Background
In patients with post-acute COVID-19-syndrome (PACS), abnormal
gas-transfer and pulmonary vascular density have been reported, but such
findings have not been related to each other, or to symptoms and
exercise limitation. The pathophysiological drivers of PACS in ever- and
never-hospitalized patients are not well-understood.
Purpose
To determine the relationship of persistent symptoms and exercise
limitation with
129
Xe MRI and CT pulmonary vascular
measurements in individuals with PACS.
Materials and Methods
In this prospective study, patients with PACS aged 18-80 years with a
positive PCR COVID test were recruited from a quaternary-care COVID-19
clinic between April and October 2021. Participants with PACS underwent
spirometry, diffusing-capacity-of-the-lung- for-carbon-monoxide
(DL
co
),
129
Xe MRI, and chest CT. Healthy
controls had no prior history of COVID-19 underwent spirometry,
DL
co
, and
129
Xe MRI. The
129
Xe MRI
red-blood-cell (RBC) to alveolar-barrier signal ratio, RBC
area-under-the-curve (AUC), CT volume-of-pulmonary-vessels with
cross-sectional-area <5mm
2
(BV5), and
total-blood-volume (TBV) were quantified. St. George's
Respiratory Questionnaire (SGRQ), International Physical Activity
Questionnaire (IPAQ) and modified Borg Dyspnea Scale (mBDS) measured
quality-of-life, exercise limitation and dyspnea. Differences between
groups were compared using Welch's T-tests or Welch's
ANOVA. Relationships were evaluated using Pearson (r) and Spearman
(ρ) correlations.
Results
Forty participants were evaluated including six controls (mean age,
35±15 years[standard deviation], 3 women) and 34 participants
with PACS (mean age, 53±13 years[SD], 18 women), of which 22 were
never-hospitalized. The
129
Xe MRI RBC:barrier ratio was lower
in ever- hospitalized participants (P=.04) compared to controls. BV5
correlated with RBC AUC (ρ=.44,P=.03). The
129
Xe MRI
RBC:barrier ratio was related to DL
co
(r=.57,P=.002) and
FEV
1
(ρ=.35,P=.03); RBC AUC was related to dyspnea
(ρ=-.35,P=.04) and IPAQ score (ρ=.45,P=.02).
Conclusion
129
Xe MRI measurements were lower in ever- hospitalized
participants with post- acute COVID-19-syndrome, 34±25 weeks
post-infection compared to controls.
129
Xe MRI measures were
associated with CT pulmonary vascular density, DL
co
, exercise
capacity, and dyspnea.
ClinicalTrials.gov
: NCT04584671
See also the editorial by
Wild and Collier
.