Rotational Thromboelastometry Profile among Critically ill COVID-19 Patients

Dear Editor, Thromboinflammation has a contributing role in Coronavirus disease 2019 (COVID-19) pneumonia pathogenesis. Rotational thromboelastometry (RT) evaluates viscoelastic changes during the coagulation process and could enable the identification of hypercoagulability, as an indirect marker of pulmonary microvascular thrombosis in real-time2–4. Therefore, we propose to study the modifications in maximum clot firmness (MCF) and other RT parameters in critically-ill COVID-19 patients compared with healthy controls (HC). A prospective observational cohort study was performed at a high complexity hospital in Argentina. In the COVID-19 cohort, we included adult patients admitted to ICU due to COVID-19, between August and November 2020. In the HC cohort, we included healthy non-hospitalized volunteers. Exclusion criteria were: age <18 years or >80 years, anticoagulant use, tocilizumab use, transfusion of blood products (<7 days), hereditary thrombophilia or bleeding disorders, pregnancy, and active cancer. In ICU patients, blood samples were collected at ICU admission (T1), and 5 (T5) and 10 days (T10) after ICU admission. In RT, only NaHEPTEM assay, which evaluates blood clot formation by recalcification without activators with adjunct heparinase, and is considered more sensitive to detect hypercoagulable states, was performed. RT were performed in a ROTEM® Delta instrument (Tem Innovations GmbH, Munich, Germany). Patient demographics and comorbidities were recorded. Also, standard basic coagulation tests were performed to all participants. We calculate a sample size to test the hypothesis that the MCF was significantly higher in COVID-19 patients than in HC. We assumed a mean MCF of 69 mm for healthy people and 75 mm for COVID-19 patients, with a standard deviation of 6 for healthy people and 7 for COVID-19 patients, based on the study of Pavoni et al. With a power of 80% and alpha of 0.5, a ratio of COVID-19/HC of 1.2, with a two-sided test, the sample size was 23 for COVID-19 patients and 19 HC. Statistical differences between groups were evaluated by the chi–squared test. Correlation by Spearman Rank test when appropriate. A two–tailed P–value < 0.05 was considered significant. All statistical tests were performed using IBM SPSS 23. One hundred seventeen patients were admitted to our ICU with COVID-19 during the study period. Ninety-four patients were excluded, mainly due to convalescent plasma therapy. Thus, 23 COVID-19 patients and 19 HC were included in the final analysis (Supplemental Material) We observed significantly higher values of MCF in COVID-19 patients at ICU admission (T1) against HC group (64 [IQR 59-68] vs 56 [IQR 52-60], p < 0.001). In the COVID-19 group the MCF also had a significant increase at T5 (69 [IQR 64-70]), compared to T1 (p= 0.011). Additionally, higher fibrinogen levels and MFC were found in COVID-19 group at any time point, (T1, T5 and T10) compared to HC (Figure 1).