Electrical Posterior Box Isolation in Repeat Ablation for Atrial Fibrillation: A Prospective Randomized Clinical Study

Objectives: This study investigated whether additional electrical posterior box isolation (POBI) may improve the rhythm outcome of repeat ablation in atrial fibrillation (AF). Background: Although electrically reconnected pulmonary veins (PVs) are the main mechanism of AF recurrence, it is unclear whether linear ablation in addition to circumferential PV isolation (CPVI) improves rhythm outcomes after repeat ablation. Methods: The authors prospectively randomized 150 patients with PV reconnection undergoing redo procedures to either a CPVI-alone group (n = 75) or an additional POBI group (n = 75). The primary endpoint was AF recurrence after a single procedure, and the secondary endpoints were recurrence pattern, cardioversion rate, and response to antiarrhythmic drugs. Results: After a median follow-up of 17 months, the clinical recurrence rate did not significantly differ between the CPVI-alone and additional-POBI groups (30.7% vs 30.7%; log-rank P =0.828). Of the 46 patients with clinical recurrence, the recurrences as atrial tachycardia (8.7% vs 30.4%; P =0.137) and cardioversion rates (21.7% vs 47.8%; P =0.122) were not significantly different between the CPVI-alone and additional-POBI groups. Major complication rates did not differ between the 2 groups (1.3% vs 5.3%; P = 0.363), but the total ablation time was significantly longer in the additional-POBI group than in the CPVI-alone group (median: 1,084 [IQR: 704–1,664] vs 1,595 [IQR: 1,244–2,302] seconds; P < 0.001). Conclusions: Among patients undergoing redo AF ablation with reconnected PVs, the addition of POBI to CPVI did not improve rhythm outcomes or influence overall safety, whereas leading to a longer ablation time than that with CPVI alone.