Circumferential ablation around pulmonary vein ostia by CARTO system was performed in 98 patients with paroxysmal and 29 with permanent atrial fibrillation (AF). Preablation and postablation activation, propagation and voltage maps were obtained. A total of 135 +/- 18 radiofrequency pulses were delivered. After a follow-up of 14.7 +/- 3.3 months, 84 patients with paroxysmal and 22 with chronic AF are in sinus rhythm and 75 of them without antiarrhythmics. Only the area extent of low voltage potentials within and just around the lesions distinguished patients with and without successful ablation. Pulmonary vein isolation is an effective procedure to cure resistant AF; the extent of lesion area around pulmonary vein ostia may be crucial in predicting the outcome.