Inferior STEMI can be recognized by which ECG finding?

• A. ST elevation in II, III, aVF
• B. ST elevation in I, aVL
• C. ST elevation in V1-V3
• D. ST depression in II, III, aVF

Answer: (A)

Inferior STEMI is identified on the ECG by ST-segment elevation in the inferior leads II, III, and aVF. These leads view the inferior wall of the heart, so acute transmural injury there produces elevations in these angles. In many cases this result comes from occlusion of the right coronary artery (or, less commonly, the left circumflex). You may see reciprocal changes in other leads (such as ST depression in anterior or lateral leads), but the telling sign is the inferiors. Patterns such as ST elevation in the lateral leads (I, aVL) or in the anterior leads (V1–V3) point to other wall involvements, and ST depression in the inferior leads would be reciprocal rather than the primary inferior infarct sign.