Early Outcome of Bilateral Versus Single Internal Mammary Artery Grafting in the Elderly

Background: Bilateral internal mammary artery (BIMA) grafting is increasingly used in elderly patients without evidence of its risks or benefits compared with single internal mammary artery (SIMA) grafting. Methods: In all, 2,899 patients aged 70 years or older (855 [29.5%] underwent BIMA grafting) operated on from January 2015 to December 2016 and included in the prospective multicenter Outcome After Coronary Artery Bypass Grafting (E-CABG) study were considered in this analysis. Results: One-to-one propensity matching resulted in 804 pairs with similar preoperative risk profile. Propensity score matched analysis showed that BIMA grafting was associated with a nonstatistically significant increased risk of inhospital death (2.7% versus 1.6%, p = 0.117). The BIMA grafting cohort had a significantly increased risk of any sternal wound infection (7.7% versus 5.1%, p = 0.031) as well as higher risk of deep sternal wound infection/mediastinitis (4.0% versus 2.2%, p = 0.048). The BIMA grafting cohort required more frequently extracorporeal membrane oxygenation (1.0% versus 0.1%, p = 0.02), and the intensive care unit stay (mean 3.6 versus 2.6 days, p < 0.001) and inhospital stay (mean 11.3 versus 10.0 days, p < 0.001) were significantly longer compared with the SIMA grafting cohort. Test for interaction showed that urgent operation in patients undergoing BIMA grafting was associated with higher risk of inhospital death (5.6% versus 1.3%, p = 0.009). Conclusions: Bilateral internal mammary artery grafting in elderly patients seems to be associated with a worse early outcome compared with SIMA grafting, particularly in patients undergoing urgent operation. Until more conclusive results are gathered, BIMA grafting should be reserved only for elderly patients with stable coronary artery disease, without significant baseline comorbidities and with long life expectancy.