In multivariate regression analysis RBC transfusion considerably blunted the HIF-1α response when significant baseline characteristics were included in the model (BMI, preoperative paroxysmal atrial fibrillation, previous myocardial infarction, treatment for dyslipidemia, carotid artery disease, hypothyroidism, operation type coronary artery bypass (CABG), operation indication non-ST-elevation myocardial infarction (NSTEMI) for CABG, RBC transfusion). The gene discussed is HIF1A; the disease is atrial fibrillation.