Confounding factors about microvolt T-wave alternans testing and lifethreatening ventricular arrhytmias

We have read a very interesting article by Özyılmaz and Püşüroğlu (1). We want to add some comment about methodology and definitons of the study. First of all, the connection between microvolt T-wave alternans (TWA) and beta blockers remains poorly understood. It is generally accepted that beta blockers should be stopped before applying the TWA test; however, it is only described, for the spectral method but there is not information for mma-TWA method for beta blocker using. Absence of apical aneurysm diagnosis in HCM patients of this study is interesting and may be explained by their increase in >65 TWA group. For example, prevalance of apical aneurysm in HCM patients, from 2% to 4%-8% at previous studies (2, 3). Also ventricular tachycardia and mortality were higher in that group. Absence of any apical aneursym in HCM patients evaluated with echocardiography and magnetic resonance imaging is interesting. In previous two studies, cutoff value with ambulatory rhythm holter and mma-TWA were 40 msn and 60 msn, respectively. However, authors took 65 msn as the cutoff value (which is cutoff value for patients with 110 bpm, and is used in exercise test) and nonlinear value of mma-TWA may create a tendency regarding this consequence (4, 5).