A 78-year-old patient with congestive heart failure and hypertension develops atrial fibrillation. CHADS2 score is 4. What is the preferred anticoagulation?

• A. Aspirin
• B. Clopidogrel
• C. Warfarin
• D. No therapy

Answer: (C)

Atrial fibrillation increases stroke risk because irregular atrial contractions promote blood clots that can travel to the brain. The CHADS2 score tallies risk factors, and a score of 4 means a high baseline risk of embolic stroke. In this setting, antiplatelet therapy alone provides far less protection than anticoagulation. Warfarin, when kept in the therapeutic INR range (about 2.0–3.0), offers substantial reduction in stroke risk compared with aspirin or clopidogrel alone. With such high risk, no therapy would leave the patient exposed to preventable strokes, and aspirin or clopidogrel do not adequately mitigate this risk. So, the preferred anticoagulation is warfarin to best prevent embolic events while monitoring for bleeding.