Morbidity of bleeding after cardiac surgery: is it blood transfusion, reoperation for bleeding, or both?

Etiology for increased morbidity in patients (2% to 8%) undergoing reoperation for bleeding after cardiac surgery is unclear. Recent work suggests that it may be related to red-cell transfusion, but what role does reoperation itself play? We sought to determine prevalence of and risk factors for reoperation for bleeding, separate the effect of reoperation from that of transfusion on hospital mortality and major morbidity, and identify the source of bleeding.

From January 1, 2000 to January 1, 2010, 18,891 primary and repeat coronary artery bypass grafting, valve, or combined operations were performed. Risk factors for reoperation were identified by multivariable logistic regression. Hospital mortality and major morbidity were compared in propensity-matched patients requiring reoperation and not. Medical records from 2005 to 2010 were reviewed to determine bleeding source.

A total of 566 patients (3.0%) underwent reoperation for bleeding, with considerable variability over time. Risk factors included older age, higher acuity, greater comorbidity, aortic valve surgery, longer myocardial ischemic and cardiopulmonary bypass durations, and surgeon. Mortality was higher for propensity-matched patients requiring reoperation; 8.5% (68% confidence interval [CI] 7.3% to 9.9%) versus 1.8% (CI 1.2% to 2.5%). Both greater transfusion and reoperation were independently associated with increased risk of mortality and major morbidity. At reoperation, technical factors (74%), coagulopathy (13%), both (10%), or other (3.3%) causes were responsible for bleeding.

Transfusion and reoperation for bleeding both contribute to postoperative mortality and morbidity. Technical reasons are at the root of most bleeding, emphasizing a major focus for process improvement to minimize need for reoperation and blood use.