MSRA-0068

An 80-year-old man with a history of hypertension and ischaemic heart disease comes in for a check-up. He had a heart attack two decades ago but has been symptom-free since. His current medications include bisoprolol, ramipril, atorvastatin, and clopidogrel. He has been experiencing dizziness lately, and an ECG reveals that he has atrial fibrillation. What is the appropriate antithrombotic medication for him now?