Evolution of post–pulmonary vein isolation atrial fibrillation inducibility at redo ablation: Electrophysiological evidence of extra–pulmonary vein substrate progression

Background The electrophysiological substrate underlying atrial fibrillation (AF) progression remains difficult to identify. Objective The goals of this study were to study the evolution of post–pulmonary vein isolation (PVI) AF inducibility (AFI) after AF ablation and to compare patients with organized atrial tachycardia recurrence (OATr) versus those with paroxysmal or persistent AF recurrence. Methods We studied 99 patients who underwent de novo AF ablation (p1) and redo ablation (p2) for AF recurrence (AFr) or OATr. Stepwise AF ablation was performed at p1 and p2: (1) PVI, (2) coronary sinus defragmentation, and (3) left atrial (LA) defragmentation. Burst pacing followed each step, with AFI defined as sustained AF >5 minutes, triggering the next step. Patients with OATr underwent OAT ablation and inducibility testing post-redo PVI. Inducibility progression (IP) was defined as AFI at further steps of p2 compared to p1. Results Among patients with AFr, 34 of 72 patients (47%) exhibited post-PVI IP vs 2 of 27 (7.4%) patients with OATr (P = .0002). Stratification for persistent AF/paroxysmal AF/OATr showed a consistent association between recurrence phenotype and IP. Pulmonary vein (PV) reconnection incidence was 90%, without association with recurrence type or IP. LA volume was larger in patients with IP than in those without IP (86.7 ± 25.3 mL vs 72.0 ± 28.9 mL; P = .001). Right atrial dimensions increased between p1 and p2 in patients with IP vs no IP and in patients with AFr vs OATr. Conclusion Patients with AFr after first ablation exhibit IP more frequently at redo ablation than do patients with OATr. IP correlates with more advanced AFr type, larger LA volumes, and progressive right atrial enlargement. PV reconnection is not associated with AFr. Changes in post-PVI AFI may accurately indicate progression of extra-PV AF-maintaining substrate.