What is the specific therapy for heparin-induced thrombocytopenia (HIT)?

Specific Therapy for Heparin-Induced Thrombocytopenia

The specific therapy for heparin-induced thrombocytopenia (HIT) is lepirudin, a direct thrombin inhibitor, which is recommended by the American College of Chest Physicians as a first-line treatment option along with argatroban and danaparoid. 1

First-Line Treatment Options

• In patients with HIT (with or without thrombosis), the American College of Chest Physicians recommends the use of non-heparin anticoagulants, specifically lepirudin, argatroban, or danaparoid, over continued use of heparin, LMWH, or vitamin K antagonists (VKAs) 1
• For patients with normal renal function, lepirudin, argatroban, or danaparoid are all suggested as appropriate first-line therapies 1
• The choice between these agents depends on patient-specific factors such as renal function, hepatic function, and drug availability 1, 2

Patient-Specific Considerations

• For patients with renal insufficiency, argatroban is preferred over lepirudin since argatroban is hepatically metabolized 1, 3
• For patients requiring urgent cardiac surgery, bivalirudin is suggested over other non-heparin anticoagulants 1, 2
• For patients undergoing percutaneous coronary intervention with HIT, argatroban is FDA-approved for this indication 4

Important Management Principles

• All forms of heparin must be immediately discontinued when HIT is suspected 2
• Low-molecular-weight heparin (LMWH) is contraindicated due to high cross-reactivity with HIT antibodies 5
• Vitamin K antagonists (like Coumadin/warfarin) should not be used as monotherapy during the acute phase of HIT as they can potentially worsen thrombosis 1, 5
• Platelet transfusions should be avoided unless there is active bleeding or an invasive procedure with high bleeding risk 1

Transition to Oral Anticoagulation

• VKAs should only be initiated after platelet count recovery (usually >150 × 10^9/L) 1, 3
• When starting a VKA, it should be overlapped with a non-heparin anticoagulant for at least 5 days and until the INR is within target range 1
• Initial VKA dosing should be low (maximum 5 mg warfarin) to reduce risk of venous limb gangrene 1

Duration of Therapy

• For patients with isolated HIT (without thrombosis), treatment should continue until laboratory evidence shows HIT antibodies are no longer detectable 5
• For patients with thrombosis associated with HIT, treatment with a direct thrombin inhibitor at therapeutic doses is recommended for 7-10 days before transitioning to warfarin 5, 6

Emerging Options

• Direct oral anticoagulants (DOACs) are increasingly being used off-label in appropriate cases of acute HIT due to their ease of administration and cost-effectiveness 7
• Fondaparinux has been used in small case series but requires further study before it can be widely recommended 6

Based on the evidence provided, lepirudin (option e) is the correct specific therapy for heparin-induced thrombocytopenia among the given options.