Unstable Angina/Non-ST-Segment Elevation MI - Quick Consult
Last Updated / Reviewed: June 2022

Definition
Key History
Key Physical Exam
Risk Factors for Coronary Artery Disease
Differential Diagnosis
Diagnostic Testing
Clinical Risk and Safety Pearls

Definition

Acute Coronary Syndromes (ACS) include ST-Elevation MI (STEMI), Non-ST-Elevation MI (NSTEMI) and Unstable Angina (UA). Non-ST-Elevation MI (NSTEMI) and Unstable Angina (UA) are closely related conditions whose pathogenesis and presentations are similar but vary in severity. If a patient does not have STEMI, and cardiac biomarkers are elevated in an appropriate clinical context, the patient is considered to have NSTEMI. The patient in a similar clinical context whose cardiac biomarkers are not elevated is considered to have UA.

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Key History

  • Precordial pressure or heaviness may radiate to back, shoulders, neck, jaw, teeth, arms
  • Symptoms increased with exercise, emotional stress, cold air, meals, or smoking
  • Symptoms relieved with rest or nitrates
  • Dyspnea on exertion
  • Choking sensation
  • Fatigue

Atypical ACS presentation in women may include:

  • Fatigue
  • Sleep disturbance
  • Pain is tight / catching / sharp
  • Palpitations
  • Indigestion
  • Loss of appetite
  • Dizziness
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Key Physical Exam

  • Exam is typically normal.
  • Pulmonary Exam: Rales suggest left ventricular dysfunction.
  • Cardiac Exam: S3 suggests left ventricular dysfunction; mitral regurgitation.
  • Peripheral Vascular: Bruits or pulse deficits suggest extracardiac vascular disease. Patient at higher risk for ACS.
  • Consider Extracardiac Disease: TAD – Unequal pulses, murmur of aortic regurgitation; acute pericarditis – pericardial friction rub; cardiac tamponade – pulsus paradoxus.
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Risk Factors for Coronary Artery Disease

  • Family history
  • Obesity
  • Elevated triglycerides
  • Smoking
  • Hypertension
  • Diabetes
  • Cocaine use
  • Metabolic syndrome – abdominal obesity with decreased HDL levels
  • Scleroderma
  • Systemic lupus erythematosis
  • Kawasaki syndrome
  • Polyarteritis nodosa
  • Takayasu arteritis
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Differential Diagnosis

  • Anxiety disorder
  • Aortic stenosis
  • Cholecystitis
  • Cholelithiasis
  • Congestive heart failure
  • Coronary artery disease
  • Costochondritis
  • Esophageal rupture
  • Esophagitis
  • Gastritis
  • GERD
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Diagnostic Testing

  • A normal ECG does not exclude ACS and occurs in 1% to 6% of patients.
  • ECG changes consistent with NSTEMI include: ST depression, transient ST-elevation, or new T-wave inversion.
  • Cardiac troponins are the most sensitive and specific biomarkers for NSTEMI.
  • Chest X-ray can identify other potential causes for chest pain.
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Clinical Risk and Safety Pearls

  • Don’t use a patient’s response to nitroglycerin as a ‘test’ to differentiate cardiac from non-cardiac causes of pain or discomfort.
  • Don’t use a patient’s response to an antacid or ‘GI cocktail’ as a test to differentiate cardiac from non-cardiac causes of pain or discomfort.
  • A normal ECG performed during chest pain does not rule out acute coronary syndrome.
  • Be wary of computer-generated ECG interpretations.
  • If there is an old ECG available for interpretation, get it and document a comparison.
  • A non-specific ECG is NOT synonymous with a normal ECG.
  • The likelihood of a patient presenting with a complaint other than chest pain increases with age and is greater in women than men.
  • Don’t anchor on a diagnosis of acute coronary syndrome; always consider a differential, which should include acute aortic dissection and pulmonary embolism.
  • Be on guard for atypical ischemic presentations in women, including insomnia, irritability and unusual patterns of discomfort.
  • Beware the consultant who recommends discharge of the chest pain patient if you believe the patient may be unstable related to an acute coronary syndrome.
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This is intended solely as reference material and is not a recommendation for any specific patient. The practitioner must rely upon his or her own professional judgment and medical decision-making to determine whether it is relevant in a particular case. Materials are derived from medical and nursing texts, medical literature and national guidelines and should not be considered complete or authoritative. Users must rely on specific patient presentation, experience and judgment when utilizing any of the information contained herein relative to an actual patient.
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