Mediastinitis after coronary artery bypass graft surgery: influence of the mammary grafting for diabetic patients.

Mediastinitis is a severe complication of coronary artery bypass graft surgery (CABG) particularly when harvesting internal mammary arteries (IMA). CABG in diabetic patients often uses two IMA because the saphenous graft is damaged. To our knowledge this risk of mediastinitis has not previously been reported in diabetic patients. All consecutive diabetic patients undergoing CABG over a three-year period from 1998 to 2000 were included in the study. Data recorded were: age, sex, duration of stay, whether one or two IMA were used, diagnosis of mediastinitis. Calculation of relative risk and analysis of trends by chi2 trend tests was also performed. In total 256 diabetic patients were included in the cohort. The incidence of mediastinitis was 4.3% (11/256). The risk of mediastinitis was higher in patients with two IMA than in patients with one IMA (relative risk 5.97, 95 CI 1.63-21.93, P=0.004). Age and sex were not confounding factors. No patients with mediastinitis died. Bilateral IMA grafting is associated with higher risk of mediastinitis in diabetic patients. The authors suggest that the risk of mediastinitis in diabetic patients should be taken into consideration when cardiac surgeons choose unilateral or bilateral IMA harvesting for surgery.