AIM: Sinus tachycardia has been observed following radiofrequency (RF) catheter ablation for various kinds of supraventricular tachycardia. This study is aimed at determining the occurrence of changes in sinus-rhythm heart rate (HR) after pulmonary vein (PV) isolation in patients with paroxysmal/persistent atrial fibrillation (AF), prospectively. METHODS: Patients with a history of AF underwent segmental or circumferential isolation of the PVs. A total of 62 consecutive patients, mean age 55 +/- 10, was included. Clinical evaluation was performed before and one, three, six, nine, and 12 months following the procedure. RESULTS: Following PV isolation, the mean HR significantly increased from 58 +/- 10 bpm at baseline to 67 +/- 12 bpm at one month, 71 +/- 13 bpm at three months, 69 +/- 12 bpm at six months, 69 +/- 13 at nine months, and 70 +/- 13 at 12 months follow-up. The ablation success significantly correlated with the increase in HR at one month follow-up. In three patients the mean HR increased > 25 bpm resulting in symptoms necessitating therapy with rate-controlling drugs. CONCLUSION: PV isolation in patients with AF may result in increased HR, which positively correlated with the ablation success. This change does not seem to resolve spontaneously after a follow-up of 12 months. Approximately 5% of patients may develop symptoms due to an increased HR, necessitating treatment with rate-controlling drugs.