Inferior wall ST-segment elevation in acute anterior wall MI

A 50-year old female, known diabetic under medicine, was referred from a local hospital to our ER. She gave a history of central chest pain associated with sweating and one episode of vomiting. The pain was radiating to her left shoulder. In that hospital she was seen by an orthopedic surgeon who did X-ray left shoulder and found 'nothing'. Then he referred her to a physician who did one ECG which showed some ischemic changes in the anterior leads (see below) and referred her to a cardiologist.

Echo was done and labeled “Normal Echo Study”!!!. She had increasing chest pain and her family members took her to the ER of the same hospital. Another ECG was taken which showed extensive ST elevation in the anterior leads and even in the inferior leads (see below). She was diagnosed as a case of anterior wall MI and referred to our hospital.

On arrival, she had ongoing central chest discomfort. Repeat ECG showed ST elevation in the leads V2-V6 and II, III, aVF. She was taken to the cath lab. Coronary angiography showed near total thrombotic occlusion in the LAD and 95% stenosis in the LCX. Both LAD and LCX were stented with DES and shifted to the CCU.

She is now chest pain free and doing fine.

Inferior ST-segment elevation during anterior wall acute MI due to LAD occlusion is unusual and was rarely investigated. There are some possible conditions where an inferior ST-segment elevation occurs during acute anterior wall MI. 

1. Mass of ischemic anterior wall myocardium is relatively small, resulting in a weaker anterior injury current and less reciprocal inferior ST-segment depression

2. There is concomitant inferior wall transmural ischemia that further shifts the inferior ST segments upward

3. LAD artery extension onto inferior wall of left ventricle ('wrap around LAD')
4. Collateral flow from LAD artery to inferior wall.
(Latter two leads to inferior wall transmural ischemia.)

Ref:

[Am J Cardiol 1992;69:860-5]