Background Laser balloon ablation (LBA) is a balloon-based catheter ablation technology used for atrial fibrillation (AF) ablation in recent years. The laser balloon has the potential to extend the isolation area because of its changeable balloon size. The purpose of the study was to investigate the feasibility and safety of extended LBA technique, and to compare the isolation area with an established balloon technique using the cryoballoon ablation (CBA). Methods From June 2020 to July 2021, 76 consecutive patients with paroxysmal AF who underwent initial pulmonary vein isolation were enrolled. Of these, 65 patients were included in the study, excluding 11 who met the exclusion criteria; 32 and 33 patients were in the LBA and CBA groups, respectively. In the LBA group, after standard ablation of each PV, additional extended posterior wall ablation was performed by increasing the balloon size to the maximum (the extended LBA technique). In the CBA group, cryoablation was performed using a 28-mm balloon. In both groups, voltage maps were created for measuring the isolated surface area (ISA) by the CARTO mapping system pre- and post-ablation. Results In the LBA group, the extended LBA technique was feasible in all patients. The total ISA after the extended LBA technique was significantly larger than before (32.4±6.5 vs 22.3±4.1 cm 2, p<0.001) and the non-isolated posterior wall area was significantly smaller (8.9 ± 3.5 vs 13.3 ± 3.7 cm2, p<0.001). Although the percentage of esophageal temperature elevation (>39.0°C) was higher during the extended LBA than during the standard LBA (LIPV: 26/32 [81%] vs. 7/32 [22%], p<0.001; LSPV: 10/32 [31%] vs. 2/32 [6%], p<0.001), symptomatic gastric hypomotility or esophageal mucosal injury was not observed in all patients. Comparing the extended LBA and the CBA group, IASA-R (18.1 ± 4.6 vs 15.9 ± 3.5, p=0.033) and non-isolated posterior wall (8.9 ± 3.5 vs 12.4 ± 3.7, p<0.001) were significantly greater in the extended LBA, but cardiac enzyme elevation after ablation was lower than the CBA group. No significant differences were found between the two groups in perioperative major complications or AF-free survival at 3 and 6 months. Conclusions LBA with extended posterior wall isolation technique was safe and feasible. Long-term effectiveness studies should be evaluated in a larger sample size.