1.21

Minnesota Code 1-2-1: moderate Q wave (Q/R ≥ 1/3, Q 0.02–0.03 s).

Code 1.21 — Minnesota Code 1-2-1: moderate Q/QS wave. This code describes a Q wave that is deep relative to the R wave (Q/R ≥ 1/3) but only 0.02–0.03 s wide. It belongs to the "moderate" Q codes: such Q waves suggest a possible previous myocardial infarction, especially when accompanied by ST-segment or T-wave abnormalities.

Minnesota Code 1Moderate Q wavePossible myocardial infarction

CriterionQ/R ≥ 1/3 and Q 0.02–0.03 s

CategoryModerate Q wave

Risk with ST-T changesModerate–high

NovacodeNC-5.2 / 5.3

What the code means

A Q wave that is relatively deep but not wide may reflect a smaller or non-transmural scar, or a normal variant. Its significance increases markedly when the same leads also show ST-segment deviation or T-wave inversion: the combination "moderate Q + ST-T abnormality" (Novacode 5.2) is classified as probable Q-wave myocardial infarction, while a moderate Q wave without ST-T changes (Novacode 5.3) is regarded as possible infarction. Clinical guidance for this category describes a moderate risk of ischaemic injury when Q ≥ 30 ms is combined with ST deviation.

Figure 1. Left: normal. Right: moderate Q wave (Minnesota 1-2-1) — Q/R ≥ 1/3 but duration only 0.02–0.03 s.

Criteria by lead group

Q amplitude must be at least 0.1 mV. Usual exclusions for Q coding apply (WPW, pacemaker, complete AV block, etc.).
Region	Leads examined	Code 1-2-1 criterion
Anterolateral	I, aVL, V6	Q/R ≥ 1/3 and Q 0.02–0.03 s in lead I or V6
Posterior (inferior)	II, III, aVF	Q/R ≥ 1/3 and Q 0.02–0.03 s in lead II
Anterior	V1–V5	Q/R ≥ 1/3 and Q 0.02–0.03 s in any of V2–V5

Clinical significance and next steps

Interpretation depends on the context: symptoms, risk factors, previous ECGs and the presence of ST-T changes.
An isolated moderate Q wave in lead III or aVL can be a normal variant, especially with changes of body position or breathing.
When combined with ST-T abnormalities, an echocardiogram and cardiology assessment are advisable; stress testing or imaging may be needed to look for coronary artery disease.
In epidemiological studies, moderate Q waves are associated with higher long-term cardiovascular risk than a normal ECG.

Seek urgent care

if the finding is new and you have chest pain, shortness of breath, cold sweat or fainting.

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.
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

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

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