Possible Cause of a Positive Exercise Test Early After Successful Coronary Angioplasty

Background. The mechanism responsible for exercise-induced myocardial ischemia early after successful coronary angioplasty (PTCA) is poorly understood. Methods and Results. Twelve patients who underwent one-vessel PTCA were studied. Exercise testing was performed before and on day 7 after PTCA, which was repeated after 10 mg sublingual isosorbide dinitrate if the test was positive. Quantitative coronary arteriography was also performed on day 8 after PTCA in the basal state, after intracoronary infusion of 0.9% saline, 1, 5, 10, and 20 jig ergonovine, and after 300 gg nitroglycerin. All patients had a positive exercise test before PTCA but on day 7, sixpatients had a positive exercise test (group 1) and six patients (group 2) had a negative exercise test. In group 1, all positive exercise tests on day 7 became negative when repeated after isosorbide dinitrate. Intracoronary ergonovine was associated with a dose-dependent constriction of the PTCA segment, a segment distal to it, and a control segment, with no significant difference in the magnitude of the response between the two groups; maximum constriction for group 1 was 19±-3%, 23+±2%, and 16±3% (p<0.001