This randomized, double-blind, placebo-controlled study will evaluate the efficacy and safety of RO4905417 in patients with non ST-elevation myocardial infarction (Non-STEMI) undergoing percutaneous coronary intervention (PCI). Patients will be randomized to receive an intravenous infusion of either 5 mg/kg RO4905417 or 20 mg/kg RO4905417 or placebo before PCI. Follow-up will be for 4 months.

Inclusion Criteria:

• Adult patients, >18 to <75 years of age
• Non ST-elevation myocardial infarction
• Woman of childbearing potential will be allowed only if using two acceptable methods of contraception
• Body mass index (BMI) </= 40 kg/m2

Exclusion Criteria:

• Acute ST-elevation myocardial infarction (STEMI)
• Culprit coronary lesion with a total thrombotic occlusion or a lesion requiring the use of distal embolization protection or thrombectomy devices
• Percutaneous coronary intervention (PCI) within the past 72 hours
• Thrombolytic therapy within the past 7 days
• Major surgery within the past 3 months
• History of cerebral vascular disease or stroke in the past 3 months
• Bleeding disorders
• Inadequately controlled severe hypertension
• Prior coronary artery bypass graft (CABG) surgery
• Decompensated heart failure (oedema and/or rale)
• Acute infection at screening or active chronic infection within 3 months prior to PCI
• Patients known to be HIV positive, patients receiving antiretroviral drugs, or immuno-suppressed patients
• Uncontrolled diabetes mellitus (HbA1C >10%) at baseline