Warfarin versus aspirin: using CHADS2 to guide therapy for stroke prevention in nonvalvular atrial fibrillation.

Atrial fibrillation (AF) results in nearly a quarter of the strokes suffered in patients 80 to 89 years of age. Aspirin and warfarin are primary choices for preventing these ischemic strokes. CHADS2 (Congestive heart failure, Hypertention, Age, Diabetes, Stroke) is a validated assessment tool for cardioembolic stroke in AF. Ischemic stroke rates increase from 1.9 to 18.2 events per 100 patient-years with CHADS2 scores of 0 and 6, respectively. Warfarin is more effective than aspirin at preventing stroke in AF, but is associated with more hemorrhagic events. The American College of Chest Physicians recommends the use of warfarin in patients with a CHADS2 score of 2 or higher and suggests warfarin be used in patients with a score of 1. We recommend a patient-specific approach to therapy in which warfarin is offered to patients with a CHADS2 score of 1 or higher unless the patient is at high risk for a hemorrhagic event or cannot attain regular warfarin monitoring.