Low molecular weight heparin use in COVID-19 is associated with curtailed viral persistence-a retrospective multicenter observational study

AIM: Anticoagulation was associated with improved survival of hospitalized COVID-19 patients in large-scale studies. Yet, the development of COVID-19 associated coagulopathy (CAC) and the mechanism responsible for improved survival of anticoagulated patients with COVID-19 remain largely elusive. This investigation aimed to explore the effects of anticoagulation and low molecular weight heparin (LMWH) in particular on patient outcome, CAC development, thromboinflammation, cell death, and viral persistence. METHODS AND RESULTS: Data of 586 hospitalized COVID-19 patients from three different regions of Austria were evaluated retrospectively. Of these 419 (71.5%) patients received LMWH and 62 (10.5%) received non-vitamin-K antagonist oral anticoagulants (NOAC) during hospitalization. Plasma was collected at different time points in a subset of 106 patients in order to evaluate markers of thromboinflammation (H3Cit-DNA) and the cell death marker cell-free DNA (cfDNA). Use of LMWH was associated with improved survival upon multivariable Cox-regression (hazard ratio = 0.561, 95% confidence interval: 0.348-0.906). Interestingly, neither LMWH nor NOAC was associated with attenuation of D-dimer increase over time, or thromboinflammation. In contrast, anticoagulation was associated with a decrease in cfDNA during hospitalization and curtailed viral persistence was observed in patients using LMWH leading to a four-day reduction of virus positivity upon quantitative polymerase chain reaction (13 [interquartile range: 6-24] versus 9 [interquartile range: 5-16] days, p = 0.009). CONCLUSIONS: Time courses of hemostatic and thromboinflammatory biomarkers were similar in patients with and without LMWH, indicating either no effects of LMWH on hemostasis or that LMWH reduced hypercoagulability to levels of patients without LMWH. Nonetheless, anticoagulation with LMWH was associated with reduced mortality, improved markers of cell death, and curtailed viral persistence, indicating potential beneficial effects of LMWH beyond hemostasis, which encourages use of LMWH in COVID-19 patients without contraindications. TRANSLATIONAL PERSPECTIVE: The data gathered in this retrospective multicenter observational study could confirm an association of improved survival and anticoagulation and could link LMWH use to improved biomarkers of cell death and curtailed persistence of SARS-CoV-2. This encourages the use of this drug in patients without known contraindications in case this effect can be consolidated in randomized controlled trials. Currently performed prospective trials using LMWH in COVID-19 should focus on viral persistence in order to explore an additional field of application for LMWH during this pandemic.