Abstract Number: PB1420
Meeting: ISTH 2020 Congress
Background: Heparin-induced thrombocytopenia (HIT) is a serious drug induced reaction caused by antibodies against platelet factor 4 (PF4)/heparin complexes. Since thrombocytopenia and thrombosis are common findings in intensive care (ICU) patients undergoing extracorporeal circulation (ECC) it is a diagnostic challenge to confirm or rule out HIT based on clinical manifestations alone and the high rate of IgG immunization limits the use of immunoassays in the diagnostic approach.
Aims: Evaluation of the frequency of HIT and HIT testing results in intensive care patients with extracorporeal circulation.
Methods: Data were collected from surgical ICU patients with suspected HIT (n=340), of whom 83 had ECC. Inclusion criteria were thrombocytopenia and or thrombosis under heparin treatment. The diagnosis of HIT was verified using the 4Ts-score, an IgG specific immunoassay and the function assay (HIPA).
Results: Antibodies against PF4/heparin were found in 55/257 (21%) surgical patients and in 27/83 (33%) patients with ECC. 10/55 (18.18%) EIA positive patients with surgery had platelet activating antibodies. One patient had a heparin-independent platelet activation. In contrast, sera from 7/27 EIA positive patients with ECC tested positive in the HIPA test. 3/27 sera showed heparin-dependent and 4/27 (14.8%) sera showed heparin-independent platelet activation. While prevalence of HIT seems to be similar between patients with and without ECC (3.5% vs. 3.6%), higher amount of heparin-independent platelet activation was observed in patients with ECC compared to surgical patients (4.8% vs. 0.38%, respectively). [BT1] 13 sera had an optical density above 2.0. Interestingly 46% of these sera revealed HIPA negative results.
Conclusions: Our study demonstrates the challenges in the current diagnostic approach for HIT in ICU with surgery and ECC. The higher incidence IgG immunization against PF4/heparin complexes impairs the performance of a standardized diagnostic algorithm and the magnitude of the OD of the antibodies is not predictive for HIPA result.
To cite this abstract in AMA style:Althaus K, Straub A, Häberle H, Rosenberger P, Hidiatov O, Hammer S, Bakchoul T. Heparin-Induced Thrombocytopenia in Intensive Care Patients with Extracorporeal Circulation [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/heparin-induced-thrombocytopenia-in-intensive-care-patients-with-extracorporeal-circulation/. Accessed January 28, 2022.
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