Involvement of the contact pathway in COVID-19 coagulopathy

ABSTRACT

Background: A novel acquired coagulopathy characterized by a severe procoagulant imbalance is common in COVID-19 patients and is associated with the clinical severity of the disease. Aim(s) Our study aims to elucidate the underlying mechanisms of coagulation activation in COVID-19 patients. Method(s) Symptomatic COVID-19 patients during Milan first wave were consecutively enrolled and stratified into 3 groups based on the intensity of care Low, requiring only high-flow oxygen by nasal cannula;intermediate, requiring continuous positive airway pressure;high, requiring mechanical ventilation. Blood samples were tested for markers of activation of the intrinsic pathway (FXIa, FXIIa) together with its physiologic inhibitor (C1-inhibitor), of the extrinsic pathway (FVIIa), of global activation of the coagulation cascade (D-dimer, FDP, FM) and of fibrinolysis (plasminogen, t-PA, alpha2-antiplasmin, PAI-1). Result(s) 111 patients were included 26 at low, 42 intermediate and 43 high care-intensity. Median age was 59 +/- 12 (34 patients >65 years);32 patients (29%) developed a venous thrombosis and 12 (11%) died (Table). Median D-dimer, FDP and FM plasma levels were higher in COVID-19 patients compared to controls, with a gradient of increase across the three care intensities, while all the fibrinolytic pathway parameters were in the normal range. Median plasma levels of FVIIa were lower in COVID-19 patients (27.5 mU/ml) than in controls (40.1 mU/ml) while median plasma levels of FXIIa and FXIa were higher in COVID-19 patients (11.2 and 11.3 mU/ml) than in controls (7.2 and 5.5 mU/ml), with a gradient of increase across the three care intensities. C1-inhibitor plasma levels were above the normal range in all the 3 COVID-19 patients' groups (Figure). Conclusion(s) Our study showed a prevalent activation of the contact pathway over the extrinsic pathway of the coagulation cascade in COVID-19 patients, which is proportional to the clinical severity of the infection, opening the possibility for targeted anticoagulant therapies. (Table Presented).