Gaps after linear ablation of persistent atrial fibrillation (Marshall-PLAN): Clinical implication.

Background: Beyond pulmonary vein (PV) isolation, anatomic isthmus transection is an adjunctive strategy for persistent atrial fibrillation. Data on the durability of multiple lines of block remain scarce.
Objective: The purpose of this study was to evaluate the impact of gaps within such a lesion set.
Methods: We followed 291 consecutive patients who underwent (1) vein of Marshall ethanol infusion, (2) PV isolation, and (3) mitral, cavotricuspid, and dome isthmus transection. Dome transection relied on 2 distinct strategies over time: a single roof line with touch-ups applied in case of gap demonstrated by conventional maneuvers (first leg), and an alternative floor line if the roof line exhibited a gap during high-density mapping with careful electrogram reannotation (second leg).
Results: Twelve-month sinus rhythm maintenance was 70% after 1 procedure and 94% after 1 or 2 procedures. Event-free survival after the first procedure was lower in case of residual gaps within the lesion set (log-rank, P = .004). Delayed gaps were found in 94% of a second procedure performed in the 69 patients relapsing despite a complete lesion set with PV gaps increasing the risk of recurrence of atrial fibrillation (67% vs 34%; P = .02) and anatomic isthmus gaps supporting a majority of atrial tachycardias (60%). Between the first leg and the second leg, a significant decrease was found in roof lines considered blocked during the first procedure (99% vs 78%; P < .001) and in delayed dome gaps observed during a second procedure (68% vs 43%; P = .05).
Conclusion: Gaps are arrhythmogenic and can be reduced by optimized ablation and assessment of lines of block. Closing these gaps improves sinus rhythm maintenance.
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