title: Is it possible to have had a heart attack and not know it?  My doctor took an EKG and said it showed some changes.  How can I prevent another heart attack?
mesh_terms: D004562:Electrocardiography; D005260:Female; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis / Q000517:prevention & control*; D055502:Secondary Prevention