Research In Brief

Is MTWA useful? Two new studies cast doubt on the potential for microvolt T-wave alternans (MTWA) testing to predict ventricular tachyarrhythmic events in heart failure patients. Results of a 490-patient substudy of Medtronic's Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) published in the journal Circulation found that MTWA testing did not predict arrhythmic events or mortality, suggesting that MTWA is "not useful as an aid in clinical decision making on implantable cardioverter defibrillator therapy among patients with heart failure and left-ventricular diastolic dysfunction," according to authors Michael Gold, Medical University of South Carolina, et al.. Results of the 575-patient Microvolt T Wave Alternans Testing for Risk Stratification of Post-Myocardial Infarction Patients (MASTER) trial, recently published in the Journal of the American College of Cardiology, found that the risk of ventricular tachyarrhythmia did not correlate to differences in MTWA test results in heart failure patients with an ICD that was implanted to prevent sudden cardiac death (1"The Gray Sheet" Nov. 12, 2007, p. 17). More studies needed: In an editorial accompanying the Gold study in Circulation, an expert on mechanisms of cardiac arrhythmias, David Rosenbaum, Case Western Reserve University in Cleveland, points out that the SCD-HeFT substudy suggests MTWA "does indeed track susceptibility to sudden cardiac death in a population where primary prevention strategies are highly relevant ... Further advances in risk stratification will also require trials where therapy is randomized on the basis of risk markets that reflect electrophysiological substrates for sudden cardiac death.