Differences in electrocardiographic response to exercise of women and men: a non-Bayesian factor.

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Abstract
The ability of ST segment analysis during submaximal exercise tolerance testing (85% predicted age-adjusted heart rate) to a diagnose the presence of significant coronary artery stenosis (.gtoreq. 75% cross sectional area narrowing) was evaluated 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 [not significant]). Predictive value of a positive exercise test (PV (+ET)) as defined by 1 mm ST segment depression 0.08 s 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 without 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 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).