The composite ischaemic endpoint of death , myocardial infarction , unplanned revascularization of the infarct-related artery , stent thrombosis , or stroke occurred in 13 patients ( 4.8 % ) in the prasugrel plus bivalirudin group and 15 patients ( 5.5 % ) in the clopidogrel plus heparin group ( relative risk , 0.89 ; 95 % CI 0.40-1 .96 , P = 0.894 ) .