Characterization and Quantification of Platelet/Leukocyte Aggregates in Patients With Suspected Heparin-induced Thrombocytopenia

Study Overview
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Brief Summary
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The investigators would like to analyze platelet/leukoplak activation, quantify and morphologically characterize these aggregates using in vitro analysis, directly on whole blood from adult patients with suspected HIT. This would enable to better describe the in vivo pathophysiology of the HIT-suspect patient, and eliminate the need for platelet donors to perform the usual confirmatory techniques, whose inter- and intra-individual variability is very high. What's more, the SRA test, evaluated as the reference test, requires the use of radioisotopes and is therefore only carried out in a few biological expertise centers, resulting in a very long delay in the delivery of results. It should also be noted that, in practice, HÉPARINE is immediately stopped in patients with suspected HIT, and they are put on an expensive anticoagulant (DANAPAROIDE SODIQUE or ARGATROBAN) in curative doses until the results of the confirmatory tests are back. In this serious, life-threatening condition, it is essential to have a sensitive, specific test to confirm HIT as quickly as possible. Each patient with suspected HIT (rapid >30% reduction in platelet count after initiation of heparin therapy) should have 4 tubes of 3.2% citrated whole blood (2.7ml) collected at the time of suspected HIT (D0) and before any therapeutic switch (or 24 h max after switch). A new sample (4 citrated tubes) will be taken at D4, D7 and D14 during hospitalization, in patients who test positive for anti-PF4/H Ac. All patients with suspected HIT will follow the standard diagnostic pathway, i.e. a screening test (immunological test for anti-PF4/heparin antibodies, total Ig, ACL TOP, Werfen) followed by a confirmatory test (platelet aggregation on TA-8V, STAGO and/or SRA). Doppler ultrasonography of the lower limbs will be performed in HIT-suspect patients with a positive anti-PF4/H antibody test, as currently performed as part of routine care.

Official Title
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Characterization and Quantification of Platelet/Leukocyte Aggregates in Patients With Suspected Heparin-induced Thrombocytopenia

Conditions
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HIT, Heparin-induced Thrombocytopenia, Platelet Activation, Platelets, Leukocytes, Platelet/Leukocyte Aggregates, HITSTREAM, Flow Cytometry

Intervention / Treatment
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* Biological: blood sample


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 18 years Any adult patient suspected of having HIT, with a positive anti-PF4/H antibody test Patient signed consent to study participation Patient with social security coverage Exclusion Criteria: All adult patients with suspected HIT and negative anti-PF4/H antibody test. Protected adults (guardianship, under curators) or deprived of liberty

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: suspected heparin-induced thrombocytopenia:<br> | Biological: blood sample<br>* blood sample<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| percentage of CD41a+/CD45- platelet clusters | percentage of CD41a+/CD45- platelet clusters relative to platelet count by Flow Imaging ImageStream | day 1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Heparin-induced Thrombocytopenia