Transient ischemic attack

A 58-year-old man presents to the emergency department for evaluation following a 30-minute episode of left hand weakness. During the episode, the patient was unable to pick anything up with his left hand. He was able to lift his arm during the incident. He denies any difficulty with ambulation or speaking during the episode. The patient has a past medical history of uncontrolled hypertension and type 2 diabetes mellitus. He has a 20-pack-year history of smoking cigarettes. His temperature is 37°C (98.6°F), pulse is 101/min and irregularly irregular, and blood pressure is 196/98 mmHg. The patient’s pulse oximetry is 99% on room air. He is alert and oriented, with fluent, clear speech. Motor strength is normal in all extremities, and there are no focal deficits appreciated. Non-contrast CT-brain does not demonstrate an acute intracranial process. CT angiogram of the head and neck demonstrates diffuse calcific atherosclerosis. Without appropriate medical treatment, which of the following adverse events is this patient most likely to sustain?