Blood group AB is associated with reduced blood loss but also elevated cardiovascular mortality in aortocoronary bypass surgery.

Patient blood group (BG) is predictive for von-Willebrand-factor (VWF) and Factor VIII variation. The clinical impact of this ABO-effect on blood loss, cardiovascular complications and outcome has been described for several patient cohorts. The aim of this study was to investigate the impact of patient BG on blood loss and outcome after coronary artery bypass surgery (CABG). Patient records, intraoperative data and perioperative transfusion records of 5713 patients receiving an on-pump CABG procedure between 05/2004 and 12/2018 were analyzed. A logistic regression model for death due to perioperative myocardial ischaemia (PMI) was developed from initially 24 variables by using an univariate and multivariate selection process. BG AB patients required less blood transfusions as compared to the other blood groups, especially in case of emergency operations. However, BG AB patients also had a higher mortality which was due to secondary cardiovascular complications. The impact of blood type on the rate of cardiovascular mortality was confirmed in the logistic regression model. BG AB patients have a worse outcome after CABG surgery due to an increased incidence of fatal cardiovascular complications. As perioperative myocardial ischemia due to graft occlusion appears to be the most likely explanation, stricter anticoagulation for BG AB patients should be discussed.