['The aims of this observational study were to evaluate (i) the feasibility of obtaining bidirectional pulmonary vein (PV) isolation by means of circumferential radiofrequency ablation of the antral aspect of the PV ostium; (ii) whether the electrophysiological demonstration of bidirectional PV isolation predicts freedom from atrial tachyarrhythmia recurrence after ablation in patients with paroxysmal atrial fibrillation.', 'The study group comprised 28 patients affected by frequent recurrences of paroxysmal atrial fibrillation refractory to antiarrhythmic drugs, who underwent transcatheter ablation of the PVs by means of a non-fluoroscopic navigation system. Radiofrequency pulses were delivered in a point-by-point fashion at the antral aspect of the ostium of each vein presenting distal PV potentials. After ablation of each PV, bidirectional isolation was tested by means of a basket catheter. No antiarrhythmic drugs were prescribed on discharge. Outpatient visits, 24-h electrocardiographic Holter monitoring, and continuous 7-day digital electrocardiogram were scheduled at 3, 6, and 12 months.', 'A distal potential was detected in 101/123 (82%) mapped PVs. Bidirectional isolation was obtained in 81/101 (80%) PVs; bidirectional isolation of all targeted PVs was obtained in 17 (61%) patients. After a mean follow-up of 12.2 +/- 4.2 months, clinical success was observed in 15 (53%) patients. On multivariate analysis, only bidirectional isolation of all targeted PVs predicted the clinical success of ablation (P < 0.003; hazard ratio 7.504; confidence interval 1.943-28.990).'] Does pulmonary vein isolation predict freedom from arrhythmia after circumferential antral ablation for paroxysmal atrial fibrillation?