A 68-year-old man with nonvalvular atrial fibrillation has hypertension and type 2 diabetes. Creatinine is 1.0 mg/dL and weight is 85 kg. His CHA2DS2-VASc score is 3 (age 65-74, hypertension, diabetes). He has no mechanical valve or moderate-to-severe mitral stenosis. What is the most appropriate strategy for stroke prevention?