Why are redo AF ablations required and what does it take? Type of index PVI predicts pattern of redo ablations

Funding Acknowledgements Type of funding sources: None. Background Catheter ablation targeting isolation of the pulmonary veins (PVI) is the most effective treatment for atrial fibrillation (AF). Despite its high overall effectiveness, repeat AF ablations (re-do procedures, RDP) are often required to maintain sinus rhythm. Purpose Determine predictors for multiple and/or complex RDP, evaluate reference values for procedure duration and radiation exposure during index PVI (iPVI) and nth RDP in a large cohort. Methods and Results Data mining identified 934 (mean age 62.6 ± 12.3 years, 346 females) out of 6848 total AF ablation patients from a large German AF ablation center between 09/2008 and 09/2021 with an index PVI and at least one RDP. Analysis included 2152 procedures (out of 8750 total AF-related ablations). At iPVI, AF pattern was classified as paroxysmal AF (PAF) in 387 patients (41%). All others (59%) were classified as non-paroxysmal AF (Non-PAF). Non-PAF was significantly more frequent in males (64% vs. 49%, p iPVI was classified as PVI-only or PVI with additional substrate modification (SM). 724/934 patients (78%) received PVI-only as initial procedure. Of these, 572 (79%) had only 1 RDP, 116 (16%) had 2 RDP and 36 (5%) had 3 or more RDP. This distribution was 77%, 15% and 8% for 1, 2 and 3 or more RDP for patients with complex PVI as iPVI. An algorithm based on regular expressions classified all RDP as repeat PVI (Re-PVI) due to reconduction (PV reconduction), ablation of atrial tachycardia (AT) or SM, e. g. defragmentation of fractionated signals, or combinations. The results were manually quality-controlled. 798/934 (85%) patients required PV re-isolation due to PV reconduction, 298/934 (32%) required ablation for atrial tachycardia (AT) at least once during FU (Figure 1B). Comparing PVI-only iPVI patients with patients who received substrate modification during iPVI, significantly less patients with PVI-only iPVI had RDP for AT compared to those with SM during iPVI (27% vs. 50%, p Conclusion Redo AF ablations procedures are mainly required due to reconnected pulmonary veins or AT. Patients with PAF at iPVI are less likely to require more than one RDP which provides indirect support for early rhythm control in treatment of AF. SM at iPVI might be a predictor for occurrence of AT in the further course.