Aching left shoulder and nausea at rest

The case

58-year-old woman. Aching left shoulder and nausea at rest

She has type 2 diabetes and hypertension, both on treatment. The discomfort began at rest about an hour ago and has not changed with movement.

On arrival

SpO2: 98% on air
Heart rate: 84
Blood pressure: 158/92

Stage 1 of 3

An ECG is recorded on arrival.

Tracing 1 of 2 for the quiz “Aching left shoulder and nausea at rest”. — 12-lead, 25 mm/s Open this tracing in the studio

Observations

Heart rate: 84

What is the most important abnormality on this ECG?

AST depression in lead III with ST elevation in I and aVL Correct answer Your answer
BNormal ECG with no acute changes Your answer
CDiffuse ST elevation suggesting pericarditis Your answer
DAnterior ST elevation in V1 to V4 Your answer

Leads I and aVL each show just under 1 mm of ST elevation, which alone would not meet conventional STEMI criteria. The key finding is the reciprocal ST depression in lead III, which is the mirror image of the high lateral elevation and distinguishes early ischaemia from a normal variant. The changes are not diffuse and V1, V3 to V6 are unremarkable, so pericarditis and anterior STEMI do not fit.

What is the most appropriate next step?

ARepeat ECG at 15 to 30 minute intervals Correct answer Your answer
BDischarge if the initial troponin is negative Your answer
CAdminister IV amiodarone Your answer
DRequest a CT pulmonary angiogram Your answer

The ECG changes are subtle but suspicious, and a single normal troponin does not exclude an evolving infarction in the first hour. Serial ECGs at short intervals are the correct response to a presentation that could be an acute coronary syndrome with borderline changes. There is no arrhythmia to treat and no clinical suggestion of pulmonary embolism.

Stage 2 of 3

Twenty-five minutes later the discomfort has worsened and a repeat ECG is recorded. The initial high-sensitivity troponin result is still pending.

Tracing 2 of 2 for the quiz “Aching left shoulder and nausea at rest”. — 12-lead, 25 mm/s Open this tracing in the studio

Observations

Heart rate: 92
Blood pressure: 148/88

What is the diagnosis?

AHigh lateral ST-elevation myocardial infarction Correct answer Your answer
BWellens syndrome Your answer
CTakotsubo cardiomyopathy Your answer
DBenign early repolarisation Your answer

Leads I and aVL now show nearly 2 mm of ST elevation with deep reciprocal depression in III, meeting STEMI criteria. V2 elevation with quiet V3 to V6 completes the high lateral pattern. Wellens syndrome involves deep T-wave inversion, not ST elevation. Benign early repolarisation does not produce reciprocal depression, and takotsubo typically causes widespread precordial changes.

Which coronary artery is the most likely culprit?

AFirst diagonal branch of the LAD Correct answer Your answer
BRight coronary artery Your answer
CProximal left anterior descending artery Your answer
DLeft circumflex artery Your answer

The combination of ST elevation in I, aVL and V2 without changes in V3 to V6 or the inferior leads is characteristic of a first diagonal branch occlusion. A proximal LAD occlusion would produce anterior ST elevation across V1 to V4. RCA occlusion causes inferior elevation, the opposite of what is seen. The circumflex typically affects the lateral precordial leads V5 and V6, which are unremarkable here.

Stage 3 of 3

She remains haemodynamically stable, with ongoing discomfort. The interventional cardiologist is on the phone.

Observations

Heart rate: 92

What is the most appropriate management now?

APrimary percutaneous coronary intervention Correct answer Your answer
BIntravenous thrombolysis Your answer
CAnticoagulation and observation in a coronary care unit Your answer
DUrgent coronary artery bypass grafting Your answer

This is an evolving STEMI, so the priority is reperfusion, and primary percutaneous coronary intervention (PCI) is the standard of care when it can be delivered within the guideline time window. Thrombolysis is reserved for settings where timely PCI is not available. Anticoagulation and observation leave the artery occluded, and bypass grafting is not a first-line treatment for a single acutely occluded vessel.

Diagnosis

High lateral STEMI from first diagonal branch occlusion

The first ECG showed ST elevation of just under 1 mm in leads I, aVL and V2, easy to dismiss in isolation. The reciprocal ST depression in lead III was the clue that this was real ischaemia rather than a baseline variant. A repeat tracing 25 minutes later confirmed the diagnosis, with ST elevation now well above 1 mm in I and aVL and deepening reciprocal changes inferiorly.

The combination of high lateral elevation (I, aVL) with V2 involvement and no ST change in V3 to V6 could be associated with an occlusion to the first diagonal branch of the left anterior descending artery. This territory is served by fewer leads than an inferior or anterior wall, so the changes are easy to underread. The practical lesson is that ST depression in lead III on a tracing that otherwise looks unremarkable should prompt a careful look at leads I and aVL, and a repeat ECG at short intervals when the story fits acute coronary syndrome.

References

Durant E, Singh A. Acute first diagonal artery occlusion: a characteristic pattern of ST elevation in noncontiguous leads. Am J Emerg Med. 2015;33(9):1326.e3-5.
Thygesen K, Alpert JS, Jaffe AS, et al. Fourth Universal Definition of Myocardial Infarction (2018). Circulation. 2018;138(20):e618-e651.

This tracing was generated, not recorded. It opens in the studio with every dial live.

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Discussion

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