Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) is a new myocardial-specific ablation technology for atrial fibrillation (AF). Direct current electric energy is applied to cells and disrupts cell membranes by creating pores. Data regarding midterm outcome are sparse. Purpose The aim of this single-center study was to report midterm clinical outcomes following PFA-based pulmonary vein isolation (PVI). Methods Consecutive patients with symptomatic AF were enrolled to undergo PFA-PVI based on the "5S Study" ablation strategy. Procedures were done between March 2021 and January 2022. A dedicated catheter with five splines delivering bipolar energy with a voltage of 1.8-2.0 kV was used. Arrhythmia recurrence was defined as documented AF/atrial tachycardia (AT) lasting more than 30 seconds after a 90 days blanking period (BP). Procedural and demographic data were analysed. Results 231 patients (42% female, age 69±12, 55% paroxysmal atrial fibrillation [PAF]) were included in this preliminary analysis. 901 pulmonary veins (PV) were identified, and all PVs could be isolated using solely the PFA device. 895 (99.3 %) PVs were isolated with the first application. 32±4 applications per patient were delivered. The overall complication rate was 3.5% (vascular access complication: 2.2%, stroke: 0.9%, tamponade: 0.4%). Median follow-up time was 323 days. 22% of patients experienced a recurrence during the BP after a median of 23 days. Kaplan Meier estimated freedom of AF/AT out of the BP was 75% at one year, 83% for PAF and 64% for persistent atrial fibrillation (persAF, p< 0.0036). In a multivariate analysis blanking recurrence (p<0.001) and female sex (p=0.002) were the only independent predictors for late recurrence. Conclusions This study indicates high acute efficacy of PFA based PVI. 75% of patients are free of AF at one year. Blanking recurrence is an independent predictor for late recurrence after PFA-PVI: further studies are required to better define the duration of the BP after PFA PVI.