Moderate Risk Acute Coronary Syndrome Management

Aka: Moderate Risk Acute Coronary Syndrome Management, NSTE-ACS Protocol, Non-ST elevation MI, Non-ST elevation Myocardial Infarction, Non-Q-Wave MI, Myocardial Ischemia Protocol, NSTEMI

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II. Background

  1. NSTE-ACS Protocol now includes both NSTEMI and Unstable Angina
    1. As of 2017, both diagnoses follow the same protocol

III. Epidemiology

  1. NSTEMI and Unstable Angina (NSTE-ACS) accounts for 70% of the 1.4 Million ACS cases in U.S. each year
    1. Kumar (2009) Mayo Clin Proc 84(10): 917-38 [PubMed]

IV. Indications: Suspected NSTEMI or Unstable Angina

  1. Electrocardiogram changes as below OR
  2. Troponin elevation (see below) OR
  3. Concerning history and findings despite non-diagnostic EKG and Serum Cardiac Markers

V. Criteria: Electrocardiogram

  1. EKGs should be done serially
    1. Acute Coronary Syndrome should not be excluded based on a single EKG
    2. Perform EKG at time of serial Troponins, as well as with changes in patient symptoms (e.g. increased Chest Pain)
    3. Formal guidelines define serial EKG as every 15-30 minutes for first hour of presentation (not evidence based)
  2. Myocardial Ischemia (Unstable Angina) or NSTEMI
    1. ST Depression >1 mm
    2. Symmetrical T-wave inversion in precordial leads (>0.2 mV)
    3. Dynamic ST Segment and T Wave changes with pain
  3. Less interpretable EKG findings increasing risk that Chest Pain has cardiac origin
    1. Bundle Branch Blocks
    2. Paced Rhythm

VI. Imaging: Echocardiogram

  1. Echocardiogram may assist in risk stratification of a patient with active Chest Pain
  2. Most helpful if completely normal
  3. Helpful also if significantly abnormal with wall motion abnormality (unless prior MI in the same region)

VII. Labs: Serum Troponin

  1. Serum Troponin at presentation and again at 3-6 hours after first Troponin
  2. Normal Troponins
    1. Two serial Troponins at adequate intervals exclude Myocardial Infarction
    2. Myocardial Ischemia and Unstable Angina are not fully excluded by serial Troponins
  3. Abnormal Troponins suggestive of Myocardial Infarction (NSTEMI)
    1. Increasing serial Troponins with >20% rise over baseline AND
    2. At least one Troponin above upper limit of normal

VIII. Management: Cardiac Angiography Indications

  1. Cardiac ischemia associated with one of the following
    1. Persistent or recurrent pain or EKG changes despite aggressive medical management
    2. Hemodynamic instability or ventricular Arrhythmia
    3. Acute Heart Failure
  2. Diagnostic findings
    1. Diffuse or widespread EKG changes
    2. Serum Cardiac Marker (e.g. Troponin) Increased >20% over baseline (with at least one above baseline)

IX. Management: Initial

  1. See MI Adjunctive Therapy
  2. Aspirin 324 mg chewable orally (on presentation) AND
  3. P2Y Receptor Antagonist (Clopidogrel or Ticagrelor)
    1. Keep in mind, will delay emergent CABG by 24 hours and elective CABG by 5-7 days
  4. Unfractionated Heparin
    1. Alternatively, Enoxaparin (Lovenox) or Fondiparinux may be used (but not if angiogram is planned)
    2. Heparin is considered a Class I recommendation for NSTEMI and definite Acute Coronary Syndrome
    3. Also start for those planned for cardiac catheterization in the next 24 hours
    4. No evidence of mortality benefit, but may decrease progression to Myocardial Infarction
    5. Risk of Heparin-related major bleeding is 4% (NNH 25)
  5. Glycoprotein IIB/IIIA Inhibitor (Eptifibatide, Tirofiban) Indications
    1. High risk patient (e.g. high risk features, Troponin positive)
    2. May be used as an alternative to P2Y Receptor Antagonist (e.g. Clopidogrel)

X. Management: Invasive - Angiography (PCI) Indications

  1. Immediate Invasive (within 2 hours)
    1. Refractory Angina
    2. Signs or symptoms of Heart Failure
    3. New or worsening Mitral Regurgitation
    4. Hemodynamic instability
    5. Recurrent Angina or ischemia at rest or low level activity despite intensive medical therapy
    6. Sustained Ventricular Tachycardia or Ventricular Fibrillation
  2. Early Invasive (within 24 hours)
    1. GRACE risk score >140
    2. Troponin Increase over time
    3. Presumably new ST depression
  3. Delayed Invasive (within 25 to 72 hours)
    1. Diabetes Mellitus
    2. Renal Insufficiency (GFR <60)
    3. Reduced LV Function (ejection fraction <40%)
    4. Early postinfarction Angina
    5. PCI within 6 months
    6. Prior CABG
    7. GRACE risk score 109 to 140
    8. TIMI Score 2 or more

XI. Management: Other measures

  1. See MI Adjunctive Therapy
  2. Beta Blocker
    1. Improves mortality, cardiac remodeling if started in first 24 hours of STEMI, NSTEMI and ST depression ACS
    2. May be started in Emergency Department or by hospitalist service (need not be immediate)
      1. Delay Beta Blockers if hypotensive, bradycardic or concern for Cardiogenic Shock
      2. Consider starting Beta Blocker in emergency department for additional indications
        1. Refractory Hypertension despite nitrates
        2. Rate control of Atrial Fibrillation or Atrial Flutter

XII. References

  1. Orman and Mattu in Herbert (2017) EM:Rap 17(12): 5-6
  2. Orman and Mattu in Herbert (2015) EM:Rap 15(5): 9-10
  3. (2000) Circulation 102(suppl I):I172-203 [PubMed]
  4. Amsterdam (2014) Circulation 130(23): 2354-94 [PubMed]
  5. Anderson (2017) N Engl J Med 376(21):2053-64 +PMID:28538121 [PubMed]
  6. Switaj (2017) Am Fam Physician 95(4): 232-40 [PubMed]

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