DIFFERENCES IN ELECTROCARDIOGRAPHIC RESPONSE TO EXERCISE OF WOMEN AND MEN - NON-BAYESIAN FACTOR

We evaluated the ability of ST-segment analysis during submaximal exercise tolerance testing (85% predicted age-adjusted heart rate) to diagnose the presence of significant coronary artery stenosis (≥ 75% cross sectional area narrowing) in a group of 85 men and 92 women with chest pain syndromes and no previously documented myocardial infarctions. Disease prevalence by selective coronary angiography was 36% for men and 33% for women(NS). Predictive value of a positive exercise test (PV(+ET)) as defined by 1 mm ST-segment depression 0.08 second after the J point was significantly higher for men than for women (77% vs 47%,p<0.05). Predictive value of a negative test (PV(-ET)) was not significantly different for men (81%) and women (78%). Analysis of the 66 men and 66 women not taking digitalis preparations again showed that PV(+ET) was significantly higher for men than for women (90% vs 45%, p<0.01). Multivariate analysis showed that patients with angiographically significant coronary disease had significantly lower attained heart rates and shorter exercise duration than those witout significant stenosis, independent of ST-segment responses. A discriminant function using ST-segment response, attained heart rate and a sex-dependent ST-segment response factor was developed. Duration of exercise was not an independent predictor by our analysis. This function improved the PV(+ET) and PV(-ET)for the total group and for the women; for men, the PV(-ET)improved, while the PV(+ET)fell slightly. This function has not yet been used prospectively. In patients with chest pain and no previously documented myocardial infarction, men have a significantly higher PV(+ET) than women, which cannot be accounted for simply by a difference in disease prevalence (i.e., Bayes' theorem).