Incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium 201 imaging in patients with ST-T abnormalities on their resting electrocardiograms

Abstract

The incremental prognostic value of thallium 201 imaging in patients with nonspecific ST-T abnormalities on the resting electrocardiogram (ECG) may be different from those with a normal resting ECG. Nine hundred thirty-nine consecutive patients with nonspecific ST-T abnormalities on their resting ECG who had undergone exercise 201 Tl imaging were followed for a median duration of 7.0 y (94% complete). The Cox proportional hazards regression model was used in a stepwise fashion to generate (1) a clinical (Cl) model, (2) a clinical and exercise (Cl + Ex) model, (3) and a clinical, exercise, and thallium (Cl + Ex + Tl) model, for the prediction of cardiac death. Age, sex, and diabetes composed the Cl model (chi2 = 63, P < .0001). The Duke treadmill score added to the Cl + Ex model (chi2 = 71, P < .0001). Increased lung uptake (P < .0001) added significantly and summed reversibility score ( P = .03) added modestly to the Cl + Ex + Tl model (chi2 = 96, P < .0001). On the basis of the Cl + Ex + Tl model, the low-, intermediate-, and high-risk groups had a 7-y survival free of cardiac death of 99%, 88%, and 58%, respectively (P < .0001). Using the Cl + Ex + Tl model, only a small number of low-risk and high-risk patients by the Cl + Ex model were reclassified. However, 48% of the 230 patients in the intermediate-risk group by the Cl + Ex model were reclassified as low risk or high risk. 201 Tl imaging has incremental prognostic value in patients with nonspecific abnormalities on their resting ECG. However, patients classified as low risk or high risk by exercise testing using the Cl + Ex model do not require 201 Tl imaging. Intermediate-risk patients should be further risk-stratified by 201 Tl imaging.