ACCURACY OF EXERCISE TL-201 MYOCARDIAL SCINTIGRAPHY IN ASYMPTOMATIC YOUNG MEN

Background. Little is known about the diagnostic usefulness of TI-201 scintigraphy for detecting asymptomatic coronary artery disease in apparently healthy men. We thus evaluated planar TI-201 exercise myocardial scintigraphy in 845 asymptomatic male military aircrew undergoing coronary arteriography because of abnormal noninvasive tests suggesting possible myocardial ischemia. Methods and Results. Patients were stratified by prior disease risk into six subgroups using age (<45 and greater-than-or-equal-to 45 years) and ratio of total to high density lipoprotein cholesterol (<4.5, 4.5-6.0, and >6.0). Significant coronary artery disease (greater-than-or-equal-to 50% diameter stenosis in any major coronary artery) was present in 143 (16.9% prevalence). Overall sensitivity and specificity of Tl-201 scintigraphy adjusted for verification bias were estimated to be 45+/-4% and 78+/-1%, respectively. These values are lower than corresponding values accepted for clinical populations. Positive and negative predictive values varied across subgroups. A normal thallium scan indicated low risk of disease, but an abnormal test was likely to be a false-positive result. A logistic equation was retrospectively fit to the data for estimating the probability of disease given age, cholesterol ratio, and thallium results. Within each quintile of estimated risk, the average risk did not differ significantly from the observed disease prevalence. Conclusions. Exercise Tl-201 scintigraphy is limited by the frequent occurrence of false-positive tests in detecting asymptomatic, anatomic coronary artery disease in young men in accordance with Bayesian probability theory.