ST-T Alternans in Acute Myocardial Infarction as a Risk Predictor for Fatal Ventricular Arrhythmia

Abstract

To the Editor Xu et al 1 present the electrocardiogram findings of a patient in their 50s with syncope and palpitation and amaurosis, followed by loss of consciousness for several minutes without preceding position change, cough, chest pain, or shortness of breath. The authors highlight that "giant R-wave syndrome is distinguished by delayed depolarization and repolarization of the myocardium, which is a predictor of the onset of ventricular fibrillation." 1 The authors focused only on giant R-wave syndrome as a predictive factor for ventricular arrhythmias in patients with acute myocardial infarction and ignored the presence of cardiac electrical alternances. Obvious in the Holter recording (Figure in the case report 1 ) is a clear macro-ST-T-wave alternans observed in leads V 2 through V 4 . Therefore, it is reasonable to conclude that, in addition to the presence of giant R-wave syndrome, the electrical alternans of ST-T may play a more crucial role in polymorphic ventricular tachycardia. 2 ST-T alternans have been associated with spontaneous ventricular arrhythmias during myocardial ischemia. 2 Janse et al 3 observed that ventricular premature beats usually follow deep negative T waves in ischemic myocardium when injury currents across the ischemic border were maximal, and the earliest activity routinely occurred at the normal zone where Purkinje activity was recorded. These au-thors concluded that 2 mechanisms are responsible for the very early ischemic arrhythmias: a focal mechanism located on the normal side of the ischemic border, possibly induced by injury currents in normal Purkinje fibers, and a mechanism involving macro-and micro-reentry in the ischemic myocardium. In their research, ST-T alternans were often preceded by ventricular premature beats.