Experimentally, hemorrhage and extension of myocardial infarction occur commonly when there is reperfusion after coronary artery occlusion. To investigate this hazard in a clinical setting, we compared the histopathologic picture of myocardial infarction in 44 patients who had undergone aortocoronary bypass: 14 (Group I) had myocardial infarction that predated aortocoronary bypass by 1 to 7 days; 13 (Group II) had infarction 1 to 14 days after the surgery; and 17 (Group III) had infarction 15 to 90 days postoperatively. All 44 patients had two or more coronary arteries with luminal narrowing of more than 75 per cent and patent vein grafts to arteries supplying areas of infarction. Hemorrhagic infarcts were present in 57 per cent of patients (eight of 14) in group I and 38 per cent of patients (five of 13) in Group II, contrasting with 6 per cent of patients (one of 17) in Group III (P < 0.005 and P < 0.05, respectively). In hemorrhagic infarcts, the extravasated blood formed irregular intramural dissecting tracts beyond the area of infarction, and foci of myocardial necrosis were present in the border zones. Infarcts affected more than 50 per cent of the left ventricular muscle in 64 per cent of cases of hemorrhagic infarction and in 13 per cent of cases of nonhemorrhagic infarction (P < 0.05). The prevalence of hemorrhagic infarction after revascularization may account for the high mortality of evolving and perioperative myocardial infarction associated with aortocoronary bypass, and this finding militates against wholesale immediate revascularization in patients who have uncomplicated myocardial infarction.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine