- Researchers do not yet fully understand the underlying mechanism of long COVID symptoms.
- A new study shows that 28% of individuals with long COVIDs have high levels of markers associated with clot formation.
- Abnormal levels of these markers were associated with decreased athletic performance, but not with other long COVID symptoms.
- These results may be useful for future research on treatments to reduce such abnormalities associated with blood clotting in people with long COVIDs.
Recent studies published in the journal Blood Advance More than 1 in 2 (55%) with long COVIDs and abnormal exercise test results were found to have elevated levels of blood coagulation markers.
Individuals with elevated blood coagulation marker levels were four times more likely to exhibit a persistent lack of athletic performance.
These results suggest that individuals with long COVIDs need to be screened for markers associated with decreased athletic performance and blood clotting. The author of this study, Dr. Nithya Prasannan, a researcher at the University College London Hospital, said:
“I hope people see this study as a step towards understanding the causes of long-term COVID. I hope this will guide future treatment options.”
To date, more than 500 million people worldwide have been diagnosed with COVID-19, according to the World Health Organization. Estimates vary widely, but recent meta-analyses suggest that nearly one-third of all individuals with COVID-19 may experience persistent symptoms 3 months after the onset of symptoms. It has been.
These COVID-19 symptoms, which last for at least 3 months after SARS-CoV-2 infection, are summarized as follows:
Despite the increasing number of individuals with long COVID, the underlying mechanism of these persistent symptoms of COVID-19 is not well understood.
Recent studies have shown that people with long COVIDs are more likely to develop the disease.
Acute COVID-19 is associated with an increased risk of blood clots. Consistently, people with acute COVID-19 are more likely to have elevated levels of proteins that promote blood clotting.
One such protein is the von Willebrand factor (VWF). This helps to form a blood clot to block the damaged blood vessels at the site of injury. An enzyme called ADAMTS13 then cleaves the VWF protein into smaller pieces, reducing its activity and preventing the formation of blood clots in the blood vessels.
An increased ratio of VWF to ADAMTS13 is associated with an increased risk of blood clotting in acute COVID-19. Such a condition with an increased risk of blood clots is called a thrombus-promoting condition.
In this study, the authors investigated whether such thrombus-promoting conditions were associated with the severity of long-term COVID symptoms, including athletic performance.
The study consisted of 330 individuals who had persistent symptoms more than 3 months after SARS-CoV-2 infection and visited a long outpatient COVID clinic. The majority (83%) had never been hospitalized.
At the time of the visit, the researchers conducted two tests to assess the endurance and athletic performance of the participants. In these exercise tests, we walked at a normal pace for 6 minutes and repeatedly switched from sitting to standing for 1 minute.
Researchers used an oxygen monitor to measure blood oxygen levels during the test. They also measured changes in blood lactate levels produced by the body when there was not enough oxygen supply to maintain muscle activity.
To assess the risk of blood clotting, researchers used blood samples to divide participants into two groups based on whether the VWF / ADAMTS13 ratio was normal (less than 1.5) or abnormal (greater than or equal to 1.5). I classified it.
Researchers have found that approximately 28% of study participants have anomalous VWF / ADAMTS13 levels. The VWF / ADAMTS13 ratio did not correlate with the severity of long-term COVID symptoms such as headache, malaise, and cognitive impairment.
However, abnormal VWF / ADAMTS13 levels were associated with decreased athletic performance, as measured by blood oxygen and lactate levels. Almost 20% of participants showed diminished athletic performance, and 55% of individuals in this group showed elevated VWF / ADAMTS13 levels.
Elevated VWF / ADAMTS13 levels could be four times higher in individuals with reduced athletic performance than in individuals showing normal performance on exercise tests. In addition, VWF and blood coagulation protein factor VIII levels were also higher in individuals with impaired athletic performance.
Dr. Artur Fedorowski, a professor at the Karolinska University Hospital in Stockholm, Sweden, said: MNT About research. He w
“A high VWF / ADAMTS13 ratio means that some long COVID patients tend to produce microclots, which can impair normal blood flow through various important areas such as lungs and cerebral circulation. Therefore, under normal conditions, the patient may feel normal and compensated, but physical or mental effort reveals a lack of compensatory reserve. , May cause characteristic symptoms. ”
“This hypothesis is mechanically very attractive, but it should be remembered that the majority of long COVID patients had a normal VWF / ADAMTS13 ratio. The detected anomalies are many of the long COVIDs. It may be just one of the symptom-generating mechanisms of the disease, or it may not be causal. ”
“Instead, a really long COVID mechanism can cause increased symptoms and increased thrombus formation promotion in some sensitive patients,” Dr. Fedrovsky added.
Dr. Prasanan said about the direction of future research MNT“The assessment of the VWF / ADAMTS13 ratio is part of the routine study conducted in patients with Long COVID.”
“As part of an ongoing study at the Hemostasis Research Unit, we are using a shear flow-based assay, a platform that mimics blood flow through blood vessels, to assess the formation of microclots in patients with long COVIDs. “
