What are the diagnostic criteria for Acute Coronary Syndrome (ACS)?

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Last updated: April 24, 2025View editorial policy

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From the Guidelines

To diagnose acute coronary syndrome (ACS), you should first obtain a detailed history focusing on chest pain characteristics, perform a physical examination, order an ECG immediately, and check cardiac biomarkers like troponin, as recommended by the 2021 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation 1. The classic presentation includes chest pain or discomfort that may radiate to the jaw, neck, back, or arms, often accompanied by shortness of breath, nausea, diaphoresis, or lightheadedness.

Key Diagnostic Steps

  • Obtain a detailed history focusing on chest pain characteristics
  • Perform a physical examination
  • Order an ECG immediately to differentiate between ST-segment elevation ACS and non-ST-segment elevation ACS (NSTE-ACS) 1
  • Check cardiac biomarkers like troponin, with serial measurements taken at presentation and 3-6 hours later, as elevated levels indicate myocardial injury 1

Additional Tests

  • Complete blood count
  • Basic metabolic panel
  • Lipid profile
  • Chest X-ray If initial tests are inconclusive but suspicion remains high, consider stress testing or coronary CT angiography.

Special Considerations

  • Women, elderly patients, and those with diabetes may present atypically without classic chest pain 1
  • Risk stratification tools like TIMI or GRACE scores can help determine prognosis and guide management Early diagnosis is crucial as timely intervention significantly improves outcomes in ACS, and the 2021 ESC guidelines provide the most up-to-date recommendations for diagnosis and management 1.

From the FDA Drug Label

Non-ST-segment elevation acute coronary syndrome is defined as prolonged (≥10 minutes) symptoms of cardiac ischemia within the previous 24 hours associated with either ST-segment changes (elevations between 0.6 mm and 1 mm or depression >0. 5 mm), T-wave inversion (>1 mm), or positive CK-MB. To diagnose acute coronary syndrome, specifically Non-ST-segment elevation acute coronary syndrome, look for:

  • Prolonged (≥10 minutes) symptoms of cardiac ischemia within the previous 24 hours
  • Associated with either:
    • ST-segment changes (elevations between 0.6 mm and 1 mm or depression >0.5 mm)
    • T-wave inversion (>1 mm)
    • Positive CK-MB 2

From the Research

Diagnosing Acute Coronary Syndrome

To diagnose acute coronary syndrome (ACS), several steps and considerations are involved:

  • Electrocardiography (ECG): Should be performed immediately (within 10 minutes of presentation) to distinguish between ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation ACS (NSTE-ACS) 3, 4, 5, 6.
  • Symptom Evaluation: Chest discomfort at rest is the most common presenting symptom of ACS, but approximately 40% of men and 48% of women present with nonspecific symptoms such as dyspnea 3.
  • Troponin Measurements: High-sensitivity troponin measurements are the preferred test to evaluate for non-STEMI (NSTEMI) 3, 4, 7.
  • Risk Stratification: Tools like the Thrombosis in Myocardial Infarction (TIMI) or HEART score can be used for risk stratification if the ECG is normal and troponin tests are negative 4.
  • Further Evaluation: May include exercise treadmill testing, stress echocardiography, myocardial perfusion scintigraphy, or coronary computed tomography angiography to exclude coronary artery disease (CAD) 4.

Specific Conditions

  • STEMI: Caused by complete coronary artery occlusion, accounts for approximately 30% of ACS. Rapid reperfusion with primary percutaneous coronary intervention (PCI) within 120 minutes reduces mortality 3, 6.
  • NSTE-ACS: Accounts for approximately 70% of ACS, caused by partial or intermittent occlusion of the artery. Prompt invasive coronary angiography and percutaneous or surgical revascularization within 24 to 48 hours are associated with a reduction in death in high-risk patients 3, 7.

Management Considerations

  • Aspirin: Should be administered as soon as possible if not contraindicated 6.
  • Reperfusion Therapy: Should be initiated promptly for STEMI, typically via PCI within 120 minutes of first medical contact, or fibrinolytic therapy if PCI cannot be performed in time 3, 6.
  • Dual Antiplatelet Therapy, Anticoagulation, Statin Therapy, Beta-Blocker Therapy, and Sodium-Glucose Cotransporter-2 Inhibitor Therapy: Are important considerations in the management of ACS 7.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

ECG diagnosis and classification of acute coronary syndromes.

Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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