—Chest pain is a common complaint evaluated at EDs throughout the United States every day, accounting for approximately 5 million visits annually. It is essential that emergency physicians evaluate these patients appropriately, to both reduce the risk of overlooking atypical presentations representing unstable angina and acute myocardial infarctions, as well as to deliver cost efficient care to the vast majority of these patients that do not have serious underlying heart disease. As recently as the late 1980s and early 1990s, organized emergency medicine recognized the need for the development of observation medicine to assist in these efforts.