Typical atrial flutter mimicking a pacemaker-mediated tachycardia

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• A 64-year-old male patient with a history of congestive heart failure, nonischemic cardiomyopathy, and prior valve replacements presented with tachycardia.
• The patient had a biventricular cardioverter-defibrillator (ICD) implanted for his cardiac condition.

Observation:

• The tachycardia presented with a biventricular paced rhythm, a short R-P interval, and a concentric atrial activation sequence in the coronary sinus.
• These characteristics initially suggested a pacemaker-mediated tachycardia (PMT).

Findings:

• The tachycardia was ultimately diagnosed as counterclockwise cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL).
• Linear ablation targeting the CTI effectively eliminated the observed tachycardia.

Implications:

• This case demonstrates that typical atrial flutter can present with features mimicking PMT.
• Severe conduction delay across the CTI can lead to this diagnostic challenge in patients with cardiac devices.