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Daily Bulletin

Study Examines Blood, Vascular Mechanisms Underlying Long COVID

Tuesday, Nov. 29, 2022

Aortic vascular changes and endothelial dysfunction may be at the root of ongoing illness in some long COVID sufferers.



"It was clear even early in the pandemic that SARS-CoV-2 infection resulted in cardiovascular injury and inflammation in a sub-set of patients," said Christian Houbois, MD, assistant professor of radiology at the University of Toronto, Sunnybrook Health Sciences Center. "There is now more evidence to suggest that cardiovascular injury and endothelial dysfunction may be underlying pathophysiologic mechanisms of long COVID."

In a Monday session, Dr. Houbois shared the results of this study, examining cardiovascular effects of COVID-19 using cardiac imaging and blood biomarkers. This analysis is a sub-study of a larger multi-disciplinary study at Toronto General Hospital, University Health Network, University of Toronto led by Kate Hanneman, MD, MPH, FRCPC, Paaladinesh Thavendiranathan, MD, Kathryn Howe, MD, PhD, and Jason Fish, PhD.

The study included participants who had recovered from COVID-19 two to three months prior and a control group of participants with no history of COVID-19.

The researchers performed cardiac MRI including 4D flow and evaluated a blood sample for biomarkers of systemic inflammation and endothelial cell activation.

"To our knowledge there is no data on 4D flow parameters in recently recovered patients," Dr. Houbois said. "Based on what is known about COVID-19 pathophysiology, we anticipated that vascular changes in recently recovered patients might be detectable using imaging and blood biomarkers."

Blood Biomarkers, Inflammation Found in COVID-19 Patients

The team evaluated 47 participants approximately 67 days after COVID-19 diagnosis. The group was compared with 30 COVID-19 negative controls.

"A total of 19 participants in the COVID-19 group had persistent symptoms of chest pain, palpitations and/or shortness of breath at the research visit," Dr. Houbois said.

Imaging revealed that peak wall shear stress in the ascending aorta was lower in the COVID-19 group than in controls.

Blood biomarkers E-selectin, endothelin-1, IL-6 and MPO were higher in the COVID group than in controls while other select blood biomarkers did not differ between the two groups.

"E-selectin correlated negatively with wall shear stress," Dr. Houbois said.

He noted that the correlation demonstrated between MRI 4D flow wall shear stress and circulating levels of E-selectin supports the hypothesis that endothelial dysfunction occurs in some patients post COVID-19 infection and is a potential mechanism underlying long COVID.

"Identification of blood biomarkers linked to endothelial dysfunction and long COVID could be useful to monitor disease progression or regression and may be useful for therapeutic development," Dr. Houbois said.

Data analysis from patients in the larger study is ongoing, and the researchers are tracking longitudinal changes over time along with the relationship of imaging findings to longer term outcomes.

"Further research is needed to evaluate the association of imaging and blood biomarkers with the development of atherosclerotic disease and adverse events," Dr. Houbois said.

Access the presentation, "Combined FDB-PET/MRI – 4D-flow and Blood Biomarker Evaluation of Vascular Inflammation and Endothelial Dysfunction After COVID-19," (M5B-STCE-1) on demand at