The purpose of this study is to evaluate the safety and efficacy of various doses of YM150 (the experimental drug) in the prevention of ischemic vascular events in subjects with recent acute coronary syndromes.

Inclusion Criteria:

• has a diagnosis of STE-ACS, NSTE-ACS as index event according to accepted guidelines such as the ESC or AHA guidelines
• has elevated cardiac biomarkers

Exclusion Criteria:

• is planned for myocardial revascularization (e.g., Coronary Artery Bypass Graft (CABG) or elective or staged PCI) or any other invasive procedure with increased risk for bleeding (i.e. elective surgical procedures) within 60 days after randomization
• has had recent stroke or TIA ≤ 12 months prior to index event
• has persistent BP of 160 mmHg systolic or higher and/or 100 mmHg diastolic or higher at baseline with or without medication
• has participated in another clinical trial of an investigational drug (including placebo) or device within 30 days (or the limit set by national law, whichever is longer) of signing informed consent for the present study
• has participated in any YM150 clinical trials
• requires ongoing parenteral or oral anticoagulant therapy
• has active bleeding or is in the opinion of the investigator at high risk of bleeding during the study