A randomized, double blind, double dummy, parallel group, placebo controlled study to evaluate the pharmacodynamic and pharmacokinetic response and safety and tolerability of SB424323 (250 mg, 375 mg and 500 mg) administered twice daily for 16 weeks, on top of aspirin (325 mg, qd) in men and women with non valvular atrial fibrillation at a low or intermediate risk for stroke
