Non-ST-segment elevation myocardial infarction is described by which of the following?

• A. No ST-segment elevation or Q waves with positive troponin
• B. ST-segment elevation with negative troponin
• C. ST-segment elevation with positive troponin
• D. ST depressions with negative troponin

Answer: (A)

NSTEMI is defined by positive troponin indicating myocardial injury, without ST-segment elevation on the ECG. The ECG in NSTEMI may show ST depression or T-wave inversion rather than the ST elevations seen in STEMI, and there are no new Q waves indicating transmural infarction. So describing NSTEMI as no ST-segment elevation or Q waves with positive troponin fits best. The other patterns align with STEMI (ST elevation with positive troponin) or with unstable angina (troponin not elevated).