Faculty Bibliography

BACKGROUND/UNASSIGNED:Pulsed field ablation therapies need to be optimized to maximize lesion depth while mitigating heat and musculoskeletal stimulation. We describe the adjustment of biphasic pulsed field ablation parameters for an irrigated tip catheter. METHODS/UNASSIGNED:Experimental models all used an 8F, flexible-tip, irrigated ablation catheter. Computer simulation models were designed to assess the effects of bipolar versus monopolar applications. A vegetal (potato) model was used to assess the effects of voltage, pulse width, and number of pulses per burst on lesion depth. In-vitro testing on bovine cardiac muscle was performed with temperature sensors at the surface and 3 and 7 mm beneath the surface to measure temperature rises. Finally, an in vivo canine model was used to assess for musculoskeletal stimulation caused by the pulsed field ablation therapies established with the vegetal/in vitro testing. RESULTS/UNASSIGNED:Monopolar delivery consistently delivered more tissue depth than bipolar configurations. Adjustments from n to n+1.0 µs and increasing pulses per burst from 50 to 250 increased lesion depth but also increased musculoskeletal stimulation. The optimized burst count was 5 R-wave-gated bursts over 4 to 9 seconds. The optimized therapy had a minimal observed depth of >5 mm and minimized musculoskeletal stimulation. Final selected therapies did create temperature rises, which were completely offset by irrigation rates of 7 to 13 mL/min. CONCLUSIONS/UNASSIGNED:Pulse width and number of pulses per burst are important contributors to lesion depth, musculoskeletal stimulation, and incident heating. Even small adjustments in these parameters can alter lesion depth, muscle stimulation, and thermal effects, which will differentiate optimal from suboptimal pulsed field ablation.

BACKGROUND:The value of additional lesion sets beyond pulmonary vein isolation (PVI) for atrial fibrillation (AF) ablation is unclear. However, existing studies evaluated the utility of substrate modification with conventional energy sources. There is limited data evaluating PVI with posterior wall isolation (PWI) using pulsed field ablation (PFA). METHODS:We studied consecutive cases of patients with paroxysmal AF undergoing first-time ablation with PFA between May 6, 2024 and March 10, 2025. Procedural data collected included the number of PFA applications administered, total procedure time, and major periprocedural complications. Clinical data collected included atrial tachyarrhythmia (ATA) recurrence, stroke, and major bleeding at 1-year follow-up. Outcomes were compared in patients undergoing PVI alone versus PVI plus PWI. RESULTS:A total of 249 patients were included in this study (104 PVI alone, 145 PVI plus PWI). There was no difference in ATA recurrence by Kaplan-Meier survival analysis comparing PVI alone versus PVI plus PWI (log rank test p = 0.89). When comparing PVI alone versus PVI plus PWI, there was no difference in ATA recurrence at 1 year (16% vs. 16%; p = 0.92), AF burden on continuous monitoring (2% vs. 2%; p = 0.81), total procedure time (114 vs. 107 min; p = 0.14), or major periprocedural complications (0 vs. 3; p = 0.14). CONCLUSION/CONCLUSIONS:PFA for paroxysmal AF with PVI alone or PVI plus PWI produces similar sinus rhythm maintenance without affecting procedure times or complication rates.

BACKGROUND:The optimal number of pulsed field ablation (PFA) applications during atrial fibrillation (AF) ablation is unclear. We hypothesized that the number of PFA applications would predict atrial tachyarrhythmia (ATA) recurrence rates. OBJECTIVE:To determine whether higher numbers of PFA applications would decrease ATA recurrence rates. METHODS:We studied cases of patients with AF undergoing first-time ablation with PFA between 5/6/24 and 10/7/24. All patients underwent pulmonary vein and posterior wall isolation. The primary outcome was ATA recurrence. Additional outcomes included stroke, post-procedural acute kidney injury (AKI), total procedure time, and major periprocedural complications. Univariable and multivariable analyses were performed to determine if the number of PFA applications predicted ATA recurrence. RESULTS:In a cohort consisting of 177 patients, univariable and multivariable analysis showed that the number of PFA applications split at the smallest quartile (< 57 applications) versus the largest three quartiles (≥ 57 applications) was the strongest predictor of ATA recurrence (p = 0.03). ATA recurrence at 1 year (29% vs. 8%; p < 0.01) and AF burden on continuous monitor (4% vs. 0%; p < 0.01) was higher with the standard (< 57 applications) vs higher (≥ 57 applications) PFA dose groups. When comparing the standard versus higher PFA dose groups, there was no difference in total procedure time (106 vs. 107 min; p = 0.77), major periprocedural complications (0% vs. 2%; p = 0.33), or post-procedural AKI (2% vs. 2%; p = 0.69). CONCLUSION/CONCLUSIONS:Increasing number of PFA applications is associated with reduced ATA recurrence. A higher number of PFA applications may decrease ATA recurrence without affecting procedure times or complication rate.

BACKGROUND:Intracardiac echocardiography (ICE) is widely used during electrophysiology and structural heart procedures; however, image interpretation remains operator-dependent and procedural views are not standardized. Although artificial intelligence has been increasingly applied to transthoracic and transesophageal echocardiography, applications to ICE remain limited. OBJECTIVES/OBJECTIVE:The objective of the study was to develop and evaluate Auto-Contour, a deep-learning pipeline for multistructure semantic segmentation of ICE anatomy and assess its feasibility for real-time procedural guidance. METHODS:In this retrospective multicenter study, 5,496 deidentified ICE cine loops from 249 procedures of unique patients, including routine clinical cases and the ViewFlex™ X first-in-human study, were analyzed. ICE experts classified each cine into 1 of 20 procedural views and annotated key anatomic structures, including the left atrium, left atrial appendage, pulmonary vein ostia, valves, cusps, papillary muscles, and left ventricle, at end-systole, and end-diastole, yielding 65,117 segmentations. A deep-learning segmentation model was trained using patient-level splits, standard augmentations, and early stopping. RESULTS:Segmentation performance was highest for larger cardiac chambers, with Dice scores of 0.94 for the left atrium and 0.82 for the left ventricle, and corresponding 95th-percentile Hausdorff distance values of 1.18 mm and 3.27 mm. Smaller structures also demonstrated acceptable performance, including the left atrial appendage, pulmonary veins, papillary muscles, and aortic cusps. The mean per-frame inference time was <0.03 seconds. CONCLUSIONS:Auto-Contour demonstrated robust multistructure segmentation of ICE anatomy with real-time inference, supporting prospective evaluation of artificial intelligence-assisted ICE for procedural standardization, efficiency, and safety.

Randomized trials of ethanol infusion into the vein of Marshall (EIVOM) have shown efficacy in preventing atrial fibrillation (AF) recurrence in patients presenting for de novo ablation. The utility of EIVOM in AF patients who present for redo ablation is unclear. This meta-analysis was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Medline, Scopus, and Cochrane Central Register of Controlled Trials were systematically searched to identify relevant studies. Risk of bias was assessed using the Modified Newcastle-Ottawa scale. Eligible studies reported outcomes in AF patients with previous ablation who underwent redo catheter ablation (CA) alone vs. combined redo CA and EIVOM. Five observational studies comprising 568 patients were included. When comparing combined redo CA and EIVOM vs. redo CA alone, pooled results showed no difference in freedom from arrhythmia (FFA) in all patients (risk ratio [RR] 1.13; 95% confidence interval [CI] 0.96-1.33), FFA in persistent AF patients only (RR 1.08; 95% CI 0.90-1.29), total procedure time (mean difference -0.59; 95% CI -41.04-39.85), or major periprocedural complications (RR 0.81; 95% CI 0.06-11.64). Patients with AF recurrence after ablation represent a difficult-to-treat population. Salvage therapy with combined CA and EIVOM did not improve arrhythmic outcomes compared to CA alone in AF patients who presented for redo ablation.

BACKGROUND:Using high-frequency jet ventilation (HFJV) to improve catheter stability with conventional energy sources during atrial fibrillation (AF) ablation is associated with higher ablation success and improved arrhythmic outcomes. The utility of HFJV with pulsed field ablation (PFA) for AF is unclear. We investigated the utility of HFJV vs. standard ventilation in PFA for AF. METHODS:We studied consecutive cases of patients with AF undergoing PFA between 5/6/24 to 10/10/24. Procedural data collected included total procedure time and major periprocedural complications. Clinical data collected included atrial tachyarrhythmia (ATA) recurrence, stroke, and major bleeding at one-year follow-up. Outcomes were compared in cases where HFJV was used vs. standard ventilation. RESULTS:A total of 512 patients were included in this study (307 standard ventilation, 205 HFJV). There was no difference in ATA recurrence by Kaplan-Meier survival analysis between standard ventilation and HFJV groups (log rank test p = 0.59). When comparing standard ventilation vs. HFJV groups, there was no difference in ATA recurrence at one year (23% vs. 26%; p = 0.43), AF burden on continuous monitoring (9 ± 5% vs. 8 ± 24%; p = 0.85), total procedure time (114 ± 38 vs. 115 ± 33 min; p = 0.78), or major periprocedural complications (3% vs. 2%; p = 0.64). There was no difference in arrhythmic outcomes when patients were stratified by AF type and whether patients presented for first-time or redo ablation. CONCLUSION/CONCLUSIONS:Using HFJV in PFA for AF produces similar sinus rhythm maintenance overall and when stratified by AF type without affecting procedure times or complication rate.

BACKGROUND:Pulmonary vein isolation (PVI) and posterior wall isolation (PWI) are frequently used in the treatment of persistent atrial fibrillation (AF). Minimal data support adjunct PWI, possibly due to lack of durability via epicardial reconnections. OBJECTIVE:To determine the impact of very high output PW pace-capture testing in patients with persistent AF on AF/AT recurrence. METHODS:We performed a retrospective study of consecutive patients who underwent radiofrequency ablation for persistent AF and received PVI and PWI, as well as a cavotricuspid isthmus line (CTI). After the creation of three linear PW lesions (roof, carina-to-carina, and inferior PV levels), pace-capture testing was performed on the PW. The first cohort confirmed PWI using 10 mA at 2 ms (10 × 2) to pace capture. Sequentially, the second cohort utilized 20 mA at 10 ms (20 × 10). If the PW was captured, additional lesions were performed. Patients were excluded if additional lesion sets beyond PVI, PWI, and CTI were performed. RESULTS:A total of 232 patients were included. Of these, 129 (56%) patients were in the 20 × 10 group, and 103 (44%) patients were in the 10 × 2 group. The two groups did not differ in age, sex, proportion of comorbidities, presenting rhythm, left ventricular ejection fraction, or left atrial size. Despite the increase in procedure time and lesion number, in the time-to-event analysis, patients in the 20 × 10 group experienced recurrent AF/AT more frequently than those in the 10 × 2 group (log rank p = 0.01). CONCLUSION/CONCLUSIONS:Testing PWI in persistent AF with pace capture at 20 mA at 10 ms did not improve freedom from arrhythmia and may paradoxically be associated with harm. Our findings question whether PWI, regardless of durability, is effective in treating persistent AF.

INTRODUCTION/BACKGROUND:A lower frequency early electrogram (EGM) or broad area of early activation during premature ventricular contraction (PVC) mapping may be associated with a PVC origin in an opposing chamber or deep within the mapped surface. The utility of quantifying EGM frequency at early activation sites and isochronal activated surface area (IASA) is unclear. Our study aimed to investigate the utility of EGM frequency analysis and IASA mapping to complement activation mapping during PVC ablation. METHODS:High density PVC activation and IASA maps were created using a multi-electrode mapping catheter in 25 patients undergoing PVC ablation. EGMs in early activation regions were retrospectively studied. IASAs in each mapped chamber were analyzed. RESULTS:within 10 ms was unsuccessful. CONCLUSION/CONCLUSIONS:Higher EGM frequency and smaller IASA were associated with successful ablation of PVCs. Ablation at sites with EGM frequency > 325 Hz was successful in all patients. The utility of identifying higher frequency EGMs at early activation sites requires further study.

BACKGROUND:Identifying nearfield and farfield signals is critical to mapping and ablating cardiac arrhythmias. This assessment is qualitative, depending on the "sharpness" of pulmonary vein (PV) electrograms. Electrogram peak frequency (PF) analysis is hypothesized to be a quantitative measure of signal proximity. OBJECTIVE:To confirm if PF defines nearfield versus farfield electrical signals and if it can be used during ablation to establish pulmonary vein isolation (PVI). METHODS:We created a cohort of 30 patients with AF undergoing PVI. Left atrial and PV maps of PF were generated before and after PVI. In the first 10 patients with paroxysmal AF (cohort 1), a cutoff value was selected to predict nearfield versus farfield signals. This cutoff was validated in a cohort of 10 patients with paroxysmal AF (cohort 2) and a cohort of 10 patients with persistent AF (cohort 3). RESULTS:PF was lower in farfield electrograms than nearfield electrograms. A PF cutoff of 300 Hz had a sensitivity of 93.2% (95% CI 81.3% - 98.6%) in cohort 1, 90.0% (95% CI 76.3 - 97.2) in cohort 2, and 98.6% (95% CI 90.1 - 99.7%) in cohort 3 for differentiating farfield from nearfield electrograms. The specificity was 100.0% (95% CI 98.2% - 100.0%) and the AUC was 0.99 (95% CI 0.97 - 1.00) in all patients. CONCLUSIONS:We confirmed the hypothesis that PF distinguishes nearfield from farfield electrograms. PF analysis improves the recognition of PV isolation. Mapping and ablation strategies utilizing PF should be pursued to improve ablation outcomes.