A randomized trial of antithrombin concentrate for treatment of heparin resistance

Background. Heparin resistance is an important clinical problem traditional ly treated with additional heparin or fresh frozen plasma. We undertook a r andomized clinical trial to determine if treatment with antithrombin (AT) c oncentrate is effective for treating this condition. Methods. Patients requiring cardiopulmonary bypass who were considered to b e heparin resistant (activated clotting time < 480 seconds after > 450 IU/k g heparin) were randomized to receive either 1000 U AT or additional hepari n. Results. AT concentrate was effective in 42 of 44 patients (96%) for immedi ately obtaining a therapeutic activated clotting time. This compared favora bly to 28 of 41 patients (68%) treated with additional heparin (p = 0.001). All patients who failed heparin therapy were successfully treated with AT. The patients receiving AT required less time to obtain an adequate ACT but there was no difference in clinical outcomes among the groups. Study patie nts had deficient AT activity at baseline (56% +/- 25%), which improved in those given AT concentrate (75% +/- 31% versus 50% +/- 23%, p < 0.0005). Conclusions. Heparin resistance is frequently associated with AT deficiency . Treating this deficiency with AT concentrate is more effective and faster for obtaining adequate anticoagulation than using additional heparin. (Ann Thorac Surg 2000;70:873-7) (C) 2000 by The Society of Thoracic Surgeons.