Predictors of Prolonged Cardiopulmonary Exercise Impairment After COVID-19 Infection: A Prospective Observational Study

Abstract

<b>Objectives:</b> Coronavirus disease 2019 (COVID-19) is a global pandemic affecting individuals to varying degrees. There is emerging evidence that even patients with mild symptoms will suffer from prolonged physical impairment. <b>Methods:</b> In this prospective observational study, lung function, and cardiopulmonary exercise testing have been performed in 100 patients for 3-6 months after COVID-19 diagnosis (post-CoVG). Depending on the severity of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection, patients were divided into asymptomatic, or mild to moderate (mild post-CoVG), and severe post-CoVG [hospitalization with or without intensive care unit/non-invasive ventilation (ICU/NIV)]. Results have been compared with age, sex, and body mass index (BMI) matched control group (CG, <i>N</i> = 50). <b>Results:</b> Both lung function (resting) and exercise capacity (peak workload, Wpeak and peak oxygen uptake, VO₂ peak - % predicted) were considerably affected in patients with severe post-CoV (81.7 ± 27.6 and 86.1 ± 20.6%), compared to the mild post-CoVG (104.8 ± 24.0%, <i>p</i> = 0.001 and 100.4 ± 24.8; <i>p</i> = 0.003). In addition, also the submaximal exercise performance was significantly reduced in the severe post-CoVG (predicted VT1/VO₂ peak; <i>p</i> = 0.013 and VT2/VO₂ peak; <i>p</i> = 0.001). Multiple linear regression analyses revealed that 74 % (adjusted <i>R</i> ²) of the variance in relative VO₂ peak of patients who had CoV could be explained by the following variables: lower age, male sex, lower BMI, higher DLCO, higher predicted heart rate (HR) peak, lower breathing reserve (BR), and lower SaO₂ peak, which were related to higher relative VO₂ peak values. Higher NT-proBNP and lower creatinine kinase (CK) values were seen in severe cases compared to patients who experienced mild CoV. <b>Discussion:</b> Maximal and submaximal exercise performance in patients recovering from severe COVID-19 remain negatively affected for 3-6 months after COVID-19 diagnosis. The presented findings reveal that impaired pulmonary, cardiac, and skeletal muscle function contributed to the limitation of VO₂ peak in those patients, which may have important implications on rehabilitation programs.