The objectives were to analyze the evolution of the postoperative bleeding after coronary artery bypass grafting and to determine which factors impacted on this evolution.

This is a single-center retrospective study including 4590 patients undergoing coronary bypass surgery between 1995 and 2017. The study period was divided into 3 same-sized periods. We analyzed the evolution of the bleeding according to: the chest volume bleeding over the first 24hours, the severity and the rate of transfusion during the hospital stay. Intrahospital outcomes were compared between “minor” and “major” bleedings. The risk factors of major bleeding were analyzed by multiple logistic regression.

The chest volume decreased particularly during the first years of the study period. Major bleedings decreased over the periods (7.3%, 4.9% and 3.8% respectively, P<0.0001), as did the rate of transfusion (26.4%, 23.5% and 19.6% respectively, P<0.0001). Major bleedings were correlated with hospital mortality (8.2% versus 1.1%, P<0.0001). The risk factors of major bleeding were the period 1 (1995 to 2003), a renal failure, a resternotomy, the EuroSCORE, the hematocrit prior to cardiopulmonary bypass and the duration of cardiopulmonary bypass.

Postoperative bleeding decreased mainly in the 1990s. Progressive changes in bleeding prevention and blood recovery, surgical techniques, haemoglobin threshold for transfusion decision and practitioners’ experience have contributed to these results and must be continued to optimize the postoperative outcomes.