Reproducibility of multistage graded exercise testing in patients with chronic stable angina.

Exercise testing is widely used for the diagnosis of ischaemic heart disease and for the evaluation of antianginal drugs. To assess reproducibility, analysis was carried out on 128 paired graded exercise tests from 103 patients performed at the same time of day and under identical conditions. Six different parameters were evaluated and compared between the basal test (no treatment) and the placebo test. During the basal period the mean (+/- SEM) exercise time to the development of angina was 6.0 (+/- 0.2) min and the 1 mm ST depression time was 4.1 (+/- 0.2) min. After 2 weeks of placebo the exercise time was 6.1 (+/- 0.2) min (P = NS) and the 1 mm ST depression time was 4.2 (+/- 0.2) min (P = NS). There was no significant difference between the resting or maximum heart rate on either test and the maximum ST segment depression (leads CM5 and CC5) was unaltered. In a second group of 17 patients where the basal tests were performed in the afternoon and the placebo tests in the morning, heart rate and ST segment were found to be reproducible but there was a significant difference in exercise time: 5.7 (+/- 0.7) min for the basal test and 8.3 (+/- 0.5) min for the placebo test (P less than 0.001); and of the 1 mm ST depression time: 2.7 (+/- 0.4) min for the basal test, and 5.4 (+/- 0.5) min for the placebo test (P less than 0.001). We conclude that exercise tests done under standardised conditions in the morning are highly reproducible in patients with chronic stable angina and therefore provide a valuable test for the evaluation of antianginal drugs.