Abstract
BACKGROUND: The aim of the study was to identify factors that may cause the presence of long COVID and to assess factors that affect chronic limited exercise tolerance in spiroergometry after one-year follow-up in patients who had recovered from COVID-19. METHODS: Of 146 patients hospitalised in the Cardiology Department, 82 completed a one-year follow-up (at least 15 months post-COVID-19 recovery). We compared their conditions at initial screening and follow-up to analyse the course of long COVID and exercise intolerance mechanisms. Clinical examinations, laboratory tests, echocardiography, cardiopulmonary exercise testing, and body composition analysis were performed. RESULTS: The patients, after one-year follow-up, had significantly higher levels of high-sensitivity cardiac troponin T (hs-cTnT) (p = 0.03), left atrium diameter (LA) (p = 0.03), respiratory exchange ratio (RER) (p = 0.008), and total body water content percentage (TBW%) (p < 0.0001) compared to the 3-month assessment. They also had lower forced vital capacity in litres (FVC) (p = 0.02) and percentage (FVC%) (p = 0.001). The factors independently associated with a decline in maximum oxygen uptake (VO(2max)) after one-year follow-up included the percentage of fat (OR 2.16, 95% CI: 0.51-0.77; p = 0.03), end-diastolic volume (EDV) (OR 2.38, 95% CI 0.53-0.78; p = 0.02), and end-systolic volume (ESV) (OR 2.3, 95% CI: 0.52-0.78; p = 0.02). CONCLUSIONS: Higher left ventricular volumes and fat content (%) were associated with a reduced peak VO(2max) when assessed 15 months after COVID-19 recovery.