What is the management of Heparin-Induced Thrombocytopenia (HIT) in the United Kingdom?

From the Guidelines

Management of heparin-induced thrombocytopenia (HIT) in the UK involves immediate cessation of all heparin products and switching to alternative anticoagulants, with argatroban or lepirudin being the preferred options for patients with normal renal function, as suggested by the American College of Chest Physicians evidence-based clinical practice guidelines 1. For patients with confirmed or suspected HIT, the following management strategies are recommended:

• Immediate cessation of all heparin products
• Switching to alternative anticoagulants, such as argatroban (starting dose 2 μg/kg/min, adjusted to maintain APTT ratio 1.5-3.0) or lepirudin, which are preferred options for patients with normal renal function 1
• Danaparoid may be used as an alternative, but it is less commonly available
• Treatment should continue until platelet count recovers (typically >150 × 10^9/L) and then transition to oral anticoagulation with warfarin or direct oral anticoagulants (DOACs) can occur
• Warfarin should only be started once platelets have recovered and with at least 5 days of overlap with parenteral anticoagulants to avoid warfarin-induced skin necrosis
• Platelet transfusions should be avoided unless there is life-threatening bleeding The American College of Chest Physicians guidelines also recommend that for patients receiving heparin in whom clinicians consider the risk of HIT to be > 1%, platelet count monitoring be performed every 2 or 3 days from day 4 to day 14 (or until heparin is stopped, whichever occurs first) 1. In patients with HIT with thrombosis (HITT) or isolated HIT who have normal renal function, the use of argatroban or lepirudin is recommended over other nonheparin anticoagulants 1. It is essential to note that HIT requires specialized management because it's an immune-mediated disorder where antibodies form against platelet factor 4-heparin complexes, causing platelet activation, thrombocytopenia, and paradoxical thrombosis risk.

From the FDA Drug Label

Argatroban is a direct thrombin inhibitor indicated: (1) For prophylaxis or treatment of thrombosis in adult patients with heparin-induced thrombocytopenia (HIT) The dose for heparin-induced thrombocytopenia without hepatic impairment is 2 mcg/kg/min administered as a continuous infusion

The management of heparin-induced thrombocytopenia in the UK with argatroban involves:

• Discontinuing heparin therapy
• Administering argatroban at a dose of 2 mcg/kg/min as a continuous infusion for patients without hepatic impairment
• Adjusting the dose as clinically indicated after the initial dose
• Monitoring therapy and dosage adjustments recommendations should be followed 2 Key considerations:
• Use with caution in patients at risk of hemorrhage
• Adjust starting dose and titrate carefully in patients with moderate or severe hepatic impairment
• Avoid use in PCI in patients with clinically significant hepatic impairment 2

From the Research

Management of Heparin-Induced Thrombocytopenia in the UK

• The management of heparin-induced thrombocytopenia (HIT) in the UK involves early recognition and urgent intervention with discontinuation of heparin and initiation of non-heparin anticoagulation 3, 4, 5.
• The Haemostasis and Thrombosis Task Force of the British Committee for Standards in Haematology has produced a concise practical guideline for the management of HIT, which includes recommendations for platelet count monitoring and alternative anticoagulation therapy 5.
• The guideline recommends that all patients who are to receive heparin should have a platelet count on the day of starting treatment, and that patients who have been exposed to heparin in the last 100 days should have a baseline platelet count and a platelet count 24 hours after starting heparin 5.
• If the platelet count falls by 50% or more, or falls below the laboratory normal range, and/or the patient develops new thrombosis or skin allergy between days 4 and 14 of heparin administration, HIT should be considered and a clinical assessment made 5.
• Treatment options for HIT include intravenous administration of argatroban, lepirudin, and bivalirudin, as well as subcutaneous administration of fondaparinux 4, 5, 6.
• Direct-acting oral anticoagulants (DOACs) are also being increasingly used in the treatment of HIT, particularly in clinically stable patients without severe thrombotic complications 3, 6.
• However, the use of DOACs in acute HIT is still off-label and should be reserved for patients without severe renal insufficiency 6.

Diagnosis of HIT

• The diagnosis of HIT is based on the presence of clinical features, including a 50% fall in platelet count, appropriate timing of thrombocytopenia, development of new thrombosis despite thrombocytopenia and heparin therapy, and the absence of a more likely cause of thrombocytopenia 4, 7.
• Laboratory tests, such as platelet activation assays and antigen-based assays, can also be used to support the diagnosis of HIT 5, 6.
• The 4Ts clinical scoring system can be used to assess the pretest probability of HIT, and to guide further laboratory testing and treatment 7.

Treatment Options

• Alternative anticoagulation therapy, such as argatroban, lepirudin, and bivalirudin, should be started immediately if HIT is suspected, and heparin should be discontinued 4, 5, 7.
• DOACs, such as rivaroxaban, apixaban, and dabigatran, may also be used in the treatment of HIT, particularly in clinically stable patients without severe thrombotic complications 3, 6.
• Fondaparinux may also be used as an alternative anticoagulant, particularly in patients with severe renal insufficiency 6.