Usefulness of the dipyridamole-exercise echocardiography test for diagnosis of coronary artery disease

Abstract

To test the hypothesis that a dipyridamole infusion might sensitize the myocardium to exercise-induced ischemia, 33 patients with effort chest pain syndrome—including 24 with and 9 without angiographically documented coronary artery disease (CAD)-and 10 control subjects were studied. As inclusion criterion, all enrolled subjects had a negative resting high-dose dipyridamole-echocardiography test result for both mechanical (development of a transient asynergy) and electrocardiographic (>0.1 mV ST-segment shift) changes. All performed 2 supine exercises during 2-dimensional echocardiography and 12-lead electrocardiography monitoring, immediately after high-dose (0.84 mg/kg over 10 minutes) dipyridamole (dipyridamole-xercise stress test) or placebo (exercise stress test) infusion. The overall sensitivity (by electrocardiographic, echocardiographic or combined criteria) for CAD detection was 10 of 24 for exercise stress test and 21 of 24 for dipyridamole-exercise stress test (42 vs 88%, p <0.01). The specificity was 19 of 19 for exercise stress test and 18 of 19 for dipyridamole-exercise stress test (100 vs 95%, difference not significant). Both exercise stress test and dipyridamole-exercise stress test yielded negative results in the 10 control subjects, with a similar peak rate-pressure product (X 1/100) reached in the 2 tests (287 ± 55 vs 274 ± 42, difference not significant). Eight patients (all with significant CAD) had positive results of their exercise stress test and all 8 had also positive dipyridamole-exercise stress test results, at a significantly lower ratepressure product with respect to the exercise stress test (253 ± 49 vs 204 ± 35, p<0.05). It is concluded that a dipyridamole infusion does not block the heart rate and blood pressure responses to exercise, but lowers the ischemic threshold in exercise stress tests that were already positive. The dipyridamole-exercise stress test reveals the presence of myocardial ischemia in a significant number of CAD patients in whom this diagnosis was missed by conventional stress interventions.