What ECG change is expected in myocardial infarction?

What ECG change is expected in myocardial infarction?

• A. ST wave elevation
• B. T wave inversion
• C. U waves
• D. Prolonged QT interval

Answer: (A)

In acute myocardial infarction, especially a STEMI where the infarct affects the full thickness of the heart muscle, the ECG shows ST-segment elevation in the leads over the affected area. This happens because the injured myocardium creates a current of injury that shifts the resting potential, so during the early phase of the ECG cycle the ST segment is carried above the isoelectric baseline. You’ll see this elevation in contiguous leads corresponding to the infarct, often with reciprocal ST depression in opposite leads. T wave inversion and other changes can occur as the situation evolves, but the classic early sign of an acute transmural infarct is ST-segment elevation. U waves are not characteristic of MI, and a prolonged QT interval is not the defining feature.

In acute myocardial infarction, especially a STEMI where the infarct affects the full thickness of the heart muscle, the ECG shows ST-segment elevation in the leads over the affected area. This happens because the injured myocardium creates a current of injury that shifts the resting potential, so during the early phase of the ECG cycle the ST segment is carried above the isoelectric baseline. You’ll see this elevation in contiguous leads corresponding to the infarct, often with reciprocal ST depression in opposite leads. T wave inversion and other changes can occur as the situation evolves, but the classic early sign of an acute transmural infarct is ST-segment elevation. U waves are not characteristic of MI, and a prolonged QT interval is not the defining feature.