Intraprocedural atrial flutter transition predicts arrhythmia-free survival after “2C3L Plus” ablation for long-standing persistent atrial fibrillation

Background Long-standing persistent atrial fibrillation (LSPAF) remains a challenge of catheter ablation. The efficiency and optimal procedural endpoints of “2C3L plus” approach—a strategy combining pulmonary vein isolation (PVI) with linear and complex fractionated atrial electrogram (CFAEs) ablation—is unclear. Methods This single-center, retrospective cohort study included 260 consecutive patients with LSPAF (defined as continuous AF lasting > 12 months) who underwent de novo radiofrequency catheter ablation between January 2020 and January 2022. All patients received a standardized “2C3L plus” strategy. The primary endpoint was freedom from any documented atrial tachyarrhythmia lasting >30 s, off antiarrhythmic drugs, at 1-year follow-up. Predictors of recurrence were analyzed using multivariable Cox regression analysis. Results Intraprocedural atrial fibrillation (AF) termination was achieved in 103 of 260 (39.6%) patients and 90 (34.6%) patients converted to atrial flutter (AFL) during ablation. Acute termination of AF directly to sinus rhythm (SR) was not associated with a lower risk of recurrence (adjusted HR: 0.765, 95% CI: 0.410–1.428, P = 0.400). However, intraprocedural conversion from AF to AFL was associated with significantly reduced recurrence risk (Uni: HR: 0.319, 95% CI: 0.142–0.714, P = 0.005; adjusted HR: 0.306, 95% CI: 0.133–0.704, P = 0.005). Further analysis revealed that the sequential intraprocedural conversion of AF-AFL-SR during ablation was a strong and independent predictor of arrhythmia-free survival (Uni: HR: 0.275, 95% CI: 0.108–0.696, P = 0.006; adjusted HR: 0.305, 95% CI: 0.119–0.784, P = 0.014). Conclusion In patients with LSPAF undergoing extensive “2C3L Plus” substrate ablation, the intraprocedural organization of AF-AFL-SR, rather than AF termination itself, emerged as a powerful independent predictor of 1-year arrhythmia-free survival, suggesting its value as a more meaningful prognostic endpoint.