Preoperative use of enoxaparin is not a risk factor for postoperative bleeding after coronary artery bypass surgery

Background: The purpose of this study was to determine whether the use of low-molecular-weight heparin before coronary artery bypass surgery would be associated with an increase in bleeding and use of blood products after the operation. Methods: Sixty-four patients (48 men and 16 women) aged 64 ± 10 years who were undergoing primary coronary artery bypass surgery were prospectively studied. Forty-one patients were treated with either subcutaneous enoxaparin 1 mg/kg twice daily (n = 21; enoxaparin group) or intravenous heparin (n = 20; heparin group). Patients received the last dose of enoxaparin 8.7 ± 0.75 hours (range, 8-10 hours) before skin incision. Heparin was stopped before transfer to the operating room. An additional 23 consecutive patients who received neither enoxaparin nor heparin served as controls (n = 23). Anti-factor Xa activity, a measure of enoxaparin and heparin activity, was measured at the start of the operation in all patients. Results: There was no perioperative mortality. The length of stay and frequency of postoperative complications were similar between groups. Preoperative anti-factor Xa activity was present only in the enoxaparin group (0.43 ± 0.25 IU/mL). Chest tube drainage at 24 hours was 553 ± 160 mL, 532 ± 140 mL, and 587 ± 230 mL for the enoxaparin, heparin, and control groups, respectively (P = .48). There was no difference among groups in the amount of blood products transfused. Conclusions: Enoxaparin administration more than 8 hours before coronary artery bypass surgery is not associated with increased postoperative bleeding or blood product transfusion.