Which sign on an EKG is most associated with postoperative myocardial infarction (MI)?

A pathologic Q-wave on an EKG is most associated with postoperative myocardial infarction (MI) because it indicates that a significant portion of the heart muscle has undergone necrosis, typically due to a lack of blood supply. After an MI, a Q-wave can become pathologic when it is deeper and wider than what is normally considered within the limits of a healthy heart's electrical activity.

In the context of postoperative patients, especially those who may already have compromised heart function or be at higher risk due to factors such as extensive surgery or pre-existing coronary artery disease, the emergence of a pathologic Q-wave is a significant indicator of an MI. It represents irreversible damage to the myocardial tissue and signifies that the patient has likely experienced a heart attack.

This condition is critical to recognize as it may prompt immediate intervention to manage cardiac complications and improve patient outcomes. Other EKG changes such as ST elevation and inverted T-waves can be indicative of myocardial ischemia or injury, but pathologic Q-waves specifically signal that necrosis has occurred, making them the most pertinent sign following a surgical procedure.