Prognostic Utility of Microvolt T-Wave Alternans in Risk Stratification of Patients With Ischemic Cardiomyopathy

Prognostic Utility of Microvolt T-Wave Alternans in Risk Stratification of Patients With Ischemic Cardiomyopathy Theodore Chow, Dean J. Kereiakes, Cheryl Bartone, Terri Booth, Edward J. Schloss, Theodore Waller, Eugene S. Chung, Santosh Menon, Brahmajee K. Nallamothu, Paul S. Chan Microvolt T-wave alternans (MTWA) has been proposed as an effective tool for identifying high-risk patients with ischemic cardiomyopathy who are likely to benefit from implantable cardioverter-defibrillator (ICD) therapy. However, prior studies have been unable to adjust for potential confounders. We assessed whether MTWA was an independent predictor of mortality in patients with ischemic cardiomyopathy after adjusting for demographic, clinical, and treatment differences including ICD status, age, left ventricular ejection fraction, and prolonged QRS duration. We found that a non-negative MTWA result was associated with higher rates of all-cause and arrhythmic mortality but not of nonarrhythmic mortality. The purpose of this study was to assess if microvolt T-wave alternans (MTWA) is an independent predictor of mortality in patients with ischemic cardiomyopathy. Microvolt T-wave alternans has been proposed as an effective tool for identifying high-risk patients with ischemic cardiomyopathy who are likely to benefit from implantable cardioverter-defibrillator (ICD) therapy. However, earlier studies have been limited in their ability to control for baseline differences between MTWA-negative and -non-negative (positive and indeterminate) patients. We enrolled 768 consecutive patients with ischemic cardiomyopathy (left ventricular ejection fraction ≤35%) and no prior history of ventricular arrhythmia. All patients underwent baseline MTWA testing and were classified as MTWA negative or non-negative. Multivariable Cox regression analyses, stratified by ICD status, were used to determine the association between MTWA testing and mortality after adjusting for demographic, clinical, and treatment differences between MTWA-negative and -non-negative patients. We identified 514 (67%) patients with a non-negative MTWA test. After multivariable adjustment, a non-negative MTWA test was associated with a significantly higher risk for all-cause (stratified hazard ratio [HR] = 2.24 [95% confidence interval 1.34 to 3.75]; p = 0.002) and arrhythmic mortality (stratified HR = 2.29 [1.00 to 5.24]; p = 0.049) but not for nonarrhythmic mortality (stratified HR = 1.77 [0.84 to 3.74]; p = 0.13). In subgrou