STRESS ECHOCARDIOGRAPHY - COMPARISON OF EXERCISE, DIPYRIDAMOLE AND DOBUTAMINE IN DETECTING AND PREDICTING THE EXTENT OF CORONARY-ARTERY DISEASE

Objectives. This study was designed to compare exercise, dipyridamole and dobutamine echocardiography in the same patients and to evaluate, by measuring physiologic and echocardiographic variables, the mechanisms by which exercise and dobutamine induce ischemia. Background. The diagnostic value of stress echocardiography has been widely reported, but the specific effects of exercise, dipyridamole and dobutamine have not been directly compared. Furthermore, no echocardiographic study has evaluated left ventricular volume changes at ischemic threshold during exercise and dobutamine administration. Methods. One hundred patients with suspected (Group A, n = 60) or known (Group B, n = 40) coronary artery disease underwent all three tests in random order. Results. In Group A, the sensitivities of exercise (mean 76%, 95% confidence interval [CI] 58% to 94%) and of dobutamine echocardiography (72%, 95% CI 53% to 91%) were higher than that of dipyridamole (52%, 95% CI 31% to 73%; p = 0.01 and p = 0.02, respectively). Specificity did not differ significantly among tests (94% for exercise [95% CI 86% to 100%] and 97% for dipyridamole and dobutamine [95% CI 91% to 100%]). Accuracy was identical for exercise and dobutamine (87%) and higher than that for dipyridamole (78%, p = 0.06). In Group B, the accuracy in predicting coronary disease extent was 71% for exercise, 33% for dipyridamole and 75% for dobutamine. At ischemic threshold, end-systolic volume index and the ratio of systolic blood pressure to end-systolic volume, a variable related to myocardial contractility, were significantly lower and higher, respectively, with dobutamine than during exercise (p < 0.05). Conclusions. In a clinical setting, exercise echocardiography should represent the first diagnostic approach because it has high diagnostic efficacy and provides additional information on exercise capacity; pharmacologic stress, particularly that of dobutamine, provides a pivotal diagnostic toot when exercise is not feasible or its results are nondiagnostic. Our preliminary data on echocardiographic evaluation at ischemic threshold support the view that myocardial contractility is a major factor in inducing ischemia during dobutamine infusion.