Combined assessment of T-wave alternans and late potentials used to predict arrhythmic events after myocardial infarction - A prospective study

OBJECTIVES The aim of the present study was to determine whether the combin ation of two markers that reflect depolarization and repolarization abnorma lities can predict future arrhythmic events after acute myocardial infarcti on (MI). BACKGROUND Although various noninvasive markers have been used to predict a rrhythmic events after MI, the positive predictive value of the markers rem ains low. METHODS We prospectively assessed T-wave alternans (TWA) and late potential s (LP) by signal-averaged electrocardiogram (ECG) and ejection fraction (EF ) in 102 patients with successful determination results after acute MI. RESULTS The TWA was analyzed using the power-spectral method during supine bicycle exercise testing. No antiarrhythmic drugs were used during the foll ow-up period. The study end point was the documentation of ventricular arrh ythmias. The TWA was present in 50 patients (49%), LP present in 21 patient s (21%), and an EF <40% in 28 patients (27%). During a follow-up period of 13 +/- 6 months, symptomatic, sustained ventricular tachycardia or ventricu lar fibrillation occurred in 15 patients (15%). The event rates were signif icantly higher in patients with TWA, LP, or an abnormal EF. The sensitivity and the negative predictive value of TWA in predicting arrhythmic events w ere very high (93% and 98%, respectively), whereas its positive predictive value (28%) was lower than those for LP and EF. The highest positive predic tive value (50%) was obtained when TWA and LP were combined. CONCLUSIONS The combined assessment of TWA and LP was associated with a hig h positive predictive value for an arrhythmic event after acute MI. Therefo re, it could be a useful index to identify patients at high risk of arrhyth mic events. (C) 2000 by the American College of Cardiology.