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Chapter 49: Acute Coronary Syndromes

Deborah B. Diercks; Judd E. Hollander; Anna Marie Chang

INTRODUCTION

Content Update: High-Sensitivity Cardiac Troponins and Acute Myocardial Ischemia March 2021

Hs-cTns (high-sensitivity cardiac troponins) improve ability to detect acute coronary ischemia.

Type 1 and type 2 myocardial ischemia, and the use of Hs-cTns in ED patients with chest pain are discussed in important updates in the section “Serum Markers of Myocardial Injury.”

Cardiac Complications of COVID-19 June 2020

Acute Coronary Syndrome and STEMI management present unique challenges during the COVID-19 pandemic. Treatment options require close collaboration between EMS systems, emergency departments, and cardiology services. See addition ‘Cardiac Complications of COVID-19’ in the section SPECIAL POPULATIONS at the end of this chapter.

EPIDEMIOLOGY

Ischemic heart disease is the leading cause of death among adults in the United States, with more than 400,000 people dying annually. Atherosclerotic disease of the epicardial coronary arteries—termed coronary artery disease—accounts for the vast majority of patients with ischemic heart disease. The predominant symptom of coronary artery disease 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 49-1Three Principal Presentations of Unstable Angina
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TABLE 49-1 Three Principal Presentations of Unstable Angina
Class Presentation
Rest angina* Angina occurring at rest and that is prolonged, usually >20 min
New-onset angina New-onset angina that markedly limits ordinary physical activity, such as walking 1–2 blocks or climbing 1 flight of stairs or performing lighter activity
Increasing angina Previously diagnosed angina that has become distinctly more frequent, has a longer duration, or is lower in threshold, limiting ability to walk 1–2 blocks or climb 1 flight of stairs or perform lighter activity

*Patients with non–ST-segment elevated myocardial infarction usually present with angina at rest.

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 49-2Short-Term Risk of Death or Nonfatal Myocardial Infarction by ...

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