Superficial and deep sternal wound infection after more than 9000 coronary artery bypass graft (CABG): Incidence, risk factors and mortality

Background: Sternal wound infection ( SWI) is an uncommon but potentially life-threatening complication of cardiac surgery. Predisposing factors for SWI are multiple with varied frequencies in different studies. The purpose of this study was to assess the incidence, risk factors, and mortality of SWI after coronary artery bypass grafting ( CABG) at Tehran Heart Center. Methods: This study prospectively evaluated multiple risk factors for SWI in 9201 patients who underwent CABG at Tehran Heart Center between January 2002 and February 2006. Cases of SWI were confirmed based on the criteria of the Centers for Disease Control and Prevention. Deep SWI ( bone and mediastinitis) was categorized according to the Oakley classification. Results: In the study period, 9201 CABGs were performed with a total SWI rate of 0.47 percent ( 44 cases) and deep SWI of 0.22 percent ( 21 cases). Perioperative ( in-hospital) mortality was 9.1% for total SWI and about 14% for deep SWI versus 1.1% for non-SWI CABG patients. Female gender, preoperative hypertension, high functional class, diabetes mellitus, obesity, prolonged intubation time ( more than 48 h), and re-exploration for bleeding were significant risk factors for developing SWI ( p = 0.05) in univariate analysis. In multivariate analysis, hypertension ( OR = 10.7), re-exploration ( OR = 13.4), and female gender ( OR = 2.7) were identified as significant predictors of SWI ( p < 0.05 for all). The rate of SWI was relatively similar in 3 groups of prophylactic antibiotic regimen ( Cefazolin, Cefazolin + Gentamycin and Cefazolin + Amikacin: 0.5%, 0.5%, and 0.34% respectively). Conclusion: Rarely reported previously, the two risk factors of hypertension and the female gender were significant risk factors in our study. Conversely, some other risk factors such as cigarette smoking and age mentioned as significant in other reports were not significant in our study. Further studies are needed for better documentation.