Introduction

Studies have reported an abnormal breathing pattern (BrP) during cardiopulmonary exercise testing (CPET) in some patients with post COVID-19 condition. We aimed to study if an abnormal BrP at CPET in patients with post COVID-19 condition was normalized at repeated CPET after 1 year.

Methods

A maximal cycle ergometer CPET was performed in 48 patients referred for symptoms >12 weeks following mild COVID-19 infection. BrP was categorized as normal, abnormal or borderline by three independent physicians, using a recently published 4-plot method (von Gruenewaldt, A. et al. Physiol Rep 2022; 10(4):e15197). We re-invited patients with an abnormal or borderline BrP for a 1 year follow-up, and a control group of 7 patients with a normal BrP. Categorization of BrP at 1-year was performed blinded to baseline BrP.

Results

At baseline, 15 patients (31%) had an abnormal BrP and 3 (6%) had a borderline BrP. Of these 18, 16 subjects were available for 1 year follow-up (Figure 1). Of 13 subjects with abnormal BrP at baseline, 7 (54%) improved over 1 year (5 to normal, and 2 to borderline), while 1 of 3 subjects with borderline improved to normal BrP. No subject changed from normal or borderline to abnormal BrP.

Conclusions

Approximately 30% of patients referred for CPET due to post COVID-19 condition had an abnormal BrP during exercise, of which around 50% were normalized in BrB after 1 year.