BACKGROUND The Emory Angioplasty Versus Surgery Trial (EAST) was designed to determine whether percutaneous transluminal coronary angioplasty (PTCA) is as effective as coronary artery bypass graft surgery (CABG) in restoring arterial perfusion capacity in eligible patients with multivessel disease. RESULTS Of 392 patients in EAST, 198 were randomized to PTCA and 194 to CABG. Index lesions (2.7 +/- 1.0 per patient) were those with > or = 50% stenosis judged treatable by both angioplasty and surgery. Coronary segments jeopardized by these index lesions were designated as index segments (4.4 +/- 1.4 per patient). Percent stenosis was measured by quantitative angiography at the point of greatest obstruction in the main perfusion path of each index segment. The EAST primary arteriographic end point was the percent of a patient's index segments with < 50% stenosis in the main perfusion pathways at 1 and 3 years. At baseline, the percent of index segments for which revascularization was attempted was 85% for PTCA and 98% for CABG (P < .0001). At 1 year, PTCA patients had a smaller percentage of successfully revascularized index segments than CABG patients (59% versus 88%, P < .001). At 3 years, the findings were similar but less striking (70% versus 87%, P < .001). When only "high-priority" index segments (2.1 +/- 1.6 per patient) were considered, baseline attempts were comparable (96% versus 99%, P = NS); despite this, CABG remained more successful at 1 (64% versus 93%, P < .001) and 3 (76% versus 89%, P < .01) years. However, the mean percent of index segments free of severe stenosis (> or = 70%) did not differ between PTCA and CABG patients at 3 years (93% versus 95%, P = NS). Furthermore, the frequency of patients with all index segments free of severe stenosis did not differ between the two groups at 1 (76% versus 83%, P = NS) or 3 (82% for both PTCA and CABG) years. CONCLUSIONS In patients with multivessel disease, index segment revascularization was more complete with CABG than PTCA at both 1 and 3 years. However, when the physiological priority of the target lesion and the measured severity of the residual stenosis are taken into account, the advantage of CABG becomes less significant or nonsignificant. This may, in part, explain why these two strategies did not differ in terms of the EAST primary clinical end points over 3 years.