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

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.