ABSTRACT
The ST segment lies between the end of the S wave and the start of the T wave. Normally, the ST segment is isoelectric, meaning that it lies at the same level as the electrocardiogram’s baseline, the horizontal line between the end of the T wave and the start of the P wave. ST segment elevation should never be ignored, as it often indicates a serious problem that warrants urgent attention. ST segment elevation can represent anything from a potentially life-threatening condition to a normal variant, making it particularly important to identify the cause. The ST segment elevation of vasospastic angina may be accompanied by tall ‘hyper-acute’ T waves or, sometimes, T wave inversion. Elevation of the ST segment is sometimes seen in the anterior chest leads as a variant of normal, and is referred to as ‘high take-off’ or ‘early repolarization’.
