Abstract Number: PB0861
Meeting: ISTH 2021 Congress
Background: Extracorporeal circulations (ECC) are increasingly used in critically ill patients with respiratory or cardiac failure. Patients with extracorporeal membrane oxygenations (ECMO) receive continuous infusion of unfractionated heparin (UFH) for circuit patency and are at high risk for heparin induced thrombocytopenia (HIT). The diagnosis of HIT is, however, very challenging in critically ill patients undergoing ECC. In addition, switching anticoagulation to non-heparin agents in thrombocytopenic patients is associated with increased bleeding risk.
Aims: To assess the incidence and risk factors of HIT among patients under ECC.
Methods: Consecutive clinical and laboratory data of patients undergoing ECC were prospectively collected. Blood samples were taken at day 0, 1, 6 and 10 after ECC implementation. Patients with history of coagulation and/or platelet disorders were excluded. Diagnosis of HIT was made by using the 4Tscore, the Platelet factor 4 (PF4)/heparin IgG EIA and the functional assay (HIPA). HIT was defined as a positive EIA and HIPA.
Results: From 56 patients with ECC, 31 patients received veno-arterial (va) ECMO, 14 patients veno-venous (vv) ECMO and 11 patients LVAD. All patients received UFH. In 61% patients ECC could be explanted, 66% of the patients were discharged from hospital. Within 10 days 88% showed bleeding and 54% thrombotic events.
According to the 4T-Score 5%, 14%, 66%, and 65% had clinically suspicion of HIT (score >3) at day 0, 1, 6 and 10, respectively. Seroconversion (new PF4/heparin IgG-antibodies) was found in 23% and 42% patients at day 6 and 10, respectively. The Frequency of HIT was estimated to be 3.57% and 4% at day 6 and 10.
Conclusions: Incidence of clinically relevant HIT with ECC is low despite the high prevalence of thrombocytopenia (95%) and IgG seroconversion (42%). Diagnosis of HIT requires confirmation platelets activating antibodies in a functional assay to avoid overdiagnosis of HIT.
To cite this abstract in AMA style:Gaupp A, Hidiatov O, Nowak-Harnau S, Straub A, Häberle H, Rosenberger P, Bakchoul T, Althaus K. Incidence of Heparin-induced Thrombocytopenia in Patients Treated with Mechanical Circulatory Support: Results from a Prospective Study [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/incidence-of-heparin-induced-thrombocytopenia-in-patients-treated-with-mechanical-circulatory-support-results-from-a-prospective-study/. Accessed September 16, 2021.
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