What are the signs of an inferior myocardial infarction (MI) on an electrocardiogram (EKG)?

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Last updated: April 24, 2025View editorial policy

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From the Guidelines

Inferior infarct on an ECG is diagnosed by ST-segment elevation in leads II, III, and aVF, and immediate management includes aspirin, clopidogrel, and consideration of emergency reperfusion therapy, as recommended by the 2017 ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation 1.

Key Diagnostic Criteria

  • ST-segment elevation in leads II, III, and aVF
  • Reciprocal ST depression in leads I and aVL
  • Right-sided leads (V3R-V4R) should be checked for ST elevation indicating right ventricular involvement

Management

  • Aspirin 325mg chewed
  • Clopidogrel 600mg loading dose
  • Emergency reperfusion therapy (primary PCI preferred if available within 90 minutes, otherwise fibrinolytic therapy)
  • Anticoagulation with heparin
  • Beta-blockers (such as metoprolol 5mg IV followed by oral dosing)
  • Pain control with morphine if needed

Important Considerations

  • Avoid nitrates in patients with right ventricular involvement due to risk of profound hypotension
  • Monitor for bradycardia and heart blocks due to involvement of the AV node, potentially requiring temporary pacing
  • Prompt recognition and treatment are crucial as timely reperfusion significantly improves outcomes and reduces mortality, as emphasized in the 2017 ESC guidelines 1.

From the Research

Inferior Infarct in the EKG

  • An inferior infarct in the EKG is a type of ST-elevation myocardial infarction (STEMI) that occurs when there is a blockage in one of the coronary arteries that supply blood to the inferior wall of the heart 2, 3.
  • The diagnosis and management of inferior STEMI is critical to achieving optimal patient outcomes, and immediate reperfusion therapy is essential to reduce mortality and limit infarct size 4, 5.
  • The American College of Cardiology Foundation (ACCF)/American Heart Association (AHA) guidelines recommend primary percutaneous coronary intervention (pPCI) as the preferred treatment for STEMI, but if pPCI is not available, fibrinolytic therapy is indicated if there are no contraindications 4, 2.
  • The management of inferior STEMI includes the use of antiplatelet agents, anticoagulants, and other pharmacological treatments, such as aspirin, statins, and beta-blockers, to reduce the risk of further ischemic events and improve patient outcomes 6, 4, 5.
  • Simulation scenarios can be used to teach different levels of learners about the presentation, diagnosis, and management of inferior myocardial infarctions, and to incorporate advanced cardiovascular life support (ACLS) protocols and communication skills 3.

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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