A predictive scoring system for deep sternal wound infection after bilateral internal thoracic artery grafting

Despite long-term survival benefits, the increased risk of sternal complications limits the use of bilateral internal thoracic artery (BITA) grafts for myocardial revascularization. The aim of the present study was both to analyse the risk factors for deep sternal wound infection (DSWI), which complicates routine BITA grafting and to create a DSWI risk score based on the results of this analysis.

BITA grafts were used as skeletonized conduits in 2936 (70.6%) of 4160 consecutive patients with multivessel coronary artery disease who underwent isolated coronary bypass surgery at the authors' institution from 1 January 1999 to 2013. The outcomes of these BITA patients were reviewed retrospectively and a risk factor analysis for DSWI was performed.

A total of 129 (4.4%) patients suffered from DSWI. Two multivariable analysis models were created to examine preoperative factors either alone or combined with intraoperative and postoperative factors. Female gender, obesity, diabetes, poor glycaemic control, chronic lung disease and urgent surgical priority were the predictors of DSWI common to both models. Two (preoperative and combined) models of a new scoring system were devised to predict DSWI after BITA grafting. The preoperative model performed better than five of six scoring systems for sternal wound infection that were considered; the combined model performed better than three considered scoring systems.

A weighted scoring system based on risk factors for DSWI was specifically created to predict DSWI risk after BITA grafting. This scoring system outperformed the existing scoring systems for sternal wound infection after coronary bypass surgery. Prospective studies are needed for validation.