Inclusion Criteria:  acute myocardial infarction diagnosed by a physician undergoing percutaneous coronary intervention Exercise testing and stress echocardiography are performed with the approval of the physician.  Exclusion Criteria:  Severe cardiac valve disease Left bundle branch block Uncontrolled diabetes or hypertension Orthopedics or other conditions that hinder from exercise Uncontrolled sinus tachycardia (greater than 120 beats per minute)