Abstract 4371696: Pulsed Field Ablation Is Not Functionally Benign: Left Atrial Impact Mirrors Radiofrequency Ablation

Introduction: Pulsed field ablation (PFA) offers a non-thermal approach to atrial fibrillation ablation, aiming to preserve tissue structure and function. However, its effects on left atrial (LA) remodeling and function, especially with extra-pulmonary vein (extra-PV) ablation, remain unclear. Objective: To assess the effects of PFA compared to radiofrequency (RF) ablation on left atrial remodeling and function, with a focus on patients receiving extra-PV ablation. Methods: We collected data from a retrospective cohort undergoing RF and PFA ablation from March 2020 to January 2025. Patients were matched by age, sex, and LA volume. After matching, 45 patients were included in the analysis, 24 having undergone a PFA ablation and 21 having undergone an RF ablation. Patients had an MRI in the 30 days prior to and 3 months following the procedure. Patient characteristics and outcomes were compared using Wilcoxon tests, t-tests, and Chi-square tests accordingly. Results: The patients were balanced in terms of age, sex, LA volume, AF type, and comorbidities, besides the RF group having a higher BMI at baseline (22 kg/m 2 in PFA vs 33 kg/m 2 in RF, p<0.05) (Table 1). The majority of patients in both groups had undergone extra-PV ablation (posterior wall, roof line, anterior line, wall line), with 19 (79%) in the PFA group and 15 (71%) in the RF group (p>0.05). There were no differences in baseline fibrosis (18.84% ± 7.89 in PFA vs 18.03 ± 7.75 in RF, p>0.05) and LA volume index (LAVI, 48.89 ± 14.94 in PFA vs 54.17 ± 20.43 in RF, p>0.05) between the patients. Following the procedure, there was a significant difference in the LAVI (58.32 mL/m 2 in PFA vs 46.84 mL/m 2 in RF), and both arms exhibited a significant decrease in EndoGLS (PFA: 35.7% Peak Strain Pre ablation vs 22.13% Peak Strain Post Ablation, p<0.05&RF: 22.74% Pre ablation vs 14.87% Post Ablation, p<0.05). Interestingly, there was no difference in the decrease in strain and function between both arms (13.6% in PFA vs 8.82% in RF, p>0.05). Conclusion: PFA may be safe, but it's not immune. Despite its non-thermal nature, PFA affects left atrial remodeling and function much like RF, especially with extra-PV ablation. Caution is needed to balance efficacy with atrial preservation.