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 mechanis ms by which exercise and dobutamine induce ischemia. Background. The d iagnostic value of stress echocardiography has been widely reported, b ut the specific effects of exercise, dipyridamole and dobutamine have not been directly compared. Furthermore, no echocardiographic study ha s evaluated left ventricular volume changes at ischemic threshold duri ng exercise and dobutamine administration. Methods. One hundred patien ts with suspected (Group A, n = 60) or known (Group B, n = 40) coronar y artery disease underwent all three tests in random order.Results. In Group A, the sensitivities of exercise (mean 76%, 95% confidence inte rval [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 9 7% 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 c oronary disease extent was 71% for exercise, 33% for dipyridamole and 75% for dobutamine. At ischemic threshold, end-systolic volume index a nd the ratio of systolic blood pressure to end-systolic volume, a vari able 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 diagnosti c efficacy and provides additional information on exercise capacity; p harmacologic stress, particularly that of dobutamine, provides a pivot al diagnostic toot when exercise is not feasible or its results are no ndiagnostic. Our preliminary data on echocardiographic evaluation at i schemic threshold support the view that myocardial contractility is a major factor in inducing ischemia during dobutamine infusion.