To the Editor—“Specialization” of Microvolt T-wave Alternans and Electrophysiological Study in Predicting Different Ventricular Arrhythmias in Patients with Ischemic Cardiomyopathy To the editor—Microvolt T-wave alternans, electrophysiologic study, and ventricular arrhythmias

Abstract

The article by Amit et al 1 Amit G. Rosenbaum D.S. Super D.M. Costantini O. Microvolt T-wave alternans and electrophysiologic testing predict distinct arrhythmia substrates: implications for identifying patients at risk for sudden cardiac death. Heart Rhythm. 2010; 7: 763-768 Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar published in Heart Rhythm [June 2010] provides new insight that noninvasive microvolt T-wave alternans (MTWA) technology and invasive electrophysiologic study (EPS) predict distinct types of malignant ventricular arrhythmias in patients with ischemic cardiomyopathy, left ventricular ejection fraction (LVEF) ≤40.0, and a history of nonsustained ventricular tachycardia. Using data from the 566 patients of the Alternans Before Cardioverter Defibrillator (ABCD) trial, the authors showed that MTWA predicted unstable ventricular tachyarrhythmic events (U-VTE), defined as polymorphic ventricular tachycardia (PVT), ventricular fibrillation (VF), or sudden cardiac death (SCD), whereas EPS did not. On the other hand, EPS predicted stable monomorphic ventricular tachyarrhythmic events (S-VTE), whereas MTWA did not. Stratification of LVEF to ≤0.30 versus 0.31–0.40 did not predict events. MTWA predicted events better than EPS in patients with LVEF ≤0.30, whereas EPS predicted events better than MTWA in patients with LVEF 0.31–0.40. Finally, the combination of MTWA and EPS predicted events better than either modality alone. As we “digest” the novel knowledge provided by this study, the authors could help by responding to and commenting on the following points. (1) The inclusion of patients with only previous nonsustained S-VTE in the ABCD trial, 2 Costantini O. Rosenbaum D.S. Hohnloser S.H. et al. ABCD InvestigatorsThe Alternans Before Cardioverter Defibrillator (ABCD) trial: a noninvasive strategy for primary prevention of sudden cardiac death using T-wave alternans. J Am Coll Cardiol. 2009; 53: 471-479 Abstract Full Text Full Text PDF PubMed Scopus (207) Google Scholar instead of also including patients with U-VTE (PVT and VF), constitutes a somewhat biased database for the study of subsequent distinct types of ventricular arrhythmic substrates. (2) The authors reported on outcomes occurring during 1-year follow-up. It would be useful to evaluate whether their findings persist at 18- and 24-month follow-up. (3) The distinction between subgroups with LVEF ≤0.30 versus 0.31–0.40 suggests that cardiologists should become more diligent than they are currently in evaluating the LVEF of their patients, perhaps emulating the practice of serial assessment of LVEF using the same modality and the concern shown by oncologists when administering anthracyclines. (4) What was the outcome in terms of arrhythmic events of the 73 or 74 patients who did not receive an implantable cardioverter-defibrillator (ICD) and/or received an ICD following a negative MTWA and EPS? Microvolt T-wave alternans and electrophysiologic testing predict distinct arrhythmia substrates: Implications for identifying patients at risk for sudden cardiac deathHeart RhythmVol. 7Issue 6PreviewBetter risk stratification of patients receiving an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death (SCD) is needed. Although microvolt T-wave alternans (MTWA) and electrophysiologic study (EPS) are independent markers for SCD, the Alternans Before Cardioverter Defibrillator (ABCD) trial found the combination to be more predictive than either test alone. Full-Text PDF ErratumHeart RhythmVol. 9Issue 12PreviewThe reply by Carl R. Reynolds and Michael R. Gold Optimizing right ventricular lead position for defibrillation should have also published in the March 2011 issue of HeartRhythm as a response to Mark Kroll's letter End of the apex era? (2011;8:e9-e10). Full-Text PDF Author Reply–To the Editor: Microvolt T-wave alternans and electrophysiological testing predict distinct arrhythmia substratesHeart RhythmVol. 9Issue 12PreviewWe thank Dr. Madias for his kind comments and the interest in our article,1 and we would like to respond to the points raised. Full-Text PDF