The American Heart Association (AHA)/American Stroke Association (ASA) Stroke Council leadership has issued guidelines on the management of cerebral venous sinus thrombosis (CVST) with vaccine-induced immune thrombotic thrombocytopenia (VITT), which have been published in the journal Stroke.

Let’s first understand the definitions of these terms.

• CVST is formation of clots in the veins (cf. in most cases of stroke, clots are formed in the arteries of the brain).
• CVST and thrombocytopenia together are 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 may be roughly divided into four syndromes:

• isolated headache or increased intracranial pressure
• focal neurological presentations
• subacute encephalopathy
• cavernous sinus syndrome/multiple cranial neuropathies

CVST is not easy to diagnose as its symptoms resemble several other neurological disorders and can include severe headache, blurry vision, fainting or loss of consciousness, weakness, sensory changes, confusion or trouble speaking, seizures, abdominal pain, leg pain, difficulty breathing or shortness of breath.

If associated with the COVID-19 vaccine, cases of TTS/VITT occurred several days up to 2-1/2 weeks after being vaccinated with the Johnson & Johnson (Janssen) COVID-19 vaccine in the US, or up to 3-1/2 weeks after receiving the AstraZeneca COVID-19 vaccine in Europe. All patients who present to the ER with a suspected clot should be screened for a recent history of COVID-19 vaccine. However, the risk of CVST blood clots was 8-10 times higher following a COVID-19 infection as compared to the risk associated with a COVID-19 vaccine. The guideline also says that whether an association between the vaccine and PF4 antibody, thrombocytopenia, and thrombosis exists or not is not definitive as at present there is no data about people who did not develop CVST, TTS or VITT after a COVID-19 vaccine for comparison.

Key recommendations 

• 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, peripheral smear, prothrombin time, partial thromboplastin time, fibrinogen test, D-dimer test and PF4 antibody ELISA test (PF4 antibodies are sometimes formed 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.
• 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.
• All cases of thrombosis after a COVID-19 vaccine should be reported to the US Department of Health and Human Services Vaccine Adverse Event Reporting System. This data will be important to understanding the incidence of CVST, TTS and VITT. In our country, such ADRs (or any other) can be reported to PvPI.

(Source: AHA Press release, April 29, 2021)

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA