Argatroban is a direct thrombin inhibitor that is metabolized by the liver, making it useful for treating HIT patients with renal failure. Lepirudin also is a potent antithrombin agent; however, it is metabolized and excreted by the kidneys, which makes it less than ideal for the patient described. Although LMWH is much less likely to cause or worsen HIT than unfractionated heparin, it has been shown to be 100% cross-reactive with HIT antibodies. It should therefore never be used in the treatment of HIT. Aspirin is considered to be of marginal therapeutic benefit in HIT but can be started in those patients judged to be at high risk for arterial thrombosis. Ancrod is defibrinogenating snake venom that has had some benefit in HIT patients in uncontrolled studies.1 However, it is not ideal for treatment for several reasons. First, it may actually increase thrombin generation (which is the underlying pathophysiologic problem in HIT). Second, its effects are unpredictable and highly patient specific. Finally, it must be administered slowly. Of particular note is that the most important factor in the treatment of HIT is the immediate cessation of all heparin-containing products and treatments (including heparin flushes).
1. Warkentin TE. Heparin-induced thrombocytopenia: a ten-year retrospective. Annu Rev Med 1999;50:12947.
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