What does ST segment change on an electrocardiogram (ECG) mean?

ST segment changes in electrocardiography (ECG) are a common abnormal finding in clinical cardiology. They typically reflect the myocardial repolarization process and indicate the blood supply to the myocardium. The ST segment refers to the isoelectric line between the end of the QRS complex and the beginning of the T wave. Under normal conditions, it should remain at the baseline; slight deviations may not be clinically significant, but marked elevation or depression suggests certain cardiac abnormalities. Below is a list of possible causes and characteristics of ST segment changes on ECG:

1. Physiological factors: Such as intense physical activity or emotional excitement, which may cause transient ST segment changes.

2. Pathological factors: Including cardiac diseases such as coronary artery disease, myocardial ischemia, heart failure, and myocarditis.

3. Electrolyte imbalances: Caused by systemic conditions such as hyperthyroidism and viral myocarditis.

ST segment depression is commonly seen in non-ST-segment elevation myocardial infarction (NSTEMI), unstable angina, and myocardial ischemia, reflecting a mild to moderate state of myocardial ischemia. However, certain medications such as digitalis and electrolyte disturbances like hypokalemia can also cause ST segment changes.