Abstract
BACKGROUND: Patients often report persistent symptoms beyond the acute infectious phase of COVID-19. Hyperpolarised (129)Xe MRI provides a way to directly measure airway functional abnormalities; the clinical relevance of (129)Xe MRI ventilation defects in ever-hospitalised and never-hospitalised patients who had COVID-19 has not been ascertained. It remains unclear if persistent symptoms beyond the infectious phase are related to small airways disease and ventilation heterogeneity. Hence, we measured (129)Xe MRI ventilation defects, pulmonary function and symptoms in ever-hospitalised and never-hospitalised patients who had COVID-19 with persistent symptoms consistent with post-acute COVID-19 syndrome (PACS). METHODS: Consenting participants with a confirmed diagnosis of PACS completed (129)Xe MRI, CT, spirometry, multi-breath inert-gas washout, 6-minute walk test, St. George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (mMRC) dyspnoea scale, modified Borg scale and International Physical Activity Questionnaire. Consenting ever-COVID volunteers completed (129)Xe MRI and pulmonary function tests only. RESULTS: Seventy-six post-COVID and nine never-COVID participants were evaluated. Ventilation defect per cent (VDP) was abnormal and significantly greater in ever-COVID as compared with never-COVID participants (p<0.001) and significantly greater in ever-hospitalised compared with never-hospitalised participants who had COVID-19 (p=0.048), in whom diffusing capacity of the lung for carbon-monoxide (p=0.009) and 6-minute walk distance (6MWD) (p=0.005) were also significantly different. (129)Xe MRI VDP was also related to the 6MWD (p=0.02) and post-exertional SpO(2) (p=0.002). Participants with abnormal VDP (≥4.3%) had significantly worse 6MWD (p=0.003) and post-exertional SpO(2) (p=0.03). CONCLUSION: (129)Xe MRI VDP was significantly worse in ever-hospitalised as compared with never-hospitalised participants and was related to 6MWD and exertional SpO(2) but not SGRQ or mMRC scores. TRIAL REGISTRATION NUMBER: NCT05014516.