4.11

Minnesota Code 4-1-1: horizontal or down-sloping ST depression ≥ 2 mm — a major ECG sign of myocardial ischaemia.

Code 4.11 — Minnesota Code 4-1-1: marked ST depression. The ST junction (J point) is depressed by 2.0 mm (0.2 mV) or more below the PR baseline, and the ST segment is horizontal or down-sloping. This is the most pronounced grade of ST depression in the Minnesota Code. It most often reflects myocardial ischaemia, meaning that part of the heart muscle is not getting enough blood and oxygen.

Minnesota Code 4ST depressionMyocardial ischaemia

ST-J depression≥ 2.0 mm

ST shapehorizontal or down-sloping

Classmajor abnormality

Usually withT-wave code (5-x)

How ST depression is graded

The Minnesota Code measures the depression of the J point (end of the QRS) relative to the PR segment and evaluates the slope of the ST segment. It assigns codes separately for three lead groups: anterolateral (I, aVL, V6), inferior (II, III, aVF) and anterior (V1–V5). The code is not assigned when WPW, complete LBBB or RBBB, or non-specific IVCD is present, because these change repolarisation themselves.

Figure 1. Left: normal ST segment at baseline. Middle: horizontal ST-J depression ≥ 2 mm. Right: down-sloping ST depression ≥ 2 mm merging into a negative T wave. Both right-hand patterns meet Minnesota 4-1-1.

Minnesota Code ST-depression scale

Code	Criterion	Weight
4-1-1	ST-J ≥ 2.0 mm, horizontal or down-sloping	major
4-1-2	ST-J 1.0–< 2.0 mm, horizontal or down-sloping	major
4-2	ST-J 0.5–< 1.0 mm, horizontal or down-sloping	major/moderate
4-3	ST-J < 0.5 mm, down-sloping ST, T nadir ≥ 0.5 mm below baseline	minor
4-4	ST-J ≥ 1.0 mm, up-sloping or U-shaped ST	minor

Causes

Myocardial ischaemia: stable angina during exertion, acute coronary syndrome (non-ST-elevation infarction or unstable angina), reciprocal change of ST-elevation infarction
Left ventricular hypertrophy with strain
Digoxin effect (typically a "scooped" ST)
Low potassium, tachycardia, after a cardioversion

Clinical significance

Marked horizontal or down-sloping ST depression is one of the most important ECG signs of ischaemia. In the Fourth Universal Definition of Myocardial Infarction, new horizontal or down-sloping ST depression ≥ 0.5 mm in two contiguous leads is an ischaemic ECG change; depression of 2 mm or more indicates a larger area at risk. In population studies, ST depression on a resting ECG is associated with higher coronary and overall mortality.

Call emergency services

if ST depression is found together with chest pain or pressure, breathlessness, cold sweat, nausea, or pain in the arm, jaw or back. Troponin testing and urgent cardiology assessment are needed.

Without symptoms

Even without symptoms, marked ST depression needs a prompt cardiology assessment. This includes comparison with previous ECGs, echocardiography and tests for coronary artery disease.

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, Surawicz B, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval. Circulation. 2009;119(10):e241–e250. doi:10.1161/CIRCULATIONAHA.108.191096
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

Medical Book

Showing results for: Array