A comparison of T-wave alternans, signal averaged electrocardiography and programmed ventricular stimulation for arrhythmia risk stratification

OBJECTIVES The goal of this study was to compare T-wave alternans (TWA), si gnal-averaged electrocardiography (SAECG) and programmed ventricular stimul ation (EPS) for arrhythmia risk stratification in patients undergoing elect rophysiology study. BACKGROUND Accurate identification of patients at increased risk for sustai ned ventricular arrhythmias is critical to prevent sudden cardiac death. T- wave alternans is a heart rate dependent measure of repolarization that cor relates with arrhythmia vulnerability in animal and human studies. Signal-a veraged electrocardiography and EPS are rnore established tests used for ri sk stratification. METHODS This was a prospective, multicenter trial of 313 patients in sinus rhythm who were undergoing electrophysiologic study. T-wave alternans, asse ssed with bicycle ergometry, and SAECG were measured before EPS. The primar y end point was sudden cardiac death, sustained ventricular tachycardia, ve ntricular fibrillation or appropriate implantable defibrillator (ICD) thera py, and the secondary end point was any of these arrhythmias or all-cause m ortality. RESULTS Kaplan-Meier survival analysis of the primary end point showed that TWA predicted events with a relative risk of 10.9, EPS had a relative risk of 7.1 and SAECG had a relative risk of 4.5. The relative risks for the se condary end point were 13.9, 4.7 and 3.3, respectively (p < 0.05). Multivar iate analysis of 11 clinical parameters identified only TWA and EPS as inde pendent predictors of events. In. the prespecified subgroup with known or s uspected ventricular arrhythmias, TWA predicted primary end points with a r elative risk of 6.1 and secondary end points with a relative risk of 8.0. CONCLUSIONS T-wave alternans is a strong independent predictor of spontaneo us ventricular arrhythmias or death. It performed as well as programmed sti mulation and better than SAECG in risk stratifying patients for life-threat ening arrhythmias. (C) 2000 by the American College of Cardiology.