Postoperative bleeding is a major concern in cardiac surgery, often leading to significant transfusion requirements. Despite this high transfusion demand, the use of postoperative autologous blood transfusion (PABT) remains underexplored.

This large-scale, single-blind randomized controlled trial with a 30-day follow-up enrolls patients undergoing elective on- or off-pump coronary artery bypass grafting. Patients with shed mediastinal blood volumes over 500 mL within the first 6 hours postoperatively are randomly assigned 1:1 to either the PABT group or the standard care group. The PABT group receives postoperative autotransfusion and additional allogeneic RBC transfusions if needed, while the standard care group receives allogeneic RBC transfusions only when clinically necessary, without postoperative autotransfusion. The primary efficacy endpoint is the postoperative allogeneic RBC transfusion volume, defined as the cumulative amount transfused from the day of surgery to discharge. Secondary efficacy endpoints include postoperative allogeneic RBC and non-RBC transfusion rates, perioperative hematologic recovery, drainage volume, mechanical ventilation duration, ICU and hospital length of stay. The primary safety endpoint is the incidence of a composite of postoperative infections (pneumonia, bloodstream infections, and surgical site infections). Secondary safety endpoints include a composite of other postoperative complications (renal dysfunction, myocardial infarction, stroke, deep vein thrombosis, and all-cause mortality), individual components of these composites, and 30-day mortality and morbidity. The estimated sample size is 1,232 participants. Patient recruitment is planned from January 2026 to December 2029 and is currently in the preparatory phase. The study is registered at the Chinese Clinical Trial Registry (ChiCTR2500103269, https://www.chictr.org.cn/) and was registered on May 27, 2025.

The study is designed to identify the efficacy and safety of PABT after cardiac surgery. We hypothesize that PABT has superior efficacy and noninferior safety to the standard care.