S25 Cardiopulmonary exercise testing to evaluate exercise limitation and shortness of breath in long COVID

IntroductionApproximately 10% of COVID survivors experience long-term sequelae, with fatigue and exercise limitation most frequently reported. The physiological drivers of these symptoms remain unclear. Incremental cardiopulmonary exercise testing (CPET) is a routine clinical assessment used to evaluate exercise limitation but its utility in long COVID is unknown.MethodsConsecutive patients with non-hospitalised SARS-CoV2 infection referred for standard-of-care CPET to investigate persistent exercise limitation were identified. Patient demographic and clinical information were extracted, and standard CPET parameters were collected and analysed. Ethical approval was obtained under the UHS REACT COVID observational database (REC-20/HRA/2986).ResultsNine patients were included in this pilot analysis. 55% male, median (mdn) 47 years, 6 to 12 months post SARS-CoV-2 infection. Reported pre-morbid exercise and fitness levels were above average. Patients demonstrated impaired exercise capacity, peak oxygen uptake [VO2peak] (mdn 23.3ml/kg/min, 81% predicted) and oxygen uptake at anaerobic threshold [AT] (mdn 13.4 ml/kg./min). AT as percentage of VO2peak was reduced (mdn 45%) suggesting significant deconditioning. Oxygen-pulse (O2 pulse) percentage predicted was reduced (mdn 80%) suggesting impaired oxygen delivery and/or muscle oxygen utilisation (table 1). None of the patients demonstrated respiratory limitation to exercise. All patients had normal baseline cardiac function. Six were referred for a Cardiac MRI after CPET, all of which demonstrated normal biventricular function.Abstract S25 Table 1Preliminary CPET data for patients with persistent symptoms following non-hospitalised SARS-CoV2 infection, demonstrating reduced levels of aerobic fitness compared to% predicted, as assessed by oxygen uptake at peak exercise, oxygen uptake at anaerobic threshold (AT) and O2 pulse. Patient number Peak oxygen uptake as% predicted Peak AT as% of peak oxygen uptake O2 pulse as% predicted VEVCO2 slope Breathing reserve (litres/minute) 1 110 69 101 26.9 59 2 70 31 76 22.6 138 3 91 45 80 31.4 36 4 108 63 93 28.1 84 5 81 46 78 27.7 31 6 81 44 82 26.4 71 7 111 47 106 25.4 69 8 61 33 70 27.5 96 9 64 43 78 29.6 40 ConclusionsCPET provided an objective measure of functional limitation in our preliminary patient cohort, profound deconditioning was apparent. Given that our patient has normal cardiac function, it is possible that the reduction in O2 pulse reflects an intrinsic impairme