Which electrocardiogram finding is often associated with myocardial ischemia?

• A. ST-segment elevation
• B. Normal sinus rhythm
• C. ST-segment depression
• D. QRS complex widening

Answer: (C)

ST-segment depression is a key electrocardiogram finding often associated with myocardial ischemia. This phenomenon occurs when the heart muscle does not receive enough blood flow, particularly during physical activity or stress, leading to a mismatch between oxygen supply and demand. On an ECG, this manifests as a downward deflection of the ST segment from the baseline, which indicates potential ischemic changes occurring within the heart.

When myocardial cells are deprived of oxygen, they may not conduct electrical impulses efficiently, resulting in alterations that can be observed on an ECG during both stress testing and resting states. In contrast, other options may indicate different cardiac conditions. For instance, ST-segment elevation typically suggests an acute myocardial infarction, where there is a complete obstruction of blood flow. Normal sinus rhythm indicates a healthy electrical conduction system without ischemic impairment, and QRS complex widening may suggest ventricular conduction delays or other issues that are not directly specific to ischemia. Thus, ST-segment depression serves as a critical indicator for clinicians evaluating potential myocardial ischemia.