Reproducibility of symptom-limited exercise-stress testing performed 2 and 6 weeks after myocardial infarction

To assess the reproducibility of variables with prognostic value from exercise testing, two symptom-limited treadmill exercise tests were performed in 76 consecutive patients at 2 weeks (predischarge) and 6 weeks after myocardial infarction. In addition, cardiac catheterization was performed at 6 weeks. Exercise duration showed a moderate increase from 7.9 +/- 4.4 min to 8.8 +/- 3.0 min (NS). The rate-pressure product increased from 22,377 +/- 5491 to 24,832 +/- 7261 (P less than 0.001). Reproducibility of ST-segment depression was dependent on the initial response: among the group of 25 patients with ST-segment depression at 2 weeks, only 13 (52%) patients had a reproducible result, whereas among the group of 51 patients without initial ST-segment depression, 40 (78%) patients showed reproducibility. There was no difference in coronary anatomy or ejection fraction between the groups with and without reproducibility results. Among the 30 patients with initial ST-segment elevation, 15 (50%) patients showed reproducibility, while among the 46 patients without initial ST-segment elevation, 42 (91%) patients showed reproducibility: the ejection fraction was significantly higher in the latter group than in the group of patients with lower reproducibility. Thus predischarge exercise testing in postinfarction patients identifies a different group of patients at risk compared to exercise testing after 6 weeks, due to considerable variation between the two tests.