Multicenter, double-blind, randomized, controlled trial. All prospective participants received active warfarin treatment for a month prior to randomization. Only participants demonstrating a minimal reaction to warfarin and consuming over 90 percent of the prescribed medication were randomized. Dietary modification to lower serum cholesterol, an exercise program, and a smoking cessation program were implemented. Patients were randomly assigned in a 2 X 2 factorial design in four treatment groups: aggressive LDL-C lowering with lovastatin 40 to 80 mg/d and, as necessary cholestyramine 8 mg/d to achieve and LDL-C of 60 to 85 mg/dl; moderate LDL-C lowering with lovastatin 2.5 to 5 mg/d, with cholestyramin as needed, to achieve a LDL-C of 130 to 140 mg/dl; warfarin 1 to 4 mg/d to achieve an INR of 1.8 to 2.0; and warfarin-placebo. All participants were followed for five years, at the end of which selective coronary and graft angiography was performed. The primary angiography endpoint was the proportion of major SVG per patient that showed substantial reduction (0.06 mm or greater) in lumen diameter. Biobehavioral studies were conducted in 750 participants.