The efficacy of low molecular weight heparin is reduced in COVID-19

BACKGROUND: A significant degree of mortality and morbidity in COVID-19 is through thromboembolic complications, only partially mitigated by anticoagulant therapy. Reliable markers of infection severity are not fully established. OBJECTIVES: This study investigated whether visco-elastic biomarkers predict disease severity on presentation to the Emergency Department (ED) and how they measure response to anticoagulation METHODS: Patients testing positive for COVID-19 at a large University Teaching Hospital ED were recruited at presentation. Multiple blood samples were taken throughout hospital admission to monitor disease progression with end outcome recorded. Visco-elastic markers, fractal dimension (d(f)) and Time to Gel Point (TGP) which measure the properties of the incipient clot were compared in patients with and without anticoagulation by Low Molecular Weight Heparin (LMWH). RESULTS: TGP and d(f) did not predict severity of infection with COVID-19. Although LMWH prolonged TGP, there was no change in d(f) indicating LMWH did not change clot microstructure. CONCLUSIONS: Therapeutic efficacy of LMWH appears blunted in COVID-19 infection. This may be due to the inflammatory state creating a resistance to LMWH activity, which may explain why LMWH appears less effective in COVID-19 compared to other disease states. COVID-19 was not predicted by visco-elastic testing at the time of ED presentation.