Background: To assess the yield of exercise myocardial stress tomogammagraphy (SPET) with methoxy-isobutyl-isonitrile-technetium-99m (99mTc-MIBI) in the diagnosis of coronary artery disease.
Methods: Seventy-two consecutive patients, without previous myocardial infarction and with coronary angiography, were investigated. All underwent a symptom-limited exercise test with intravenous infection of 15 mCi of 99mTc-MIBI 30-60 seconds before the end of exercise. Detection of tomographic images 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%), specificity (93%), global value (87%), positive predictive value (95%), and negative predictive value (79%) of 99mTc-MIBI were significantly higher than those of conventional exercise electrocardiogram (46%, 69%, 55%, 69% and 46%, respectively). These values were lower when exercise test was insufficient (peak heart rate below 80% in the absence of angina). 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 prevalences ranging between 30% and 70%.
Conclusion: The efficacy of 99mTc-MIBI SPET for the diagnosis of coronary artery disease was satisfactory, particularly when exercise was sufficient and with a prevalence of coronary artery disease ranging between 30% and 70%.