Identification of Ischemic Myocardium with Simultaneous Dobutamine Stress Echocardiography and 99mTc-MIBI SPECT in Patients with Suspected Coronary Artery Disease

ABSTRACT

BACKGROUND: To compare the diagnostic usefulness of dobutamine stress echocardiography(DSE) and 99mTc-methoxyisobutyl isonitrile SPECT (MIBI SPECT), two studies were performed simultaneously. METHOD: Fifty-six consecutive patients undergoing coronary angiogram and MIBI SPECT for clinical indications without clincal evidence of myocardial infarction were studied prospectively. During the DSE, MIBI was injected at peak stress, and post-stress images of MIBI SPECT were required on hour later. Both echocardiographic and MIBI SPECT images were visually analysed in a blind fashion. RESULTS: On the basis of coronary angiographic findings, the sensitivites of the DSE and MIBI SPECT (n=36) were 89% and 86%, respectively. The specificities of those (n=20) were 90% and 85%, respectively. Among 33 patients without resting perfusion defect on MIBI SPECT, resting regional wall motion abnormalities on DSE were found in only one patient, whereas, resting perfusion defect on MIBI SPECT were found in 9 patients among 41 patients without resting regional wall motion abnormalities on DSE. Among 17 patients who had resting perfusion defects with partial reversibility on MIBI SPECT, resting wall motion abnormalities were present in 11 patients and five of them showed improvement in the regional wall motion during low dose dobutamine infusion. CONCLUSION: Both dobutamine stress echocardiography and MIBI SPECT are useful methods in the detection of the coronary artery disease, however, MIBI SPECT seems to overestimate the regional ischemic myocardium with contractile reserve that can hardly be evaluated with MIBI SPECT.