What does the ST segment indicate on an ECG?

The ST segment on an electrocardiogram (ECG) is crucial for assessing the heart's electrical activity after the ventricles have depolarized. It represents the phase of early ventricular repolarization, which occurs after the QRS complex. During this time, the myocardial cells are recovering from the depolarization that led to ventricular contraction, preparing the heart for the next cycle of electrical activity.

Monitoring the ST segment is vital for identifying abnormalities such as ischemia or infarction. Elevation or depression of the ST segment can indicate pathological changes in the heart, suggesting the need for further clinical evaluation.

In light of this, while ventricular depolarization is represented by the QRS complex and atrial repolarization is reflected in the T wave, the ST segment's primary significance lies in its role in early ventricular repolarization.