An anterior wall myocardial infarction — also known as anterior wall MI, or AWMI, or anterior ST segment elevation MI, or anterior STEMI — occurs when anterior myocardial tissue usually supplied by the left anterior descending coronary artery suffers injury due to lack of blood supply. When an AWMI extends to the septal and lateral regions as well, the culprit lesion is usually more proximal in the LAD or even in the left main coronary artery. This large anterior myocardial infarction is termed an extensive anterior.
The ECG findings of an acute anterior myocardial infarction wall include:
- ST segment elevation in the anterior leads (V3 and V4) at the J point and sometimes in the septal or lateral leads, depending on the extent of the MI. This ST segment elevation is concave downward and frequently overwhelms the T wave. This is called “tombstoning” for obvious reasons; the shape is similar to that of a tombstone.
- Reciprocal ST segment depression in the inferior leads (II, III and aVF).
According to the American College of Cardiology/American Heart Association guidelines for STEMI, there must be “new ST segment elevation at the J point in at least two contiguous leads of ≥ 2 mm (0.2 mV) in men or 1.5 mm (0.15 mV) in women in leads V2-V3 and/or of ≥ 1 mm (0.1 mV) in other contiguous chest leads or the limb leads.” This means 1 millimeter in any two contiguous leads, except leads V2 or V3, where the elevation must be 2 mm in men or 1.5 mm in women.
See the full 12-lead ECG example below and a few more at the bottom.
The ECG findings of an old anterior wall MI include the loss of anterior forces, leaving Q waves in leads V1 and V2. This is a cause of poor R wave progression, or PRWP.
Here is an example of an old anterior wall MI:
Note: To distinctly say that an old anterior wall MI is present on the ECG, there must be no identifiable R wave in lead V1 — and usually V2, as well. If there is an R wave in V1 or V2, the term poor R wave progression, but not old anterior wall MI, can be used.
On rare occasions, persistent ST segment elevation may be seen in V1 and/or V2, indicating a ventricular aneurysm — a known complication of a myocardial infarction. Visit Left Ventricular Aneurysm ECG Review or Left Ventricular Aneurysm Topic Review. An example of an old anterior myocardial infarction with a left ventricular aneurysm is below.
1. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
2. Surawicz B, et al. AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram. Circulation. 2009;doi:10.1161/CIRCULATIONAHA.108.191095.