This electrocardiogram shows an acute anterior wall myocardial infarction. The characteristic feature demonstrated here is the marked ST segment elevation in the precordial leads that reflect the anterior wall. In addition, the ST segment elevation in leads I and aVL is consistent with involvement of the lateral wall. There is also some reciprocal ST segment depression in leads that reflect the inferior wall, especially in lead III. The ST segment elevations are diagnostic of acute anterior wall injury that almost always evolves to infarction in the absence of early intervention.