Background To determine the protective value of serum Pro-BNP in the recurrence of late atrial fibrillation after pulmonary vein isolation in paroxysmal and persistent atrial fibrillation.Methods Ninety-four patients in the present study had symptomatic paroxysmal AF and had failed to respond to at least one anti-arrhythmic drug.All patients underwent electrophysiological study and circumferential pulmonary vein isolation (CPVI) till to achieve PV isolation.Cardiac structure and function were measured with 2-D echocardiogram,and the cardiac biomarker N-terminal pro-brain natriuretic peptide (NT-pro-BNP) was measured before ablation and at long-term follow-up.