Prognostic Factors in Acute Myocardial Infarction treated in a Coronary Care Unit*

Summary: Prognostic factors in 269 cases of acute myocardial infarction treated in a coronary unit were analysed using a computer. The mortality rate was significantly higher in the elderly (≤60 years) and those with extensive infarction, shown by prolonged cardiac pain (>4 hours) or high serum enzyme levels (SGOT> 200 Sigma-Frankel units/ml; LDH> 2,000 Berger-Broida units/ ml). It was high also with tachycardia (sinus, supraventricular or ventricular), complete heart block, and complete bundle branch block. It increased progressively with severity of myocardial failure. Secondary cardiac arrect had a high mortality. Clinical signs of catecholamine hypersecretion (sinus tachycardia, pallor, sweating), hypoxaemia (central cyanosis), or low cardiac output (peripheral cyanosis, cold extremities, oliguria) greatly increased the mortality rate. Radiological cardiomegaly and pulmonary congestion each doubled it. An insignificant mortality increase accompanied ventricular and supraventricular ectopics, atrial fibrillation, incomplete heart block, and previous myocardial infarction, angina, and hypertension. There was no significant relationship between mortality and admission delay, sex, tobacco consumption, diabetes, or family history of ischaemic disease or diabetes. Only one patient died of primary cardiac arrest. Sinus bradycardia was a good prognostic sign. Analysis of the literature showed its lower mortality rate to be significant. Since intravenous atropine may cause arrhythmias, it should be reserved for sinus bradycardia with hypotension. It was suggested that patients with adverse prognostic signs short of extreme myocardial decompensatiqn should be monitored longer. Younger patients without severe infarction had a low mortality rate. Investigation of these may reveal a group which can be discharged safely from hospital soon after the completion of monitoring.