Perioperative Red Blood Cell Transfusion and Long-Term Mortality in Coronary Artery Bypass Grafting: On-Pump and Off-Pump Analysis

<b>Background/Objectives</b>: The impact of different coronary artery bypass grafting (CABG) strategies, particularly on-pump versus off-pump techniques, on red blood cell (RBC) transfusions and their associated outcomes has not been fully investigated. This study aims to evaluate the association between RBC transfusion and survival in CABG patients, focusing on-pump strategy. <b>Methods</b>: Data from CABG patients were retrieved from the National Health Insurance Service database (2003 to 2019). Perioperative RBC transfusions were classified into three groups: no transfusion, RBC 1, and RBC ≥ 2 units. The primary endpoint was all-cause mortality rate. Subgroup analysis assessed the impact of RBC transfusion on mortality across the conventional on-pump (CCAB) and off-pump (OPCAB) groups. <b>Results</b>: Among the 6150 participants who underwent CABG, 2028 underwent CCAB and 4122 underwent OPCAB. The mean age was 66.2 ± 9.7 years, with a mean follow-up of 2.9 (2.53-3.35) years. Multivariable analysis showed a significant association between transfusion of ≥2 RBC units and increased mortality risk (HR 2.34 [1.65-3.32], <i>p</i> < 0.001). Subgroup analysis showed a similar trend in both CCAB and OPCAB groups (<i>p</i> for interaction = 0.2). Transfusion of ≥2 units significantly increased mortality in OPCAB (HR 2.28 [1.55-3.37], <i>p</i> < 0.001) but not in CCAB (HR 2.96 [0.97-9.06], <i>p</i> = 0.057). OPCAB and surgery at large volume center was associated with a reduced risk of RBC transfusion (<i>p</i> < 0.01). <b>Conclusions</b>: Increased RBC transfusion is associated with higher long-term mortality in patients undergoing CABG. Based on a large cohort predominantly consisting of OPCAB patients, OPCAB is associated with decreased RBC transfusion requirements.