DISTINCTION BETWEEN ARRHYTHMIC AND NONARRHYTHMIC DEATH AFTER ACUTE MYOCARDIAL-INFARCTION BASED ON HEART-RATE-VARIABILITY, SIGNAL-AVERAGED ELECTROCARDIOGRAM, VENTRICULAR ARRHYTHMIAS AND LEFT-VENTRICULAR EJECTION FRACTION

Objectives. We investigated whether heart rate variability, the signal -averaged electrocardiogram (EGG), ventricular arrhythmias and left ve ntricular ejection fraction predict the mechanism of cardiac death aft er myocardial infarction. Background. Postinfarction risk stratificati on studies have almost exclusively focused on predicting the risk of a rrhythmic death. The factors that identify and distinguish persons at risk for arrhythmic and nonarrhythmic death are poorly known. Methods. Heart rate variability, the signal averaged EGG, ventricular arrhythm ias and left ventricular ejection fraction were assessed in 575 surviv ors of acute myocardial infarction. The patients were followed up for 2 years; arrhythmic and nonarrhythmic cardiac deaths were used as clin ical end points. During the follow up period, 47 cardiac deaths occurr ed, 29 (62%) arrhythmic and 18 (38%) nonarrhythmic. Results. All risk factors were associated with cardiac mortality in univariate analysis. With the exception of left ventricular ejection fraction, they were a lso predictors of arrhythmic death. Depressed heart rate variability ( p < 0.001), ventricular ectopic beats (p < 0.001) and low ejection fra ction (p < 0.001) were related to nonarrhythmic death. In multivariate analysis, depressed heart rate variability (p < 0.001) and runs of ve ntricular tachycardia (p < 0.05) predicted arrhythmic death. Nonarrhyt hmic death was associated with depressed heart rate variability (p < 0 .001), ventricular ectopic beats (p < 0.001) and low ejection fraction (p < 0.01). By selecting patients with depressed heart rate variabili ty, long filtered QRS duration or ventricular arrhythmias and excludin g patients with the lowest ejection fraction, we identified a group in which 75% of deaths were arrhythmic. Similarly, by selecting patients with a low ejection fraction and excluding patients with the lowest h eart rate variability, we identified a group in which 75% of deaths we re nonarrhythmic. Conclusions. Arrhythmic death was associated predomi nantly with depressed heart rate variability and ventricular tachycard ia runs, and nonarrhythmic death with low ejection fraction, ventricul ar ectopic beats and depressed heart rate variability. A combination o f risk factors identified patient groups in which a majority of deaths were either arrhythmic or nonarrhythmic.