Prognosis after acute myocardial infarction: a multivariate analysis of mortality and survival.

Abstract

Early mortality (within 30 days) and survival (beyond 30 days) after acute myocardial infarction were examined in 22 patients by screening 158 variables measured soon after the patient''s admission to the hospital. Of these measurements, 19 had predictive value, but each variable alone was relatively insensitive. Groups of variables were subjected to stepwise discriminant function analysis and classification rates were estimated by calculating 95% confidence intervals using a jackknife procedure. When factors from the history, physical examination and noninvasive assessment were combined, 70% of deaths (confidence interval 48-80%) and 94% (90-98%) of survivors were identified; when 11 selected variables including hemodynamic data were combined, 86% (66-98%) of deaths and 96% (92-100%) of survivors (93% overall accuracy) were identified. The validity of this method was tested in 150 patients. Using the original discriminant functions, classification rates based on noninvasive and hemodynamic data fell within predicted limits, although the number of patients studied hemodynamically was unrepresentative and too small to allow overall predictive accuracy. The entire population (371 patients) was randomly divided into a base sample from which new discriminant functions were constructed, with which the remaining patients were classified. The classification rates for the validation sample fell within the predicted confidence intervals. This method provides a reliable approach for predicting the risk of early death or the likelihood of survival in patients soon after acute myocardial infarction.