In a late-stage STEMI, which of the following is most likely to show signs of active necrosis?

In the context of a late-stage ST-Elevation Myocardial Infarction (STEMI), the presence of Q waves is indicative of significant myocardial necrosis. Q waves develop as a result of the heart muscle dying due to prolonged ischemia, which is a crucial aspect of the infarction process. In a late-stage STEMI, the damage to the heart tissue has progressed, leading to the formation of these pathological Q waves. Their appearance on an electrocardiogram (EKG) signifies that a portion of the heart muscle has undergone cell death and is not recovering, which distinguishes it as evidence of active necrosis.

In contrast, other signs mentioned, like ST depression and T wave inversions, can indicate ischemia but may not necessarily point to irreversible damage as they are often seen in prior ischemic episodes or as transient changes. Bradycardia can occur during various cardiac events but does not specifically indicate the presence of necrosis, and a normal EKG would suggest that there is no ongoing ischemic injury or prior necrosis. Hence, the identification of Q waves is a clear and critical marker for recognizing active necrosis in a late-stage STEMI.