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3.42

Minnesota Code 3-4 with left ventricular predominance and strain: high R voltage with ST depression and T inversion — a marker of advanced hypertrophy.

Code 3.42 — Minnesota Code 3-4 with left ventricular predominance and repolarisation changes. This is a variant of combined high R voltage (criteria 3-1 and 3-2 together) in which the left ventricle dominates and the high R waves are accompanied by ST depression and T-wave inversion ("strain"). In the Minnesota Code the ST and T changes are coded separately (codes 4 and 5); together with high voltage they point to significant, often long-standing hypertrophy.

Minnesota Code 3Left ventricular hypertrophyStrain pattern

Voltagecriteria 3-1 and 3-2

ST segmentdown-sloping depression in V5–V6

T waveasymmetric inversion

Separate codes4-x (ST), 5-x (T)

What "strain" means

In a markedly thickened ventricle, repolarisation is altered and the inner layers of muscle may receive too little oxygen relative to demand. This shows on the ECG as a down-sloping ST segment, which merges with an asymmetrically inverted T wave in leads with tall R waves (I, aVL, V5–V6). The strain pattern is a marker of more advanced hypertrophy and fibrosis.

Figure 1. Left: high R voltage with normal ST-T. Right: high R voltage with 'strain' — down-sloping ST depression and asymmetric T inversion in V5–V6.

Causes

Long-standing or poorly controlled arterial hypertension
Severe aortic stenosis or aortic regurgitation
Hypertrophic cardiomyopathy
Combined left and right heart load: mitral valve disease with pulmonary hypertension, congenital defects

Similar ST-T changes may be caused by digoxin, myocardial ischaemia or bundle branch block; the doctor takes these into account when reading the ECG.

Clinical significance

Left ventricular hypertrophy with strain on the ECG has been associated with a substantially higher risk of heart failure, myocardial infarction, stroke and cardiovascular death than hypertrophy without strain. Effective treatment of the cause, especially blood pressure control, can reduce hypertrophy and the strain pattern over time.

Seek urgent care

if you have chest pain, severe breathlessness or fainting. ST-T changes like these cannot be distinguished from acute ischaemia without a doctor's assessment and comparison with previous ECGs.

Planned evaluation

Echocardiography and a cardiology consultation are recommended for anyone with this finding.

References

Hancock EW, Deal BJ, Mirvis DM, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy. Circulation. 2009;119(10):e251–e261. doi:10.1161/CIRCULATIONAHA.108.191097
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
Sokolow M, Lyon TP. The ventricular complex in left ventricular hypertrophy as obtained by unipolar precordial and limb leads. Am Heart J. 1949;37(2):161–186. doi:10.1016/0002-8703(49)90562-1

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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