Life-threatening ventricular arrhythmias provoked by amiodarone treatment

We report two patients who developed symptomatic life-threatening ventricular tachyarrhythmias with changing QRS axes (resembling torsades de pointes), during treatment of their supraventricular tachycardias with oral amiodarone. Like other effects of amiodarone on the body, the arrhythmias became evident several days after initiating therapy, at which time electrocardiographic QT prolongation was present. The arrhythmias subsided after amiodarone treatment was withdrawn. No other drugs or electrolyte disturbances could be incriminated as a cause.