Abstract 4137447: Length of WACA line Affects 1 ^st Pass Success rates in PVI

Background: Standard ablation for atrial fibrillation consists of wide antral pulmonary vein isolation, efficacy for which depends on a contiguous series of ablation lesions. The larger a circumference ablated around the pulmonary veins, the more challenging it may be to ensure durable isolation, due to technical and anatomic factors, which may in turn contribute to higher rates of atrial fibrillation (AF) recurrence. The relationship between WACA size and success rates may inform procedural methods and optimize outcomes. Objective: To examine the relationship between length of WACA lines and ablation success in patients that have undergone a PVI ablation. Methods: We performed a single-center, retrospective analysis of a consecutive series of 258 patients who underwent 1 st pulmonary vein isolation (PVI) for the treatment of atrial fibrillation, between 1/1/2022 and 6/30/2023. Radiofrequency ablation (RFA) was performed using 50 W with a contact-force sensing irrigated catheter. Information on acute 1 st pass success for left and right vein was recorded. The length of each WACA line was traced out manually, following the center of the ablated lesions. Follow up information consisted of AF recurrence at three, six, and twelve months. Student t-test was used for comparison of means and Chi-square test was used for categorical variables. Results: All veins were successfully isolated in all patients. WACA 1 st pass success rates were 87% in the left veins, and 83% in the right veins. Right WACA lines were generally longer. In patients with Left WACA 1 st pass success, the average length of the WACA line was 94.8cm, compared to 100.1cm in the group without 1 st pass success (p=0.025). In patients with right WACA 1 st pass success, the average length of the WACA line was 105.8cm, compared to 110.6cm in the group without 1 st pass success (p=0.07). When evaluating post PVI patients for recurrence of AF at 1year, there was a non-statistically significant association of AF recurrence with longer combined L+R WACA lines during index PVI (205.5cm vs 197.0cm, p=0.065). Conclusion: Longer WACA lines during index PVI are associated with failure of 1 st pass isolation. Further study is needed to address the mechanism by which longer WACA lines affect ablation efficacy, whether due to technical factors reflecting something intrinsic to underlying substrate.