Outcomes of atrial functional substrate mapping based ablation detected by isochronal late activation mapping in addition to pulmonary vein isolation in atrial fibrillation

Background Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. Notably, in persistent AF the effectiveness of PVI is limited by underlying atrial remodeling and extra pulmonary vein triggers. Functional substrate mapping (FSM) facilitates the detection of slow conduction zones, which may correspond to critical atrial regions involved in AF. Purpose This study aimed to evaluate the efficacy of FSM-guided ablation as an adjunct to PVI and to identify clinical predictors of arrhythmia recurrence in patients with AF. Methods We retrospectively analyzed 206 patients with AF who underwent voltage and isochronal late activation mapping (ILAM) during sinus/coronary sinus–paced rhythm to identify deceleration zones (DZs). Patients were divided into two groups based on the presence of DZ during ILAM: DZ (–) and DZ (+). Patients in the DZ (–) group underwent PVI alone, whereas those in the DZ (+) group received additional ablation targeting the DZs in addition to PVI. Results The mean number of DZs identified per left atrium was 1.45 ± 0.6. In the DZ (+) group, 43 atrial tachycardias (ATs) were inducible in 35 patients, with 81.4% (35/43) of the critical isthmuses colocalizing with the DZs identified during ILAM. Over a median follow-up of 12.5 (8–23) months, atrial tachyarrhythmia (ATa)–free survival was significantly higher in the DZ (–) group than in the DZ (+) group (p = 0.004, Figure 1A). When the subgroups of paroxysmal (PAF) and persistent (PeAF) atrial fibrillation were considered, a significant difference in the Kaplan–Meier analysis (Figure 1B) was observed only between the DZ (–) PAF group undergoing PVI alone and the DZ (+) PeAF group that underwent additional DZ ablation in addition to PVI (p= 0.003; Bonferroni-corrected significance level, log-rank p < 0.0083). In multivariate Cox regression analysis, the presence of a DZ (HR = 2.152, 95% CI 1.051–4.404; p= 0.036) was the only independent predictor of ATa recurrence. Conclusions DZs identified by ILAM during AF ablation may represent critical substrates and ablation of these areas in addition to PVI may improve atrial tachyarrhythmia-free survival.