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Ischemic heart disease is the leading cause of death among adults in the United States, with more than 405,000 people dying annually. Atherosclerotic disease of the epicardial coronary arteries—termed coronary artery disease (CAD)—accounts for the vast majority of patients with ischemic heart disease. The predominant symptom of CAD is chest pain, and patient concern over potential acute heart disease contributes to the >8 million visits each year to U.S. EDs. In a typical adult ED population with acute chest pain, about 15% of patients will have an acute coronary syndrome (ACS). ACS encompasses unstable angina through acute myocardial infarction (AMI). Of patients with an ACS, approximately one third have an AMI, and the remainder have unstable angina.

The three principal presentations of unstable angina are listed in Table 49-1.1 These definitions assume that the anginal chest pain is due to ischemia, and this categorization does not apply to patients presenting to the ED with chest pain from other causes. During the initial ED assessment, it may not be possible to determine whether the patient has or will sustain permanent damage to the myocardium, has reversible ischemia (injury or unstable angina), or has a noncardiac cause of symptoms.

Table 49–1

Three Principal Presentations of Unstable Angina

The American College of Cardiology and American Heart Association have a tool for estimating the short-term risk for death or AMI in patients with unstable angina (Table 49-2).1

Table 49–2

Short-Term Risk of Death or Nonfatal Myocardial Infarction by Risk Stratification in Patients with Unstable Angina

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