Unstable coronary artery disease in post-menopausal women. Identifying patients with significant coronary artery disease by basic clinical parameters and exercise test. IRIS Study Group.

Abstract

The diagnostic information from an ECG taken while at rest and an exercise test is considered less reliable in women than in men, mostly due to a high percentage of false-positive tests. This can be explained by a lower pre-test likelihood of coronary heart disease. To evaluate the diagnostic information that can be gained from basic clinical parameters, an ECG and exercise test in a group of post-menopausal women with symptoms of unstable coronary artery disease in order to identify patients with significant coronary artery stenoses. We prospectively studied 200 post-menopausal women admitted to the coronary care unit with symptoms of unstable coronary artery disease and ECG changes suggestive of ischaemia. The diagnostic value of common risk factors, myocardial enzymes and an early exercise test were assessed. A coronary angiogram was performed within 60 days. Median age was 67 years. On admission, 38% had ST depression on an ECG taken while at rest, 76% had T-wave inversion, and 41% increased enzyme levels. The coronary angiogram revealed that 15% had no atherosclerosis, 14% had atherosclerosis but not lesion > or = 50% of luminal diameter and 71% had at least one significant stenosis. Of patients with known indicators of atherosclerotic disease, all but one had atherosclerosis visualized on the coronary angiogram. A relative ST depression > or = 0.1 mV and a low maximum workload at exercise test were strong predictors of significant coronary artery disease. The positive predictive value of ST depression was 91% and of low maximum workload 84% In post-menopausal women with signs of unstable angina and ischaemia on an ECG taken while at rest, the prevalence of coronary atherosclerosis is high, 85%. Contrary to earlier studies, ST T-changes at the early exercise test had a high positive predictive value, especially in combination with a low maximum workload with no false-positive results.