Abstract Number: PB0290
Meeting: ISTH 2021 Congress
Background: COVID-19 patients show profound hemostatic abnormalities and are at increased risk for thrombosis. Native rotational thromboelastometry (NATEM-ROTEM) is a viscoelastic assay in which the patient sample is solely re-calcified in absence of an activator of hemostasis and hence the activation originates from the sample itself. NATEM might better reflect in vivo hemostatic abnormalities in COVID-19 patients.
Aims: We aimed to evaluate the applicability of NATEM to detect hemostatic abnormalities in critically ill COVID-19 patients and the association with contact activation biomarkers.
Methods: NATEM was performed in whole blood(WB) and platelet poor plasma(PPP) with and without a thermostable inhibitor of contact activation(TICA) in 13 COVID-19 patients. All patients were admitted to the ICU and received prophylactic(n=6) or therapeutic(n=7) LMWH. Prolonged clotting time(CT), in WB and PPP, was expected due to LMWH administration[Scharbert, 2012]. Healthy volunteers served as NATEM controls. Activated coagulation factor inhibitor complexes (thrombin:antithrombin(T:AT), FXIa:AT, FXIa-a1AT, FXIa:C1Inh, and FIXa:AT) were measured by ELISA to evaluate in vivo coagulation status in COVID-19 patients.
Results: CT did not differ in WB between COVID-19 patients and controls, but was prolonged in PPP NATEM(Table 1). In contrast, Maximum clot firmness(MCF) was increased in WB in COVID-19 patients compared to controls, but PPP did not differ between the groups. Addition of TICA resulted in prolonged CT values. Contact activation biomarkers(FXIa:inhibitor complexes, FIXa:AT) were generally within the normal range and did not correlate with NATEM parameters or TICA-mediated changes; T:AT levels showed a negative correlation with CT(ρ=-0.76, p<0.01).
|Parameter||Manufacturer reference values
||p-value (Mann-Whitney U)|
|Clotting time (in s)||300-1000||808 [651-1106]||817 [661-868]||0.66|
|Maximum clot firmness (in mm)||40-65||73 [59-75]*||52 [48-55]||<0.001|
|Platelet poor plasma||N=13||N=17|
|Clotting time (in s)||–||2141 [1378-3873]||966 [831-1273]||<0.001|
|Maximum clot firmness (in mm)||–||30 [21-35]**
Conclusions: NATEM shows a hypercoagulable phenotype in WB samples from COVID-19 patients, illustrated by increased MCF and a lack of LMWH-mediated CT prolongation, that is absent in PPP. Contact activation biomarkers did not explain the observed results, suggesting other factors are important for NATEM clot development. This might suggest a role for endogenous tissue factor expression, leukocytes or platelets in COVID-19-associated hypercoagulability.
To cite this abstract in AMA style:Hulshof A-, Nagy M, Tjahjadi F, Heubel-Moenen F, Hackeng T, ten Cate H, van Bussel B, Spronk H, Henskens Y. Native Rotational Thromboelastometry Observations in Critically Ill COVID-19 Patients [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/native-rotational-thromboelastometry-observations-in-critically-ill-covid-19-patients/. Accessed November 29, 2023.
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