Directional variability in the R wave response during serial exercise testing in patients with coronary artery disease.

The reproducibility of the direction of R wave amplitude response to exercise was analyzed in patients with coronary artery disease. Forty-three serial exercise tests were performed by 10 patients with exertional angina pectoris and documented coronary artery disease (CAD). Seventeen tests (37%) resulted in no change or an increase in R wave amplitude (abnormal response). Twenty-six tests (63%) resulted in a decrease in R wave amplitude. The direction of the R wave amplitude response was variable in at least one exercise test in 7 of 10 patients with CAD, all of whom had reproducible ischemic ST segment responses during serial testing. The inconsistent R wave response in these patients was unrelated to heart rate, workload, or duration of exercise. Because of the variability in the directional R wave response during serial exercise testing in CAD patients, we conclude that the R wave response during exercise is unreliable for the detection of CAD or ischemia-related myocardial dysfunction.