A 58-year-old man develops sudden diaphoresis and severe chest pain. ECG shows ST segment elevation in leads II, III and aVF. Which coronary artery is most likely occluded?

• A Left anterior descending artery
• B Left circumflex artery
• C Diagonal branch of the left anterior descending artery
• D Posterior descending branch of the right coronary artery ✓

Explanation

Leads II, III and aVF face the inferior surface of the heart, so this is an inferior infarct. In about 85 to 90 percent of people the posterior descending artery arises from the right coronary artery (right dominance), so inferior STEMI localizes to right coronary occlusion. Anterior and anteroseptal leads would be affected in left anterior descending occlusion, while lateral leads I, aVL, V5 and V6 reflect circumflex territory.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.