The ADAMTS13-von Willebrand factor axis in COVID-19 patients.

BACKGROUND: Severe coronavirus disease 2019 (COVID-19) is characterized by an increased risk of thromboembolic events, with evidence of microthrombosis in the lungs of deceased patients. OBJECTIVES: To investigate the mechanism of microthrombosis in COVID-19 progression. PATIENTS/METHODS: We assessed VWF antigen (VWF:Ag), VWF ristocetin-cofactor (VWF:RCo), VWF multimers, VWF propeptide (VWFpp) and ADAMTS13 activity in a cross-sectional study of 50 patients stratified according to their admission to three different intensity of care units: low (requiring high-flow nasal cannula oxygenation, n=14), intermediate (requiring continuous positive airway pressure devices, n=17), high (requiring mechanical ventilation, n=19). RESULTS: Median VWF:Ag, VWF:RCo and VWFpp levels were markedly elevated in COVID-19 patients and increased with intensity of care, with VWF:Ag being 268, 386 and 476 IU/dL, VWF:RCo 216, 334 and 388 IU/dL, and VWFpp 156, 172 and 192 IU/dL in patients at low, intermediate and high intensity of care, respectively. Conversely, the high-to-low molecular weight VWF multimers ratios progressively decreased with increasing intensity of care, as well as median ADAMTS13 activity levels, which ranged from 82 IU/dL for patients at low intensity of care to 62 and 55 IU/dL for those at intermediate and high intensity of care. CONCLUSIONS: We found a significant alteration of the VWF-ADAMTS13 axis in COVID-19 patients, with an elevated VWF:Ag to ADAMTS13 activity ratio that was strongly associated with disease severity. Such an imbalance enhances the hypercoagulable state of COVID-19 patients and their risk of microthrombosis.