In patients who come to the ER complaining of chest pain, shortness of breath or some other symptom of a heart attack, we will: (1) record continuous, 24 hour, standard ECGs (usual, current method used) and at the same time (2)record continuous 24 hour experimental recordings from which a body surface map will be calculated. Two experts who do not know whether the patient actually had a heart attack or not will analyze these 2 methods for signs of heart attack. We expect that more correct diagnoses will happen with the new experimental body mapping technique. The correct diagnosis will be based upon a blood test which is considered the best test to prove there is heart damage. The blood test does not become abnormal until hours after the attack, however, so the ECG diagnosis must be made and treatment initiated before results of the blood test are available.