Atrioventricular Nodal Reentrant Tachycardia Mimicking A-flutter and Presenting as Tachycardia-Induced...

Tachycardia-induced cardiomyopathy (TIC) is most commonly associated with atrial fibrillation or atrial flutter, whereas atrioventricular nodal reentrant tachycardia (AVNRT) is rarely implicated because of its typically paroxysmal nature. We present the case of a 69-year-old man with a history of atrial fibrillation who presented with progressive dyspnea and persistent regular narrow-complex tachycardia initially interpreted as atypical atrial flutter with 2:1 atrioventricular conduction. Repeat electrical cardioversion was unsuccessful, and transthoracic echocardiography (TTE) demonstrated a newly reduced left ventricular ejection fraction (LVEF 20%) with global hypokinesis, while ischemic evaluation was negative. Due to refractory tachyarrhythmia and new non-ischemic cardiomyopathy, the patient underwent a comprehensive electrophysiology study with three-dimensional mapping, which revealed inducible typical AVNRT successfully treated with slow pathway modification. Pulmonary vein isolation and cavotricuspid isthmus ablation were additionally performed because of the patient's prior clinical history of atrial fibrillation and suspected atrial flutter. Following ablation, the patient experienced marked symptomatic improvement with recovery of LVEF to 50% at three-month follow-up, consistent with TIC. This case highlights the diagnostic limitations of surface electrocardiography in differentiating supraventricular tachycardias and demonstrates that AVNRT may rarely masquerade as atrial flutter and contribute to reversible cardiomyopathy, emphasizing the importance of an electrophysiology study in establishing a definitive diagnosis and guiding management.