Preoperative antithrombin supplementation in cardiac surgery: A randomized controlled trial

OBJECTIVES: Purified antithrombin supplementation in cardiac surgery has been suggested for the treatment of heparin resistance and the prevention of thromboembolic complications. This study is a randomized controlled trial of preoperative purified antithrombin supplementation, with the primary end point of avoiding low (<58%) postoperative antithrombin activity levels and secondary end points including avoidance of heparin resistance, clinical outcome, and safety end points. METHODS: Two hundred patients were randomly allocated to the antithrombin group and the control group. Patients in the antithrombin group received a dose of purified antithrombin to reach an antithrombin activity value of 120%, whereas patients in the control group did not receive antithrombin. RESULTS: The antithrombin activity values were significantly higher in the antithrombin group at all postoperative determinations until discharge. Antithrombin activity levels <58% at admission to the intensive care unit were found in 26.6% of patients in the control group versus none in the antithrombin group (P = .001). Heparin resistance rate was significantly (P = .001) higher in the control group (38.2%) versus the antithrombin group (17%). Patients in the antithrombin group had a significant but clinically irrelevant (8 mL/hour) higher postoperative bleeding, with no differences in transfusion rates. No differences were found for clinical outcomes, and no safety issues were identified. CONCLUSIONS: Preoperative antithrombin supplementation prevents heparin resistance and avoids excessive postoperative decrease of antithrombin activity.