Clinical Utility of Microvolt T-wave Alternans Testing In Identifying Patients at High or Low Risk of Sudden Cardiac Death

• Authors: Faisal M Merchant, Emory University; Takanori Ikeda, Toho University; Roberto F. E. Pedretti, Scientific Institute of Tradate; Jorge A. Salerno-Uriarte, University of Insubria; Theodore Chow, Regional Medical Center of San Jose; Paul S. Chan, University of Missouri; Cheryl Bartone, The Christ Hospital; Stefan H. Hohnloser, J. W. Goethe University; Richard J. Cohen, J. W. Goethe University; Antonis A. Armoundas, Massachusetts General Hospital
• Journal Title: Heart Rhythm
• Volume: Volume 9, Number 8
• Publisher: Elsevier | 2012-08-01, Pages 1256-+
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1016/j.hrthm.2012.03.014
• Subjects: Health Sciences, General
• Keywords: Science & Technology; Life Sciences & Biomedicine; Cardiac & Cardiovascular Systems; Cardiovascular System & Cardiology; T-wave alternans; Arrhythmia; Sudden cardiac death; Risk stratification; ICD; heart failure; IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR; LEFT-VENTRICULAR DYSFUNCTION; ACUTE MYOCARDIAL-INFARCTION; CONGESTIVE-HEART-FAILURE; DILATED CARDIOMYOPATHY; PREDICTIVE-VALUE; ARRHYTHMIA VULNERABILITY; ISCHEMIC CARDIOMYOPATHY; SYSTOLIC DYSFUNCTION; EJECTION FRACTION

Abstract

Background: Previous studies have demonstrated that microvolt T-wave alternans (MTWA) testing is a robust predictor of ventricular tachyarrhythmias and sudden cardiac death (SCD) in at-risk patients. However, recent studies have suggested that MTWA testing is not as good a predictor of " appropriate" implantable cardioverter-defibrillator (ICD) therapy as it is a predictor of SCD in patients without ICDs. Objective: To evaluate the utility of MTWA testing for SCD risk stratification in patients without ICDs. Methods: Patient-level data were obtained from 5 prospective studies of MTWA testing in patients with no history of ventricular arrhythmia or SCD. In these studies, ICDs were implanted in only a minority of patients and patients with ICDs were excluded from the analysis. We conducted a pooled analysis and examined the 2-year risk for SCD based on the MTWA test result. Results: The pooled cohort included 2883 patients. MTWA testing was positive in 856 (30%), negative in 1627 (56%), and indeterminate in 400 (14%) patients. Among patients with a left ventricular ejection fraction (LVEF) of ≤35%, annual SCD event rates were 4.0%, 0.9%, and 4.6% among groups with MTWA positive, negative, and indeterminate test results. The SCD rate was significantly lower among patients with a negative MTWA test result than in patients with either positive or indeterminate MTWA test results (P <.001 for both comparisons). In patients with an LVEF of >35%, annual SCD event rates were 3.0%, 0.3%, and 0.3% among the groups with MTWA positive, negative, and indeterminate test results. The SCD rate associated with a positive MTWA test result was significantly higher than that associated with either negative (P <.001) or indeterminate MTWA test results (P =.003). Conclusions: In patients without ICDs, MTWA testing is a powerful predictor of SCD. Among patients with an LVEF of ≤35%, a negative MTWA test result is associated with a low risk for SCD. Conversely, among patients with an LVEF of >35%, a positive MTWA test result identifies patients at significantly heightened SCD risk. These findings may have important implications for refining primary prevention ICD treatment algorithms.