Predictive significance for sudden death of microvolt-level T wave alternans in New York Heart Association class II congestive heart failure patients : A prospective study

Abstract

Background Sudden cardiac death (SDC) is responsible for approximately 60–70% of deaths in New York Heart Association (NYHA) class II congestive heart failure (CHF) patients. Recently, microvolt-level T wave alternans has been proposed as a new noninvasive tool to identify CHF patients at risk for SCD and ventricular tachycardia/fibrillation (VT/VF). Objectives To determine the prognostic value of MTWA in NYHA class II patients. Methods Among 181 consecutive CHF patients with ischemic and nonischemic cardiomyopathy, 73 patients in NYHA class II with left ventricular ejection fraction <45% were selected and prospectively investigated. MTWA was determined during bicycle exercise testing. The study end point was defined as SCD, documented sustained VT/VF and appropriate implantable cardioverter defibrillator (ICD) shock. Results MTWA was positive in 30 (41%) patients, negative in 26(36%) patients and indeterminate in 17 (23%) patients. During an average follow-up of 17.1±7.4 months, seven patients had an arrhythmic event in the MTWA positive group, whereas one and no events occurred in the indeterminate and negative group, respectively. From Kaplan–Meier univariate analysis and multivariate Cox analysis, MTWA was a significant arrhythmic risk stratifier ( p=0.01 and p=0.03, respectively). Sensitivity, specificity, negative and positive predictive values of MTWA were 100%, 53%, 100% and 24%, respectively. Conclusion Our data suggest that MTWA is a promising predictor of arrhythmic events in NYHA class II CHF patients.