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    Patent Pending

    Subtle Anterior STEMI Calculator (4-Variable)

    Differentiates normal variant ST elevation (benign early repolarization) from anterior STEMI, more sensitive than 3-variable version.

    INSTRUCTIONS

    Note: this calculator replaces the older 3-variable version and is recommended by MDCalc and Dr. Stephen Smith. Before using this calculator, make sure the EKG shows ≥1 mm ST elevation (STE) in ≥1 of the precordial leads V2-V4. If it shows any one of the following, then it is NOT normal variant, and is very likely to be LAD occlusion; such cases were excluded from the study as "obvious" MI:

    • >5 mm STE.
    • Non-concave STE.
    • Inferior reciprocal changes.
    • Anterior ST depression.
    • Terminal QRS distortion in V2 or V3:
    • Q waves in any of V2 to V4.
    • Any T wave inversion from V2 to V6.
    When to Use
    Pearls/Pitfalls
    Why Use

    Use in chest pain patients presenting with an EKG that is non-diagnostic but suspicious for anterior MI.

    • The authors specifically excluded patients with obvious MI. Using the calculator in cases that were excluded in the study may lead to a wrong result.

    Tips for EKG interpretation:

    • Measure STE at 60 ms in lead V3:

    • ST elevation at 60 ms after the J-point in lead V3, relative to the PR segment
      • Measure STE 60 ms (1½ small box after J point).
      • The baseline is the PR segment.
      • In this example, STE 60 = 4 mm.
    • Measure amplitude of R wave in V4:

    • In this example, RV4 = 9 mm.
    • Read the QTc: QTc is simply read from the computerized interpretation (uses Bazett's formula).
    • Both benign early repolarization and STEMI cause ST elevation. The challenge is to differentiate the two entities.
    • Some patients present with subtle EKG changes nondiagnostic for STEMI but still have 100% coronary artery occlusion and benefit from acute percutaneous transluminal coronary angioplasty (PTCA).
    • Using the equation in such cases can lead to timely cath lab activation, or more intensive evaluation.
    mm
    mm
    mm

    Result:

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    Next Steps
    Evidence
    Creator Insights
    Dr. Stephen W. Smith
    Are you Dr. Stephen W. Smith? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
    Content Contributors
    • Dominic Larose, MD
    About the Creator
    Dr. Stephen W. Smith
    Are you Dr. Stephen W. Smith?
    Content Contributors
    • Dominic Larose, MD