductive heating, with higher power favoring broader surface lesions and longer duration contributing to deeper tissue penetration [19].\u003c/p\u003e\n\u003cp\u003eCatheter orientation also influenced lesion characteristics, with oblique applications producing broader lesions and perpendicular applications resulting in deeper lesions. No steam pops were observed in this experimental setting.\u003c/p\u003e\n\u003cp\u003eIn the exploratory cohort, AID%-guided ablation was implemented without procedural complications, and first-pass isolation rates were numerically higher compared with the conventional cohort, although differences were not statistically significant. Given the small sample size and non-randomized design, these findings should be interpreted as hypothesis-generating.\u003c/p\u003e"},{"header":"5. Study limitations","content":"\u003cp\u003eFirst, the clinical analysis was retrospective and conducted at a single center, which may limit generalizability. Second, AID% is a parameter specific to TFSE and cannot be measured using other ablation catheters or systems. Third, although omnipolar voltage data were included in the sub-analysis, not all RF applications had corresponding electroanatomical map data, potentially introducing selection bias. Fourth, all clinically relevant factors were included in the multivariable regression model, and despite the significant findings, the potential influence of collinearity among energy-delivery parameters (power, contact force, and duration) cannot be fully excluded. Fifth, \u003cem\u003eex vivo\u003c/em\u003e validation was performed on porcine myocardium under non-beating, temperature-controlled conditions, which might not fully replicate the clinical environment of a beating human heart. Finally, the comparison between the conventional and AID%-guided protocols was exploratory and based on a small retrospectively evaluated subgroup, which may limit the statistical power of the findings. Although numerically higher rates of PV isolation were observed without steam pops in a limited number of AID%-guided cases, further prospective studies are required to clarify the clinical implications of AID%-guided ablation.\u003c/p\u003e"},{"header":"6. CONCLUSION","content":"\u003cp\u003eAID% is associated with lesion formation characteristics under both clinical and controlled experimental conditions, despite a variability in discriminative performance across RF power settings. These findings suggest that AID% may be useful as a physiological indicator of lesion formation dynamics, reflecting real-time tissue response during RF application using TFSE, rather than serving as a standalone predictor of lesion durability.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u0026nbsp;\u003c/strong\u003eThe authors thank Editage for English-language editing, and Kim Sugi, Keisuke Hayashi, Taisuke Kanaoka, Masato Okamoto (Abbott Medical Japan), and Toru Yamaguchi (Nihon Kohden) for their technical assistance with the ex vivo validation study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u0026nbsp;\u003c/strong\u003eThe data that support the findings of this study are not publicly available due to ethical and privacy restrictions, but are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding statement:\u0026nbsp;\u003c/strong\u003eN/A.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest disclosure:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKengo Kusano received speaker honoraria from Daiichi Sankyo Company and Medtronic, and research grants from Medtronic and JSR outside the submitted work. Koji Miyamoto received funding, grants, and speaker honoraria from Medtronic, Biosense Webster, Abbott, and Boston Scientific outside the submitted work. He is also affiliated with a department endowed by Medtronic outside the submitted work. Tsukasa Kamakura received honoraria from Biosense Webster, Medtronic, and Boston Scientific outside the submitted work. Nobuhiko Ueda and Satoshi Oka received honoraria for lectures from Medtronic outside the submitted work. Akinori Wakamiya received honoraria for lectures from Biosense Webster, Medtronic, and BIOTRONIK outside the submitted work. The other authors had no conflicts of interest to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval statement:\u003c/strong\u003e The ethics committee of the National Cerebral and Cardiovascular Center approved the clinical part of this study (Study 1 and 3, M26-148). Study 2 (the experimental part of this study) did not require ethics approval because it did not involve either clinical or animal experimentation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatient consent statement: \u003c/strong\u003eAll patients provided written informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRegistry:\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnimal studies:\u0026nbsp;\u003c/strong\u003eNo animal experimentation was performed in this study, while the non-flesh porcine left ventricular myocardium was used for \u003cem\u003eex vivo\u003c/em\u003e analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCapsule Summary:\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe averaged impedance drop was associated with conduction-gap formation and ex vivo lesion geometry during pulmonary vein isolation, supporting its role as a real-time indicator of lesion-formation dynamics.\u0026nbsp;\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eN.N. conceived and designed the study, collected and analyzed the data, and drafted the initial manuscript. S.O. supervised the study, contributed to study design and data interpretation, and critically revised the manuscript for important intellectual content. A.W., N.U., K.N., T.K., M.W., Y.I., K.M., H.M., and K.K. contributed to data acquisition and interpretation and provided important intellectual input. All authors reviewed and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHa\u0026iuml;ssaguerre M, Ja\u0026iuml;s P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998;339:659\u0026ndash;66. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1056/NEJM199809033391003\u003c/span\u003e\u003cspan address=\"10.1056/NEJM199809033391003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNinomiya Y, Inoue K, Tanaka N, et al. Absence of first-pass isolation is associated with poor pulmonary vein isolation durability and atrial fibrillation ablation outcomes. J Arrhythm. 2021;37:1468\u0026ndash;76. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/joa3.12629\u003c/span\u003e\u003cspan address=\"10.1002/joa3.12629\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOsorio J, Hunter TD, Rajendra A, Zei P, Silverstein J, Morales G. Predictors of clinical success after paroxysmal atrial fibrillation catheter ablation. J Cardiovasc Electrophysiol. 2021;32:1814\u0026ndash;21. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jce.15028\u003c/span\u003e\u003cspan address=\"10.1111/jce.15028\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOkamatsu H, Okumura K, Onishi F, et al. Predictors of pulmonary vein non-reconnection in the second procedure after ablation index-guided pulmonary vein isolation for atrial fibrillation and its impact on the outcome. J Cardiovasc Electrophysiol. 2023;34:2452\u0026ndash;60. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jce.16084\u003c/span\u003e\u003cspan address=\"10.1111/jce.16084\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMatsumoto K, Tanaka N, Sasaki W, et al. Feasibility and efficacy of 50 W ablation with the TactiFlex catheter for the initial pulmonary vein isolation of atrial fibrillation. J Arrhythm. 2025;41:e13191. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/joa3.13191\u003c/span\u003e\u003cspan address=\"10.1002/joa3.13191\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYamaguchi J, Takigawa M, Goya M, et al. Safety verification of a novel irrigation catheter with flexible tip of laser-cut kerfs and contact force sensor. Pacing Clin Electrophysiol. 2023;46:1536\u0026ndash;45. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/pace.14868\u003c/span\u003e\u003cspan address=\"10.1111/pace.14868\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMatsumoto K, Kawano D, Sasaki W, et al. Detailed investigation of the lesion formation with a novel contact force sensing catheter with a mesh-shaped irrigation tip. J Arrhythm. 2023;39:166\u0026ndash;74. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/joa3.12835\u003c/span\u003e\u003cspan address=\"10.1002/joa3.12835\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDello Russo A, D'Angelo L, Compagnucci P, et al. High-power short-duration catheter ablation of atrial fibrillation: is it really a new era? Comparison between new and old radiofrequency contact force-sensing catheters. J Interv Card Electrophysiol. 2024;67:549\u0026ndash;57. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10840-023-01612-x\u003c/span\u003e\u003cspan address=\"10.1007/s10840-023-01612-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMattia L, Crosato M, Indiani S, et al. Prospective Evaluation of Lesion Index-Guided Pulmonary Vein Isolation Technique in Patients with Paroxysmal Atrial Fibrillation: 1-year Follow-Up. J Atr Fibrillation. 2018;10:1858. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4022/jafib.1858\u003c/span\u003e\u003cspan address=\"10.4022/jafib.1858\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaneko Y, Naruse Y, Narumi T, Sano M, Urushida T, Maekawa Y. Evaluation and comparison of impedance and amplitude changes in lesion index-guided pulmonary vein isolation. J Arrhythmia. 2024;40:100\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/joa3.12966\u003c/span\u003e\u003cspan address=\"10.1002/joa3.12966\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLang RM, Badano LP, Mor-Avi V, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2015;16:233\u0026ndash;70. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/ehjci/jev014\u003c/span\u003e\u003cspan address=\"10.1093/ehjci/jev014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDittrich S, Scheurlen C, van den Bruck JH, et al. The omnipolar mapping technology\u0026mdash;a new mapping tool to overcome bipolar blindness resulting in true high-density maps. J Interv Card Electrophysiol. 2024;67:399\u0026ndash;408. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10840-023-01562-4\u003c/span\u003e\u003cspan address=\"10.1007/s10840-023-01562-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInoue K, Tanaka N, Ikada Y, et al. Characterizing clinical outcomes and factors associated with conduction gaps in VISITAG SURPOINT-guided catheter ablation for atrial fibrillation. J Arrhythm. 2021;37:574\u0026ndash;83. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/joa3.12544\u003c/span\u003e\u003cspan address=\"10.1002/joa3.12544\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKautzner J, Neuzil P, Lambert H, et al. EFFICAS II: optimization of catheter contact force improves outcome of pulmonary vein isolation for paroxysmal atrial fibrillation. Europace. 2015;17:1229\u0026ndash;35. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/europace/euv057\u003c/span\u003e\u003cspan address=\"10.1093/europace/euv057\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYokoyama K, Nakagawa H, Shah DC, et al. Novel contact force sensor incorporated in irrigated radiofrequency ablation catheter predicts lesion size and incidence of steam pop and thrombus. Circ Arrhythm Electrophysiol. 2008;1:354\u0026ndash;62. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1161/CIRCEP.108.803650\u003c/span\u003e\u003cspan address=\"10.1161/CIRCEP.108.803650\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIkeda A, Nakagawa H, Lambert H, et al. Relationship between catheter contact force and radiofrequency lesion size and incidence of steam pop in the beating canine heart: electrogram amplitude, impedance, and electrode temperature are poor predictors of electrode-tissue contact force and lesion size. Circ Arrhythm Electrophysiol. 2014;7:1174\u0026ndash;80. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1161/CIRCEP.113.001094\u003c/span\u003e\u003cspan address=\"10.1161/CIRCEP.113.001094\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReichlin T, Knecht S, Lane C, et al. Initial impedance decrease as an indicator of good catheter contact: insights from radiofrequency ablation with force sensing catheters. Heart Rhythm. 2014;11:194\u0026ndash;201. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.hrthm.2013.10.048\u003c/span\u003e\u003cspan address=\"10.1016/j.hrthm.2013.10.048\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTakigawa M, Miyazaki S, Yamamoto T, et al. Significance of the local largest bipolar voltage for the optimized ablation strategy using very high-power short-duration mode. J Cardiovasc Electrophysiol. 2025;36:111\u0026ndash;23. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jce.16453\u003c/span\u003e\u003cspan address=\"10.1111/jce.16453\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuga K, Yamazaki K, Sakurai T, et al. Evaluation of averaged impedance drop percent as a real-time parameter for safe and effective prolonged radiofrequency ablation using the TactiFlex SE catheter: an ex vivo study. J Interv Card Electrophysiol. 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10840-025-02112-w\u003c/span\u003e\u003cspan address=\"10.1007/s10840-025-02112-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(A) Baseline clinical characteristics, echocardiographic findings, and laboratory data in the Conventional and AID%-guided protocols\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(B) Comparison of ablation parameters between gap and non-gap segments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis table summarizes the baseline characteristics of the 53 enrolled patients (A) and parameters involved in ablation lesion formation (B). Data are presented as means \u0026plusmn; standard deviations (normally distributed data), medians and interquartile ranges (non-normally distributed data), and n (%). All statistical tests were 2-tailed, and p\u0026lt;0.05 was considered significant (*).\u003c/p\u003e\n\u003cp\u003eAbbreviations: eGFR, estimated glomerular filtration rate; BNP, brain natriuretic peptide\u003cstrong\u003e;\u0026nbsp;\u003c/strong\u003eCF, contact force; AID, averaged impedance drop; GID, generator impedance drop.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1A\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"624\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAll\u0026nbsp;\u003cbr\u003e\u0026nbsp;(n = 53)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eConventional protocol\u003cbr\u003e\u0026nbsp;(n = 30)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAID%-guided protocol\u003cbr\u003e\u0026nbsp;(n = 23)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eClinical backgrounds\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eAge [years]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e70 \u0026plusmn; 9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e70 \u0026plusmn; 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e70 \u0026plusmn; 11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.78\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eMale sex [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e31 (58)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e17 (57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e14 (61)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eBody mass index [kg/m\u003csup\u003e2\u003c/sup\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e24 \u0026plusmn; 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e24 \u0026plusmn; 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e23 \u0026plusmn; 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eParoxysmal atrial fibrillation [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e24 (45)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e13 (43)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e11 (48)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eCHADS2 Score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2 [1-3]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2 [1-3]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2 [1-3]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.61\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eCHA2DS2-VA Score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3 [2-4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3 [2-4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3 [2-4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eCongestive heart failure [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e26 (49)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e16 (53)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e10 (43)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eHypertension [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e42 (79)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e25 (83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e17 (74)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eDiabetes mellitus [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e15 (28)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e7 (23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e8 (35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eHistory of stroke [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e3 (6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e2 (7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e1 (4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026gt;0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eStructural heart disease [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e14 (26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e9 (30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e5 (22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.55\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eChronic kidney disease [(%)]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e22 (42)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e15 (50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e7 (30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eImaging variables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eLeft ventricular ejection fraction [%]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e60 [55-63]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e60 [49-63]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e60 [57-64]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eLeft atrial diameter [mm]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e43 \u0026plusmn; 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e44 \u0026plusmn; 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e42 \u0026plusmn; 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eLeft atrial volume index [mm/m\u003csup\u003e2\u003c/sup\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e55 \u0026plusmn; 21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e56 \u0026plusmn; 19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e55 \u0026plusmn; 24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLaboratory data\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eeGFR [mL/min/1.73 m\u003csup\u003e2\u003c/sup\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e60 \u0026plusmn; 14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e58 \u0026plusmn; 13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e63 \u0026plusmn; 16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 163px;\"\u003e\n \u003cp\u003eBNP [pg/mL]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e111 [61-230]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e163 [83-271]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 131px;\"\u003e\n \u003cp\u003e71 [51-169]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e.066\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 1B\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"624\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAll\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=1423)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGap segment\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=138)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNon-gap segment\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=1285)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eAverage CF (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e11 [8-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e11.5 [8-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e11.0 [8-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eMaximum CF (g) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e25 [18-38]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e27.5 [19-46.8]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e25.0 [18-38]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.042 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eMinimum CF (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e2 [0-4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e2 [1-4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e2 [0-4]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eMaximum temperature (℃)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e34 [33-36]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e34 [33-36]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e34 [33-36]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eAverage power (W) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e44 [39-48]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e42 [39-48]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e44 [39-48]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.002 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eDuration (s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e21 [18-25]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e21.5 [18-27]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e21.0 [18-25]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eEnergy (W)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e977 [824.5-1076.5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e953.5 [782-1099.5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e977.0 [834-1073]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eILD (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e3.7 [2.9-4.5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e3.6 [2.8-4.6]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e3.7 [2.9-4.5]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eGID (\u0026Omega;) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e13 [11-16]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e12 [10-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e13 [11-16]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.002 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eGID (%) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e13 [11-15]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e12 [10-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e13 [11-15]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.014 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eAID(\u0026Omega;) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e11 [9-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e10 [8-12]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e11 [9-14]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u0026lt;.001 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 156px;\"\u003e\n \u003cp\u003eAID (%) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 126px;\"\u003e\n \u003cp\u003e11 [9-13]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e10 [8-12]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 136px;\"\u003e\n \u003cp\u003e11 [9-13]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e.002 *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 10px;\"\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\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Logistic regression analysis for predicting the formation of gap segments.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll statistical tests were 2-tailed, and p\u0026lt;0.05 was considered significant (*).\u003c/p\u003e\n\u003cp\u003eAbbreviations: CI, confidence interval; CF, contact force; AID, averaged impedance drop; GID, generator impedance drop\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"636\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 263px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUnivariate Logistic analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 258px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMultivariate Logistic analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOdds Ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOdds Ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eGID % \u0026lt;10%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.55 \u0026ndash; 1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.38 \u0026ndash; 1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eAID % \u0026lt;10% *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e1.05 \u0026ndash; 2.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e.025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e1.09 - 2.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e.016 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eAverage power (W) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.91 - 0.98\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e.002\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.91 - 0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e.004 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eAverage\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eCF (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.95 - 1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.96 \u0026ndash; 1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eILD (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.86 - 1.10\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.89 \u0026ndash; 1.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 98px;\"\u003e\n \u003cp\u003eDuration (s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70px;\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.99 - 1.06\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 65px;\"\u003e\n \u003cp\u003e.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 129px;\"\u003e\n \u003cp\u003e0.98 \u0026ndash; 1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Logistic regression analyses for factors associated with lower AID% attainment during PVI.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll statistical tests were 2-tailed, and p\u0026lt;0.05 was considered significant (*).\u003c/p\u003e\n\u003cp\u003eAbbreviations: CI, confidence interval; CF, contact force; PVI, pulmonary vein isolation.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"629\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 242px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUnivariate Logistic analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 242px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMultivariate Logistic analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOdds Ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 18px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOdds Ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003eAverage power (W) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e1.04 - 1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u0026lt;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 18px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e1.05 - 1.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u0026lt;.001 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003eAverage CF (g) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e1.06 - 1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u0026lt;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 18px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e1.07 - 1.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e\u0026lt;.001 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003eDuration (s) *\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e0.98 - 1.02\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 18px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e1.00 - 1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e.026 *\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 127px;\"\u003e\n \u003cp\u003eOmnipolar voltage (mV)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e0.93 - 1.03\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 18px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 106px;\"\u003e\n \u003cp\u003e0.94 \u0026ndash; 1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 68px;\"\u003e\n \u003cp\u003e.94\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"atrial fibrillation, averaged impedance drop, generator impedance drop, catheter ablation, radiofrequency ablation","lastPublishedDoi":"10.21203/rs.3.rs-9473730/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9473730/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eReal-time monitoring of myocardial tissue response during radiofrequency applications using a mesh-shaped flexible irrigation tip ablation catheter (TactiFlex) is currently limited by the lack of lesion size index guidance. This study assessed the dynamics of averaged impedance drop percentage (AID%), a novel ablation parameter, and the association with lesion formation characteristics through clinical and experimental analyses.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eWe retrospectively analyzed 1,423 radiofrequency applications in 30 patients undergoing initial pulmonary vein (PV) isolation using TactiFlex to examine relationships between AID% and conduction-gap formation. Mechanistic validation was performed using an ex vivo porcine myocardial model (152 lesions). AID%-guided ablation protocol (n\u0026thinsp;=\u0026thinsp;23) was compared with the conventional protocol.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eAID% values were modestly lower in conduction-gap segments compared with non-gap segments (10% vs. 11%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002). Overall discrimination was limited [area under the curve (AUC) 0.58, 95% confidence interval (CI) 0.53\u0026ndash;0.63; optimal cutoff 13%], whereas impedance behavior varied with power settings. The highest correlation was observed within the 41\u0026ndash;45 W range (AUC 0.78, 95% CI 0.70\u0026ndash;0.85). Ex vivo experiments demonstrated that lesion geometry depended strongly on both power and AID% targets. Compared with a 10% target, a 13% target produced deeper and larger lesions without steam pops. The first-pass PV isolation percentage was numerically higher in the AID 11\u0026ndash;13%-targeted protocol (left, 78% vs. 67%; right, 87% vs. 73%).\u003c/p\u003e\u003ch2\u003eConclusion:\u003c/h2\u003e \u003cp\u003eAID% is associated with lesion formation characteristics and may serve as an indicator of lesion formation dynamics, reflecting real-time tissue response during RF applications using TactiFlex.\u003c/p\u003e","manuscriptTitle":"Averaged Impedance Drop as an Indicator of Lesion Formation Dynamics During Radiofrequency Catheter Ablation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-11 05:08:09","doi":"10.21203/rs.3.rs-9473730/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cb5d7ffe-0782-43ca-9b5c-ab8a3d191358","owner":[],"postedDate":"May 11th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"151912358679819509060181163014378415970","date":"2026-05-17T08:19:15+00:00","index":14,"fulltext":""},{"type":"reviewerAgreed","content":"108937272016572185736664929023535435860","date":"2026-05-14T22:26:34+00:00","index":13,"fulltext":""},{"type":"reviewerAgreed","content":"179129219219367366871329063761791311272","date":"2026-05-02T14:54:50+00:00","index":8,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-11T05:08:10+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-11 05:08:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9473730","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9473730","identity":"rs-9473730","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}