Postoperative red blood cell transfusion and morbid outcome in uncomplicated cardiac surgery patients.

OBJECTIVE: To evaluate postoperative red blood cell (RBC) transfusion and its association with postoperative cardiac events and multiorgan morbidity in uncomplicated cardiac surgery patients.
METHODS: A cohort of 945 patients from the 5,436 coronary artery bypass grafting patients enrolled in the international Multicenter Study of Perioperative Ischemia (McSPI) Epidemiology II (EPI II) study was investigated. Inclusion criteria were low to moderate risk profile, postoperative hemoglobin level ≥ 10 g/dl, minimal postoperative blood loss, and no evidence of any morbid event on the day of surgery. RBC transfusion was assessed during the first 24 postoperative hours and cardiac as well as multiorgan outcomes from postoperative day 2 to hospital discharge. Multivariate analysis was applied to assess the effect of RBC transfusion on multiorgan outcomes. A secondary propensity score analysis was performed in 4,465 patients without early postoperative morbid outcomes.
RESULTS: Transfused patients (193/945, 20.4%) were more likely to suffer cardiac events (P = 0.03), harvest-site infection (P = 0.002), and composite morbidity outcome (P = 0.04). RBC transfusion was associated with cardiac events on multivariate as well as on propensity score analysis (adjusted odds ratio, 1.39; 95% confidence interval, 1.01-1.92; P = 0.04), and with harvest-site infection on multivariate analysis. Additionally, propensity score analysis suggested possible associations of RBC transfusion with increased risks for composite morbidity outcome and in-hospital mortality, renal morbidity, pneumonia, and mediastinitis.
CONCLUSIONS: The data suggest a potential association between postoperative RBC transfusion and increased morbidity for cardiac surgery patients with low to moderate mortality risk profiles, adequate hemoglobin levels, and low bleeding rates.