Incidence, Mechanistic Insights, and Ablation of Atrial Tachycardia Occurring After Pulsed Field Ablation for Atrial Fibrillation: Results From a Large International Registry.

BACKGROUND

Understanding the mechanisms and anatomical substrates underlying postablation atrial tachycardia (AT) is essential for guiding targeted mapping and successful re-ablation strategies.

OBJECTIVE

This study analyzed patients referred for repeat ablation for AT after first-time atrial fibrillation ablation with a pentaspline pulsed field ablation (PFA) catheter.

METHODS

High-density electroanatomical mapping was performed to identify the mechanism of post-PFA ATs and assess lesion durability. Re-entrant circuits were analyzed according to the principles of topology (paired rotations, identification of critical boundaries, and ablation strategies).

RESULTS

Among 4,144 patients, 236 underwent repeat ablation (160 for atrial fibrillation [3.9%] and 76 for AT [1.8%]), and this constituted the final cohort. A total of 87 ATs were mapped: 21 in the right atrium (4 focal and 17 peri-tricuspid valve re-entry) and 66 in the left atrium (1 focal and 65 re-entry). Pulmonary vein and posterior wall isolation durability were 84% and 89%, respectively. Left atrial (LA) re-entry mechanisms comprised single-loop (n = 9) and predominantly dual-loop (n = 56) re-entry, including circuits defined by anatomical boundaries (n = 32) or involving an anterior scar (n = 24). In all cases of LA re-entrant AT, sinus rhythm was restored when ablation connected the 2 critical boundaries. Topological principles accurately explained the observed activation patterns and responses to ablation.

CONCLUSIONS

The incidence of repeat ablation for AT after pentaspline PFA was low, likely reflecting the high durability of the index lesion sets. Most post-PFA ATs manifested as dual-loop LA re-entry. Retrospective application of the topological framework provided coherent mechanistic interpretations of AT behavior and accurately predicted the response to direct and indirect critical boundary-targeted ablation.