BACKGROUND: There is a lack of evidence for choosing the second conduits in coronary artery bypass grafting (CABG) surgery as surgical characteristics that influence graft failure are still uncertain. This study describes the graft patency of the left internal mammary artery (LIMA), radial artery (RA), saphenous vein (SV), and right internal mammary artery (RIMA) 1 year after CABG surgery.
METHODS AND RESULTS: This substudy randomized 1,448 COMPASS trial patients 4 to 14 days after CABG surgery to receive the combination of rivaroxaban plus aspirin, rivaroxaban alone, or aspirin alone. Overall, 1,448 patients (3,460 grafts) were recruited from 78 centers in 22 countries that were included in our graft-level analysis. Grafts were categorized by quality (conduit and target vessel), location (proximal and distal sites) and percentage of target vessel stenosis. We defined graft failure to include all grafts with string sign in addition to those that had completely occluded. There were no differences in rates of graft failure between drug treatment groups as diagnosed by computed tomography (CT) angiogram 1 year after CABG surgery. Failure of LIMA grafts were infrequent at 6.4% (69/1065 patients, 95% CI 5.1–8.1%) and depended on the quality of the conduit but not on the quality of distal target territory. The RA had an overall rate of graft failure of 9.9% (9/91, 95% CI 5.1–17.9%) and its failure was associated with the percentage of target vessel stenosis. The overall rate of graft failure of the SV conduit was 10% (222/2221, 95% CI 8.8–11.8%) and its failure was independent of the quality of the conduit or the percentage of target vessel stenosis. The overall failure rate of RIMA grafts was 21.7% (18/83, 95% CI 14.1–31.8%) but with unacceptably high rate of graft failure 65% (11/17, 95% CI 41–83%) when directly anastomosed to the left circumflex territory with a posterior cardiac approach but with a lower rate of graft failure 23% (3/13, 95% CI 7.5–50.9%) when used as a free graft/piggyback anastomosed to the left circumflex territory.
CONCLUSION: The LIMA is the first choice conduit unless it is of poor quality. The RA is an excellent second conduit unless the proximal target vessel stenosis is less than 80%. SV grafts perform well in all situations and are excellent choice for a second or third conduit. RIMA directly anastomosed to the left circumflex territory had an unacceptably high graft failure rate.