What does a flattened or inverted T wave indicate?

A flattened or inverted T wave is primarily indicative of myocardial ischemia. When there is a lack of blood flow and oxygen to the heart muscle, the repolarization process—reflected by the T wave on an EKG—can be affected, resulting in these abnormal T wave appearances. Ischemia can cause changes in the T wave morphology due to alterations in the ionic currents that occur during cardiac repolarization, making it a key marker for identifying potential heart issues related to reduced blood supply.

In contrast, flattened or inverted T waves are not typical for normal heart function, as healthy hearts usually exhibit well-defined, positive T waves. While hyperkalemia can lead to characteristic changes such as peaked T waves, it's not specifically associated with T wave flattening or inversion. Atrial enlargement, on the other hand, is more commonly indicated by changes in the P wave morphology rather than T wave changes, making them less relevant in this context.