Inferior wall MI is most commonly caused by occlusion of which artery?

• A. Left anterior descending
• B. Right coronary artery
• C. Left circumflex
• D. Posterior descending

Answer: (B)

The main idea is that the inferior wall of the left ventricle is supplied mainly by the posterior descending artery, which in the vast majority of people arises from the right coronary artery. When the right coronary artery becomes occluded, the posterior descending artery is affected, leading to an inferior wall myocardial infarction. In most people with right-dominant circulation, this is the typical pattern. There is a minority with left-dominant circulation where the posterior descending artery comes from the left circumflex, so occlusion of that branch could cause an inferior MI there, but the most common cause remains occlusion of the right coronary artery. Clinically, inferior MIs often present with ST elevations in leads II, III, and aVF and can be associated with bradycardia or AV nodal involvement due to RCA supply to the AV node.