CLOSE protocol versus lower ablation index value for paroxysmal atrial fibrillation: A randomized noninferior clinical trial

Introduction The optimized ablation index (AI) value for catheter ablation of atrial fibrillation (AF) remains to be defined. We aimed to compare the efficacy and safety of CLOSE protocol and lower AI protocol in paroxysmal AF. Methods and Results Patients with symptomatic, drug‐resistant paroxysmal AF for first ablation were prospectively enrolled from September 2020 to January 2022. The patients were randomly divided into CLOSE group (AI ≥ 550 for anterior/roof segments and ≥400 for posterior/inferior segments) and lower AI group (AI ≥ 450 for anterior/roof segments and ≥350 for posterior/inferior segments). First‐pass isolation, acute pulmonary vein (PV) reconnections, 1‐year arrhythmia recurrence, and major complications were assessed. Of the 270 enrolled patients, 238 completed 1‐year follow‐up (118 in CLOSE group and 120 in lower AI group). First‐pass isolation in left PVs was higher in CLOSE group (71.2% vs. 53.3%, p = .005). Acute PV reconnections were comparable between groups (9.3% vs. 14.2%, p = .246). At 1 year, 86.4% in CLOSE group versus 81.7% in lower AI group were free from atrial arrhythmia (log rank p = .334). The proportion difference was −4.8% (95% CI: −14.1% to 4.6%), and p = .475 for noninferiority. Stroke occurred in four patients of lower AI group, and no cardiac tamponade, atrioesophageal fistula, major bleeding or death occurred post procedure. Conclusion For patients with paroxysmal AF and treated by AI‐guided PV ablation, lower AI is not noninferior to CLOSE protocol.