Successful Reversal of Tachycardia Induced Cardiomyopathy After Flecainide Therapy in an Infant With Focal Atrial Tachycardia

Abstract

Arife Sancaktar, Tugba Burcu Ozturk Gomec, Irem Ersayoglu

Introduction: Focal atrial tachycardia (FAT) is an uncommon but clinically important cause of persistent supraventricular tachycardia in infancy and may lead to tachycardia-induced cardiomyopathy (TIC) when rhythm control cannot be achieved. Early recognition and effective rhythm control are essential to prevent progressive myocardial dysfunction.

Case Presentation: We report a 4.5-month-old former preterm infant with structurally normal heart anatomy who presented with persistent narrow QRS atrial tachycardia detected on Holter monitoring. Initial treatment with propranolol followed by continuous intravenous amiodarone achieved partial rate control but failed to restore sinus rhythm. During follow-up, progressive myocardial dysfunction developed, with a decline in left ventricular ejection fraction from 66% to 58%, left ventricular dilatation, and worsening atrioventricular valve regurgitation. Because of persistent arrhythmia and evolving TIC, flecainide therapy was initiated in combination with propranolol. Sinus rhythm was rapidly restored after flecainide administration, and subsequent Holter monitoring confirmed rhythm stability without recurrent tachycardia. Echocardiographic follow-up demonstrated improvement in ventricular systolic function and marked regression of valvular insufficiency. Clinically, feeding intolerance, reduced activity, and overall functional status improved significantly.

Conclusions: This case highlights the importance of early rhythm control in infantile FAT and demonstrates that partial rate control alone may be insufficient to prevent ongoing myocardial injury. Prompt restoration of sinus rhythm may be crucial for reversing TIC and achieving complete functional recovery. In addition, limited regional availability of flecainide represented a significant therapeutic challenge during management.

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