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Heparin-induced thrombocytopenia

Guidelines

Key sources

The following summarized guidelines for the evaluation and management of heparin-induced thrombocytopenia are prepared by our editorial team based on guidelines from the Society for Cardiovascular Angiography and Interventions (SCAI/AHA/ACC 2022), the French Working Group on Perioperative Hemostasis (GIHP 2020), the Canadian Association of Interventional Cardiology (CAIC 2019), the European Society of Cardiology (ESC/EACTS 2019), the American Society of Hematology ...
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Screening and diagnosis

Indications for monitoring, baseline platelet count: as per GIHP 2020 guidelines, obtain baseline measurement of platelet count before initiating heparin (or alternatively as soon as possible after the first injection, before day 4), whether UFH or LMWH.
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  • Indications for monitoring (low risk)

  • Indications for monitoring (moderate-to-high risk)

  • Indications for monitoring (after surgery)

  • Indications for monitoring (recent heparin exposure)

  • Indications for testing (low pretest probability)

  • Indications for testing (moderate-to-high pretest probability)

  • Indications for testing (acute systemic reaction)

  • Diagnosis

Classification and risk stratification

Pretest probability
As per GIHP 2020 guidelines:
Use the 4T score (outside a cardiac surgery context) to determine the clinical probability of HIT in patients with suspected HIT.
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Consider classifying the risk of HIT during heparin administration into three groups:
Situation
Guidance
Low (< 0.1%)
Treatment with LMWH in medicine (except cancer), obstetrics (except surgery including C-section), or in the course of minor trauma
Treatment with fondaparinux
Isolated UFH injection for an endovascular procedure or simple surgery
Treatment with UFH or LMWH lasting > 1 month
Intermediate (0.1-1%)
Prophylactic treatment with UFH in medicine/obstetrics
Prophylactic treatment with LMWH in patients with cancer or severe trauma or in postoperative care (including cardiac surgery)
High (> 1%)
Prophylactic treatment with UFH in surgery (including circulatory assistance) or for RRT
All curative treatments with UFH in medicine/surgery/obstetrics
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  • Classification

Diagnostic investigations

Immunoassays
As per GIHP 2020 guidelines:
Consider obtaining anti-PF4 antibodies as soon as possible in patients with suspected HIT with intermediate or high clinical probability.
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Obtain biological tests to detect anti-PF4 antibodies in patients with intermediate (4T = 4-5) or high (4T ≥ 6) pretest probability.
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  • Platelet function tests

  • Screening for asymptomatic DVT

Medical management

Continuation of heparin: as per GIHP 2020 guidelines, consider continuing or resuming heparin therapy, with close monitoring of platelet count, after the exclusion of HIT based on the absence of anti-PF4 antibodies in patients with intermediate clinical probability.
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  • Discontinuation of heparin

  • Initiation of non-heparin anticoagulants, HIT without thrombosis (general principles)

  • Initiation of non-heparin anticoagulants, HIT without thrombosis (direct thrombin and factor Xa inhibitors)

  • Initiation of non-heparin anticoagulants, HIT without thrombosis (DOACs)

  • Initiation of non-heparin anticoagulants, HIT without thrombosis (VKAs)

  • Initiation of non-heparin anticoagulants, HIT with thrombosis (general principles)

  • Initiation of non-heparin anticoagulants, HIT with thrombosis (direct thrombin and factor Xa inhibitors)

  • Initiation of non-heparin anticoagulants, HIT with thrombosis (VKAs)

  • Duration of anticoagulation

  • Antiplatelet therapy

  • IVIG

Therapeutic procedures

Platelet transfusion: as per GIHP 2020 guidelines, do not administer platelet transfusion in the acute phase of HIT in the absence of life-threatening or functional bleeding.
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  • IVC filter placement

Specific circumstances

Pediatric patients
As per GIHP 2020 guidelines:
Consider using the same procedures for monitoring platelet counts in pediatric patients treated with heparin as in adult patients.
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Initiate sodium danaparoid or argatroban, with rigorous dose adjustment based on weight and bioassay results, in pediatric patients with HIT.
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  • Pregnant patients (management)

  • Pregnant patients (diagnosis)

  • Patients with hepatic impairment

  • Patients with renal impairment

  • Patients requiring RRT

  • Patients requiring PCI

  • Patients requiring cardiac surgery

  • Patients requiring non-cardiac surgery

  • Patients with non-HIT-related thrombosis

Preventative measures

Secondary prevention: as per GIHP 2020 guidelines, consider initiating an OAC (VKA or DOAC) or fondaparinux in patients with a history of HIT requiring prophylactic or curative anticoagulation. Consider initiating argatroban, bivalirudin, or danaparoid only when OACs and fondaparinux are contraindicated.
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Quality improvement

Documentation: as per GIHP 2020 guidelines, consider obtaining a hemostasis consultation within 3 months of the diagnosis of HIT and provide a card attesting this complication, specifying the results of the biological tests, and recommending the exclusion of all heparin treatment to the patient.
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  • Medical alert bracelet