Prolonged elevation of plasma argatroban in a cardiac transplant patient with a suspected history of heparin-induced thrombocytopenia with thrombosis.

BACKGROUND: Direct thrombin inhibitors (DTIs) provide an alternative method of anticoagulation for patients with a history of heparin-induced thrombocytopenia (HIT) or HIT with thrombosis (HITT) undergoing cardiopulmonary bypass (CPB). In the following report, a 65-year-old critically ill patient with a suspected history of HITT was administered argatroban for anticoagulation on bypass during heart transplantation. The patient required massive transfusion support (55 units of red blood cells, 42 units of fresh-frozen plasma, 40 units of cryoprecipitate, 40 units of platelets, and three doses of recombinant Factor VIIa) for severe intraoperative and postoperative bleeding. STUDY DESIGN AND METHODS: Plasma samples from before and after CPB were analyzed postoperatively for argatroban concentration using a modified ecarin clotting time (ECT) assay.
RESULTS: Unexpectedly high concentrations of argatroban were measured in these samples (range, 0-32 microg/mL), and a prolonged plasma argatroban half life (t(1/2)) of 514 minutes was observed (published elimination t(1/2) is 39-51 minutes [< or = 181 minutes with hepatic impairment]).
CONCLUSIONS: Correlation of plasma argatroban concentration versus the patient's coagulation variables and clinical course suggest that prolonged elevated levels of plasma argatroban may have contributed to the patient's extended coagulopathy. Because DTIs do not have reversal agents, surgical teams and transfusion services should remain aware of the possibility of massive transfusion events during anticoagulation with these agents. This is the first report to measure plasma argatroban concentration in the context of CPB and extended coagulopathy.