Right Side Accessory Pathway Mediated Cardiomyopathy Treated with Amiodarone: First Adult Case Report.

BACKGROUND

Right-sided accessory pathways can cause ventricular dyssynchrony through early right ventricular preexcitation, mimicking left bundle branch block and leading to reversible cardiomyopathy even without sustained tachycardia. Although catheter ablation is standard, pharmacologic reversal in adults has not been reported.

DATA SOURCES: Single-patient case from a US community hospital. Literature review (PubMed/Embase) confirmed no previous adult cases of complete pharmacologic reversal.

MAIN FINDINGS: A 44-year-old man with known Wolff-Parkinson-White presented with palpitations, dyspnea, chest pain, and syncope. Electrocardiogram showed right-sided preexcitation with left bundle branch block morphology. Echocardiography demonstrated left ventricular systolic function with ejection fraction (LVEF) 10%-15% with LV dilation. Coronary arteries were normal and no other cardiomyopathy etiologies were identified. The patient declined ablation. Amiodarone was initiated. Within 2 months, preexcitation resolved (loss of delta wave) and LVEF improved to 30%-35%. By 4 months, LVEF normalized to 60% with resolution of dilation. Amiodarone was discontinued and switched to flecainide.

LIMITATIONS: No cardiac MRI performed (patient preference and rapid improvement); no extended ambulatory rhythm monitoring; and no formal electrophysiology study.

CONCLUSIONS

Amiodarone-induced suppression of antegrade right-sided accessory pathway conduction can lead to complete reversal of severe dyssynchrony-mediated cardiomyopathy in adults when ablation is declined.