AHA/ASA Publish Guidance on Treatment for Vaccine-Induced Immune Thrombotic Thrombocytopenia

April 30, 2021

The American Heart Association/American Stroke Association (AHA/ASA) Stroke Council Leadership convened quickly to provide important guidance about cerebral venous sinus thrombosis (CVST) and thrombocytopenia, together called thrombosis and thrombocytopenia syndrome (TTS), in patients who have received a coronavirus disease 2019 (COVID-19) vaccine.

The guidance is published in the journal Stroke.

“COVID-19 infection is a significant risk factor for CVST,” said Karen L. Furie, MD, Warren Alpert Medical School of Brown University, and Rhode Island Hospital, Providence, Rhode Island. “A preliminary analysis of US data during the COVID-19 pandemic found that the risk of CVST due to infection with COVID-19 is 8 to 10 times higher than the risk of CVST after receiving a COVID-19 vaccine. The public can be reassured by the CDC’s [Centers for Disease Control and Prevention] and FDA’s [US Food and Drug Administration] 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 analysis included data from 59 health care organisations, totaling 81 million patients, more than 98% of whom were in the United States. Among the nearly 514,000 patients in the database who were diagnosed with COVID-19 infection from January 20, 2020, to March 25, 2021, 20 patients were diagnosed with CVST. This data was compared with the incidence of CVST in adults who received either the Pfizer or Moderna mRNA COVID-19 vaccine before March 25, 2021, excluding those who had previously been diagnosed with COVID-19. No cases of thrombocytopenia were diagnosed among almost 490,000 vaccinated adults.

“CVST blood clots are very rare adverse events,” said Dr. Furie. “We recommend immediate screening of all patients who arrive in the ER with a suspected clot -- did they receive a COVID-19 vaccine during the recent weeks prior to this event? Patients who present with the symptoms of CVST or blood clots and who recently received the COVID-19 vaccine should be treated using non-heparin anticoagulants. No heparin products in any dose should be given for suspected CVST, TTS or VITT [vaccine-induced immune thrombotic thrombocytopenia]. With the right treatment, most patients can have a full recovery after CVST, TTS or VITT.”

If associated with the COVID-19 vaccine, cases of TTS/VITT occurred within several days, and up to 2.5 weeks after being vaccinated with the the Janssen/J&J adenovirus vector coronavirus disease 2019 (COVID-19) vaccine (Ad26COV2.S) in the United States, or up to 3.5 weeks after receiving the AstraZeneca COVID-19 vaccine in Europe.

The CDC and FDA’s report on April 23, 2021, confirms the agencies investigated 15 reported cases of TTS in the United States in women aged 18 to 59 years, from the nearly 7 million adults who received the Janssen COVID-19 vaccine before the temporary pause on April 13, 2021. The European Medicines Agency’s investigation, reported on April 7, 2021, lists 62 cases of CVST, among adults aged 22 to 60 years, mostly women, from the more than 25 million people who received the AstraZeneca COVID-19 vaccine throughout the European Union.

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 anticoagulant (DOAC). No heparin products in any dose should be given.
● MRI 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 Complete Blood Count (CBC) plus a platelet count, a peripheral smear, prothrombin time, partial thromboplastin time, a fibrinogen test, a D-dimer test, and a PF4 antibody ELISA test to test.
● Anticoagulation treatment doses may need to be tailored if platelet counts are extremely low (3) or if there is low fibrinogen.
● Anticoagulants should be used to treat CVST even if there is a secondary haemorrhage in the brain in order to prevent progressive thrombosis and to control bleeding.
● Platelet transfusion should be avoided.
● Once platelet counts return to normal (150,000-450,000/mm3), most patients can be transitioned to an oral anticoagulant if there are no contraindications.
● The authors noted that based on their evaluation of the American Society of Hematology’s recommendations and 2 recently published studies, individual patient factors should be considered regarding the use of DOAC or a vitamin K agonist after there is full platelet count recovery.

“We are learning the various intricacies of COVID-19 live, in real-time,” said Dr. Furie. “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.”

Reference: https://www.ahajournals.org/doi/10.1161/STROKEAHA.121.035564

SOURCE: American Heart Association