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

Background The incremental prognostic value of thallium 201 imaging in patients with nonspecific ST-T abnormalities on the resting electrocardiogram (EC6) may be different from those with a normal resting ECG. Methods Nine hundred thirty-nine consecutive patients with nonspecific ST-T abnormalities on their resting ECG who had undergone exercise (TI)-T-201 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. Results Age, sex, and diabetes composed the Cl model ((2)(X) = 63, P <.0001). The Duke treadmill score added to the Cl + Ex model ((2)(X) = 71, P <.0001). Increased lung uptake (P <.0001) added significantly and summed reversibility score (P=.03) added modestly to the Cl + Ex + TI model ((2)(X) = 96, P <.0001). On the basis of the Cl + Ex + TI 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 + TI 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. Conclusions (TI)-T-201.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 (TI)-T-201 imaging. Intermediate-risk patients should be further risk-stratified by 20 1TI imaging.