Initial experience and early outcomes of posterior wall ablation using pulsed-field ablation

Funding Acknowledgements Type of funding sources: None. Background The success rate of pulmonary vein isolation (PVI) is lower in patients with persistent compared to paroxysmal atrial fibrillation (AF). In patients with persistent AF, additional isolation of the posterior wall is under investigation to improve ablation success. Pulsed field ablation (PFA) might be superior to conventional methods for posterior wall isolation due to its safety profile and might allow for posterior wall ablation (PWA) rather than posterior wall isolation (PWI) based on its efficiency. Purpose To report our initial experience with PWA using a multipolar PFA catheter. Methods Consecutive patients with PWA during their first PFA procedure for AF between May 2021 and October 2022 at our institution were included. For PWA, the multipolar PFA ablation catheter was used in flower configuration only. With the wire in each of the pulmonary veins and the sheath angulated posteriorly, we first performed 2 x 2 sets of anchor lesions with the catheter rotated by ~30° between sets. Next, with the wire retracted back into the device, single sets of two applications were delivered in an overlapping fashion and without catheter rotation between lesion sets to cover the entire posterior wall between the superior and inferior pulmonary veins. Finally, completeness of PWA was verified by 3D electro-anatomical mapping. Results PWA using PFA was performed in 163 patients (mean age 67 years, 71% male). In 55 patients (34%), PWA was added to PVI during the first AF ablation procedure and the remaining 108 patients (66%) had undergone a median of two (interquartile range 1-3) previous AF ablation procedures using either cryoablation and/or radiofrequency ablation. Of all patients, 45 (28%) had paroxysmal, 93 (57%) persistent AF, and 22 patients (15%) left atrial reentry tachycardia. Median procedure duration and fluoroscopy time were 120 (70-190) min, and 18 (9-36) min, respectively. 3D-EAM showed no residual electrical signal (>0.05 mV) on the posterior wall at the end of the procedure in any patient. No cardiac tamponade, stroke, phrenic nerve injuries, atrio-esophageal fistula, or clinically manifest coronary spasm occurred. A repeat ablation was performed in seven patients (4%) and 3D-EAM showed persisting posterior wall isolation in six (86%) and recurrent roof dependent atrial flutter in one patient. Despite PWA, low-voltage signals were found in four (67%) cases on the superior aspect of the posterior wall. Conclusions Left atrial PWA can be performed safely and efficiently using PFA. Early data on the durability of PWA are promising. The impact of PWA on arrhythmia-free outcome needs to be evaluated in larger, prospective randomized trials.