Blood clotting may contribute to long COVID pathogenesis: Study

In a breakthrough study, researchers from Ireland have made a striking discovery that links long COVID syndrome with high blood clotting factors. Patients with a history of blood clots have displayed persistent symptoms including breathlessness, fatigue and decreased exercise tolerance on developing acute SARS-CoV-2 infection, the study reported.

The study, published in the Journal of Thrombosis and Haemostasis was conducted by a group of researchers from RCSI University of Medicine and Health Sciences in Dublin, Ireland. Previously, the group had also researched the dangers of clotting in patients with severe COVID-19. The current study was conducted on 50 patients, reviewed at a median of 68 days following SARS-CoV-2 infection. The patients with convalescent COVID symptoms were studied to understand the involvement of abnormal blood clotting in patients. "In addition to clinical workup, acute phase markers, EC activation and NETosis parameters and thrombin generation were assessed," the report abstract added.

Clot markers significantly elevated in the blood of patients with long COVID

As per the results, there was a considerable increase in clot markers in the blood of patients with long COVID. "Thrombin generation assays revealed significantly shorter lag times (p<0.0001, 95% CI -2.57– -1.02min), increased endogenous thrombin potential (ETP) (p=0.04, 95% CI 15–416nM/min) and peak thrombin (p<0.0001, 95% CI 39–93nM) in convalescent COVID-19 patients," the study mentioned. The clot markers were at an alert level in patients who have required hospitalisation with their initial COVID infections. Additionally, patients with acute COVID symptoms who were home-treated also displayed persistently higher Covid markers. These pro-thrombotic changes were independent of ongoing acute phase response or active NETosis, the study mentioned.

"Our results suggest that the clotting system may be involved in the root cause of long COVID syndrome," Dr. Helen Fogarty

Collectively, the findings demonstrated that sustained endotheliopathy is common in convalescent COVID-19 and raise the intriguing possibility that this may contribute to Long COVID pathogenesis. Explaining further into the research the study elucidated the relationship between inflammation and blood clot markers. Even though the relationship between long COVID and clotting was directly proportional, the markers of inflammation "had all returned to normal levels," the study reported. "Because clotting markers were elevated while inflammation markers had returned to normal," said Dr. Helen Fogarty, the study's lead author, ICAT Fellow and Ph.D. student at the Irish Centre for Vascular Biology in the RCSI School of Pharmacy and Biomolecular Sciences.

Long COVID has remained a cause of prolonged concern in the medical community. "Millions of people are already dealing with the symptoms of long COVID syndrome, and more people will develop long COVID as the infections among the unvaccinated continue to occur. It is imperative that we continue to study this condition and develop effective treatments." Dr. Fogarty added.

The discovery of the root cause has marked the first step towards solving the problem, said Dublin-based consultant Haematologist Dr. James O'Donnell. "Understanding the root cause of a disease is the first step toward developing effective treatments," Professor James said. Professor James is the Director of the Irish Centre for Vascular Biology, RCSI and Consultant Haematologist in the National Coagulation Centre in St James's Hospital, Dublin.

With inputs from @Thrombosis& Haemostasis

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