Acute chest pain in the emergency room. Identification and examination of low-risk patients.

Clinical and laboratory data from 596 patients who came to an emergency room complaining of chest pain indicated that no single variable could identify low-risk patients as well as a normal ECG. A combination of three variables--sharp or stabbing pain, no history of angina or myocardial infarction, and pain with pleuritic or positional components or pain that was reproduced by palpation of the chest wall--defined a very-low-risk group in which ECGs did not add accuracy to the evaluation and were potentially misleading; however, only 48 patients (8%) fell into this category. Standard cardiac enzyme levels were of almost no use as an emergency room indicator of myocardial infarction. These findings emphasize the difficulty of identifying patients at low risk for myocardial infarction or unstable angina in the emergency room without consideration of many factors from the history, the physical examination, and the ECG.