Case 331.

History: A 43-year-old male patient with no known past medical history presented to the emergency department with new-onset bitemporal headache, dizziness, and bilateral lower extremity weakness for 1 day. The patient denied chest pain, shortness of breath, cough, or recent exposure to sick individuals. He was not on any medications and denied alcohol or illicit drug use. Vital signs were unremarkable. Physical examination was notable for a left-sided pronator drift and bilateral dysmetria that was more pronounced on the left. Results of routine laboratory workup, including complete blood count, metabolic panel, and high-sensitivity troponin level, were normal. An electrocardiogram revealed sinus tachycardia with a heart rate of 102 beats per minute, T-wave inversions in the inferior leads, left axis deviation, incomplete right bundle branch block, and frequent premature ventricular contractions. A radiograph of the chest was unremarkable. CT of the head without contrast enhancement demonstrated no acute intracranial abnormities. MRI of the brain without contrast enhancement revealed multiple acute infarcts involving left posterior inferior cerebellar artery distribution, right cerebellar hemisphere, right mesial temporal lobe, and right posterior limb of the internal capsule. CT angiography of the head and neck showed an occlusion of the right posterior cerebral artery near its origin, with a trace of distal flow. Given that these findings were concerning for a cardioembolic etiology of acute ischemic stroke, transesophageal echocardiography was performed. This showed mild left ventricular systolic dysfunction with an ejection fraction of 40%, mild global hypokinesis, and an additional finding also seen at subsequent cardiac CT and MRI that will be disclosed in part 2 of the case. The patient was started on systemic anticoagulation and guideline-directed medical therapy for heart failure with reduced ejection fraction. CT of the chest showed no evidence of lymphadenopathy or abnormalities in the lung parenchyma or interstitium. Coronary CT angiography was performed (Fig 1), followed by cardiac MRI (Fig 2).