What might indicate a myocardial infarction on an ECG?

The presence of ST segment elevation or depression along with T wave changes on an ECG is a significant indicator of myocardial infarction. When a myocardial infarction occurs, it can affect the heart's electrical activity, leading to characteristic changes in the ECG tracing.

ST segment elevation often signifies that there is ongoing damage to the heart muscle due to a lack of blood supply, which is commonly seen in ST-Elevation Myocardial Infarction (STEMI). Conversely, ST segment depression can indicate myocardial ischemia, suggesting that areas of the heart are not receiving enough blood, especially during periods of increased oxygen demand. Additionally, T wave inversions or abnormalities can point to changes in the heart muscle’s recovery phase after ischemia. Therefore, the combination of these changes makes the detection of myocardial infarction on an ECG far more reliable and indicative than other findings.

While flat T waves and ST segment depression can occur with ischemia, they are often less definitive signs of an acute myocardial infarction compared to ST segment elevation and T wave changes. A normal heart rate and rhythm would not indicate any issues related to myocardial infarction, and a prolonged PR interval is generally associated with atrioventricular block rather than ischemic changes.