Current management of heparin-induced thrombocytopenia

Abstract

Heparin-induced thrombocytopenia (HIT) is an immune adverse reaction to heparin (both unfractionated and low-molecular-weight), which is mediated by the formation of IgG antibodies against platelet factor 4-heparin complexes. The IgG/platelet factor 4 immunocomplexes activate platelets with resulting thrombocytopenia, which is not associated with bleeding, but with paradoxical life-threatening thrombotic complications, for coagulation activation. HIT diagnosis requires the assessment of pre-test clinical probability in combination with the measurement of platelet activating antibodies against platelet factor 4-heparin complexes with immunological and functional assays. When HIT is diagnosed, any form of heparin should be stopped and a non-heparin alternative anticoagulant should be started. Argatroban and danaparoid are currently the only drugs licensed for HIT, with different country availability. Bivalirudin is an option in cardiac surgery and procedures in HIT patients.

Heparin-Induced Thrombocytopenia and COVID-19

“…The prevalence of HIT increases in parallel with the dose and the type of heparin and can reach 1% in medical patients. 13 In line with the risk of HIT that is higher for unfractionated heparin than for low molecular weight heparin, 9 HIT occurred in a patient treated with calcium heparin. Despite the widespread use of unfractionated heparin and low molecular weight heparin in COVID-19 patients, few cases have been described so far.…”

“…Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin treatment. 9 It is associated with increased in vivo thrombin generation provoking both arterial and venous thrombosis. In case of HIT, heparin in any form should be immediately withdrawn.…”

“…Pooled analyses of prospective cohort studies with historical controls have shown that untreated HIT can be complicated by further thrombotic events in 30-75% of cases with 5-10% mortality. 9,10 Since thrombocytopenia is a common finding in patients in ICU, and severe COVID-19 is often associated with thrombocytopenia, 11 HIT is seldom suspected and investigated. Here, we report a case of HIT in a patient with severe COVID-19 that received unfractionated heparin (UFH) treatment, highlighting that HIT may occur also in such patients.…”

Heparin-induced Thrombocytopenia: Pathophysiology, Diagnosis and Management

“…Heparin administration should be avoided from any source; for this reason, heparin-coated catheters should be removed. Cessation of unfractionated heparin is not sufficient to prevent thrombotic events, and an alternative anticoagulant medication should be provided, with the exception of both LMWH or warfarin, which can induce thrombin generation and increase the risk for thrombosis [42,43]. Alternative anticoagulation therapy involves direct thrombin inhibitors such as argatroban, bivalirudin, or factor Xa inhibitors such as danaparoid and fondaparinux.…”

Failure of Fondaparinux in Autoimmune Heparin-Induced Thrombocytopenia

“…Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition that is associated with increased in vivo thrombin generation that needs to be treated with nonheparin anticoagulants. 1 In the majority of cases (typical-onset HIT), after a mean of 4 to 6 days of heparin exposure, immunoglobulin (Ig)-G antibodies against platelet factor 4 (PF4) bound to heparin develop. This is followed by the onset of the platelet count fall, and finally by thrombosis.…”