A 55-year-old woman with atrial flutter and rheumatic mitral stenosis presents with dyspnea. Which of the following is the most appropriate therapy to prevent embolic stroke?

• A. Aspirin 325 mg
• B. Plavix 75 mg
• C. Dipyridamole 200 mg and aspirin 25 mg
• D. Warfarin, dosed to INRs between 2.0 and 3.0

Answer: (D)

Rheumatic mitral stenosis with atrial flutter creates a high risk of left atrial thrombus and embolic stroke due to stagnant flow in the enlarged atrium. Anticoagulation with warfarin, titrated to an INR of 2.0–3.0, provides superior stroke prevention in this valvular setting compared with antiplatelet therapy. Direct oral anticoagulants are not recommended here, and aspirin-based regimens do not offer the same level of protection against embolism in valvular atrial arrhythmias.