BOF: Clotting (Anticoagulation)

A 49 year old man is diagnosed with heparin induced thrombocytopenia (HIT) eight days following aortic valve replacement following which he was treated with unfractionated heparin. He has moderate renal impairment (creatinine 150mcmol/l).

Pre-test probability for HIT is high and he tests positive for anti PF4/heparin antibodies. There is no evidence of thrombosis. Which ONE of the following alternative anticoagulation regimens is MOST appropriate?

a) Switch to prophylactic dose danaparoid

b) Switch to attenuated dose ximelagatran

c) Switch to treatment dose low molecular weight heparin

d) Switch to warfarin titrated to INR of 2-3

e) Switch to attenuated dose lepirudin (0.01mg/kg/hr)

Answer:

Switch to attenuated dose lepirudin (0.01mg/kg/hr)

Explanation:

HIT should be treated with a non-heparin anticoagulant, and warfarinisation only commenced once platelet counts have returned to normal. All treatments should be used with caution in renal impairment. If danaparoid were to be used it would be at treatment dose. Other alternatives are the direct thrombin inhibitors bivalirudin, lepirudin or argatroban. Despite being related to heparin, fondaparinux is thought to be a safe option. Ximelagatran is a small-molecule direct thrombin inhibitor withdrawn due to concerns regarding hepatotoxicity. The novel direct acting oral anticoagulants have been investigation in this context but have yet to be proven as safe in the context of valvular heart disease or prosthetic valve anticoagulation

Reference:

Linkins L, Dans AL, Moores LK, et al. Treatment And Prevention Of Heparin-Induced Thrombocytopenia. American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (9th Edition)Chest. 2012;141(2_suppl):e495S-e530S.

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