Bi-focal Atrial Tachycardia Mimicking Atrial Fibrillation: Fusion and Interference Between Two Distinct Tachycardias


  • Manuscript received 24 January 2007; Revised manuscript received 23 February 2007; Accepted for publication 14 March 2007.

Address for correspondence: Morio Shoda, M.D., Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan. E-mail:


Irregular tachycardias mimicking atrial fibrillation (AF) have previously been described. We report a case of a 60-year-old man with an antiarrhythmic drug-resistant atrial tachycardia (AT) mimicking AF. The tachycardia consisted of two distinct ATs with interference of one repetitive AT with another sustained AT. Radiofrequency (RF) ablation of two distinct right atrial foci eliminated the irregular tachycardia. Although catheter-based pulmonary vein isolation has become a popular therapeutic approach for patients with symptomatic AF, careful evaluation of the intracardiac recordings in the patients undergoing RF ablation for AF is important.