male patients or postmenopausal females, hypertension,

dyslipidemia, diabetes mellitus, smoking, family history of

CAD, truncal obesity, and a sedentary lifestyle. It is important to remember that these risk factors are based on large

demographic analyses and cannot be used to predict the

presence or absence of CAD in a given patient. Approximately half of all patients presenting with ACS have no

identifiable risk factors outside of age and sex.

CLINICAL PRESENTATION

� History

A thorough history is the most sensitive tool for the detection of ACS, and an experienced clinician will always be

wary of its variable presentation. Chest pain is the most

common presenting complaint. Myocardial ischemia is

classically described as pressure-like or squeezing sensation

located in the retrosternal area or left side of the chest.

Inquire about the quality, duration, frequency, and in ten ­

sity of the pain. Determine whether there is radiation of

pain, associated symptoms, and provoking and palliating

factors. Symptoms commonly associated with myocardial

ischemia include nausea, diaphoresis, shortness of breath,

and palpitations. Anginal pain can radiate in almost any

direction depending on the individual patient and the

affected region of the heart, but radiation to the shoulder,

arm, neck, and jaw is most common. It should be noted

that the intensity of pain is not predictive of the overall

severity of the myocardial insult, and even minimal symptoms can correlate with significant mortality.

Up to a third of patients with ACS will present with

symptoms other than chest pain. Also known as "anginal

equivalents;' these presentations further complicate the

accurate diagnosis of ACS. Possible complaints include

dyspnea, vomiting, altered mental status, abdominal pain,

and syncope. Patients at an increased risk of atypical pre ­

sentations include the elderly, women, diabetics, polysubstance abusers, psychiatric patients, and nonwhite

minorities. These patients have a near 4-fold increase in

mortality owing to inherent delays in their diagnosis, treatment, and disposition. Always obtain a detailed social history and inquire about any recent and chronic substance

abuse. Habitual tobacco use has been proven to be an

independent risk factor for CAD, whereas cocaine use can

not only induce significant coronary spasm in the acute

setting, but also accelerate the atherosclerotic process when

chronically abused.

� Physical Examination

There are no physical findings specific for ACS, and the

exam is frequently normal. Obtain a complete set of vital

signs and closely monitor unstable patients. Bradycardia is

common with inferior wall ischemia owing to an increase

in vagal tone, whereas tachycardia may represent compensation for a reduction in stroke volume. Concurrent hypertension increases the myocardial 02 demand and may

exacerbate the underlying ischemia, whereas acute cardio ­

genic shock has an extremely poor prognosis.

Carefully auscultate the heart for any abnormal sounds.

Acute changes in ventricular compliance may result in an

S3, S4, or paradoxically split S2. The presence of a new

systolic murmur may signify either papillary muscle infarction with secondary mitral valve insufficiency or ventricu ­

lar septal infarction with secondary perforation. Look for

signs of acute congestive heart failure (CHF), including

jugular venous distension, hepatojugular reflux, and inspiratory crackles. Perform a rectal exam to look for evidence