ECG shows ST segment elevation in leads II, III, and aVF. This pattern is most consistent with a myocardial infarction in which area?

• A. Anterior wall
• B. Inferior wall
• C. Posterior wall
• D. Lateral wall

Answer: (B)

ST elevations in the inferior leads reflect injury of the inferior wall of the left ventricle. Leads II, III, and aVF view the inferior surface; when there is transmural ischemia or infarction in this region, the current of injury is directed toward these leads, producing ST elevation. The inferior wall is most commonly supplied by the right coronary artery, so occlusion there often causes this pattern (though anatomy can vary). In contrast, an anterior wall infarct would show ST elevations in the precordial leads V1–V4, and a lateral wall infarct would show elevations in leads I, aVL, V5–V6. Posterior wall infarction typically presents with ST depression in the anterior leads and reciprocal changes in V1–V2. Therefore this ECG pattern best indicates an inferior wall myocardial infarction.