1.11
Code 1.11 — Minnesota Code 1-1-1: major Q/QS wave. A Q wave is an initial negative deflection of the QRS complex. Code 1-1-1 is assigned when the Q wave is both deep (Q/R amplitude ratio ≥ 1/3) and wide (duration ≥ 0.03 s) in the leads of one anatomical region. It is one of the "major" Q-wave codes and is the classic electrocardiographic sign of a previous (old) myocardial infarction in that region.
Why Q waves appear
Normally the ventricular septum is activated first, from left to right, producing a small and narrow "septal" q wave in leads I, aVL and V5–V6. When part of the ventricular wall dies after a myocardial infarction, the scar no longer generates electrical forces. An electrode facing the scar then "looks through" it at the opposite wall and records a deep, wide negative wave — a pathological Q wave — or even a completely negative QS complex.
Criteria by lead group
| Region | Leads examined | Code 1-1-1 criterion |
|---|---|---|
| Anterolateral | I, aVL, V6 | Q/R ≥ 1/3 and Q duration ≥ 0.03 s in lead I or V6 |
| Posterior (inferior) | II, III, aVF | Q/R ≥ 1/3 and Q duration ≥ 0.03 s in lead II |
| Anterior | V1–V5 | Q/R ≥ 1/3 and Q duration ≥ 0.03 s in any of V2–V5 |
Clinical significance
- A major Q wave in two contiguous leads of one region is a strong marker of prior myocardial infarction, often with loss of contracting muscle in that wall.
- In population studies such Q waves are frequently found in people who never had symptoms — unrecognised ("silent") infarction, which carries a prognosis similar to recognised infarction.
- Major Q waves are associated with increased risk of heart failure, arrhythmias and cardiovascular death.
Possible causes other than infarction
- Hypertrophic cardiomyopathy (deep narrow septal Q waves)
- Left bundle branch block, left ventricular hypertrophy, dilated cardiomyopathy
- Infiltrative diseases (amyloidosis, sarcoidosis), myocarditis
- Pulmonary embolism, pneumothorax, chest deformities
- Electrode misplacement — the most common technical cause
Recommended next steps
- Compare with previous ECGs
- Echocardiography to look for regional wall-motion abnormality or scar
- Assessment of risk factors (blood pressure, lipids, glucose, smoking)
- Depending on findings: stress testing, cardiac MRI or coronary imaging
if a new Q wave appears together with chest pain, breathlessness, sweating or fainting — this may be an evolving myocardial infarction and requires emergency evaluation.
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
- 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
- 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