Perioperative Anemia and Transfusions and Late Mortality in Coronary Artery Bypass Patients

BACKGROUND Perioperative anemia and transfusions are associated with adverse operative outcomes after coronary artery bypass graft surgery (CABG). Their individual association with long-term outcomes is unclear.METHODS Patients aged 65 years and older who had undergone CABG and were in The Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database (n [ 504,596) from 2011 to 2018 were linked to Centers for Medicare and Medicaid Service data to assess long-term survival. The association of intraoperative anemia defined by intraoperative nadir hematocrit (nHct) and red blood cell (RBC) transfusions, and their interactions, on long-term mortality were assessed with Kaplan-Meier estimates and multivariable Cox regression. Restricted cubic splines were used to explore the association between nHct as a continuous variable and long-term mortality.RESULTS 258,398 on-pump CABG STS Adult Cardiac Surgery Database patients surviving the perioperative period were linked to Centers for Medicare and Medicaid Service claims files. Per World Health Organization criteria, 41% had pre-operative anemia. Mean intraoperative nHct was 24%; RBC transfusion rate was 43.7%. Univariable analysis associated both RBC transfusion and lower nHct with worse survival. Lower nHct was only marginally associated with risk-adjusted mortality: adjusted hazard ratio (AHR) 1.04 (95% CI, 1.01-1.06) and 1.07 (95% CI, 1.00-1.14) at nHct 20% and at nHct 14%, respectively. RBC transfusion was associated with significantly higher adjusted mortality irrespective of timing of trans-fusion: AHR intraoperative 1.21 (95% CI, 1.18-1.27); AHR postoperative 1.26 (95% CI, 1.22-1.30); AHR both 1.46 (95% CI, 1.40-1.52) and across all levels of nHct. RBC transfusion was not associated with improved survival at any level of nHct.CONCLUSIONS Among Medicare CABG patients, RBC transfusions were associated with increased risk-adjusted late mortality across all levels of nHct whereas intraoperative anemia was only marginally so. Tolerance of lower intra-operative nHct than currently accepted may be preferable to transfusions.(Ann Thorac Surg 2023;115:759-70)(c) 2023 by The Society of Thoracic Surgeons