Background: High-power radiofrequency ablation (HPRFA) appears to be a novel concept for atrial fibrillation (AF) treatment but there are scarce data in conscious patients. The lesion size index (LSI) value has been associated with durability of pulmonary vein isolation (PVI) lesions. Objectives: We hypothesised that HPRFA applications based on LSI were not inferior to standard approach in terms of patient’s pain sensationas well as safety, effectiveness, and procedure duration. Methods: Retrospectively, we analysed 218 patients who had performed ablation of AF based on LSI (LSI 4-4.5 on posterior wall, LSI 5-5.5 in other locations) who were propensity score matched to 3 different RF power settings: group-30W (45oC, 30 W and 25 W on posterior wall), group-40W (45oC, 40 W) and group-50W (45oC, 50 W). Results: Comparing group-30W vs group-40W and group-50W, procedure and left atrium dwell time (minutes) were 190±32, 161±41, 102±8 (p<0.0001) and 154±53, 113±29, 79±10 (p<0.0001), respectively. With comparable number of RF applications (p>0.05) between the groups, total RF and fluoroscopy time (minutes) were 62±17,38±10, 28±5 (p<0.0001) and 6±3, 6±2, 4±1 (p=0.08), respectively. Number of stopped painful RF applications were 19±9, 9±5 and 7±2 (p<0.0001), respectively. No serious complications were observed in any of the group. No difference in 1-year ablation efficacy was observed between the groups (p=0.78). Conclusions: HPRFA based on LSI is less painful, faster and safe in conscious patients than standard approach with comparable effectiveness in one year follow-up.