Direct Epicardial Mapping and Ablation Revealing Three‐Dimensional Roof‐Dependent Macroreentrant Atrial Tachycardia Breaking Into Bachmann's Bundle

Catheter ablation for macroreentrant atrial tachycardia (AT) that recurs after atrial fibrillation (AF) ablation is occasionally difficult because of epicardial connections. Here, we report the case of a patient who underwent ablation for recurrent AT after AF ablation. Endocardial mapping of the left atrium (LA) showed a centrifugal pattern from the base of the appendage, and the LA roof showed discontinuous activation from the posterior LA. Direct epicardial mapping was performed, revealing the roof-dependent macroreentrant AT using the epicardial connection from the LA posterior to the Bachmann bundle. The entrainment pacing from the exit site of the epicardium was within the tachycardia circuit, and epicardial ablation successfully terminated the AT. Epicardial mapping and ablation can improve the procedural success rate of reentrant AT recurrence after endocardial ablation.