AHA Guidance on COVID-19 related rare blood clots treatment

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.