and admit for inpatient observation.

SUGGESTED READING

Anderson JL, Adams CD, Antman EM, et al. ACC/ AHA 2007

Guidelines for the management of patients with unstable

angina/non ST-elevation MI: A report of the ACC/AHA

task force of practice guidelines. Circulation. 2007;116:

el48.

Fesmire FM, Brown MD, Espinosa JA, et a!. Critical issues in the

evaluation and management of adult patients presenting to

the emergency department with suspected pulmonary embolism. Ann Emerg Med. 20 1 1;57:628-652.

Green GB, Hill PM. Chest pain: Cardiac or not. I n: Tintinalli

JE, Stapczynski JS, Ma OJ, Cline DM, Cydulka RK, Meckler

GD. Tintinalli's Emergency Medicine: A Comprehensive

Study Guide. 7th ed. New York, NY: McGraw-Hill, 20 1 1,

pp. 36 1-367 .

Swap CJ, Nagumey JT. Value and limitations of chest pain his ­

tory in the evaluation of patients with acute coronary syn ­

dromes. JAMA. 2005;294:2623-2639.

Acute Coronary Syndromes

Ch ristopher Ross, MD

Key Points

• Consider acute coronary syndrome (ACS) in the initial

assessment of all patients presenting with chest pa in

and/or d ifficu lty breathing.

• Atypical presentations are common, especially in

women, the elderly, and diabetics.

• Obta in an emergent el ectroca rdiogram in all

patients with concern for ACS to ra pidly identify

INTRODUCTION

Acute coronary syndrome (ACS) encompasses a spectrum

of disease that includes unstable angina (UA), nonST-segment elevation myocardial infarctions (NSTEMI),

and ST-segment elevation myocardial infarctions (STEM!).

The distinction between the 3 is based on historical factors,

electrocardiogram (ECG) analysis, and cardiac biomarker

measurements. ACS is the leading cause of mortality in the

industrialized world and accounts for more than 25o/o of all

deaths in the United States. More than 5 million patients

per year present to U.S. emergency departments with

symptoms concerning for ACS, although fewer than lOo/o

will be diagnosed with acute myocardial infarctions (AMI).

That said, between 2o/o and 4o/o of all patients with ACS are

initially misdiagnosed and improperly discharged from the

ED, resulting in significant morbidity and mortality and

accounting for the leading source of malpractice payouts

in the United States.

The pathophysiology of myocardial ischemia can be

broken down into a simple imbalance in the supply and

demand of coronary perfusion. Atherosclerosis is responsible for almost all cases of ACS. This insidious process

begins with the deposition of fatty streaks in the coronary

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