What ECG changes are commonly observed in a patient with NSTEMI?

In the context of a Non-ST-Elevation Myocardial Infarction (NSTEMI), the most prevalent electrocardiogram (ECG) changes include ST-segment depression and/or T-wave inversion. These abnormalities indicate that there is myocardial ischemia, which is a reduction in blood flow to the heart muscle.

ST-segment depression typically suggests subendocardial ischemia, a hallmark of NSTEMI, which occurs when the heart muscle is not receiving enough oxygen due to a partially blocked artery. T-wave inversion can also be an indication of ischemia, reflecting changes in the repolarization phase of the cardiac cycle due to the weakened state of the myocardial cells.

In contrast, ST-segment elevation is associated with ST-Elevation Myocardial Infarction (STEMI), where full-thickness heart muscle damage is evident due to complete obstruction. Normal sinus rhythm can occur in many cases but is not indicative of the ischemia seen in NSTEMI. Widespread T-wave flattening is more nonspecific and can occur in various conditions, making it less relevant to diagnosing NSTEMI specifically. Therefore, recognizing ST-segment depression and T-wave inversion is crucial for identifying NSTEMI and guiding appropriate intervention.