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Acute coronary syndromes (ACS) encompass a spectrum of cardiac disorders with myocardial ischemia and/or injury. These include ST-elevation myocardial infarction (STEMI), non-STEMI (NSTEMI), and unstable angina.


Chest pain is the most common symptom for patients with ACS. Important elements of the history include the timing of symptom onset, location, quality, severity, and duration. Also important is whether the pain is intermittent, constant, or waxing and waning. Twenty percent to 30% of all patients diagnosed with ACS report atypical symptoms, and their chief complaint may not include chest pain. These atypical symptoms can include shortness of breath, nausea, diaphoresis, back pain, abdominal pain, dizziness, or palpitations. Clinical features associated with chest pain that is diagnosed as ACS include substernal or left-sided chest pain, radiation of pain to one or both arms, and chest pain accompanied with nausea, vomiting, or diaphoresis.

Discuss risk factors for coronary artery disease (CAD) with patients to stratify the risk of ACS. These risk factors include older age, male gender, family history, smoking, hypertension, hypercholesterolemia, and diabetes. Patients with a long history of cocaine use may be at risk for accelerated CAD development, and recent use can cause acute ischemia from coronary vasospasm. The presence of absence of risk factors alone are poorly predictive of the likelihood of myocardial infarction in a patient presenting with acute symptoms. Physical examination can help identify signs of hemodynamic dysfunction from cardiac strain or acute heart failure such as pallor, diaphoresis, altered mental status, elevated jugular venous distension, peripheral edema, or rales on pulmonary exam.


Consider alternative diagnoses for patient symptoms based on clinical assessment, which may include diseases such as pulmonary embolism, congestive heart failure, gastroesophageal reflux disease, symptomatic hiatal hernia, chronic obstructive pulmonary disease, asthma, pneumonia, pneumothorax, pericarditis, myocarditis, aortic dissection, chest trauma, chest wall disorders, or mediastinal disorders.

Promptly obtain an ECG to assess for signs of cardiac ischemia. Findings diagnostic for STEMI include at least one of the four criteria listed in Table 18-1.

Table 18-1

Electrocardiographic ST-Segment-Based Criteria for Acute Myocardial Infarction

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