This is a prospective, randomized (the study drug is assigned by chance), double-blind (neither physician nor participant knows the treatment that the participant receives), active-controlled (study in which the experimental treatment or procedure is compared to a standard treatment or procedure), parallel group (each group of participants will be treated at the same time), multicenter (when more than one hospital or medical school team work on a medical research study) study in participants with a recent ACS (STEMI or NSTE-ACS). All the eligible participants receiving background treatment of ASA plus clopidogrel (Stratum 1) or ASA plus ticagrelor (Stratum 2) will be randomly assigned to either receive ASA or rivaroxaban on background of P2Y12 receptor antagonists treatment. This study will include 3 phases: Screening Phase (up to 10 days, before study start on Day 1), Double-blind Treatment Phase (up to either 180 days after randomization of the last enrolled participant in the study or Day 360, whichever occurs earlier), and Follow-up Phase (up to 30 days). Participants' safety will be monitored throughout the study.
