An 80-year-old male patient complains of headache, blurred vision, and left-sided weakness. He has a history of heart problems and takes digoxin. What is the most likely cause of his symptoms?

The patient's symptoms of headache, blurred vision, and left-sided weakness, in the context of his age, medical history, and medication usage, suggest that an embolic stroke caused by atrial fibrillation is the most plausible cause.

Atrial fibrillation is a common arrhythmia, especially in older adults, that can lead to the formation of blood clots in the heart. These clots can travel to the brain and obstruct blood flow, resulting in ischemic stroke. The combination of neurological symptoms—such as left-sided weakness, which indicates a problem in the right side of the brain—along with his heart history and medication indicates that he could have an embolic source originating from his heart.

In contrast, while myocardial infarction could lead to neurological symptoms if it results in inadequate blood supply to the brain, it typically presents with chest pain and other cardiac symptoms. A transient ischemic attack (TIA) might cause similar symptoms but usually resolves quickly—typically within minutes to hours—and does not typically result in lasting neurological effects, making it less likely given the ongoing nature of his symptoms. Cerebral hemorrhage would generally present with more acute symptoms such as sudden severe headache and altered consciousness, and while it can cause neurological deficits, the symptom profile