The management of the patient with chest pain is a diagnostic
and therapeutic challenge of critical importance. Three key chapters
in this textbook discuss the identification of acute presentations
of ischemic cardiac disease and its differentiation from other life-threatening
disorders: the current chapter, Chapter 53, Acute Coronary Syndromes: Acute Myocardial Infarction and Unstable Angina, and Chapter 55, Low Probability Acute Coronary Syndrome.
The current chapter covers the assessment of acute chest pain with
emphasis on identification of patients with potentially serious
disorders and differentiating cardiac disease from noncardiac disease.
The Acute Coronary Syndromes chapter discusses ST-segment elevation
myocardial infarction (STEMI), non-STEMI (NSTEMI), and unstable
angina. The Low Probability Acute Coronary Syndrome chapter discusses
the identification and management of the remainder of patients who
do not meet criteria for acute coronary syndrome (ACS), yet require further
evaluation beyond the immediate ED period.
Approximately 5% of all U.S. ED visits, or about 5 million
visits per year, are for chest pain, but accurate diagnosis remains
a challenge.1,2 Owing to a complex interplay of
anatomic, physiologic, and psychological factors, serious illness
often mimics benign conditions.
ACS is a constellation of signs and symptoms resulting from an
imbalance between myocardial oxygen supply and demand. There are
three general classifications: unstable angina, NSTEMI, and STEMI. Unstable angina is
a type of ACS with no elevation of biomarkers and no pathologic ST-segment
elevation. NSTEMI is characterized by biomarker elevation and no
pathologic ST-segment elevation. Acute myocardial infarction (AMI)
is characterized by ST elevation and biomarker elevation (STEMI).
The phrase acute chest pain, commonly used in
emergency medicine, deserves discussion. The term acute means
of sudden or recent onset. Although there is no precise time period
defined, most studies of acute chest pain patients in the ED limit
entry to those with symptoms of <24-hours duration. In common
practice, acute means that the patient stops his or her usual activity
to seek medical attention, typically within minutes to hours. The
term chest in this context refers to a location
described by the patient on the anterior thorax, between xiphoid
and suprasternal notch and between the right and left midaxillary
lines. As the major serious thoracic disorders typically manifest
symptoms within these regions, thoracic pain localized to the back,
between the base of the neck and the lumbar region, is approached
differently (see Chapter 276, Neck and Back Pain). Occasional
patients with serious and life-threatening intrathoracic disorders
will describe the location of their pain outside the anterior thoracic boundaries
noted above. Some patients will have migratory pain that is no longer
perceived to be in the chest by the time the patient reaches medical attention.
Therefore, include significant intrathoracic disorders in the differential
diagnosis whenever patients describe symptoms in adjacent regions
(e.g., epigastric, neck, jaw, shoulder, and arm). The term pain describes
a noxious, uncomfortable sensation. However, pain perception and
description vary widely, and patients may use terms such as pressure, heaviness, ache,
or discomfort. Be attuned to variation in the patient’s
description of the perceived sensation. In summary, ...