Red Blood Cell Transfusion Is Associated With Troponin Release After Elective Off-Pump Coronary Artery Bypass Surgery

Abstract

Increased troponin levels after coronary artery bypass surgery are associated with increased risk of early and late mortality. We hypothesized that perioperative blood transfusion is associated with increased postoperative troponin release. Complete data on perioperative blood transfusion and troponin I were available for 140 patients who underwent isolated, elective off-pump coronary artery bypass graft surgery. Linear regression analysis showed that red blood cell (RBC) transfusion (p=0.007) was an independent predictor of troponin I levels on the first postoperative day. The RBC transfusion was associated with a high risk of type V myocardial infarction as indicated by troponin I levels greater than 6.6 μg/L on the first postoperative day (9 of 58 patients [15.5%] versus 1 of 82 patients [1.2%], p=0.002; adjusted analysis odds ratio 14.878, 95% confidence interval: 1.829 to 121.033). This finding did not change when hemoglobin and hematocrit nadirs were included in the analysis. Repeated-measure test showed that any blood product transfusion (p=0.040), any blood product transfusion on the operation day (p=0.025), any RBC transfusion (p=0.014), and RBC transfusion on the operation day (p=0.026) were associated with increased postoperative troponin I release. These findings persisted even after adjusting for hemoglobin and hematocrit nadirs. Red blood cell transfusion is associated with increased troponin I release after elective off-pump coronary artery bypass graft surgery independently of hemoglobin and hematocrit nadirs. These findings suggest that prevention of major bleeding requiring blood transfusion may be cardioprotective during coronary surgery. Further studies are needed to verify whether troponin release is affected simply by RBC transfusion or by unstable hemodynamic conditions in presence of mild and severe anemia.