AHA Guidance on COVID-19 related rare blood clots treatment
USA: The American Heart Association/American Stroke Association has released guidance on signs, symptoms, and treatment for rare blood clots and low platelets related to the COVID-19 vaccine.
Earlier, the US FDA had imposed a temporary pause in the administration of the Johnson & Johnson (Janssen) COVID-19 vaccine in the U.S. This was due to reports of a serious condition called cerebral venous sinus thrombosis (CVST), which refers to blood clots in the brain's veins - not in the arteries, as is the case for most strokes - in combination with thrombocytopenia (low blood platelet count). CVST and thrombocytopenia together is called thrombosis-thrombocytopenia syndrome (TTS).
When TTS is linked to receiving a COVID-19 vaccine, it is called vaccine-induced immune thrombotic thrombocytopenia (VITT). CVST has also been associated with cases of TTS in adults who received the AstraZeneca COVID-19 vaccine available in Europe, according to the European Medicines Agency, the agency responsible for the scientific evaluation, supervision, and safety of medicines in the European Union. The pause however was lifted recently on April 21st, 2021.
The goal of the report, published in the journal Stroke, is to heighten awareness of the apparent association between adenovirus SARS-CoV2 vaccinations and CVST with vaccine-induced immune thrombotic thrombocytopenia (VITT) and suggest approaches to management.
"COVID-19 infection is a significant risk factor for CVST. A preliminary analysis of U.S. data during the COVID-19 pandemic, available online, preprint on April 15, 2021, found that the risk of CVST due to infection with COVID-19 is 8-10 times higher than the risk of CVST after receiving a COVID-19 vaccine," said Karen L. Furie, lead author of the special report, chair of the department of neurology at The Warren Alpert Medical School of Brown University. "The public can be reassured by the CDC's and FDA's investigation and these statistics – the likelihood of developing CVST after a COVID-19 vaccine is extremely low. We urge all adults to receive any of the approved COVID-19 vaccines."
The special report from the Stroke Council leaders details treatment for suspected CVST, TTS or VITT:
- All patients with suspected CVST due to a COVID-19 vaccine should be treated with non-heparin anticoagulants such as argatroban, bivalirudin, danaparoid, fondaparinux or a direct oral anti-coagulant (DOAC). No heparin products in any dose should be given.
- Magnetic Resonance Imaging with a venogram (MRI/MRV) or computed tomography with venogram (CT/CTV) is recommended to accurately detect and diagnose CVST.
- Blood tests should include a CBC (Complete Blood Count) plus:
- platelet count - to determine the number of platelets per liter of blood;
- a peripheral smear - examination under a microscope to count the number of various types of blood cells and if they appear normal;
- a prothrombin time – to measure how long it takes the blood to clot;
- a partial thromboplastin time – a measurement of how long it takes the blood to clot, specifically measuring for these clotting factors: factor VIII, factor IX, factor 1V and factor XII;
- a fibrinogen test – to measure for the presence of fibrin, a protein found in the blood that indicates that blood clotting has been activated;
- a D-dimer test – to measure for the presence of D-dimer, a small protein that's made when blood clots are dissolving in the body; and
- a PF4 antibody ELISA test – to test for PF4 antibodies, which the body sometimes creates in the blood to fight against the anticoagulant heparin.
- Anticoagulation treatment doses may need to be tailored if platelet counts are extremely low (<20,000/mm3) or if there is low fibrinogen.
- Anticoagulants should be used to treat CVST even if there is a secondary hemorrhage in the brain in order to prevent progressive thrombosis and to control bleeding.
- Platelet transfusion should be avoided.
- Once platelet counts return to normal (150,000 to 450,000/mm3), most patients can be transitioned to an oral anticoagulant if there are no contraindications.
- The authors note that based on their evaluation of the American Society of Hematology's recommendations and two recently published studies, individual patient factors should be considered regarding the use of a direct oral anticoagulant (DOAC) or a vitamin K agonist (VKA) after there is full platelet count recovery.
- The authors recommend all cases of thrombosis after a COVID-19 vaccine be reported to the U.S. Department of Health and Human Services Vaccine Adverse Event Reporting System: https://vaers.hhs.gov/reportevent.html. This data will be important to understanding the incidence of CVST, TTS and VITT.
"We are learning the various intricacies of COVID-19 live, in real-time with the patients we see in our hospitals every day. CVST is extremely rare, however, further research and investigation are necessary as the pandemic continues. We will need data and robust research on the people who did not develop blood clots after the vaccine, too, so that we can fully understand the molecular and cellular mechanisms underlying CVST related to COVID-19 infection or after vaccination," concluded Furie.
Risk of CVST blood clots 8-10 times higher following a COVID-19 infection as compared to the risk associated with a COVID-19 vaccine - Special Report from the American Heart Association/American Stroke Association Stroke Council Leadership.
The report was based on data from 59 health care organizations, totaling 81 million patients, more than 98% of whom were in the U.S. Among the nearly 514,000 patients in the database who were diagnosed with COVID-19 infection from January 20, 2020 through March 25, 2021, 20 patients were diagnosed with CVST. This data was compared to the incidence of CVST in adults who received either the Pfizer or Moderna COVID-19 vaccine before March 25, 2021, excluding those who had previously been diagnosed with COVID-19. No cases of thrombocytopenia (low platelets) were diagnosed among almost 490,000 vaccinated adults.
"Diagnosis and Management of Cerebral Venous Sinus Thrombosis with Vaccine-Induced Thrombotic Thrombocytopenia," is published in the journal Stroke.