Amelioration of the bleeding tendency of preoperative aspirin after aortocoronary bypass grafting

Background. Aspirin therapy is widely used in the treatment of cardiac disease. It has been recognized as a causative factor for increased bleeding and blood loss after open heart operations. Methods. To determine whether high-dose aprotinin maintained its efficacy in reducing blood loss in the presence of aspirin pretreatment in patients undergoing aortocoronary bypass, we performed a double blind study on 60 adult patients. Half received high-dose aprotinin (Trasylol) and half placebo. Results. Total hemoglobin loss, the primary efficacy variable was reduced from 36.1 ± 31.4 g (mean ± SD) to 14.1 ± 16.0 g (p = 0.002). Blood loss was reduced intraoperatively and total loss was reduced from 837.3 mL ± 404.9 mL to 368.7 mL ± 164.3 mL (p< 0.001). The number of patients who did not receive any donor blood products was significantly higher in the aprotinin-treated patients (56.7% versus 23.3%, p = 0.008). Activation of the clotting cascade was significantly less in the treated patients toward the end of cardiopulmonary bypass both by measurement of thrombin–antithrombin III complex (p< 0.0001) and prothrombin fragment 1 + 2 (p< 0.0001). d-Dimer generation was significantly less from the onset of bypass and after reversal of heparin in the aprotinin-treated patients (p< 0.0001). Conclusions. High-dose aprotinin was highly effective in reducing bleeding in this high-risk group of patients. Biochemical analyses suggest the mechanism by which aspirin increases blood loss after cardiopulmonary bypass is different from the blood-preserving effects of aprotinin, which is acting as an antifibrinolytic agent.