ABSTRACT NUMBER: ESOC2026A2171 SEVERE CAROTID T OCCLUSION ISCHEMIC STROKE AS THE FIRST MANIFESTATION OF A JAK2 V617F–ASSOCIATED PROTHROMBOTIC STATE

Abstract Background and aims Ischemic stroke in young adults often remains cryptogenic despite diagnostic work-up. Myeloproliferative neoplasms associated with JAK2 mutations are an underrecognized cause of arterial thrombosis. We report a case of ischemic stroke due to carotid T occlusion in a young patient, in whom an underlying JAK2-associated prothrombotic state was identified after a subsequent major arterial event. Methods A 44-year-old man with no relevant past medical history but a family history of early- onset ischemic stroke was admitted for acute ischemic stroke. Initial multimodal CT revealed an ASPECTS of 4, petechial hemorrhagic transformation and unfavorable perfusion imaging, precluding reperfusion therapy. Brain MRI and MR-angiography demonstrated complete occlusion of the internal carotid artery from its origin to the carotid T bifurcation. Results The patient presented with deficits including aphasia, right hemiplegia and hemisensory loss, right lower facial palsy and absent right threat response. Lab results were normal. Continuous cardiac monitoring during 8-day hospitalization showed no emboligenic arrhythmias, and echocardiography was unremarkable. One year later, the patient suffered an anterolateral ST-elevation myocardial infarction (Killip IV), requiring stenting of the anterior descending artery. Left ventricular ejection fraction was reduced (20%). Laboratory tests revealed thrombocytosis, prompting hematological evaluation and detection of a JAK2 V617F mutation. Anticoagulation and dual antiplatelet therapy were started. Conclusions JAK2 mutation testing is not routinely performed when initial hematological studies are normal; this case raises the question of whether such testing should be considered when standard work-up is negative. Conflict of interest Samuel Cajaraville: nothing to disclose