SYNERGY: Open Study of Enoxaparin Versus Unfractionated Heparin in Patients With Acute Coronary Syndromes

Inclusion Criteria * Male or nonpregnant female greater than or equal to 18 years old * Ischemic pain originating or persisting at rest, or its clinical equivalent, lasting greater than or equal to 10 minutes and occurring within the 24 hours before enrollment * At least 2 of the following: * ECG changes: New or presumably new ST-segment depression greater than or equal to 0.1 mV (greater than or equal to 1 mm), or transient (\<30 minutes) ST-segment elevation greater than or equal to 0.1 mV (greater than or equal to 1 mm) in at least 2 contiguous leads * Abnormal cardiac enzymes within the 24 hours before enrollment, defined as elevated troponin I or T greater than the established criteria at each site OR creatine kinase CK-MB level greater than the site's upper limit of normal * Age greater than or equal to 60 years Exclusion Criteria: * Known or suspected pregnancy * Increased bleeding risk: ischemic stroke within the last year or any previous hemorrhagic stroke, tumor, or intracranial aneurysm; recent (\<1 month) trauma or major surgery (including bypass surgery); active bleeding * Impaired hemostasis: known International Normalized Ratio (INR) \>1.5; past or present bleeding disorder (including congenital bleeding disorders such as von Willebrand's disease or hemophilia, acquired bleeding disorders, and unexplained clinically significant bleeding disorders), thrombocytopenia (platelet count \<100,000/mL), or history of thrombocytopenia with GP IIb/IIIa inhibitor therapy, heparin, or enoxaparin * Angina from a secondary cause such as severe, uncontrolled hypertension (systolic blood pressure \>180 mm Hg despite treatment); anemia; valvular disease; congenital heart disease; hypertrophic cardiomyopathy; restrictive or constrictive cardiomyopathy; thyrotoxicosis * PCI within the past 24 hours, not including coronary angiography only * Allergy to pork or pork products * Contraindications to UFH or LMWH * Recent (\<48 hours) or planned spinal/epidural anesthesia or puncture * Thrombolytic therapy within the preceding 24 hours * Other serious diseases, including severe liver disease or renal failure \[creatinine clearance \<30 mL/min * Treatment with other investigational agents or devices within the previous 30 days, planned use of investigational drugs or devices, or previous enrollment in this trial * Inability to give informed consent or high likelihood of being unavailable for follow-up * Not a candidate for intervention, (angiography or PCI) * Treatment with a direct thrombin inhibitor or a low molecular weight heparin other than enoxaparin in the 7 days preceding enrollment.