What is the rationale for using bilateral internal mammary arteries (BIMA) versus single LIMA in CABG?

• A. BIMA can provide superior long-term patency and survival but increases risk of sternal wound complications; patient selection and risk stratification are important.
• B. BIMA can provide lower risk of sternal wound infections
• C. BIMA provides no patency advantage over LIMA
• D. BIMA is never indicated in diabetics

Answer: (A)

Using two internal mammary arteries aims to maximize long-term graft durability because arterial conduits stay patent longer and resist atherosclerosis better than vein grafts. This benefit often translates into improved long-term survival, especially in younger patients with a longer expected remaining lifespan who will live with the grafts for many years.

But harvesting both mammaries increases the extent of chest wall dissection, raising the risk of sternal wound complications, including infection and mediastinitis. That risk tends to be higher in patients with diabetes, obesity, COPD, or poor wound healing, and it can offset the long-term gains in certain individuals.

Therefore, the rationale hinges on selecting patients who are likely to derive meaningful long-term benefit from the superior patency of arterial grafts while weighing them against the higher risk of sternal wound problems. In some patients, a single LIMA to the LAD provides most of the durable benefit with a lower infection risk, and additional grafts can be planned to minimize wound complications. Techniques such as skeletonized harvesting can reduce wound risk and may expand BIMA use in select cases, but the basic trade-off remains: better long-term graft patency and potential survival benefit with BIMA, balanced against a higher risk of sternal wound complications requiring careful patient selection.