First myocardial infarction: age and ejection fraction identify a low-risk group.

This study examines patients with a first myocardial infarction (MI) (about 70% of the population, n = 2089), and identifies factors associated with 1-year cardiac mortality in patients discharged alive. With the use of multivarate analysis of variables observed at hospital discharge in patients with a first MI, age was the most important predictor, followed by left ventricular ejection fraction (LVEF) (determined in 56%) and other variables. Based on this finding, age subsets (less than or equal to 50, 51 to 70, greater than 70 years) were related to LVEF groups (less than or equal to 0.40, 0.41 to 0.50, greater than 0.50). Patients with a first MI who were less than 50 years of age with LVEF greater than 0.40 and patients between 51 and 70 years of age with LVEF greater than 0.50 had a very low risk for 1-year cardiac death, 1.2 +/- 1.1% (95% confidence interval). Such patients comprised 47% of individuals with a first MI having an LVEF determination. Mortality in the remaining patients less than 70 years was 7.4 +/- 3.5%. Mortality for patients greater than 70 years was high, 22.2 +/- 6.6%. Thus with LVEF as the only predischarge test, a sizable low risk group can be identified among patients with a first MI.