Bilateral Internal Thoracic Artery Grafting in Patients with Diabetes Mellitus

Bilateral internal thoracic artery (BITA) grafting in patients with diabetes mellitus is controversial due to a higher risk for sternal infection. The purpose of this study is to compare the rates of mediastinitis as well as mortality rates of BITA grafting to that of single internal thoracic artery (SITA) grafting and saphenous vein grafts in patients with diabetes.

Between 2007 and 2015 all consecutive diabetic patients with multivessel disease who underwent primary coronary artery bypass graft surgery with BITA were compared with patients who underwent coronary artery bypass graft surgery with SITA and saphenous vein grafts (the control group). Patients submitted to single grafts were excluded from the analysis. Propensity score matching was used to account for differences between groups in preoperative characteristics. The frequency of peri-operative mediastinitis was compared between BITA and control group. Mortality rates between were compared between groups at 1-month post-surgery and 2-year post-surgery.

A total of 1005 patients were included in our sample in which 188 (19%) patients performed BITA grafting. BITA patients were younger (BITA group mean age 60.0 years vs control group 69.9 years; p<0.001), less often female (BITA group 11.7% vs control group 28.2%; p<0.001), and less often insulin treated (BITA group 9.6% vs control group 18.8%; p=0.002) compared to the control group. All other characteristics were not statistically different between groups, namely CCS, NYHA score, three vessel coronary artery disease, left main disease, previous myocardial infarction, hypertension, COPD and body mass index. After propensity score matching, 344 patients were included in the analysis, 138 in the BITA group and 206 in the control group. In this analysis both groups were not statistically different in every characteristic evaluated including age, sex and insulin-treated diabetic patients. The rate of peri-operative mediastinitis in matched groups was comparable (BITA group 2.3% vs control group 1.5; p=0.605). Mortality rates were comparable between groups at 1-month post-surgery (BITA group 1.4% vs control group 0.5%; p=0.346) and 2-year post- -surgery (BITA group 3% vs control group 2%; p=0.557).

The findings of this sample suggest that the short and mid-term outcomes of patients with diabetes and multivessel disease who undergo BITA grafting is similar to other grafting procedures. BITA grafting in diabetic patients seems to be safe in terms of sternal wound problems. Longer term follow-up is required to determine BITA grafting survival improvement.