Which electrocardiographic finding is typical of NSTEMI as opposed to STEMI?

Which electrocardiographic finding is typical of NSTEMI as opposed to STEMI?

• A. ST Elevation
• B. ST Depression
• C. T Wave Inversion Only
• D. Q Waves

Answer: (B)

ST segment depression reflects subendocardial ischemia from partial coronary occlusion, which is characteristic of NSTEMI. In NSTEMI, the injury is not full-thickness, so you don’t see the classic ST-segment elevation that indicates transmural injury. Instead, the ECG often shows ST depression (and may have T-wave inversions) in the leads corresponding to the affected territory. ST elevation would point toward STEMI, where a complete wall infarction produces current of injury that elevates the ST segment. Q waves can develop later in infarction but are not the acute hallmark of NSTEMI. So, ST depression is the finding that best differentiates NSTEMI from STEMI.

ST segment depression reflects subendocardial ischemia from partial coronary occlusion, which is characteristic of NSTEMI. In NSTEMI, the injury is not full-thickness, so you don’t see the classic ST-segment elevation that indicates transmural injury. Instead, the ECG often shows ST depression (and may have T-wave inversions) in the leads corresponding to the affected territory. ST elevation would point toward STEMI, where a complete wall infarction produces current of injury that elevates the ST segment. Q waves can develop later in infarction but are not the acute hallmark of NSTEMI. So, ST depression is the finding that best differentiates NSTEMI from STEMI.