Abstract Number ‐ 233: Vaccine‐Induced Thrombotic Thrombocytopenia presenting as Massive Stroke: Case Report and Literature Review

Abstract

Introduction Vaccines have been pivotal for the COVID‐19 pandemic. Rare adverse effects of the vaccines such as thrombosis have been observed. Here we report a case of an acute malignant ischemic stroke in a young healthy patient caused by thrombosis due to Vaccine‐Induced Thrombotic Thrombocytopenia (VITT). Methods Electronic chart review for a case report. Results A 43‐year‐old Caucasian female with a medical history of hypertension was found unresponsive on the morning of presentation. Her Last known normal was the night before. On arrival in the emergency department, she was globally aphasic, with left eye deviation, right‐sided neglect, right facial droop, and right‐side hemiplegia. Pupils were equal and reactive to light. NIHSS was 23. Head CT showed large left middle cerebral artery and anterior cerebral artery strokes with significant cerebral edema and midline shift. Head and neck CTA showed left ICA and left MCA occlusions. She was taken for decompressive craniectomy immediately. Ten days prior to the stroke, she received her first COVID vaccination. She smoked but did not take oral contraceptives. She did not have a family history of hypercoagulability. Stroke workup showed LDL 141, A1C 4.8%, and a negative COVID test. She had normal white and red blood cell counts but low platelet counts at 73,000, which was 233,000 one month prior. 2D echocardiogram showed an ejection fraction of 54% and no patent foramen ovale or thrombus. Lower extremity doppler showed deep vein thrombosis. Because of arterial and venous thrombosis with new thrombocytopenia, hematology was consulted. She was found to have positive anti–PF4–heparin antibody, leading to a VITT diagnosis. She received IVIG, rituximab, and steroid treatments, and her platelets gradually returned to the baseline. She was later transferred to a rehabilitation facility. Conclusions VITT is characterized by thrombosis and thrombocytopenia with positive PF4 antibodies after a median of 14 days post‐vaccination. It was reported in COVID vaccines from all manufacturers. The mechanism remains unclear. The current hypothesis describes a two‐hit process through which the vaccine triggers neoantigen formation (the first hit) followed by a systemic inflammatory response (the second hit). Incidence of VITT from COVID vaccinations is unknown but the reported cases were rare. VITT‐caused acute stroke, especially malignant strokes, is even rarer.Although the COVID vaccines can cause rare life‐threatening adverse events, they are essential for controlling the pandemic. When encountering an ischemic stroke patient with thrombocytopenia, we should consider VITT. Further study with post‐vaccination registration and monitoring is warranted.