Outcomes of Functional Substrate Mapping Based Ablation in Addition to Pulmonary Vein Isolation in Atrial Fibrillation

Background Functional substrate mapping (FSM) enables the identification of slow conduction zones, which may represent critical atrial sites in atrial fibrillation (AF). This study aimed to evaluate the efficacy of FSM‐guided ablation as an adjunct to pulmonary vein isolation (PVI) and to identify clinical predictors of arrhythmia recurrence in patients with AF. Methods A total of 206 patients [mean age 61 ± 10, 105 (%51) males] with AF who underwent voltage and isochronal late activation mapping (ILAM) during sinus/paced rhythm were retrospectively included. Patients were divided into two groups based on the presence of deceleration zone (DZ) during ILAM: DZ (−) and DZ (+). While patients in the DZ (−) group underwent PVI alone, those in the DZ (+) group received additional ablation lesions targeting the DZs in addition to PVI. Results The mean number of DZs per left atrium was 1.45 ± 0.6. In the DZ (+) patients, 43 ATs were inducible in 35 patients, with 81.4% (35/43) of CIs colocalized with the DZs identified during ILAM. At a median follow‐up of 12.5 (8–23) months, atrial arrhythmia‐free survival was significantly higher in the DZ (−) group compared to the DZ (+) group ( p = 0.004). Multivariate Cox regression analysis revealed that the presence of DZ (HR: 2.152, 95%CI 1.051–4.404; p = 0.036) was the only significant predictor associated with atrial arrhythmia recurrence. Conclusions DZs identified by ILAM may serve as a critical substrate for AF and targeting these regions as an adjunct to PVI could improve procedural success especially in PAF.