Long-term and short-term outcomes of using bilateral internal mammary artery grafting versus left internal mammary artery grafting: a meta-analysis

Background: A substantial body of evidence demonstrates that myocardial revascularisation using bilateral internal mammary arteries (BIMA) improves long-term survival compared with single/left internal mammary artery (LIMA) grafting. To date, limited analyses have been made regarding other short-term and long-term outcomes in BIMA strategy. Objectives: The primary aim of the present review is to update the difference in long-term survival between BIMA and LIMA grafting and to thoroughly investigate other secondary short-term and long-term clinical outcomes between these two grafting procedures. Methods: Electronic searches were performed using three databases from their inception to November 2015. Relevant studies comparing long-term survival between BIMA and LIMA grafting were identified. Data were extracted by two independent reviewers and analysed according to predefined clinical outcomes. Results: Twenty-nine observational studies were identified, with a total of 89 399 patients. Overall, BIMA cohort had significantly improved long-term survival compared with LIMA cohort (HR 0.78; p<0.00001). BIMA cohort also had significantly reduced hospital mortality rates (1.2% vs 2.1%, p=0.04), cerebrovascular accidents (1.3% vs 2.9%, p=0.0003) and need for revascularisation (4.8% vs 10%, p=0.005), although the incidence of deep sternal wound infection (DSWI) was increased (1.8% vs 1.4%, p=0.0008) in this grafting strategy. Long-term cardiac-free, myocardial infarction-free and angina-free survivals were also superior for the BIMA cohort. Conclusions: BIMA grafting is associated with enhanced overall long-term outcomes compared with LIMA grafting. While the BIMA cohort demonstrates an increased incidence of DSWI, the survival benefits and other morbidity advantages outweigh this short-term risk.