Atrial Fibrillation Cycle Length Dynamics During Pulmonary Vein Isolation and Posterior Wall Pulsed Field Ablation

Background: The benefit of additional left atrial posterior wall ablation (LAPWA), beyond pulmonary vein isolation (PVI), in persistent atrial fibrillation (PersAF) treatment remains controversial. Objective: We investigated whether signals recorded with a pentaspline pulsed field ablation (PFA) catheter can identify PersAF patients with rapid LAPW activity who may benefit from LAPWA. We additionally evaluated whether PFA-induced atrial fibrillation cycle length (AF-CL) prolongation predicts arrhythmia-free survival. Methods: In this multicenter observational study, consecutive PersAF patients undergoing first-time PVI plus-LAPWA with a pentaspline PFA catheter were included. AF-CL was measured using the FARS-10 method at three time points: baseline, post-PVI, and post-LAPWA, using distal CS signals. LAPW-CL was measured post-PVI from multiple LAPW positions. Any atrial tachyarrhythmia (ATA) lasting >30 seconds beyond the 2-month blanking period was recorded. Results: 270 patients were included. The overall 12-month ATA-free survival was 72.6%. "Fast LAPW activity" was defined as a LAPW-CL value shorter than the mean LAPW-CL of the entire cohort (191.4±2.4 msec; ≤ 190 msec). Fast LAPW activity was not associated with arrhythmia recurrence (HR 1.263, 95% CI: 0.739-2.160; p=0.393). In contrast, a greater CS-CL prolongation was independently associated with lower arrhythmia recurrence risk (HR 0.298, 95% CI: 0.017-0.520; p<0.001). A CS-CL increase >23.5% from baseline had a sensitivity of 0.65 and specificity of 0.72 for predicting ATA-free survival. Conclusion: Post-PVI fast LAPW activity does not predict recurrence after LAPWA in PersAF patients. CS-CL prolongation >23.5% after LAPWA may serve as a useful real-time marker of effective substrate modification and arrhythmia control.