1.31
Code 1.31 — Minnesota Code 1-3-1: minor Q/QS wave. This code describes a Q wave with a Q/R amplitude ratio between 1/5 and 1/3 and a duration of 0.02–0.03 s. Minor Q waves are "equivocal" findings: they may be normal, especially in young or thin people, but in combination with ST-T changes or risk factors they may indicate a small previous myocardial infarction.
What the code means
Small Q waves in leads I, aVL, V5 and V6 are a normal consequence of septal activation. When the Q wave becomes somewhat deeper and lasts 20–30 ms, it crosses the threshold of a minor Q code. On its own this is a weak sign; Novacode classifies minor Q waves with ST-T changes as possible Q-wave infarction (NC-5.4) and isolated minor Q waves as a minor abnormality (NC-5.7).
Criteria by lead group
| Region | Leads examined | Code 1-3-1 criterion |
|---|---|---|
| Anterolateral | I, aVL, V6 | Q/R ≥ 1/5 and < 1/3, Q 0.02–0.03 s in lead I or V6 |
| Posterior (inferior) | II, III, aVF | Q/R 1/5–1/3, Q 0.02–0.03 s in lead II |
| Anterior | V1–V5 | Q/R 1/5–1/3, Q 0.02–0.03 s in any of V2–V5 |
About T-wave changes
In general, T-wave changes accompanying minor Q waves are very non-specific. They can occur with hyperventilation, anxiety, drinking hot or cold beverages, positional changes, electrolyte disturbances and medicines, so isolated minor Q waves with non-specific T changes rarely have diagnostic value on their own.
Next steps
- No specific action is usually needed in people without symptoms or risk factors.
- With chest pain, diabetes, hypertension, smoking or a family history of early coronary disease, discuss further evaluation (echocardiography, stress testing) with a doctor.
- Comparison with earlier and later ECGs helps: a newly appearing Q wave is more significant than a stable one.
References
- 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
- 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.
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