T wave alternans for ventricular arrhythmia risk stratification.

Identifying patients at high risk of sudden cardiac death is an important goal, given the magnitude of this problem. In this regard, T wave alternans (TWA) is a heart-rate-dependent measure of arrhythmia vulnerability. The predictive accuracy of this test is maximal at heart rates between 100 and 120 bpm, which are usually achieved with exercise or atrial pacing. TWA has been shown to predict inducibility of ventricular tachycardia with programmed stimulation and to predict spontaneous arrhythmic events. This test has been applied to diverse populations, including patients with coronary artery disease, nonischemic cardiomyopathy, congestive heart failure, and status post implantable defibrillators. Despite these encouraging results, the role of TWA to guide clinical therapy still must be better elucidated.