Very Late Recurrence After Atrial Fibrillation Ablation: Clinical Characteristics and Pulmonary Vein Reconnection Patterns.

BACKGROUND: Delayed recurrence of atrial fibrillation (AF) after index ablation is increasingly recognised, but its clinical and procedural phenotypes remain poorly described. OBJECTIVE: To characterise patients undergoing very late redo (VLR) AF ablation (>5 years after prior ablation) and compare pulmonary vein (PV) findings across redo interval groups. METHODS: Consecutive patients undergoing redo AF ablation at Alfred Health and Cabrini Health (2007-2025) were included and grouped by redo interval (<1 year, 1-5 years, >5 years). RESULTS: Of 596 patients undergoing redo AF ablation, 71 (12%) patients underwent VLR AF ablation (median redo interval 7.1 years [IQR 5.9-8.2]). VLR patients had a mean age of 62.1 years; 72% were male, and median CHA2DS2-VASc was 2 (IQR 1-3) with 57.7% having paroxysmal AF at redo procedure. PV reconnection (any) was less likely with increasing time from index PVI: At <1 year 80.1% (189/236), 1-5 years 65.1% (188/289), >5 years 49.3% (35/71); p<0.001. Each additional year from index to redo ablation was associated with an 8.6% lower expected number of reconnected PVs (RR 0.91, 95% CI 0.88-0.95; p<0.001). In total 32/71 (45%) of patients undergoing VLR AF ablation developed recurrent AF at a median follow-up of 243 days (IQR 103-1097) from repeat procedure. CONCLUSION: The likelihood of PV reconnection declines significantly with increasing time to redo AF ablation, with the majority of patients > 5 years having enduring PV isolation. This suggests a greater contribution from non-PV triggers and/or AF substrate in this cohort.