Long term mortality of deep sternal wound infection after coronary artery bypass surgery

Deep sternal wound infection and mediastinitis determine high in-hospital mortality. International studies show that these patients are also at increased cardiovascular mortality risk in long-term follow-up. However, data are scarce and there is no national data. The aim of this study is to evaluate the mortality and incidence of cardiovascular events in long-term follow-up of patients suffering from deep sternal wound infection and mediastinitis. Case-control study, matched by propensity score in a 1:1 proportion, in patients submitted to coronary artery bypass grafting between 2005 and 2008 at the Institute Dante Pazzanese of Cardiology (São Paulo, SP, Brazil). The primary outcome was death. As a secondary outcome, we analyzed the composite event of myocardial infarction, new revascularization, stroke or death. Of 1975 patients, 114 developed one of the infections. During the mean follow up of 3.6 years, deep sternal wound infection and mediastinitis increased the risk of death by 8.26 (95% CI 1.88-36.29, P = 0.005) and the incidence of combined end point by 2.61 (95% CI 1.2-5.69, P = 0.015). The Kaplan-Meier curves for both outcomes demonstrated that the greatest risk occurs in the first six months, followed by a period of stabilization and further increase in the incidence of events after 4 years of hospital discharge. The similarity between the curves of primary and secondary outcomes may be consequent to the predominance of death on the combined cardiovascular events. The presence of deep sternal wound infection or mediastinitis increased mortality in long-term follow-up in this sample of the Brazilian population according to the same pattern displayed by the developed countries.