RISK-FACTORS FOR OPERATIVE MORTALITY AND STERNAL WOUND-INFECTION IN BILATERAL INTERNAL MAMMARY ARTERY GRAFTING

To investigate risk factors for operative mortality and sternal infect ion in patients undergoing bilateral internal mammary artery grafting, we analyzed the data of 199 patients who underwent this procedure fro m January 1986 through June 1992. These patients were also compared wi th those who underwent only saphenous vein grafting (1664 cases) and t hose who underwent unilateral internal mammary artery grafting (3359 c ases) during the same time frame. The operative mortality was 3.52% (7 /199) in the patients having bilateral internal mammary artery graftin g, 2.71% (91/3359) in those having unilateral internal mammary artery grafting, and 8.53% (142/1664) in the patients having saphenous vein g rafting (p < 0.0001), The occurrence rate of sternal infections was 2. 45% (5/199) for bilateral internal mammary artery grafting, 1.32% (13/ 1664) for saphenous vein grafting, and 1.19% (20/3359) for unilateral internal mammary artery grafting (p = 0.27). The univariate analysis r evealed that age, history of congestive heart failure, emergency opera tion, ejection fraction, and aortic crossclamp time were significantly correlated with operative mortality and that obesity was correlated w ith sternal wound infection. Stepwise multiple logistic regression ide ntified that old age (greater than or equal to 70 years) (p < 0.0001), long perfusion time (p < 0.0001), and emergency operation (p = 0.0004 ) are risk factors for operative mortality and that obesity (p = 0.000 9) is the only significant risk factor for sternal wound infection. We conclude that bilateral internal mammary artery grafting does not inc rease operative mortality in properly selected patients. However, this procedure should be carefully chosen in elderly (greater than or equa l to 70 years) patients and for emergency operation. Obese patients ha ve a high risk for sternal infection after bilateral internal mammary artery grafting.