PreSERVE-AMI: This is a study for patients admitted with a large myocardial infarction (EF < 48%) that are treated with primary percutaneous coronary intervention (PCI). Patients that qualify for the study will undergo bone marrow harvesting on the fourth day of hospitalization and CD34+ cells will be isolated. These cells will then be injected directly through a balloon catheter into the infarct-related artery to the area of the infarct within 11 days of the PCI. This will be a double blind, placebo controlled study, and the follow-up will last three years. Subjects randomized to the placebo arm will receive placebo infusion (saline), but their cells will be stored at no charge for ten years and will be available to them if needed. Click here for more information at the NIH Clinical Trials page. The principal investigator for this study is: Luis Gruberg, MD.