smleApril 9, 2026• 3 min read

SMLE Clinical Reasoning Walkthrough: Acute Chest Pain and ECG Interpretation

Written by Dr. M. Salar Raza — MBBS, MSRA (RCGP), IMC Certified

Medically ReviewedMedically reviewed by Dr. Umer Mukhtar (MBBS, FCPS) on April 9, 2026

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This walkthrough combines clinical presentation with ECG localisation. Work through the case before reading the explanation, then identify which findings change the differential.

Clinical case

A 62-year-old man with hypertension and type 2 diabetes presents with two hours of crushing central chest pain radiating to his left arm and jaw. He is pale and diaphoretic. His blood pressure is 100/60 mmHg and heart rate is 58 beats/min. The ECG shows ST elevation in II, III and aVF, with reciprocal ST depression in I and aVL. What is the most likely diagnosis?

Anterior wall myocardial infarction
Inferior wall myocardial infarction
Acute pericarditis
Massive pulmonary embolism

Read the case in two passes

First, identify the clinical problem: acute chest pain with autonomic symptoms and cardiovascular risk factors. Second, localise the ECG changes. In this vignette, the regional inferior-lead changes and reciprocal findings support an inferior STEMI. Do not select an answer from the pain description alone.

Why each option fits or fails

A — Anterior infarction: the described changes are in the inferior limb leads rather than the anterior precordial leads. Match the answer to the supplied ECG territory.

B — Inferior infarction: this is the best answer for the presentation and ECG pattern in the stem.

C — Pericarditis: consider the pain characteristics and the distribution of ECG changes. The regional pattern with reciprocal changes in this case favours infarction over a diffuse inflammatory pattern.

D — Pulmonary embolism: this can cause acute chest pain and requires consideration in an appropriate clinical context, but it does not best explain the specific regional ECG pattern supplied here.

Compare the ECG territories

Territory	Leads to examine
Inferior	II, III, aVF
Anterior	V1–V4
Lateral	I, aVL, V5–V6
Posterior	Posterior leads V7–V9; assess suggestive changes in V1–V3

Use this table to organise your reading, not as a substitute for the full clinical picture. Lead placement, conduction abnormalities and other causes of ST changes can affect interpretation. The educational case asks for a diagnosis; real patients need urgent assessment through the appropriate acute-care pathway.

Distinguish localisation from the next management step

Knowing that an infarction is inferior does not answer every subsequent question. If the stem adds hypotension, raised jugular venous pressure or other evidence of right ventricular involvement, the reasoning changes. Review the separate hypotensive inferior STEMI case for that decision point.

Review without memorising the answer letter

Explain how the ECG changes support the chosen territory.
Describe which findings would make a different answer more likely.
Revisit a new case without looking at the answer choices first.

For related pathways, see the acute coronary syndrome clinical library page. A practice case or mock score does not guarantee an official SMLE result.

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References

Dr. M. Salar Raza

MBBS, MSRA (RCGP), IMC Certified

Dr. Muhammad Salar Raza holds an MBBS, is registered with the Irish Medical Council, has passed MSRA in the UK, and is the author of multiple peer-reviewed publications in medical journals. He reviews all clinical content to ensure accuracy for SMLE students.

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