After QT prolongation, hyperacute T waves are the earliest-described electrocardiographic sign of acute ischemia, preceding ST-segment elevation.1 Hyperacute T waves are broad-based and symmetrical, usually with increased amplitude and often associated with a depressed ST take off.1 Hyperacute T waves are most evident ...

What causes hyperacute T waves?

What are hyperacute T waves? When a coronary artery becomes occluded, the ECG begins to change over time in a predictable way. The earliest changes are in T-wave shape and size. Within 30 minutes of artery occlusion the T-wave height and width increases.

Can hyperacute T waves be normal?

Previously inverted T-waves can appear normal and upright in the setting of acute vessel occlusion. This is known as pseudonormalization. The tall T-waves associated with hyperkalemia are sharp, pointy, symmetric, and have a narrow base.