Ventilation and perfusion abnormalities following recovery from noncritical COVID-19

RATIONALE: Dyspnea and respiratory impairment are sequelae of COVID-19. OBJECTIVES: The objectives of this study were to observe the prevalence and clinical relevance of ventilation (V) and perfusion (Q) impairment, evaluated by ventilation/perfusion-single-photon emission computed tomography-computed tomography (VQ-SPECT-CT), in individuals with no history of lung disease 4-weeks after recovery from noncritical COVID-19. METHODS: We enrolled 25 COVID-19 patients' post-recovery and 11 control subjects. All participants underwent VQ-SPECT-CT using Tc-99m-Technegas for V and Tc-99m-macroaggregated albumin for Q, spirometry, six-minute-walk-test, blood draw and completed the modified Medical Research Council (mMRC) dyspnea-scale and St. Georges Respiratory Questionnaire (SGRQ). VQ-SPECT-CT was reviewed to report lung function and structure abnormalities and ventilation-heterogeneity was quantified to evaluate associations with symptoms, exercise-capacity and inflammatory markers. MEASUREMENTS AND MAIN RESULTS: Of 25 post-COVID-19 participants, 9 were hospitalized and 16 home-isolated during acute-infection. A total of 88% of hospitalized and 44% of home-isolated participants were reported to have V defects (matched VQ defects: 63% and 44%; mismatched V defects: 38% and 13%), compared to 30% of never-COVID-19 controls (matched VQ defects: 30%, mismatched V defects: 10%) (P=0.02 and P=0.68, respectively). Ventilation-heterogeneity was greater in hospitalized (P=0.003), but not home-isolated participants, compared to the never-COVID-19 controls. Post-COVID-19 ventilation-heterogeneity correlated with the dyspnea-scale (r =0.45, P=0.03), SGRQ-score (r =0.41, P=0.04), 6MWD (r=-0.49, P=0.02), Sp02 (P=-0.55, P=0.005), CT parenchymal opacities (r=0.42, P=0.04) and neutrophil percent (r=0.45, P=0.04), but not pro-inflammatory cytokines, C-reactive protein or D-dimer. CONCLUSIONS: This small functional lung imaging study revealed ventilation impairment in individuals with no history of lung disease recovering from noncritical COVID-19 that was associated with parenchymal opacities, respiratory symptoms and exercise-capacity.