Ticagrelor compared with clopidogrel by geographic region in the Platelet Inhibition and Patient Outcomes (PLATO) trial. - Mahaffey KW; Wojdyla DM; Carroll K; Becker RC; Storey RF; Angiolillo DJ; Held C; Cannon CP; James S; Pieper KS; Horrow J; Harrington RA; et al. (Circulation, 2011)