Utility of microvolt T-wave alternans to predict sudden cardiac death in patients with cardiomyopathy.
OBJECTIVE
Sudden cardiac death remains a major cause of mortality among patients with cardiomyopathy and implantable cardioverter-defibrillator therapy has been shown to improve survival in these patients. Effective use of prophylactic implantable cardioverter-defibrillator therapy requires accurate risk stratification beyond assessment of ejection fraction, however. Repolarization alternans is a harbinger of ventricular arrhythmias and its measurement from body-surface recordings, also known as microvolt T-wave alternans, is emerging as an effective prognostic tool in these patients based on recent clinical trials.


RESULTS
We review the pathogenesis and determinants of repolarization alternans. The current techniques for measuring T-wave alternans from the body surface are compared, including the spectral and modified moving average methods. Recent clinical trials evaluating the prognostic utility of T-wave alternans in patients with ischemic and nonischemic cardiomyopathy and no prior arrhythmic events are summarized. The findings of these studies are discussed in the context of implantable cardioverter-defibrillator prophylaxis. Body-surface T-wave alternans is an evolving technique and its limitations are presented along with approaches to improve its predictive accuracy.


CONCLUSIONS
Risk stratification with T-wave alternans has the potential to guide prophylactic implantable cardioverter-defibrillator therapy in a growing population of patients with cardiomyopathy.
Chauhan
Vijay S
VS
Division of Cardiology, University Health Network, Toronto, Canada. vijay.chauhan@uhn.on.ca
Selvaraj
Raja J
RJ
D001145:Arrhythmias, Cardiac / Q000150:complications / Q000401:mortality; D002304:Cardiac Pacing, Artificial / Q000379:methods; D009202:Cardiomyopathies / Q000503:physiopathology / Q000628:therapy*; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment; D013318:Stroke Volume / Q000502:physiology; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000209:etiology / Q000517:prevention & control