Identification of severe coronary artery disease in patients with a singleabnormal-coronary territory on exercise thallium-201 imaging

OBJECTIVES The aim of this study was to determine which clinical, exercise and thallium variables can aid in the identification of three-vessel or lef t main coronary artery disease (3VLMD) in patients with one abnormal corona ry territory (either a reversible or fixed defect) on exercise thallium tes ting and to test the prognostic value of these variables. BACKGROUND Although the sensitivity of detection of coronary artery disease by thallium-201 imaging is high, the actual detection of 3VLMD by thallium tomographic images alone is not optimal. METHODS A multivariate model for prediction of 3VLMD was developed from sev eral clinical, exercise and thallium-201 variables in a training population of 264 patients who had one abnormal coronary artery territory on exercise thallium testing and had undergone coronary angiography. Using this model, patients were stratified into risk groups for prediction of 3VLMD. A separ ate validation cohort of 474 consecutive patients who were treated initiall y with medical therapy and who had one abnormal coronary territory were div ided into identical risk groupings by the variables derived from the traini ng population, and they were followed for a median of 7.0 years to evaluate the prognostic value of this model. RESULTS The prevalence of 3VLMD was 26% in the training population despite one abnormal thallium coronary territory. Four clinical and exercise variab les-diabetes, hypertension, magnitude of ST segment depression, and exercis e rate-pressure product-were found to be independent predictors of 3VLMD. I n the training population, the prevalence of 3VLMD in low-, intermediate- a nd high-risk groups was 15%, 22% and 51%, respectively. When the multivaria te model was applied to the validation population, the eight-year overall s urvival rates in the low-, intermediate- and high-risk groups were 89%, 73% and 75%, respectively (p < 0.001). CONCLUSIONS A substantial proportion of patients with one :abnormal thalliu m coronary territory have 3VLMD with subsequent divergent outcomes based up on risk stratification by clinical and exercise variables. Consequently, th e finding of only a single abnormal coronary territory by thallium-201 perf usion imaging does not necessarily confer a benign prognosis in the absence of consideration of nonimaging variables. (J Am Coll Cardiol 2000;35:335-4 4) (C) 2000 by the American College of Cardiology.