Background: Severe COVID-19 pneumonia requiring intensive care treatment remains a clinical challenge to date. Dexamethasone was reported as a promising treatment option, leading to a reduction of mortality rates in severe COVID-19 disease. However, the effect of dexamethasone treatment on thromboembolic events such as pulmonary embolism remains largely elusive.

Methods: In total 178 critically ill COVID-19 patients requiring intensive care treatment and mechanical ventilation were recruited in three European medical centres and included in the present retrospective study. 113 patients (63.5%) were treated with dexamethasone for a median duration of 10 days (IQR 9-10). 65 patients (36.5%) constituted the non-dexamethasone control group.

Results: While peak inflammatory markers were reduced by dexamethasone treatment, the therapy also led to a significant reduction in peak D-Dimer levels (2.16 mg/l vs. 6.14mg/l, p=0.002). This was further reflected by a significant reduction in pulmonary embolism rate (4.4% vs. 20.0%, p=0.001). The antithrombotic effect of dexamethasone treatment was also evident in the presence of therapeutic anticoagulation (pulmonary embolism rate: 6% vs. 34.4%, p<0.001). Of note, no significant changes in baseline characteristics were observed between the dexamethasone and non-dexamethasone group.

Conclusion: In severe COVID-19, antiinflammatory effects of dexamethasone treatment seem to be associated with a significant decrease in pulmonary embolism, independent of anticoagulation. Our findings emphasize the beneficial effect of dexamethasone treatment on cardiovascular outcomes in severe COVID-19.