SIGNIFICANT DYSPNEA IN POST-ACUTE COVID-19 IS ASSOCIATED WITH ABNORMAL PULMONARY VASCULATURE ON CT DURING THE ACUTE PHASE

TOPIC: Chest Infections TYPE: Original Investigations PURPOSE: SARS-CoV-2 is a highly contagious respiratory virus associated with significant morbidity and mortality in the acute phase. It is also associated with long-term morbidity in a subset of patients. It is not clear which patients will have persistent symptoms. SARS-CoV-2 affects the pulmonary vasculature. We hypothesize that differences in blood volume measurements on CT of the chest during the acute phase are associated with significant dyspnea after the acute phase. METHODS: We retrospectively studied subjects hospitalized for COVID-19 pneumonia who had an initial and follow-up CT chest, pulmonary function tests (PFTs), 6-minute walk test (6MWT), and a clinical assessment in our post-COVID-19 clinic. We excluded subjects with pre-existing lung disease based on prior PFTs. Serum inflammatory biomarkers, CT scan, and clinical characteristics were assessed during the hospitalization. CT images were evaluated by Functional Respiratory Imaging (deep learning trained) with automated tissue segmentation algorithms of the lungs and pulmonary vasculature. Volumes of the pulmonary vessels that were ≤5mm2 (BV5), 5-10mm2 (BV5_10), and ≥10mm2 (BV10) in cross-sectional area were analyzed. Additionally, the amount of opacification on CT (i.e., ground-glass opacities, crazy paving, reticular disease and edema) was quantified in each patient. PFTs were performed <3 months after discharge. We defined a modified Medical Research Council (mMRC) score≥2 as having significant dyspnea. We compared subjects with an mMRC score≥2 to those with an mMRC score<2. BV measures were also compared to a historical cohort of healthy controls. RESULTS: 50 subjects were included. 22 had mMRC score≥2. The groups had similar baseline characteristics. Admission hemoglobin, peak inflammatory biomarkers, and follow-up PFTs were similar between groups. On 6MWT, there were no differences between groups in resting SpO2, lowest SpO2, or walk distance. On admission CT, percent BV5 was lower, and percents BV5_10 and BV10 were higher in the mMRC≥2 group compared to the mMRC<2 group. All BV measures in both groups were different compared to healthy controls. At follow-up, BV5 measures in the mMRC≥2 group improved but remained abnormal compared to healthy controls, without a statistical difference compared to the mMRC<2 group. Opacification was similar between groups on admission and follow-up CTs. CONCLUSIONS: Despite similar baseline characteristics, lung function, degree of opacification and oxygenation, persistent dyspnea after COVID-19 pneumonia is related to pruning of the small pulmonary vessels (BV5) during the acute phase and not to differences in vascular abnormalities seen in short term follow-up. CLINICAL IMPLICATIONS: Identification of markers of persistent dyspnea in post-acute COVID-19 contributes to a better understanding of the natural course and prognosis of the disease. This will impact research and patient care in the near future. DISCLOSURES: No relevant relationships by Melinda Darnell, source=Web Response Owner/Founder relationship with Fluidda Please note: $20001 - $100000 by Jan De Backer, source=Web Response, value=Ownership interest No relevant relationships by Derlis Fleitas Sosa, source=Web Response No relevant relationships by Victor Kim, source=Web Response Employee relationship with FLUIDDA Please note: 02/01/2017 - Present Added 04/26/2021 by Maarten Lanclus, source=Web Response, value=Salary No relevant relationships by Ifeoma Oriaku, source=Web Response No relevant relationships by Daniel Salerno, source=Web Response