Background: Sinus node dysfunction is commonly associated with atrial fibrillation (AF), resulted in tachycardia-bradycardia syndrome. The aim of this study was to assess clinical outcome of catheter ablation in patients with tachycardia-bradycardia syndrome related to AF. Methods: Of 181 patients who underwent catheter ablation of drug-refractory AF, 18 patients (9.9%) with frequent episodes of syncope or pre-syncope attributable to prolonged sinus pauses (��� 3 seconds) on termination of AF were enrolled in this study. The procedure included anatomical left atrial ablation combining electrical isolation of all pulmonary veins with or without linear or focal ablation. Sinus node function was assessed by 24-hours ambulatory monitoring at 3 months after ablation. Results: A total of 29 ablation sessions were performed; 1 in 10 patients, 2 in 5 patients, 3 in 3 patients. At 3 months after procedure, mean heart rate was significant increased (55.3짹10.1 vs. 65.7짹12.8 bpm, P=0.017). During a mean follow-up of 19.7짹18.0 months, 4 patients (22.2%) had recurrence of AF. Of these, one patient was free of symptoms with a previously ineffective antiarrhythmic drug. The other 3 patients had ongoing symptomatic sinus pauses on termination of AF and underwent pacemaker implantation at 23.0짹14.8 days after the last ablation session. One patient (54 years old) without recurrence of AF showed symptomatic sinus node dysfunction during follow-up of 2 months, requiring pacemaker implantation. Conclusions: 14 of 18 patients (77.8%) with highly symptomatic sinus pauses on termination of AF remained free of symptoms after successful catheter ablation for AF. Tachycardia-mediated dysfunction or remodeling of the sinus node is reversible by curative ablation of AF, thus avoiding the need for pacemaker implantation in these patients with tachycardia-bradycardia syndrome.