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