European stroke organization interim expert opinion on cerebral venous thrombosis occurring after SARS-CoV-2 vaccination.

Severe cases of cerebral venous thrombosis (CVT) with thrombocytopenia and anti-platelet factor 4 (PF4) antibodies occurring after adenoviral vector anti-SARS-CoV-2 vaccines have been recently reported. We aim to present a guidance document on the diagnosis and treatment of patients presenting with CVT after vaccination against SARS-CoV-2 infection. We reviewed the available evidence which consists on case reports, small case series, expert opinion and analogy with heparin-induced thrombocytopenia (HIT) management. Because of the low level of evidence, this is an interim document, based only on expert opinion consensus. In patients presenting with CVT after being vaccinated against SARS-CoV-2 infection, if there is thrombocytopenia a reliable HIT PF4 Antibody ELISA test should be performed, to confirm vaccine-induced immune thrombotic thrombocytopenia (VITT). In patients with CVT and thrombocytopenia, in whom VITT is suspected or confirmed, heparin (unfractionated or low molecular weight) should be avoided and non-heparin anticoagulants are preferred. If possible, platelet transfusions should be avoided. If the diagnosis of VITT is confirmed or suspected, early intravenous immunoglobulins are indicated. This expert opinion is supported by low quality evidence. It should be periodically updated, or changed to a formal guideline, as new and higher quality evidence is eventually produced. Because of their potential unfavourable clinical course, patients developing symptoms and signs suggestive of CVT after being vaccinated against SARS-CoV-2 virus should undergo urgent clinical and neuroimaging evaluation. In cases of suspected or confirmed VITT, non-heparin anticoagulants should be used, platelet transfusions avoided and intravenous immunoglobulin started early.