DIAGNOSIS OF CORONARY-DISEASE BY STRESS T OMOGAMMAGRAPHY WITH 99M-TECHNETIUM-ISONITRIL

BACKGROUND: To assess the yield of exercise myocardial stress tomogamm agraphy (SPET) with methoxy-isobutyl-isonitrile-technetium-99m (Tc-99m -MIBI) in the diagnosis of coronary artery disease. METHODS: Seventy-t wo consecutive patients, without previous myocardial infarction and wi th coronary angiography, were investigated. All underwent a symptom-li mited exercise test with intravenous injection of 15 mCi of Tc-99m-MIB I 30-60 seconds before the end of exercise. Detection of tomographic i mages was performed after one hour. Rest images were detected 24 hours later. Images with exercise perfusion defects which became normal at rest were considered as positive. RESULTS: Sensitivity (84%), specific ity (93%), global value (87%), positive predictive value (95%), and ne gative predictive value (79%) of Tc-99m-MIBI were significantly higher than those of conventional exercise electrocardiogram (46%, 69%, 55%, 69%, and 46%, respectively). These values were lower when exercise te st was insufficient (peak heart rate below 80% in the absence of angin a). The sensitivity values were similar for the diagnosis of one (81%) , two (76%), and three (93%) vessel disease. The application of Bayes' theorem disclosed that the highest yield of MIBI was achieved with pr evalences ranging between 30% and 70%. CONCLUSIONS: The efficacy of Tc -99m-MIBI SPET for the diagnosis of coronary artery disease was satisf actory, particularly when exercise was sufficient and with a prevalenc e of coronary artery disease ranging between 30% and 70%.