Squiggler

Recurrent chest pressure at rest since early morning

The case

57-year-old man. Recurrent chest pressure at rest since early morning

Hypertension and dyslipidaemia. The first pain episode resolved before the ambulance arrived; the pain returned in triage.

On arrival

HR
68
GCS
15
SpO₂ (%)
98
Respiratory rate
18
Temperature (°C)
36.8
Systolic BP (mmHg)
154
Diastolic BP (mmHg)
88

Stage 1 of 1

Pain is present during this recording. The initial high-sensitivity troponin, drawn soon after the first episode, is below the diagnostic threshold.

The tracing for the quiz “Recurrent chest pressure at rest since early morning”.
Twelve-lead recorded on arrival, 25 mm/s, 10 mm/mV. Open this tracing in the studio

Bloods

Initial high-sensitivity troponin
below diagnostic threshold
What is the principal abnormality on this tracing?

The tracing shows ST depression that is most prominent in the lateral leads V4 to V6, I and aVL, with a horizontal or downsloping morphology. The segments are depressed by about 2 mm against the PR baseline. This is not a normal rate-related pattern: the rate is only about 68 beats per minute, and rate-related changes produce upsloping depression at higher heart rates. Diffuse concave elevation and peaked T waves are not present on this tracing.

What does this pattern indicate in a patient with ongoing pain?

Horizontal ST depression in contiguous leads during ischaemic chest pain is the hallmark of active subendocardial ischaemia. The depression reflects a current of injury from the inner layer of the myocardium. Benign early repolarisation produces ST elevation rather than depression and is not associated with ongoing pain. Pericarditis causes widespread concave ST elevation with PR depression. Atrial enlargement affects P-wave morphology, not the ST segment.

How should the initially low troponin affect interpretation of this ECG?

A single high-sensitivity troponin drawn shortly after symptom onset may still be below the diagnostic threshold because the biomarker takes time to rise after myocardial injury. It does not exclude an acute coronary syndrome and does not prove that the ST depression is chronic. The ECG must be interpreted on its own merits and in the clinical context. Serial sampling, typically at one to three hours depending on the assay, is required to detect a rising pattern that confirms infarction.

Diagnosis

Acute coronary syndrome with dynamic ST depression, later confirmed as NSTEMI

This tracing shows horizontal ST depression in the lateral leads, most marked in V4 to V6, I and aVL, in a patient with ongoing ischaemic chest pain. That combination is active subendocardial ischaemia until proved otherwise, regardless of a single troponin taken early. A high-sensitivity troponin drawn soon after symptom onset may be below the diagnostic threshold because the biomarker has not yet risen; serial sampling at the interval the assay validates is essential.

Dynamic ST depression in a patient with recurrent rest pain is a high-risk feature. It does not meet STEMI criteria and does not call for emergent reperfusion, but it does demand admission, monitoring, antiplatelet therapy and early angiography as part of an acute coronary syndrome pathway.

References

  1. Collet JP, Thiele H, Barbato E, et al. 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation. Eur Heart J 2021;42(14):1289-1367.
  2. Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Eur Heart J 2019;40(3):237-269.
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Discussion

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