Myocardial infarction in the black population of South Africa: coronary arteriographic findings.

Thirteen Black patients who had classic electrocardiographic evidence of myocardial infarction supported by changes in serum enzymes were investigated by coronary arteriography. Ten of these had occlusive atherosclerosis and in none of these did the associated risk factors such as hypertension or diabetes appear to be operative, and most were manual laborers. Their mean serum cholesterol measurement was found to be 222 mg. per cent, a value which is found in 25 per cent of the urban Black population. In the remaining three patients, the coronary arteries were found to be angiographically normal and two of these were associated with the billowing mitral leaflet syndrome; it is postulated that their myocardial infarction was a result of coronary spasm, or a consequence of fibrin emboli emanating from the redundant mitral leaflets. Based on statistics from our major referring hospital, it is estimated that the prevalence rate from myocardial infarction among general admissions to a medical ward is less than 0.05 per cent, a figure lower than previously reported by clinico-electrocardiographic studies. It would appear that the prevalence of this disease has not increased over the last two decades and the immunity of the Black population is unexplained.