Impact of Antiarrhythmic Drugs on Complex Fractionated Atrial Electrograms

Background: Ablation of complex fractionated atrial electrograms (CFAE) is now performed in patients with persistent atrial fibrillation (AF). However, extensive ablation is often necessary to eliminate all CFAE or to terminate AF. The purpose of this study was to evaluate the effects of antiarrhythmic drugs (AAD) on CFAE. Methods and Results: Sixty patients, including 38 with longstanding persistent AF and 22 with persistent AF, underwent box isolation. After box isolation, CFAE maps were created before and after infusion of a pure Na+ blocker, pilsicainide (1 mg/kg), in 30 patients or a pure IKr blocker, nifekalant (0.3 mg/kg), in 30 patients. Nifekalant had a greater effect on AF termination than pilsicainide (33.3% versus 6.7%, P = 0.01). Both AADs similarly reduced CFAE. Ablation of CFAE localized by nifekalant and pilsicainide terminated AF in 26.7% and 20% of the patients, respectively. After a single ablation procedure, patients in whom AF was terminated by CFAE ablation had a lower recurrence rate than those in whom AF was not terminated despite CFAE ablation (19.2% vers us 35.3%, P = 0.04). Conclusions: Both pilsicainide and nifekalant reduce CFAE, and nifekalant has a greater effect on AF termination than pilsicainide. Ablation of only CFAE localized with AAD may be sufficient for clinical efficacy.