Regional myocardial blood flow in regions of prior myocardial infarction before and after revascularization.

In 30 patients who received 102 saphenous vein bypass grafts, 91 were patent. Preoperative intracoronary injection of 99mTc-labeled albumin particles suspended in contrast revealed 81 regions of perfusion deficit which subsequently received successful revascularization. With postoperative graft injection of isotope, 48 of these regions no longer showed a perfusion deficit (59%), while 33 showed no change (41%). In these 30 patients, 16 of 17 (94%) revealed perfusion defects in regions of prior transmural myocardial infarction. Conversely, only 55 of 96 regions distal to coronary artery stenosis of greater than 50% revealed perfusion defects (57%). Thus, 99mTc-labeled microsphere studies seem to be valuable in detecting regions of prior infarction. After angiographically documented revascularization, the method continued to reveal perfusion deficits in 41% of abnormal regions noted preoperatively, even though almost half of these same specific regions showed improved postoperative regional contractility after postextrasystolic potentiation.