176-10: Localization and Ablation of Conduction Gaps after Wide Antral Circumferential Ablation of Atrial Fibrillation

Purpose of the study: Atrial fibrillation (AF) ablation is often performed by achieving pulmonary vein (PV) isolation (PVI) using the “wide antral circumferential ablation” (WACA) technique. We analyzed the efficacy of a novel technique based on pacing maneuvers to detect gaps in an initial WACA lesion. Method used: Patients referred to our center for AF ablation during March–June 2014 were enrolled prospectively. A WACA lesion set was performed, isolating ipsilateral PVs together. If PVI was not achieved, and for all redo procedures, the atria were paced using an ablation catheter. For each pacing site, the “activation delay” and the “activation sequence” were analyzed using a circular mapping catheter. Summary of results: 26 patients (mean age 57.8 ± 10.5 years, 22 males) were included. There were 36 residual gaps in 25 WACA lesion sets in 21 patients (one gap in 16 lesion sets, two and three gaps in seven and two lesion sets, respectively). Three patterns were identified: A) the activation delays converged towards one point with the shortest delay; no modification of the activation sequence (indicating one gap); B) activation delays converged towards ≥2 close locations; no change in the activation sequence (indicating ≥2 close gaps); C) activation delays converged towards ≥2 remote locations; modification of the activation sequence (indicating ≥2 remote gaps). This allowed precise localization of the gaps, ultimately leading to PVI in all patients. Schemas showingdifferent responses to pacing around the circumferential ablation lesions, and assumptions of gap localization.