N-STEMI is diagnosed by which combination of findings?

• A. ST-segment elevation on ECG
• B. ST-segment depression on ECG
• C. Elevated troponin without ST elevation
• D. Normal troponin levels

Answer: (C)

NSTEMI is defined by myocardial injury shown by elevated cardiac troponin in the blood, with no ST-segment elevation on the ECG. The troponin rise indicates necrosis, while the lack of ST elevation tells you the infarct is not transmural. ST-segment depression or T-wave changes can occur with NSTEMI but are not by themselves diagnostic without troponin elevation. If troponin is elevated with ST elevation, that would be STEMI; normal troponin would argue against an infarction.