Microvolt T-wave alternans. Ischemic vs. nonischemic dilated cardiomyopathy

The use of implantable cardioverter defibrillators (ICD) for primary preventive therapy of sudden arrhythmogenic death has become a mainstay in selected patients with systolic congestive heart failure, particularly in the setting of ischemic and nonischemic cardiomyopathy (Moss et al., N Engl J Med 346:877–883, 2002; Bardy et al., N Engl J Med 352:225–237, 2005). However, more accurate identification of high-risk patients is desirable in order to avoid unnecessary ICD implants. Since currently available risk stratification methods have limited predictive accuracy, development of new techniques is important in order to noninvasively assess arrhythmogenic risk in patients prone to sudden death.Microvolt level T-wave alternans (mTWA) has recently been proposed to assess abnormalities in ventricular repolarization favoring the occurrence of reentrant arrhythmias (Adam et al., J Electrocardiol 17:209–218, 1984; Pastore et al., Circulation 99:1385–1394, 1999). In 1994, a preliminary clinical study by Rosenbaum et al. convincingly demonstrated that mTWA is closely related to arrhythmia induction in the electrophysiology laboratory as well as to the occurrence of spontaneous ventricular tachyarrhythmias during follow-up (Rosenbaum et al., N Engl J Med 330:235–241,1994). More recently, a number of clinical studies have examined its clinical applicability in ischemic and nonischemic cardiomyopathy.