Amiodarone-induced torsade de pointes in a child with dilated cardiomyopathy

Abstract

Amiodarone has a high incidence of side effects, but few pro-arrhythmic effects. We report a case of amiodarone-induced torsade de pointes in a child aged 10 years. The patient had severe dilated cardiomyopathy, and even though he was treated with low oral doses of amiodarone, without dosage increments and electrolyte imbalance, he developed torsade de pointes at nights, after T-wave modification and increases of the corrected QT interval (QTc, 20%), QT dispersion (QTd, 175%) and QTcd (116%). The arrhythmic events were preceded by sinus bradycardia at Holter monitoring. Amiodarone therapy was discontinued. Intravenous magnesium administration was not effective in the suppression of torsade de pointes. High-rate atrial pacing prevented recurrences of the arrhythmias and reduced the QTc interval by 20%, QTd by 50%, and QTcd by 70%; QTd and QTcd returned below normal limits. This case underscores the need of careful electrocardiographic monitoring during amiodarone therapy.