Box Lesion Isolation of the Left Atrial Posterior Wall with Radiofrequency Ablation Restricted in Predetermined Lines for the Treatment of Persistent Atrial Fibrillation: The Prognostic Role of Acute Interventional Outcome and Trigger Identification

The left atrial posterior wall (PW) is known to be a critical substrate for the initiation and perpetuation of atrial fibrillation (AF) and has been explored as a target for catheter ablation, particularly in persistent AF (PerAF). In this retrospective study, we investigate the clinical outcome of patients with PerAF who underwent PW isolation (PWI) restricted in predetermined lines in addition to pulmonary vein isolation (PVI). One hundred consecutive patients (64 ± 9.1 years, 66% male, 20% with previous PVI ablation) underwent PWI in a box lesion setting for PerAF lasting >3 months (34% long-standing PerAF). PW triggers were defined as either foci from the PW that repeatedly induced AF or as isolated AF or atrial tachycardia (AT) within the PW. After a mean follow-up period of 25.6 ± 6.7 months, 61% of the patients remained in sinus rhythm after the last procedure. In 79 patients, the PW was successfully isolated, while, in 21 patients, complete isolation was not possible due to failure in completion of the roof line (n = 16), the floor line (n = 7), or both (n = 2). Patients with incomplete isolation had similar AF/AT recurrence rates compared to those with complete PWI. In 12 patients, PW triggers were identified, and PWI in these patients was shown to have a significantly better prognosis in terms of sinus rhythm maintenance (P = .031). Failure of complete PWI does not predispose a patient to an inferior outcome nor is it responsible for iatrogenic ATs. The presence of AF triggers within the PW leads to a particularly favorable result after box lesion isolation.