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Ischemic heart disease is the leading cause of death among adults
in the U.S., accounting for more than 500,000 deaths annually. Atherosclerotic disease
of the epicardial coronary arteries—termed coronary
artery disease, or CAD—accounts for the vast majority
of patients with ischemic heart disease. The predominant symptom
of CAD is chest pain, and concern over potential CAD and myocardial
ischemia 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). An consists of unstable angina and acute myocardial
infarction (AMI). Of patients with an ACS, approximately
one third have an AMI, and the remainder have unstable angina.
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The Canadian Cardiovascular Society has developed
three schemes for categorizing angina. The first two categorize
angina (Table 53-0.1) and unstable angina (Table 53-0.2).1 Both assume
a diagnosis of ischemic heart disease but are not applicable to
the ED when patients present with symptoms that may or may not be
due to ischemic heart disease. The third categorization scheme assesses
the short-term risk for patients with unstable angina (Table 53-1).
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