Chest Pain: Patients without evidence of acute myocardial infarction or active myocardial ischemia on ECG with chest pain that is not definite angina. These patients are defined as not having features that give them an intermediate or high likelihood of significant coronary artery disease.

Unstable Angina: Patients without evidence of acute myocardial infarction who have chest pain and are felt to have an intermediate or high likelihood of significant coronary artery disease.

Acute Myocardial Infarction: Patients with symptoms suggestive of myocardial infarction and an ECG with ST elevation of 1 mm or left bundle branch block. Patients with medically refractory chest pain associated with ischemic ECG changes that persist for greater than 30 minutes (refractory unstable angina/non Q-wave myocardial infarction) are included in this category.