962-66 Simultaneous Dobutamine Stress Echocardiography/MIBI-SPECT for Diagnosis of Coronary Artery Disease

Dobutamine is a pharmacological agent able to induce myocardial ischemia; for determine the relative value of Dobutamine Stress Echocardiography and 99m-Tc Sestamibi (MIBI-SPECT) for the detection of myocardial ischemia, these techniques were simultaneously performed. Forty four consecutive patients (33 males and 11 females: 50.5±5.1 yrs.) were referred to our laboratories for a moderate level of pre-test probability for CAD; none of patients had prior myocardial infarction. None of patients had a severe degree of hypertension or recently presented unstable angina. All patients were in adequate pharmacological wash-out. Dobutamine stress echocardiography was performed following standard protocol; one minute before the stop of test, an injection of 740 MBq of 99m-Tc MIBI was i.v. infused. The stress MIBI SPECT imaging were acquired one hour after stress. For resting study patients were injected of 740 MBq of 99m-Tc MIBI between 24–36 h before stress. The tests were considered positive for ischemia in presence for Echo of new wall motion abnormalities and for SPECT of transient perfusional defects. Coronary angiography was performed in all patients (significant coronary stenosis≥50%). The agreement between the two methods was fairly good: 74% (kappa: 0.53, p<0.001). In comparison with angiography the two methods showed these level of sensitivity and specificity:EchocardiographyFisher testScintigraphyFisher testSensitivity75%p=0.00791%P=0.0001Specificity78%88%Accuracy78%90%The mechanisms of action of tests (increase of cardiac work), explains the common pathway to both ischemia or perfusional heterogeneity; besides perfusional alterations precede the development of ischemia. The relatively higher sensitivity of perfusion imaging, in comparison with echocardiography, ever since realises both in milder degree of ischemia due to singlevessel disease or in sub maximal test