Risk stratification for sudden cardiac death: is there a clinical role for T wave alternans?

The proportion of cardiovascular deaths attributable to sudden cardiac death (SCD) is on the rise. Herein lies the rationale for developing risk stratification strategies to predict who will benefit from prophylactic implantable cardioverter-defibrillator (ICD) implantation. Current guidelines recommend prophylactic ICD therapy in patients with reduced left ventricular ejection fraction (LVEF). However, there are clear limitations in using LVEF alone to decide who should receive an ICD. There is mounting evidence that microvolt-level T-wave alternans (TWA) is an important marker of arrhythmic risk. TWA is appealing because it noninvasively probes the underlying electrophysiological substrate and has been linked to cellular mechanisms for arrhythmias. This review considers the clinical role of TWA for risk stratification of SCD.