T wave alternans for predicting adverse effects of amiodarone in a patientwith dilated cardiomyopathy

An implantable cardioverter defibrillator (ICD) was used in a 62-yoar-old m an with dilated cardiomyopathy (DCM) because of hemodynamically intolerable ventricular tachycardia (VT). Amiodarone was administered after a second e pisode of ICD discharge. Three weeks Inter, incessant VT appeared, and DC d ischarge failed to terminate it. Microvolt T wave alternans (TWA) measured by a spectral method, was observed in this patient with and without amiodar one administration. The onset heart rare with TWA was lower and the alterna ns voltage as higher with amiodarone than without it. The effects of amioda rone appear ed to be related to the exacerbation of VT and an increased def ibrillation threshold. TWA might be useful in predicting the proarrhythmic effects of amiodarone in similar cases.