What is a permanent EKG change often observed following a myocardial infarction?

A permanent EKG change observed following a myocardial infarction is the presence of ST wave changes. These changes typically manifest as ST segment elevation or depression on the EKG, which are indicators of the myocardial injury that has occurred due to a heart attack. Initially, during an active myocardial infarction, ST elevation can be noted, while subsequent changes may include ST segment depression or changes in the T wave morphology as the heart heals.

These alterations in the ST segment reflect the ischemic changes in the myocardium that result from the infarction. In the long term, even after the acute phase of the infarction has resolved, these changes can remain noticeable on an EKG, signifying that some degree of myocardial damage has occurred.

In contrast, other choices like QT interval prolongation, QRS widening, and flat T waves may not specifically indicate a permanent change tied to past myocardial infarction. While these can result from various cardiac conditions or even from the effects of medications, they are not typically recognized as lasting changes following a myocardial infarction in the context of EKG interpretation.