Abstract Body (Do not enter title and authors here): INTRODUCTION AND BACKGROUND
Left lateral atrial ridge (LLR) is sited between the orifices of the left pulmonary veins (PVs) and the left atrial appendage (LAA) ostium and is the crossroads of the vein of Marshall, autonomic nervous system, LAA, PVs and intersected atrial myofibers. Therefore, it may be a substrate for focal triggers initiating AF.

RESEARCH QUESTIONS
We would assess if PVI with bilateral LLR (BLLR) ablation could be superior to PVI alone in long-term maintaining of sinus rhythm in PAF patients without antiarrhythmics drugs (AADs).

METHODS
In this 1:1 randomized controlled, superiority trial we enrolled 18-80 years old patients undergoing first PAF ablation in our high-volume center. Procedures were performed using pulse field ablation under deep sedation. The primary endpoint is freedom from atrial tachyarrhythmias 12 months after ablation without AADs. The secondary outcome is a composite safety endpoint of all-cause death, cerebrovascular events, cardiac tamponade and all major bleeding. Sample size of 121 patients per group allows to obtain 0,80 statistical power. A structured follow up at 2, 6 and 12 months was settled. Students t-test or non-parametric tests were used to compare continuous variables. Associations between categorical data was evaluated by chi-quare test or Fisher exact test. Log rank test was used to assess the primary outcome. Hazard ratios and confidential intervals were estimated with univariate Cox regression.

RESULTS AND DATA
34 randomized patients were included in this study preliminary results (mean age 61,4±7,5 years; male 19%). 16 patients were assigned to PVI + BLLR (mean age 62,5±3,9 years; male 11%) and 18 to PVI alone group (mean age 60,4±9,8 years, male 8%). Baseline characteristics of patients are exposed in fig.1. After 6 months, 15 patients (93,7%) assigned to PVI + BLLR were free from recurrent atrial arrhythmia without ADDs, compared with 17 (94,4%) assigned to PVI alone (hazard ratio 0,63; 95% CI 0,03-10,3 p 0,74; Log Rank p 0,66). No secondary outcome events occurred. Procedural time (83±16,5 min versus 82±32,4 min; p 0,4) and first-pass isolation (93,8% versus 100%; p 0,28) were similar between two groups. There was 1 vascular complication per group.

CONCLUSIONS
Preliminary results of RIDGE AF trial showed no difference in maintaining of sinus rhythm between PVI with BLLR ablation and PVI alone. Further follow up data and enrolled patients are needed to verify this research hypothesis.