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    4.2
    Home > ECG findings

    4.2

    Minnesota Code 4-2: mild horizontal or down-sloping ST depression 0.5–1 mm — when a small change matters.

    Code 4.2 — Minnesota Code 4-2: mild ST depression. The J point is depressed by 0.5 mm or more but less than 1.0 mm below the PR baseline, with a horizontal or down-sloping ST segment. The change is small, but its shape — flat or falling — makes it more significant than an up-sloping depression. In the Fourth Universal Definition of Myocardial Infarction, new horizontal or down-sloping ST depression of 0.5 mm in two contiguous leads already counts as an ischaemic ECG change.

    Minnesota Code 4ST depressionBorderline ischaemic change
    ST-J depression0.5 – < 1.0 mm
    ST shapehorizontal or down-sloping
    UDMI threshold≥ 0.5 mm in 2 contiguous leads
    Key stepcompare with earlier ECGs
    Normal ST segment compared with mild horizontal ST depression of about 0.7 millimetres Normal ST at baseline Code 4-2 ST-J ↓ 0.5–1.0 mm
    Figure 1. Left: normal ST segment. Right: mild horizontal ST-J depression of about 0.7 mm (Minnesota 4-2).

    Possible causes

    • Myocardial ischaemia (coronary artery disease, microvascular dysfunction)
    • Left ventricular hypertrophy, hypertension
    • Medicines (digoxin, some antiarrhythmics and antidepressants), low potassium
    • Fast heart rate, anaemia, fever, hyperventilation, anxiety
    • Non-specific variant, more often in women

    Clinical significance

    A single mild ST depression on a resting ECG without symptoms has limited diagnostic value. Its significance increases if it is new compared with previous recordings, appears in several neighbouring leads, is accompanied by T-wave changes, or occurs in a person with symptoms or risk factors of coronary artery disease. In population studies, even minor ST-T changes have been associated with increased cardiovascular risk.

    What to do

    Discuss the result with a doctor. Assessment of risk factors (blood pressure, cholesterol, glucose, smoking) and, if indicated, a stress test are usually recommended.

    Call emergency services

    if you have chest pain, pressure, breathlessness or cold sweat.

    References

    1. Prineas RJ, Crow RS, Zhang ZM. The Minnesota Code Manual of Electrocardiographic Findings. 2nd ed. London: Springer; 2010. doi:10.1007/978-1-84882-778-3
    2. Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Eur Heart J. 2019;40(3):237–269. doi:10.1093/eurheartj/ehy462
    3. Rautaharju PM, Surawicz B, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval. Circulation. 2009;119(10):e241–e250. doi:10.1161/CIRCULATIONAHA.108.191096

    This article is for general information and does not replace a consultation with a doctor. ECG findings must be interpreted by a physician together with symptoms and other tests.

    Published on 14 May 2019