Long-term prediction of major ischemic events by exercise thallium-201 single-photon emission computed tomography. Incremental prognostic value compared with clinical, exercise testing, catheterization and radionuclide angiographic data

Abstract

Objectives: This study sought to evaluate the prognostic role of exercise thallium-201 (Tl-201) single-photon emission computed tomography (SPECT) in patients with known or suspected coronary artery disease.

Background: Compared with planar Tl-201 scintigraphy, Tl-201 SPECT allows enhanced assessment of myocardial perfusion abnormalities. However, the long-term prognostic value of exercise Tl-201 SPECT has not been ascertained and compared with that of other techniques of investigation.

Methods: Predictors of ischemic events were sought in 217 patients with known or suspected coronary artery disease who underwent exercise Tl-201 SPECT, coronary angiography and rest radionuclide angiography and who initially received medical therapy. Predictive values were determined using Cox proportional hazards regression models.

Results: During a mean (+/- SD) follow-up period of 70 +/- 19 months, 29 patients had a major ischemic event (cardiac death or myocardial infarction). Total extent of exercise defects was the best independent predictor by Tl-201 SPECT of major events (p < 0.001) and provided additional prognostic information compared with clinical, exercise testing and catheterization variables (p < 0.02). Extent of reversible Tl-201 SPECT perfusion defects provided additional prognostic information compared with extent of irreversible defects (p < 0.001) and was the sole Tl-201 SPECT variable providing additional prognostic information compared with radionuclide left ventricular ejection fraction (p < 0.02).

Conclusions: Total extent of exercise Tl-201 SPECT defects is a powerful long-term predictor of major ischemic events that enhances the prediction provided by clinical, exercise testing and coronary angiographic data. In view of its prognostic significance, extent of reversible Tl-201 SPECT defects might provide original information about improving prognosis by coronary revascularization.