A Study to Evaluate the Safety and Efficacy of Rivaroxaban in Combination with Aspirin Alone or with Aspirin and a Thienopyridine in Subjects with Acute Coronary Syndromes.

This study is designed to evaluate the safety and efficacy of rivaroxaban in subjects with recent Acute Coronary Syndrome who are receiving background low-dose aspirin therapy (75 to 100 mg/day) without the intention to use a thienopyridine therapy or with thienopyridine therapy. There will be 2 stages. Stage 1 will be for dose escalation while Stage 2 will be for dose confirmation. In Stage 1 there will be 3 total daily dose levels of rivaroxaban or placebo. 5 mg (2.5 mg twice a day or 5 mg once daily), 10 mg (5 mg twice a day or 10 mg daily) and 20 mg (10 mg twice a day or 20 mg daily). Mode of administration is oral. Two more additional dose levels may be added depending on the safety and efficacy profile observed in the first 3 dose levels. Maximum daily dose will not exceed 30 mg. All randomised subjects are planned to receive 6 months of treatment. In Stage 2, it is intended that a rivaroxaban once daily dose, twice daily dose or both will be selected for comparison to placebo. The dosage will be dependent upon the maximum tolerable dose for individual patient that was discovered during the dose escalation stage. Treatment will also be for 6 months.