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    5.2
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    5.2

    Novacode 5.2: Q-wave myocardial infarction with moderate Q waves and ST-T changes — why the combination matters.

    Code 5.2 (Novacode NC-5.2) — Q-wave myocardial infarction with moderate Q waves and ST-T changes. The ECG shows moderate pathological Q waves together with significant ST-segment or T-wave abnormalities. The combination makes a past or recent myocardial infarction likely, even though the Q waves themselves are smaller than in class NC-5.1. The approximate Minnesota equivalent is code 1-2-x combined with 4-1/4-2 or 5-1/5-2.

    Novacode 5Myocardial infarctionQ waves + ST-T
    Novacode criterionQ-score ≥ 25 and ST-T ≥ 20
    Minnesota equivalent1-2-x + 4-1/4-2 or 5-1/5-2
    Typical Q30–40 ms
    Probability of MIhigh to moderate
    Moderate Q wave with ST depression and T wave inversion compared with a normal complex Normal q < 30 ms NC-5.2 moderate Q + ST-T
    Figure 1. Left: normal complex. Right: moderate Q wave (about 30–40 ms) with ST depression and T-wave inversion — Novacode class 5.2.

    Why the combination matters

    Moderate Q waves alone can occasionally occur without infarction, for example due to body position, hypertrophy or conduction disorders. When they occur together with ST depression or T-wave inversion in the same territory, the likelihood that they reflect myocardial scarring or ischaemic injury increases considerably. That is why Novacode classifies this pattern as ECG myocardial infarction.

    Clinical significance

    People with this pattern often have coronary artery disease and a higher risk of further cardiac events. If the changes are new, they may reflect a recent infarction. In stable patients the doctor usually recommends echocardiography, a stress test or coronary imaging, and treatment of risk factors.

    Call emergency services

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

    Planned evaluation

    Without symptoms, arrange a cardiology assessment and take previous ECGs with you for comparison.

    References

    1. Rautaharju PM, Park LP, Chaitman BR, Rautaharju F, Zhang ZM. The Novacode criteria for classification of ECG abnormalities and their clinically significant progression and regression. J Electrocardiol. 1998;31(3):157–187.
    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. 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

    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