Participants who are found to have had a heart attack but whose platelet number is more than 100,000 will be given the standard therapy for heart attack, including enteric coated aspirin 325 mg per day, and will no longer take part in this study. Participants who are found to have had a heart attack but whose platelet number is less than 20,000 will be not be included in the study and will be treated as deemed appropriate by their primary physician.