Selecting conduits for coronary artery bypass grafting: caution regarding the right internal mammary artery

This narrative review summarizes the angiographic and clinical outcome results of the most common coronary artery bypass grafting (CABG) conduits. The left internal mammary artery is the preferred first conduit to bypass the left anterior descending artery due to superior long-term survival and graft patency. Recent studies suggest the radial artery may be the preferred second conduit for the circumflex or right coronary artery territories, challenging the belief that the right internal mammary artery is the best choice. Despite their historical high failure rates, saphenous vein grafts continue to be widely used as secondary conduits. Several recent studies report suboptimal rates of right internal mammary artery graft failure, with clinical outcomes comparable to or worse than saphenous veins. The suboptimal rates of RIMA graft failure may be attributed to several factors such as improvements in vein graft failure rates, the use of in situ and non-left anterior descending artery grafting configurations, and skeletonized harvesting techniques. While observational studies favor multiple over single arterial grafting, randomized studies are needed for confirmation. The ongoing Randomized comparison of the clinical Outcome of single vs. Multiple Arterial grafts (ROMA) trial aims to determine if multiple arterial grafting reduces major adverse cardiovascular events and mortality and how secondary conduit selection influences these outcomes. Greater adoption of arterial grafting strategies is likely to come from high-quality evidence of benefit and safety from ongoing and future large pragmatic trials.