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.