Introduction: Endothelial dysfunction (ED), an important cardiovascular risk factor, represents a common denominator in patients with exacerbation of COPD (ECOPD) and COVID-19. Mechanisms of endothelial damage as higher inflammation status and oxidative stress are evident in both clinical conditions.

Objective: To compare endothelial function of hospitalised patients with ECOPD and COVID-19.

Methods: A cross-sectional observational study, which assessed 35 patients with ECOPD and 37 patients with COVID-19 in the first 48-72 hours of hospital admission. Endothelial function was assessed by brachial artery ultrasonography and Flow Mediated Dilatation (FMD) was obtained. Characterisation variables, laboratory tests, medications and handgrip strength (HGS) were collected. T test or Mann-Whitney test were used for comparison between groups.

Results: There were no differences between groups in terms of age, sex, BMI and comorbidities. However, higher rates of smokers and oxygen therapy users were found to ECOPD, and lower flow of O2 (2.2 ± 1.2 vs 4.7 ± 4.0l/min; p=0.020), HGS (20.2 ± 7.3 vs 28.1 ± 9.4Kgf, p<0.001) and C-reactive protein (5.7 ± 5.9 vs 83.2 ± 71.6mg/dL, p<0.001). In regard to ED, lower FMD was found to ECOPD compared to COVID-19 (3.8 ± 2.7 vs 5.6 ± 2.6%; p=0.035).

Conclusion: Although COVID-19 presents a more pronounced acute inflammatory status, ECOPD demonstrated worse endothelial function. These results emphasize the deleterious effects of prolonged exposure to risks and chronicity of the disease. Further research is needed to reinforce treatments aimed at protecting the endothelium.

Support: FAPESP 2015/12763-4; 2015/26501-1; 2021/03493-4; CAPES 001 and CNPq 303399/2018-0.