Comparison of ST segment depression in upright treadmill and supine bicycle exercise testing

Significant differences in the hemodynamic response to upright and supine exercise have been reported in patients with coronary artery disease. The purpose of the present study was to compare the degree of myocardial ischemia as assessed by ST segment depression during upright treadmill and supine bicycle exercise in 98 patients with coronary artery disease and in 34 patients with normal coronary arteries. The amount of ST segment depression at maximal exercise in patients with coronary artery disease was 0.90 ± 0.80 mm for treadmill and 1.34 ± 1.09 mm for supine bicycle (p < 0.001). The amount of ST segment depression during treadmill and supine bicycle exercise tests was also compared at highest similar heart rates (0.68 ± 0.77 versus 1.17 ± 1.01, p < 0.001), at highest similar rate-pressure products (0.71 ± 0.77 versus 1.08 ± 1.04, p < 0.001), at highest similar metabolic equivalents of oxygen consumption (MET) levels (0.69 ± 0.75 versus 1.20 ± 1.05 mm, p < 0.001) and at the onset of angina (0.84 ± 0.73 versus 1.18 ± 0.88 mm, p < 0.001). The rate-pressure product achieved at maximal exercise was similar in both tests (18.74 ± 5.80 × 103versus 18.81 ± 5.17 × 103, p = NS). The occurrence of angina during treadmill and supine bicycle exercise tests was similar (47 of 98 versus 48 of 98, respectively, p = NS). For the detection of coronary artery disease, the sensitivity was 50.0% for treadmill and 63.3% for supine bicycle (p < 0.05) and the specificity was 73.5 versus 70.6%, respectively (p = NS). Thus, the degree of ST segment depression in patients with coronary artery disease is significantly greater during supine bicycle exercise than during upright treadmill testing at the onset of angina, at similar rate-pressure products, at similar heart rates, at similar MET levels and at maximal exercise. Supine bicycle exercise electrocardiography is significantly more sensitive, yet equally specific for the dejection of coronary artery disease when compared with upright treadmill exercise electrocardiography.