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

Treatment for Heparin-Induced Thrombocytopenia (HIT)

For patients with heparin-induced thrombocytopenia, immediate discontinuation of all forms of heparin and initiation of a non-heparin anticoagulant such as argatroban, lepirudin, or danaparoid is strongly recommended to prevent thrombotic complications. 1, 2

Initial Management

• Immediately discontinue all forms of heparin, including heparin flushes and heparin-coated catheters, when HIT is suspected 2
• Initiate alternative non-heparin anticoagulation even before laboratory confirmation due to high thrombotic risk (17-55% in untreated patients) 1, 2
• Perform laboratory testing for HIT antibodies to confirm diagnosis 2

Choice of Alternative Anticoagulant

For HIT without thrombosis (isolated HIT):

• Use lepirudin, argatroban, or danaparoid over continuing heparin or initiating vitamin K antagonists (VKAs) alone (Grade 1C) 1
• The risk of thrombosis is approximately fivefold higher in patients who only have heparin discontinued compared to those who receive alternative anticoagulation 1

For HIT with thrombosis (HITT):

• Argatroban, lepirudin, or danaparoid are recommended as first-line therapy 2, 3
• Argatroban is specifically indicated for prophylaxis or treatment of thrombosis in adult patients with HIT 3

Special considerations for anticoagulant selection:

• For patients with renal insufficiency: prefer argatroban (hepatically metabolized) 4
• For patients with hepatic impairment: avoid argatroban or use reduced dosing (starting at 0.5 μg/kg/min instead of 2 μg/kg/min) in moderate impairment; contraindicated in severe hepatic impairment 4
• For patients requiring percutaneous coronary intervention: argatroban is specifically indicated 3

Dosing and Monitoring

Argatroban:

• Initial dose: 2 mcg/kg/min as continuous infusion for patients without hepatic impairment 3
• Target aPTT: 1.5 to 3 times the initial baseline value (not to exceed 100 seconds) 3
• Check aPTT 2 hours after initiation and after any dose change 3
• Maximum dose: 10 mcg/kg/min 3

Transitioning to Oral Anticoagulation

• Wait until platelet count has substantially recovered (usually to at least 150 × 10^9/L) before initiating VKA 2
• Use low initial doses of VKA (maximum 5 mg warfarin) 2
• Overlap VKA with non-heparin anticoagulant for a minimum of 5 days and until the INR is within target range 2
• Be aware that argatroban affects the INR, which can lead to premature discontinuation of the parenteral agent 1
• 21% of patients with INR > 3.0 while receiving argatroban and warfarin had subtherapeutic INR 4 hours after argatroban discontinuation 1

Duration of Treatment

• For patients with HITT, continue VKA therapy or an alternative anticoagulant for at least 4 weeks 1
• For isolated HIT, consider anticoagulation for up to 4 weeks due to the high risk of thrombosis that extends for 2-4 weeks after treatment initiation 1

Common Pitfalls to Avoid

• Do not wait for laboratory confirmation before initiating alternative anticoagulation when HIT is suspected 2
• Do not start VKA without concurrent parenteral non-heparin anticoagulant due to risk of venous limb gangrene 5
• Do not use low molecular weight heparins (LMWHs) as they frequently cross-react with HIT antibodies 5
• Do not interpret elevated INR as indicative of therapeutic warfarin effect when co-administered with argatroban 1
• Do not discontinue non-heparin anticoagulant prematurely during transition to VKA 1