Cardiac Medicine Certification (CMC) Practice Exam

What is the most common ECG finding associated with inferior wall myocardial infarctions?

1. ST elevation in I and aVL

2. ST elevation in II, III, and aVF

3. ST depression in V1 and V3

4. Reciprocal ST elevation in lead aVL

The correct answer is: ST elevation in II, III, and aVF

The most common ECG finding associated with inferior wall myocardial infarctions is indeed characterized by ST elevation in leads II, III, and aVF. This pattern is observed due to the involvement of the right coronary artery, which supplies the inferior portion of the heart in most individuals. When there is an inferior myocardial infarction, the elevation of the ST segment in these leads reflects the injury and ischemia occurring in the inferior wall, which is a classic presentation for this specific type of heart attack. Other options, while relevant to different types of myocardial infarctions or conditions, do not directly correlate with the typical ECG findings associated with an inferior wall MI. For example, ST elevation in leads I and aVL is more indicative of a lateral wall infarct, while ST depression in leads V1 and V3 can suggest ischemia but is not specific to inferior wall infarction. Similarly, reciprocal ST elevation in lead aVL might provide additional information about a lateral wall infarction but does not represent the primary finding for an inferior wall event. Thus, the ST elevation in leads II, III, and aVF is the hallmark finding in the context of inferior wall myocardial infarctions.