Which EKG change is indicative of myocardial ischemia?

The presence of ST segment depression on an EKG is a significant indicator of myocardial ischemia, which occurs when there is a reduced blood flow to the heart muscle, often due to narrowed or blocked coronary arteries. This change reflects a mismatch between the oxygen supply and the demand of the heart tissue. During periods of ischemia, the affected myocardial cells cannot maintain normal action potentials, leading to the changes in the ST segment.

ST segment depression typically appears during exertion or increased heart workload and may resolve with rest or supplemental oxygen as blood flow returns to normal. Recognizing this change is crucial in diagnosing conditions like angina or acute coronary syndrome, as it can guide further evaluation and management of the patient’s cardiovascular health.

In contrast, the other options provided do not indicate ischemia. For example, upright P waves indicate a normal atrial depolarization, QT interval shortening is generally associated with conditions like hypercalcemia or certain medications, and peaked P waves can signal right atrial enlargement or other atrial pathology rather than ischemic changes. Understanding these nuances underscores the importance of identifying ST segment depression as a key sign of myocardial ischemia.