Atherosclerosis in aortocoronary bypass grafts. Morphologic study and risk factor analysis 6 to 12 years after surgery.

Segments of aortocoronary vein grafts from a selective group of 42 patients who underwent a second revascularization procedure or came to autopsy 6 to 12 years after coronary bypass surgery were studied. Complex atheromata often associated with an acute thrombus were present in 71% of the grafts. In 14% of the cases, aneurysms of the atherosclerotic type were noted. The medical records of 40 of these patients were reviewed. Special attention was paid to risk factors associated with coronary artery disease. A control population of 535 patients who had undergone coronary artery bypass surgery and had not had recurrence of symptoms requiring reoperation 5 or more years later was drawn from the Milwaukee Cardiovascular Data Registry. Significantly higher triglyceride and cholesterol levels and lower high density lipoprotein levels were noted in the patients undergoing two bypass procedures. In addition more diabetics, cigarette smokers, and patients with abnormal lipoprotein phenotypes were noted in the study group. Hypertension did not appear to be a significant risk factor. Atherosclerosis appears to be an important factor in late graft failure. Vein grafts that develop atherosclerosis appear to be susceptible to aneurysm formation. Risk factors associated with atherosclerosis in coronary arteries also appear to play a role in the development of atherosclerosis in aortocoronary bypass grafts.