ST elevations in I, aVL, V4, V5, V6 indicate which MI and artery?

ST elevations in I, aVL, V4, V5, V6 indicate which MI and artery?

• A. ST elevations in I, aVL, V4, V5, V6 indicate a lateral wall MI caused by occlusion of the left circumflex artery
• B. ST elevations in I, aVL, V4, V5, V6 indicate an inferior MI caused by the right coronary artery
• C. ST elevations in I, aVL, V4, V5, V6 indicate an anterior wall MI caused by the left anterior descending artery
• D. ST elevations in I, aVL, V4, V5, V6 indicate a posterior wall MI caused by the posterior descending artery

Answer: (A)

ST-segment elevations in the lateral-facing leads reflect injury to the lateral wall of the left ventricle. The lateral wall is supplied mainly by the left circumflex artery, so occlusion here produces a lateral wall myocardial infarction with ST elevations in the lateral leads I, aVL, V5, and V6 (and sometimes V4). An inferior MI would show elevations in the inferior leads II, III, and aVF; an anterior MI would show elevations in the anterior leads V1–V4 due to LAD involvement; a posterior MI is suggested by posterior leads or reciprocal changes in anterior leads, not primarily a lateral pattern. Thus, this ECG pattern best fits a lateral wall MI from occlusion of the left circumflex artery.

ST-segment elevations in the lateral-facing leads reflect injury to the lateral wall of the left ventricle. The lateral wall is supplied mainly by the left circumflex artery, so occlusion here produces a lateral wall myocardial infarction with ST elevations in the lateral leads I, aVL, V5, and V6 (and sometimes V4).

An inferior MI would show elevations in the inferior leads II, III, and aVF; an anterior MI would show elevations in the anterior leads V1–V4 due to LAD involvement; a posterior MI is suggested by posterior leads or reciprocal changes in anterior leads, not primarily a lateral pattern. Thus, this ECG pattern best fits a lateral wall MI from occlusion of the left circumflex artery.