Tl-201 reinjection enhances the detection of myocardial ischemia after acute myocardial infarction.

BACKGROUND

Thallium 201 reinjection has been shown to enhance the detection of myocardial ischemia in patients with chronic coronary artery disease. However, limited data are available regarding its value in patients after acute myocardial infarction.

METHODS AND RESULTS

We performed adenosine Tl-201 tomography in 126 patients in stable condition at a mean of 5 +/- 3 days after acute myocardial infarction (MI). After acquisition of redistribution images, patients were reinjected with 1 mCi of Tl-201 and reinjection images were then obtained. The stress, redistribution, and reinjection images were quantified to determine the total perfusion defect size and percent ischemia and scar. The mean age of patients was 54 +/- 10 years. Of the patients, 64% were male, 56% had Q-wave MI, 46% had anterior MI, and 34% received thrombolysis. The percent total defect size was the same on the stress-redistribution and stress-reinjection images (28.3% +/- 19.0%). The reinjection images showed an increase in ischemic defect size (14.7% +/- 13.5% vs 12.8% +/- 12.0%, P =.001) and a decrease in scar defect size (13.6% +/- 13.1% vs 15.5% +/- 13.9%, P =.001) compared with the redistribution images. The enhancement in the detection of myocardial ischemia was seen in both the infarct (P =.001) and noninfarct (P =.01) zones.

CONCLUSIONS

Tl-201 reinjection enhances the detection of myocardial ischemia after acute MI compared with stress-redistribution alone.