Final answer:
The primary concern for a patient with atrial fibrillation is stroke, due to the risk of blood clots forming and traveling to the brain.
Step-by-step explanation:
One of the primary concerns for a patient presenting with atrial fibrillation is the risk of stroke. Atrial fibrillation can lead to the formation of blood clots in the heart, which can then travel to the brain and cause a stroke. This is due to the fact that the irregular heartbeats in atrial fibrillation can lead to poor blood flow and clot formation. Managing high blood pressure is crucial for stroke prevention among these patients.