Warfarin is the best drug for stroke prevention in atrial fibrillation. In people with a-fib for whom warfarin was unsuitable (unstable INR, unlikely adherence, etc, but excluding those with prior bleeding on warfarin), twice daily oral direct Xa inhibitor apixaban had a hazard ratio of 0.45 over aspirin for the primary outcome of stroke (absolute risk for stroke of 1.6% vs 3.7% per year), with equivalent risk for major bleeding (~1.3% per year, <0.4% for intracranial hemorrhage). The trial was funded by industry, who are also investigating apixaban's efficacy in treating DVT/PE. (n=5,599). NEJM 2011;364:806-817.