- Prothrombin Time-International Normalized Ratio/Partial Thromboplastin Time (PT-INR/PTT) < 1.5 x upper limit of normal. Patients who are being therapeutically anticoagulated with an agent such as Coumadin or heparin will be allowed to participate provided that no prior evidence of underlying abnormality in these parameters exists. For patients on anticoagulation therapy, at least weekly evaluations will be performed until International Normalized Ratio (INR) is stable as defined by the local standard of care