Thrombin generation kinetics, neutrophil extracellular traps, and von willebrand factor in COVID-19 associatedcoagulopathy: A pilot study

Background : SARS-CoV-2 virus infection (COVID-19) is associated with high rates of venous thromboembolism (VTE). Immune mediated thrombosis has been implicated as a driving factor. Aims : To characterize coagulopathy by assessing thrombin generation kinetics and Von Willebrand Factor (VWF) and to characterize thromboinflammation through neutrophil extracellular trap (NET) formation in COVID-19 patients (pts). Methods : We collected plasma samples from 67 COVID-19 pts in the Emergency Department (ED) and 38 healthy volunteers (HV). Plasma thrombin generation kinetics were assessed using Calibrated Automated Thrombogram (CAT) and expressed as lag time (LT), peak height (PH), time to peak (ttPeak), and endogenous thrombin potential (ETP-total thrombin generated). NET formation was quantified through citrullinated nucleosome ELISA (H3NUC). VWF antigen/activity levels were determined by latex immunoassay. Factor VIII levels were performed using one-stage optical clot detection. VTE events were tracked through electronic medical records. This study was approved by the Institutional Review Board and patients were consented. Mann-Whitney test was performed, P < 0.05 considered significant. Results : Subject characteristics are described in Table 1. Of the 67 pts, 50.7% required admission and 31.3% supplemental oxygen. COVID-19 pts had longer LT and ttPeak, greater H3NUC, VWF antigen and activity level, and Factor VIII levels as compared to HV (Table 2). Admitted pts had longer LT (4.33 min [3.67, 5.67];3.33 min [3.00, 4.00], P < 0.001), ttPeak (7.73 min [6.84, 8.50];7.15 min [6.05, 7.75], P = 0.011), greater VWF antigen (247 IU/dL [208, 298];168 IU/ dL [103, 222], P < 0.001), activity (196 IU/dL [164, 238];130 IU/dL [94, 172], P < 0.001), and Factor VIII (159 IU/dL [129, 194];119 IU/dL [88, 169], P = 0.023) as compared to those not admitted. Conclusions : Symptomatic COVID-19 pts have prolonged initiation of thrombin generation, especially those requiring admission. Greater VWF activity and NETosis suggest systemic thromboinflammation in COVID-19 associated coagulopathy.