The early posthospital phase of myocardial infarction. Prognostic stratification.

Prognostic stratification was carried out on 518 patients less than or equal to 65 years of age who were discharged from the hospital following a definite or probable acute myocardial infarction and followed for four months. The total population was made up of 272 patients hospitalzed in 1973 and 246 patients hospitalized in 1974; one hundred and forty-two variables were collected on each patient. The clinical characteristics of the 1973 and 1974 populations were remarkably similar, and both groups had a four-month posthospital cardiac mortality rate of 4%. Two prognostic stratification schemes were developed on the 1973 population which identified low and high risk groups with meaningfully different four-month cardiac death rates. Both stratification schemes were tested on the 1974 population, and one of the two schemes was validated as identifying a significantly increased cardiac mortality rate in the high as opposed to the low risk group. The four-month posthospital cardiac mortality rate was 3% in the low and 14% in the high risk group (Z = 2.70, P less than 0.003). The high risk group was characterized by two or more of the following characteristics: 1) history of angina at ordinary levels of activity or at rest; 2) CCU hypotension and/or congestive heart failure; 3) ventricular premature beat frequency greater than or equal to 20/hr on a six-hour electrocardiographic tape recording. The low risk group had none or only one of the above characteristcis. The prognostic power of this stratification scheme is such that sixteen percent of the posthospital population can be identified as high risk, and this subgroup contains forty-six percent of the patients who die of cardiac cause in the four-month posthospital interval.