Review of Acute Coronary Syndrome (ACS) Risk Stratification

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September 14, 2017 by dailybolusoflr

By: Agnes Usoro


Acute coronary syndrome (ACS) is a life threatening diagnosis associated with chest pain. It is imperative to recognize ACS as its’ treatment is time sensitive. This is particularly important because heart disease remains the leading cause of death in the United States. When a patient presents to the Emergency Department (ED) with chest pain, his or her disposition is determined by their risk factors for ACS and their ED work up.

Chest Pain Work Up and Management in the ED

  1. Administer Aspirin 162-325mg (Class 1, LOE A)
  2. Obtain an EKG within 10 minutes (Class 1, LOE C)
  3. Obtain a Troponin level (Class 1, LOE A)
    1. Other orders to supplement work up: Complete blood count, complete metabolic panel, lipase, B-type natriuretic peptide, D-Dimer (can utilize clinical decision rules such as PERC and Wells’ to determine utility of d-dimer), Chest X-ray
  4. Calculate the patient’s risk for a major adverse cardiac event (MACE) using the HEART Score (Class 1, LOE B)
    1. Risk factors for a MACE include:
      1. History of coronary artery disease (CAD), heart attack, stroke/transient ischemia attack (TIA), or peripheral vascular disease (PVD)
      2. Family history of  CAD
      3. Diabetes
      4. Hypertension
      5. Hypercholesterolemia
      6. Tobacco user
      7. Obesity (BMI > 30)
  5. If the first troponin is negative and the EKG is without ischemic changes, the HEART Score helps to risk stratify patients according to their risk for a MACE within 6 weeks. This score can then be used to determine patient disposition.

Utilizing the HEART Score for Risk Stratification

Low Risk (HEART Score < 4)
    • If the patient’s symptoms are concerning for ACS, serial troponins at 3h and 6h after symptom onset are required to trend a rise or fall in values (Class 1, LOE A). If the work up is negative, discharge home with follow up with their primary care physician.
Intermediate Risk (HEART Score 4 – 6) NO history of CAD

    • Order a coronary computed tomography angiography (CCTA), which serves as an anatomical test to assess for coronary atherosclerosis (Class 1, LOE A).  This is reported via the Agatston coronary calcium score (CCS) and the Grade of coronary artery stenosis.
      • Agatston CCS reveals the burden of plaque within coronary arteries as a numerical score. A CCS score > 100 correlates with a high plaque burden.
      • Grade of stenosis is reported as a percentage.
        • 1-25% Minimal stenosis
        • 25-50% Mild stenosis
        • 50-70% Moderate stenosis
        •  >70% Severe stenosis
      • Notably, the CCTA can also comment on high-risk unstable plaques, which exhibit particular radiologic characteristics such as: positive remodeling, low attenuation, spotty calcification or positive “napkin ring” sign, which is a ring of high attenuation around a plaque
      • According to the ROMICAT II Trial, CCTA results are currently valid for (2) years
      • Disposition based on CCTA
  • Ca score 0
  • Stenosis 0%
Discharge home
  • Ca score < 100
  • Stenosis < 50%
Continue work up with serial troponin and EKGs. Discharge if negative with:

  1. Cardiology follow up
  2. Daily Aspirin
  3. Statin
  • Ca score > 100
  • Stenosis 50-70%
Order Stress Testing
  • Ca score > 400
  • Stenosis > 70%
Admit for inpatient delayed catheterization

Initiate anticoagulant therapy (Enoxaparin or Unfractionated Heparin)


POSITIVE history of CAD

    • Continue work up with serial troponins and EKGs and consider Stress testing (Class 1, LOE B).
      • Stress testing is a functional test that tells us if an atherosclerotic lesion is the cause of the patient’s chest pain. The pathophysiology is related to a flow-limiting stenosis that creates an imbalance between cardiac oxygen supply and demand which manifests as chest pain. Stress testing does NOT detect low-mild risk stenosis, hence is not useful in patients with stenosis grade < 30%.
      • It is performed via various modalities
        • Exercise (Treadmill or Bicycle) + EKG
        • Exercise or Pharmacologic agent (Vasodilator or Inotropic) + Echo or Radionucleotide myoperfusion imaging (rMPI)


Negative Stress Test

    • Discharge home with:
      1. Cardiology follow up
      2. Daily aspirin
      3. Statin


Positive Stress Test

    • Admit for inpatient delayed catheterization (Class 1, LOE B)
    • Initiate anticoagulant therapy (Enoxaparin or Unfractionated Heparin)
High Risk (HEART Score > 6)
    • Admit for inpatient delayed catheterization (Class 1, LOE B)
    • Initiate anticoagulant therapy (Enoxaparin or Unfractionated Heparin)


  • Amsterdam, E., et al. (2014). AHA/ACC Guideline for the management of patients with Non-ST-Elevation Acute Coronary Syndromes: Executive Summary: A report of the American college of cardiology/American heart association task force on practice guidelines
  • Aye, R. and Graham, R. (2017). Risk stratification in stable coronary artery disease. Continuing Cardiology Education. March 2017; 3(1): 37-43
  • Emond, M., et al. (1994). Long-term survival of medically treated patients in the Coronary Artery Surgery Study (CASS) Registry. Circulation. Dec 1994; 90(6): 2645-57
  • Iwasaki, K and Matsumoto, T. (2016). Relationship between coronary calcium score and high-risk plaque/significant stenosis. World Journal of Cardiology. Aug 26; 8(8): 481-487
  • Pursnani, A., et al. (2015). Use of coronary artery calcium scanning beyond coronary computed tomographic angiography in the emergency department evaluation for acute chest pain: the ROMICAT II trial. Circ Cardiovascular Imaging. Mar; 8(3).
  • US Dept of Health & Human Services (2017). National Center for Health Statistics: Leading causes of death. Obtained from:

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