Enoxaparin Versus Unfractionated Heparin in Subjects Who Present to the Emergency Department With Acute Coronary Syndrome (RESCUE)

INCLUSION CRITERIA * Rest angina lasting at least 10 minutes that is highly suggestive of myocardial ischemia and is not explained by trauma or obvious abnormalities on chest x-ray, occurring within 24 hours of randomization; * TIMI risk score greater than or equal to 4 (a qualitative test for CK-MB or Troponin may be utilized for screening purposes; however, a quantitative test must still be performed.) EXCLUSION CRITERIA * Increased bleeding risk as defined by any of the following: * Ischemic stroke within the last year * Any previous hemorrhagic stroke, intracranial tumor, or intracranial aneurysm * Recent (\<1 month) trauma or major surgery (including bypass surgery) * Active bleeding (other than minor skin abrasions) * Impaired hemostasis including any one of the following: * 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) * Known or history of thrombocytopenia (platelet count \<100,000/mL) * History of thrombocytopenia with glycoprotein 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. * Bundle branch block not known to be old in the context of angina. * Undergone a percutaneous coronary intervention (PCI) within the past 24 hours. * A known allergy to heparin, low molecular weight heparin, pork or pork products. * Any contraindications to treatment with UFH or LMWH. * A recent (\<48 hours) or planned spinal/epidural anesthesia or puncture. * Thrombolytic therapy within the preceding 24 hours. * Any other clinically relevant serious diseases, including severe liver disease or renal failure \[creatinine clearance \<30 mL/min\], rendering implementation of the protocol or interpretation of the study results difficult. * Treatment with other investigational agents or devices within the previous 30 days, planned use of investigational drugs or devices, or has previously enrolled in this trial. * Inability to comply with the protocol (e.g., has uncooperative attitude, inability to return for follow-up visits). * Inability to understand the nature, scope, and possible consequences of the study or is otherwise unable to provide informed consent. * A prosthetic heart valve