Implications of positive treadmill exercise tests in asymptomatic adult African blacks

Maximal exercise tests in 225 apparently healthy adult Africans(148 men, 77 women) aged 26 to 70 years revealed 35 subjects(18 men and 17 women) with ischaemic ST changes. Out of these,6 men and 4 women developed chest pain that necessitated terminationof the tests. Significant ventricular arrhythmias were observedin 27 patients (20 men and 7 women) all of whom had an otherwisenegative response to exercise tests. During a follow-up period ranging from 6 months to 4 years,2 male positive-responders — both of whom developed chestpain during exercise testing — sustained acute myocardialinfarction. The coronary arteries of both men were found tobe normal at coronary angiography. A third male positive-responder,who also developed chest pain during exercise testing, subsequentlyexperienced repeated attacks of angina with no ECG or serumenzyme changes. Coronary angiography, in this patient, revealedsignificant proximal vessel disease necessitating coronary angioplasty. One female positive responder, who developed chest pain duringexercise-testing, experienced episodes of restrosternal discomfortof considerable duration with no ECG or serum enzyme changes.Her coronary arteries were subsequently shown to be normal. While coronary artery disease would no doubt account for a significantpercentage of positive exercise responses in adult African blacks,it seems likely that non-coronary causes play a dominant role.