Prevention of thrombosis with recombinant hirudin in patients with heparin-induced thrombocytopenia type II: a pilot study

Background: Heparin-induced thrombocytopenia (HIT) type II is a severe comp lication of heparin therapy with a high incidence of thromboembolic events. Aim: The aim of this prospective study was to evaluate efficacy and safety of prophylaxis of thromboembolism with subcutaneous r-hirudin (25 mg twice daily) in patients with HIT type II. Patients and methods: From 01/06/1997 until 01/08/1999, 19 patients were pr ospectively included into the study. During subcutaneous r-hirudin applicat ion (25 mg twice daily) the activated partial thromboplastin time (aPTT) an d ecarin clotting time (ECT) were measured twice daily prior to and a hours after the morning injection. Results: Ten patients (mean age: 68 years; two men, eight women) with throm boembolic events were intravenously treated with r-hirudin (mean 19.3 days) with a target aPTT of 1.5 to 2.5 times normal values followed by subcutane ous r-hirudin (mean 22.5 days). Five Patients without thromboembolism immed iately received subcutaneous r-hirudin (mean 25.9 days; mean age: 61 Jahre; two men, three women) after cessation of heparin. Four patients requiring prophylaxis of thromboembolism received subcutaneous r-hirudin (mean 32 day s; mean age: 68 years: four women) because of HIT type II in the past. Mean aPTT-values prior to and 1.5-2.5 hours after the morning injection were 1. 2 to 1.7 and 2.0 to 2.3 times normal values, respectively. The ECT was prol onged by 1.2 to 1.7 and 2.3 to 2.5 times the upper normal value, respective ly. Thromboembolic or bleeding events were not observed during the study. Conclusion: The subcutaneous application of r-hirudin provides an alternati ve for primary and secondary prophylaxis of thromboembolism in HIT type II patients.