Evaluation of Chest Pain in the Emergency Department

Chest pain is one of the most frequent symptoms for which patients are evaluated in an emergency department. Unless the cause of chest discomfort is clearly noncardiac, an evaluation to rule out acute myocardial infarction is usually initiated. Although the quality of chest pain can sometimes be helpful in decision making, it is clear that atypical chest pain does not exclude myocardial infarction [1-4]. Assessment of risk factors for coronary artery disease is also often unhelpful. Except for an occasional young patient with no risk factors in whom the probability of acute myocardial infarction is low, most patients with myocardial infarction who present with chest pain are middle-aged or elderly and have one or more risk factors [3, 4].

Decision making often relies on electrocardiographic results. Unfortunately, in most patients without acute myocardial infarction, electrocardiograms are not entirely normal and may show nonspecific ST-T changes [3, 4]. Classic findings of acute myocardial infarction—ST elevation with or without Q waves or new T-wave changes—are seen in less than one third of patients with acute myocardial infarction at the time of initial presentation to the emergency department [3-7]. In a few patients with acute myocardial infarction, initial electrocardiograms can also be entirely normal [3-7]. Because it takes several hours before creatine kinase levels can be detected in the blood after coronary occlusion [8], measurement of this enzyme at the time of initial presentation in the emergency department is usually also unhelpful [1].

For these reasons, physicians tend to hospitalize patients until acute myocardial infarction has been ruled out. Patients who progress to acute infarction either have electrocardiograms that indicate an infarction …