ST elevation

ST elevation is when the ST segment of the ECG rises above its normal baseline, lifting upward instead of sitting flat. In the right setting it is one of the most urgent patterns in all of cardiology, because it can signal a heart attack in progress, with a major coronary artery suddenly blocked.

The lift reflects severe, full-thickness injury to a region of heart muscle that has lost its blood supply. The injured zone holds a different electrical charge than healthy muscle during the ST segment, and that imbalance pushes the tracing upward in the leads that face the affected wall. Which leads show the elevation tells the team roughly which part of the heart, and which artery, is involved.

Not every ST elevation is a heart attack, however. Pericarditis, certain normal variants, and other conditions can also raise the ST segment, so the pattern is read together with symptoms, its distribution across leads, and any change over time. When ST elevation does indicate an acute blockage, restoring blood flow quickly — by stent or clot-dissolving drug — is the central goal, because time lost is muscle lost.