Evaluation of the redistribution in the infarcted area

Twenty-seven patients with myocardial infarction underwent exercise thallium myocardial scintigraphy. Images were obtained immediately after i.v. injection, and at 4 and 24 hours to examine the frequency and appearance of redistribution in the infarcted area at 24 hours. The patients were imaged concurrently with ECG-gated radionuclide ventriculography with Tc-99m RBC for the analysis of regional wall motion. Thirteen of the patients also underwent thallium-201 myocardial scintigraphy at rest one week after exercise loading. Of 18 patients in whom redistribution was observed in the infarcted area on the 4-hr image, 6 (33%) had new redistribution in the infarcted area on the 24-hr image. Two of the 6 patients had severe asynergy. In none of the other 9 patients, in whom redistribution was not observed on the 4-hr image, was new redistribution observed on the 24-hr image. All the 9 patients had severe asynergy. In comparing the 24-hr image with rest image, 11 (85%) of the evaluable 13 patients had the same defects in the infarcted area on both images, and the other two patients (15%) had a larger defect on the 24-hr image than the rest image. When perfusion defects became smaller insize or less visible on the 24-hr image, there was a tendency for severe stenosis of the infarct-related coronary artery and sufficient amounts of collateral circulation. (N.K.)