Changes in native coronary arteries after coronary bypass surgery. Role of graft patency, serum lipids and hypertension.

Sixty-seven patients were studied by coronary angiography early (mean 3 weeks) and late (mean 13 months) after coronary bypass surgery to assess changes in the native coronary vessels. Among the 208 nongrafted arteries progression of disease was found in 2.9 percent. In arteries that were normal before operation, the rate was 0.7 percent; in those with luminal obstructions the rate was 7.6 percent (P less than 0.05). Progression of disease occurred in 6 of the 67 patients (8.9 percent). In five bypassed arteries (5 percent), progression of disease occurred at or near the anastomotic site; in this subset the procedure was classified a technical failure. Progression of disease distal to graft insertion occurred in 2.4 percent of cases. The greatest incidence of progression took place proximal to graft insertion, in 24.2 percent of the grafted arteries. This rate differed significantly from the rate in non-grafted arteries (P less than 0.001) and in distal segments of grafted arteries (P less than 0.001). If the grafts were patent in the late control study, the progression of disease proximally occurred at a rate of 24 percent; if they were occluded, the rate was 25 percent. The data on timing of graft occlusion suggested that graft patency was related to the proximal progression. The prevalence of hyperlipidemia or hypertension did not correlate with progression of disease in any group.