USMLE (United States Medical Licensing Examination) Step 1 Practice Exam 2026 - Free USMLE Step 1 Practice Questions and Study Guide

ST elevation in leads V1-V4 indicates an injury to the anteroseptal wall of the heart, which is primarily supplied by the left anterior descending artery. These leads correspond to the regions of the heart that are positioned anteriorly and towards the septum separating the left and right ventricles.

When there is ST segment elevation observed in these leads, it typically signifies that there is an acute ischemic event, such as a myocardial infarction, affecting the anterior myocardial wall, particularly the portion that lies next to the interventricular septum.

The distinction lies in the location of other regions of the heart: the anterolateral wall would involve more lateral leads, while the inferoposterior wall is associated with leads III and aVF, and the inferolateral wall typically pertains to leads V5-V6 and the inferior leads. Therefore, the specific elevation in V1-V4 unmistakably points to the anteroseptal region being impacted.