Typical atrial flutter mimicking a pacemaker‐mediated tachycardia

A 64‐year‐old man with a history of congestive heart failure secondary to nonischemic cardiomyopathy, mitral and aortic valve replacements, and biventricular cardioverter‐defibrillator placement, developed a tachycardia. The tachycardia exhibited a biventricular paced rhythm with a short R‐P interval and concentric atrial activation sequence within the coronary sinus, suggesting that the tachycardia might be a pacemaker‐mediated tachycardia (PMT). However, the tachycardia was diagnosed as counterclockwise cavotricuspid isthmus (CTI)‐dependent atrial flutter (AFL), and linear ablation of the CTI eliminated the tachycardia. This case illustrated that typical AFL can mimic a PMT when there is a severe conduction delay through the CTI.