Thallium Reinjection Versus Standard Stress/Delay Redistribution Imaging for Prediction of Cardiac Events

Objectives. The purpose of this study was to compare thallium reinjection with standard stress/delay redistribution for the prediction of cardiac events. Background. Although thallium reinjection enhances the detection of viable myocardium, its contribution to prognosis over stress/delay redistribution in general referral population has not been clearly evaluated. Methods. This retrospective analysis included 366 consecutive patients with coronary artery disease who underwent stress/delay redistribution imaging and thallium reinjection scintigraphy, with mean follow-up of 33 ± 12 months. Results. Cardiac events occurred in 48 patients (40 deaths, 8 myocardial infarctions). Of the 366 original patients, 159 demonstrated ischemi by stress/delay redistribution, 107 showed ischemi by reinjection only, and 100 showed infarction only. Cardiac events occurred in 20 patients (12.6%) with stress/delay redistribution, 13 patients (12%) with ischemi detected by thallium reinjection only and 15 patients (15%) with infarction only. The size of the reversible thallium defect by either stress/delay redistribution imaging or reinjection scintigraphy did not predict cardiac events. Independent predictors of cardiac events included left ventricular cavity size, the size of the abnormal perfusion defect and patient age. Conclusions. Thallium reinjection does not contribute independent prognostic utility for cardiac events when compared with stress/delay redistribution. Left ventricular dilation and the size of the post-stress defect were predictors of cardiac events.