Cardiac Medicine Certification (CMC) Practice Exam

In inferior wall myocardial infarction, which leads show reciprocal ST depression?

1. Leads II and III

2. Lead aVL

3. Leads V1 and V3

4. Lead V2

The correct answer is: Lead aVL

In the context of inferior wall myocardial infarction (MI), reciprocal ST depression is often observed in particular leads that are anatomically positioned opposite the affected area of the heart. Inferior wall MIs typically involve the right coronary artery and present with ST elevation in leads II, III, and aVF, which monitor the inferior part of the heart. Lead aVL, located in the lateral view of the heart, demonstrates reciprocal ST depression as it is positioned opposite the leads that show ST elevation during an inferior wall MI. This is a characteristic finding because as the electrical activity becomes altered due to the infarction in the inferior wall, the leads that are opposite to that area will reflect appropriate changes—specifically, they will show downward deflection, or ST depression. In contrast, other options may not show the same clear reciprocal changes due to their anatomical positioning. For example, leads II and III are often the leads where ST elevation is observed in an inferior wall MI, while leads V1 to V3, being anterior leads, are not directly involved in the reciprocal response to inferior wall injury. Lead V2 also does not primarily show reciprocal ST depression in this scenario. By identifying lead aVL as the lead with reciprocal ST depression during inferior wall myocardial infar