Less transfusion is still more—red blood cell transfusion affects long-term mortality in cardiac surgery

Abstract Objective Previous studies indicated higher long-term mortality after the transfusion of allogeneic red blood cells and newer recommendations emphasize lower transfusion rates. Consequences of transfusion of red blood cells in cardiac surgery are unclear, as later studies focused on transfusion triggers and short-term outcomes and reports on long-term complications after cardiac surgery are few. Material and methods The mandatory Western Denmark Heart Registry was used to identify all adult cardiac surgeries performed in four centres from 2000–2019. Patients with multiple entries or previous cardiac surgery, special/complex procedures, dying within 30 days and not eligible for follow-up were excluded. Results A total of 32,581 adult cardiac surgeries performed in four centres from 2000–2019 were included. The Kaplan–Meier survival plot for low-risk patients undergoing simple cardiac surgery showed a significantly lower 15-year survival (0.384 vs 0.661) when receiving perioperative red blood cell transfusion (OR 2.43 (CL 2.23–2.66)). The risk decreased with increasing comorbidity or age, and in high-risk patients, no difference was found. The adjusted risk ratio, after RBC transfusion, including age, sex, comorbidity and surgery, was 1.62 (1.48–1.77). Conclusion Despite reduced transfusion rates, long-term follow-up on especially low-risk patients undergoing comparable cardiac surgery still demonstrates a substantially higher mortality in patients receiving perioperative red blood cell transfusion. Even transfusion of 1–2 units is associated with increased long-term mortality.