Aims: To evaluate the clinical outcome of pulmonary vein isolation (PVI) in radiofrequency ablation of atrial fibrillation (AF) comparing a strategy using Ablation Index (AI) and lesion contiguity with Contact Force (CF) only. Methods: In a single-center retrospective design, we included 479 patients with AF (n=341 (71.2%) paroxysmal AF (PAF) and n=138 (28.8%) persistent AF (PeAF)) treated with first time radiofrequency ablation. In 2015, 210 patients underwent PVI based on a drag-and-ablate technique using CF only. In 2017, 269 patients underwent point-by-point PVI using AI and a maximum inter-lesion distance of 6 mm ensuring contiguity. Follow-up was performed after 12 months. Outcome was freedom from documented AF/atrial tachycardia (AT) after single procedure without use of anti-arrhythmic drugs at follow-up. Results: There was no significant difference in baseline characteristics between the groups. The median procedure time and mean ablation time were significantly longer in the AI-group compared to the CF-group (131.5[113;156] min vs. 120.0[97;140] min, P < 0.01) and (44.1±10.0 min vs. 37.1±13.3 min, P < 0.01), respectively. Freedom from documented AF/AT was significantly higher in the AI-group compared to the conventional CF -group (71.0% vs. 62.4%, P = 0.046). The improvement in clinical outcome in the AI group is mainly driven by the outcome in patients with PeAF (64.9% vs. 50.0%, P = 0.078) and not PAF. Conclusion: An ablation strategy combining AI and lesion contiguity improves the clinical outcome after first time PVI in patients with AF compared to a strategy using CF only.