Purpose: Pulmonary vein isolation (PVI) using phased radiofrequency (RF) energy has been shown to be effective in the treatment of paroxysmal atrial fibrillation (AF). We characterize pulmonary vein (PV) conduction at repeat ablation in patients with AF after an initial successful PVI using phased RF technology and analyze the effects of a primary 2:1 ablation mode.Methods And Results: A primary 4:1 bipolar/unipolar mode in group A patients (n = 22) was compared with a primary 2:1 mode in group B (n = 22) acutely and during follow-up. Of all PVs, 81 % showed reconnection(s); 52 % of them had reconnected in all PVs. PVI was achieved in all patients without complications. Procedure and fluoroscopy times were shorter in group B (108 ± 15 vs. 126 ± 24 min and 17 ± 5 vs. 23 ± 7 min, respectively). This was attributed to a significant decrease of early PV reconnections within the first 30 min in 17 % of group B patients vs. 45 % of group A patients (p < 0.001). After 9.5 ± 4 months, recurrence of AF was detected in 5 of 22 patients (22.7 %) in group A vs. 3 of 22 patients (13.6 %) in group B (p = 0.722).Conclusions: Phased RF energy applied by a 2:1 bipolar/unipolar mode seems safe and effective in redo-PVI procedures, resulting in a mid-term freedom from AF in 86.4%. Significant shorter procedure and fluoroscopy times compared with a primary 4:1 ablation mode during repeat PVI are mainly attributed to a lower incidence of acutely reconnected PVs within the first 30 min.