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Acquired hemophilia A is a rare disorder of hypocoagulability which can occur at any age due to autoantibodies (Factor VIII inhibitor targeting Factor VIII). A treatment option for this disorder is emicizumab, an antibody which binds to factor IX and X, thus bypassing factor VIII in the coagulation cascade. Emicizumab can rarely and paradoxically induce a hypercoagulable state resulting in arterial and venous thrombosis. We present the case of a 72-year-old woman with acquired hemophilia A who developed an acute left middle cerebral artery occlusion secondary to emicizumab treatment. 

Case report and literature review. 

A 72-year-old woman with acquired hemophilia A [diagnosis labs: Factor VIII level <1% (50-200% normal) and Factor VIII inhibitor level 1100 Bethesda units (0.0 – 0.5 BU normal)] treated with emicizumab presented with sudden right hemiparesis and global aphasia. Her National Institute of Health Stroke Scale (NIHSS) was 15. Although eligible for IV tPA, her family decided against it due to her existing bleeding diathesis. CT angiography revealed a left medial cerebral artery occlusion. She underwent mechanical thrombectomy, achieving TICI IIB reperfusion, with new NIHSS of 1. MRI confirmed acute infarction of the left basal ganglia and insula and right occipital regions. Her factor VIII activity was 80.8% (normal) and her FVIII inhibitor level was 0.6 BU (slightly elevated). Complete stroke work up (transesophageal echo, long term cardiac monitoring, CT chest/abdomen/pelvis, hypercoagulable panel) was normal. Transient hypercoagulable state secondary to Emicizumab was the most likely explanation. Apixaban was initiated for secondary prevention with no ischemic or hemorrhagic events at 3 and 6 month follow ups.