Early assessment of risk in patients with acute myocardial infaction

Abstract

In 360 patients with acute myocardial infarction, non-invasive clinical parameters were recorded during the first 24 h following admission. Serum enzymes (CK, CK-MB, ASA T and LDH) were serially measured at 4 h intervals during three days. Forty-two patients (12%) died within two weeks of hospitalization. The study population was divided into training (159 patients) and control (201 patients) groups. As individual variables, age, previous history of infarction (PI) or angina, conduction disturbances and left ventricular impairment exerted an unfavourable influence on the short-term prognosis. Serum LDH activity observed at the time of CK peak was a better predictor of risk than ASAT and CK peak levels. No significant difference was demonstrated for CK-MB peak level between survivors and non-survivors. Stepwise logistic discrimination was applied to all parameters (clinical and biochemical) recorded within 24 h after admission in the patients of the training group. Only three variables were retained in the selection procedure namely, LDH at CK peak, age and number of previous infarctions. These variables jointly provide the best prediction of high and low risk patients. The final risk index based on the three selected parameters, i.e. R=000189LDH+0.0978age+1.37PI−11-9,was validated on the patients of the control sample. According to the risk R obtained, all patients were allocated into four classes of increasing risk. Two well-defined groups of patients could be identified readily at the end of the first day following admission: one with high risk of mortality (60% death) and one with good prognosis (37% of the total population, mortality rate <1%), the latter consisting of patients who might benefit from early discharge from the coronary care unit.