Abstract 15732: Impact of Bilateral Mammary Artery Grafting for Coronary Revascularization in the Obese Population, a Retrospective Study

Abstract

Context: The prevalence of obesity has increased over the last decade. Although bilateral internal mammary artery (BIMA) grafting for coronary revascularization is associated with better survival in the general population, it is also a risk factor for deep sternal wound infection (DSWI), a complication more frequently seen in the obese population. The aim of this study is to determine the short and long-term outcomes of the use of BIMA in obese patients undergoing cardiac surgery, assessing the impact on survival and the incidence of DSWI. Methodology: This is a single center retrospective cohort study with prospectively collected data. We included obese patients (BMI ≥ 30 kg/m2) undergoing coronary artery bypass grafting (CABG) between April 1991 and April 2014 in our institution. Propensity score matching was conducted for the entire population studied. Results: Results showed that 5608 obese patients underwent CABG during the study period. After propensity scoring, 494 patients receiving BIMA revascularization were matched to 5089 patients receiving single internal mammary artery (SIMA) revascularization. All pre-operative characteristics were comparable except for a higher prevalence of heart failure in the SIMA group. In-hospital post-operative mortality in the two groups was comparable (1.0% BIMA vs 1.8% SIMA, p=0.86). In-hospital DSWI was also comparable (1.2% BIMA vs 1.0% SIMA, p=0.63). However total DSWI (including post-discharge DSWI, median time 19 days) was significantly higher in the BIMA group compared to the SIMA group (3.6% vs 2.2%; p<0.0001). Over a median follow-up of 7.2 years (mean follow-up 7.7 ± 4.2 years), there was no observed long-term survival advantage in the BIMA vs the SIMA group (p=0.22). Conclusion: Using BIMA instead of SIMA increases the risk of DSWI in obese patients. The use of BIMA is not associated with better survival compared to the use of SIMA in this population. These results suggest that the increased short-term risk of post-operative infection associated with BIMA revascularization is not offset by a long-term survival benefit. Given the increased risk of DSWI and absence of mid- to long-term survival benefit, caution should be exerted when selecting the use of BIMA grafting in the obese population.