Inclusion Criteria- Patients in whom a requirement for clopidogrel therapy with concomitant aspirin is anticipated for at least the next 12 months. Specific conditions that may confer a need for long-term clopidogrel + aspirin therapy may include non-ST segment elevation acute coronary syndrome (unstable angina/non-Q-wave MI), ST segment elevation acute MI), or new placement of a coronary artery stent.
- For women of childbearing potential, negative pregnancy test prior to randomization and agreement to use effective method of birth control during the study.
- Able to provide written informed consent based on competent mental status.
Exclusion Criteria- Patients currently hospitalized for whom discharge is not anticipated within 48 hours of randomization.
- Requirement for current or chronic use of a proton pump inhibitor, H2 receptor blocker, sucralfate or misoprostol.
- Erosive esophagitis, esophageal or gastric variceal disease, or non-endoscopic gastric surgery. Patients with a history of GERD/erosive esophagitis or dyspepsia who do not currently require proton pump blockers will be eligible.
- Receipt of > 21 days of clopidogrel or another thienopyridine prior to randomization.
- Oral anticoagulation that cannot be safely discontinued for duration of study.
- Recent fibrinolytic therapy.
- Scheduled percutaneous coronary intervention (PCI). Patients may be enrolled upon completion of PCI.
- Recent (< 30 days prior to randomization) or scheduled coronary artery bypass graft (CABG) surgery.
- Cardiogenic shock at time of randomization, refractory ventricular arrhythmias, or congestive heart failure (NY Heart Association class IV).
- Active pathological bleeding or a history of hereditary or acquired hemostatic disorder.
- History of hemorrhagic stroke, intracranial neoplasm, arteriovenous malformation or aneurysm.
- Systemic corticosteroids except low-dose oral corticosteroids equivalent to prednisone < or equal to 5 mg/day.
- Allergy or contraindication to clopidogrel or other thienopyridine drugs, omeprazole or other proton pump inhibitor drugs, aspirin or salicylate derivatives, or other study drug ingredients.
- Treatment within 30 days prior to randomization with any investigational drug or device including investigational coronary artery stents or currently enrolled in another interventional drug or device study.
- Women who are pregnant or breastfeeding.
- Life expectancy less than 12 months.
- Laboratory abnormality at screening that is clinically significant or outside protocol-allowed limits, or any other condition that precludes participation in the study in the opinion of the Investigator.