Prognostic significance of risk stratifiers of mortality, including T wavealternans, after acute myocardial infarction: Results of a prospective follow-up study

Introduction: Occurrence of sustained microvolt-level T wave alternans (TWA ) at a specified heart rate has been suggested to predict life-threatening arrhythmic events, but its prognostic value has not been well established i n patients who survived an acute myocardial infarction (AMI). The purpose o f this prospective study was to assess the predictive significance of vario us noninvasive risk indicators of mortality, including TWA, in consecutive post-AMI patients with optimized medical therapy. Methods and Results: In addition to a symptom-limited predischarge exercise test with measurement of TWA, mortality risk was assessed using heart rate variability, 24-hour ECG recordings, baroreflex sensitivity, signal-averag ed EGG, QTc interval, QT dispersion, and echocardiographic wall-motion inde x in 379 consecutive patients. Twenty-six patients (6.9%) died during a mea n follow-up of 14 +/- 8 months. Sustained TWA was found in 56 patients (14. 7%), none of whom died. Several risk variables, e.g., incomplete TWA test ( inability to perform the exercise test or reach the required target heart r ate of 105 beats/min), increased QRS duration on signal-averaged EGG, incre ased QT dispersion, long QTc interval, nondiagnostic baroreflex sensitivity result, and low wail-motion index, predicted all-cause mortality in univar iate analyses. In multivariate analysis, the incomplete TWA test was the mo st significant predictor of cardiac death (relative risk 11.1, 95% confiden ce interval 2.4 to 50.8; P < 0.01). Conclusion: Sustained TWA during the predischarge exercise test after AMI d oes not indicate increased risk for mortality. An incomplete TWA test and s everal common risk variables provided prognostic information in this post-A MI population.