- Researchers don’t yet fully understand the mechanisms behind long-term COVID symptoms.
- A new study shows that 28% of long-term COVID patients showed higher levels of markers associated with thrombosis.
- Abnormal levels of these markers were associated with impaired exercise capacity but not with other long-term COVID symptoms.
- These results could inform future treatment studies to reduce such abnormalities associated with blood clotting in long-term COVID patients.
A study recently published in the journal blood progression More than one in two (55%) long-term COVID patients were found to have elevated levels of coagulation markers, and they also had abnormal exercise test results.
Individuals with elevated levels of coagulation markers were four times more likely to experience persistent deficits in exercise capacity.
These results suggest that individuals with prolonged COVID should be screened for markers of impaired exercise capacity and coagulation. The authors of the study, Dr. Nithya PrasannanThe researchers at UCL Hospital said:
“I hope people see this study as a step forward in understanding what causes long-term COVID, which will hopefully help us guide future treatment options.”
According to the World Health Organization, more than 500 million To date, individuals across the globe have been diagnosed with COVID-19.Although estimates vary widely, a recent meta-analysis showed that nearly one-third of COVID-19 patients may have persistent symptoms 3 months after symptom onset.
These COVID-19 symptoms that persist for at least three months after SARS-CoV-2 infection are collectively referred to as “
Despite the growing number of people with long-term COVID, the mechanisms behind these persistent symptoms of COVID-19 are unclear.
Recent research shows that people who have been infected with the new coronavirus for a long time are more likely to develop
Acute COVID-19 is associated with an increased risk of blood clots. Historically, people with acute COVID-19 were more likely to show elevated levels of proteins that promote blood clotting.
One such protein is von Willebrand factor (VWF), which helps form a clot to seal off damaged blood vessels at the site of injury.Subsequently, a method called Adams 13 The VWF protein is cleaved into smaller fragments to reduce its activity and prevent clots from forming in blood vessels.
an elevated ratio VWF to ADAMTS13 is associated with increased risk of thrombosis in acute COVID-19.This condition involving an increased risk of blood clots is called Prethrombotic state.
In the present study, the authors investigated whether this prothrombotic state is associated with the severity of long-term COVID symptoms, including exercise capacity.
This study consisted of 330 individuals with persistent symptoms 3 months or more after SARS-CoV-2 infection and who were attending a long-term COVID clinic. Most (83%) were never hospitalized.
During the visit, the researchers administered two tests to assess the participants’ endurance and exercise capacity. These exercise tests consisted of walking at a normal pace for 6 minutes and switching repeatedly from a sitting to a standing position for 1 minute.
The researchers used an oxygen monitor to measure blood oxygen levels during the test. They also measured changes in blood lactate levels, which the body produces when oxygen supply is insufficient to sustain muscle activity.
To assess the risk of blood clotting, the researchers used blood samples to divide participants into two groups based on whether their VWF/ADAMTS13 ratio was normal (less than 1.5) or abnormal (greater than or equal to 1.5).
The researchers found that approximately 28 percent of study participants had abnormal levels of VWF/ADAMTS13. The VWF/ADAMTS13 ratio was not associated with the severity of long-term COVID symptoms, including headache, fatigue, and cognitive deficits.
However, abnormal VWF/ADAMTS13 levels were associated with impaired exercise capacity as measured by blood oxygen and lactate levels. Nearly 20 percent of the participants showed impaired exercise capacity, and 55 percent of this group had elevated levels of VWF/ADAMTS13.
Individuals with impaired exercise capacity were four times more likely to have elevated VWF/ADAMTS13 levels than those with normal performance on exercise testing. In addition, levels of VWF and the coagulation protein factor VIII were also higher in individuals with impaired exercise capacity.
Dr. Artur FedorowskiProfessor at Karolinska University Hospital in Stockholm, Sweden MNT About research.he
“High VWF/ADAMTS13 ratios may indicate that some long-term COVID patients have a predisposition to microclot development, which may impair normal blood flow through various key areas such as the lungs or cerebral circulation. Therefore, under normal conditions, patients may Feeling normal and compensated, while physical or mental effort may show a lack of compensatory reserve and produce characteristic symptoms.”
“This hypothesis is very attractive mechanistically, but we should keep in mind that most long-term COVID patients have normal VWF/ADAMTS13 ratios. Either the detected abnormality is just one of many symptom-generating mechanisms of long-term COVID, or there may be no causal relation.”
“Instead, a true long-term COVID mechanism may cause symptoms and increased prothrombotic rates in some susceptible patients,” Dr. Fedorowski added.
Talking about future research directions, Dr Prasannan told MNT“Assessing the VWF/ADAMTS13 ratio has become part of routine investigations in long-term COVID patients.”
“As part of ongoing research in the Hemostasis Research Unit, a shear flow-based assay, a platform that simulates blood flow through a blood vessel, was used to assess microclot formation in long COVID patients.”