II. Indications: Assess risk Unstable Angina adverse event

  1. Risk of Myocardial Infarction or sudden death
  2. Occurs in near future in patient with Unstable Angina
  3. Directs Non-diagnostic Electrocadiogram Protocol

III. Criteria: High risk

  1. Ongoing rest Chest Pain >20 minutes
  2. Age over 75 years
  3. Clearly elevated Cardiac Markers (e.g. Troponin I)
  4. New signs of Congestive Heart Failure
    1. Pulmonary Edema related to suspected ischemia
    2. New or worsening Mitral Regurgitation murmur
    3. S3 Gallop
    4. New or worsening pulmonary rales
    5. Hypotension
  5. EKG changes
    1. New ST Segment deviation >0.5 mV with symptoms
    2. New Left Bundle Branch Block
    3. Sustained Ventricular Tachycardia

IV. Criteria: Intermediate risk (absence of above high risk features)

  1. Age over 65 years
  2. No high probability ACS physical findings
  3. Equivocal elevation of Serum Cardiac Markers
  4. Known vascular disease
    1. Prior Myocardial Infarction
    2. Known Coronary Artery Disease
    3. Prior Cerebrovascular Accident
  5. Rest Angina
    1. Lasted >20 minutes but now resolved
    2. Lasted <20 minutes and relieved with Nitroglycerin
    3. Nocturnal Angina
  6. Electrocardiogram
    1. Angina with T-wave inversion >0.2 mV
    2. Pathologic Q Waves
    3. Rest ST depression <1 mm in multiple leads

V. Criteria: Low risk (absence of above high/moderate risk features)

  1. New onset class 1-3 Angina in last 2 weeks <20 minutes
  2. Normal cardiovascular exam
  3. Normal Electrocardiogram
  4. No increase in Serum Cardiac Markers

VI. Interpretation (see Non-diagnostic EKG Protocol)

  1. High Risk by above probability of adverse event
    1. See Immediate MI Management
    2. See Myocardial Ischemia Protocol
  2. Intermediate risk by above probability of adverse event
    1. See Non-diagnostic Electrocardiogram Protocol
    2. Requires risk stratification before discharge
      1. Serial Troponin I for six hours
      2. Exercise Stress Test
  3. Low risk by above probability of adverse event
    1. See Non-diagnostic Electrocardiogram Protocol
    2. May discharge to home from emergency department
    3. Outpatient stress test within 72 hours
    4. Discuss coronary warning signs
    5. Close interval follow-up

VII. References

  1. Braunwald (1994) AHCPR Publication 94-0602

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