Lowering of the T wave alternans (TWA) onset heart rate may be a useful surrogate marker for predicting ventricular proarrhythmia in patients treated with amiodarone.
Amiodarone-related TWA lowering may flag proarrhythmic risk; leaves open surrogate validation beyond this single case report.
An implantable cardioverter defibrillator (ICD) was used in a 62-year-old man with dilated cardiomyopathy (DCM) because of hemodynamically intolerable ventricular tachycardia (VT). Amiodarone was administered after a second episode of ICD discharge. Three weeks later, incessant VT appeared, and DC discharge failed to terminate it. Microvolt T wave alternans (TWA), measured by a spectral method, was observed in this patient with and without amiodarone administration. The onset heart rate with TWA was lower and the alternans voltage was higher with amiodarone than without it. The effects of amiodarone appeared to be related to the exacerbation of VT and an increased defibrillation threshold. TWA might be useful in predicting the proarrhythmic effects of amiodarone in similar cases.
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Matsuyama et al. (2001) studied this question.
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