Heparin-induced thrombocytopenia (HIT) during extracorporeal membrane oxygenation (ECMO) in COVID-19: A case report

Background : Heparin-induced thrombocytopenia (HIT) is an antibody-mediated reaction against the heparin-platelet factor 4 complex (H-PF4). Incidence in patients with extracorporeal circulation membrane (ECMO) is unknown. Aims : We describe a case of HIT confirmed during ECMO support in a COVID-19 patient. Methods : N/A A 48 year-old man with severe COVID-19 confirmed by RT-PCR for SARS-CoV2, was admitted to intensive care unit (ICU). After 21 days of the diagnosis he required mechanical ventilation support and V-V ECMO. Since his admission he received anticoagulation with enoxaparin 80 mg SC every 12 h, when ECMO started, he continued anticoagulation with intravenous infusion of 700 U/hour of unfractionated heparin (UFH). On the third day of infusion, there was a decrease in platelets > 50% (nadir 25,000/mm3 ), it was documented 6 points in a 4T HIT score having a probability 64% for HIT. It was confirmed by functional test with platelet aggregometry induced by UFH using the Born method. UFH was suspended and fondaparinux 7.5 mg SC every 24 h. We made serial measurements of anti-Xa (Stago ® ). Therapeutic response to HIT was documented at day 9 from the start of fondaparinux, without requiring an ECMO membrane change. Conclusions : The diagnosis of HIT was made by clinical suspicion, using the 4T HIT score and later confirmation platelet aggregometryUFH induced. The usual pharmacological treatment is based on argatroban, bivalirudin, and lepirudin. To our knowledge, there is only one case reported with fondaparinux as treatment in ECMO. Determination of plasma levels by antiXa activity was used to guide dosing because previous studies have reported bleeding rates between 10 to 22% with fondaparinux. This is a success case of fondaparinux as treatment for HIT in an ICU patient with ECMO support, and the first one in the clinical context of severe COVID -19 infection.