NSTEMI vs STEMI
How to tell NSTEMI and STEMI apart when a board question makes them look alike.
NSTEMI is troponin positive without ST elevation criteria; STEMI is territorial ST elevation or equivalent occlusion pattern.
Side by side
Troponin elevation with ischemic symptoms but no ST elevation criteria; ECG may show ST depression or T-wave inversion.
Regional ST elevation in contiguous leads or equivalent pattern suggesting acute coronary occlusion requiring urgent reperfusion pathway.
Myocardial necrosis occurs without full-thickness persistent ST-elevation pattern.
Acute coronary occlusion causes transmural injury current producing ST elevation in a vascular territory.
Positive troponin without STEMI ECG criteria points NSTEMI.
Contiguous territorial ST elevation with reciprocal depression points STEMI.
The trap
STEMI equivalents that present without classic ST elevation are the high-yield trap: posterior MI (ST depression in V1 to V3 with tall R waves, reciprocal of true posterior ST elevation), new left bundle branch block with Sgarbossa criteria, de Winter T waves (upsloping ST depression with tall symmetric T waves in precordial leads), and Wellens syndrome (biphasic or deeply inverted T waves in V2 to V3 indicating critical LAD stenosis). Anatomically, NSTEMI is a subendocardial infarct and STEMI is a transmural infarct, so an occluded coronary that supplies posterior wall can show STEMI physiology with only ST depression on a standard 12-lead.
Watch it explained
The repair move
For ACS labels, use ECG first for STEMI, then troponin to split NSTEMI from unstable angina.
Try a free question
CoreA patient with chest pain has elevated troponin and ST depressions without ST elevation criteria. Which diagnosis is most likely?
Show answer and explanation
Answer: A. NSTEMI. NSTEMI is myocardial infarction with troponin elevation but without ST elevation criteria.
Why the other choices are tempting
- B. STEMI has ST elevation meeting criteria or a STEMI-equivalent pattern.
- C. Unstable angina has no troponin elevation.
- D. Stable angina has predictable exertional symptoms and negative biomarkers.
- E. Prinzmetal angina causes transient vasospastic ST elevation and usually no infarction if brief.
Flashcards
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What ECG finding makes STEMI the immediate label?
ST elevation in contiguous leads or an equivalent acute occlusion pattern should trigger the STEMI pathway.
What lab separates NSTEMI from unstable angina?
Troponin elevation means myocardial necrosis and turns an unstable-angina picture into NSTEMI.
Quick answers
What is the fastest way to tell NSTEMI from STEMI?
NSTEMI is troponin positive without ST elevation criteria; STEMI is territorial ST elevation or equivalent occlusion pattern.
What is the key clue for NSTEMI?
Troponin elevation with ischemic symptoms but no ST elevation criteria; ECG may show ST depression or T-wave inversion.
What is the key clue for STEMI?
Regional ST elevation in contiguous leads or equivalent pattern suggesting acute coronary occlusion requiring urgent reperfusion pathway.
What is the common trap with NSTEMI vs STEMI?
STEMI equivalents that present without classic ST elevation are the high-yield trap: posterior MI (ST depression in V1 to V3 with tall R waves, reciprocal of true posterior ST elevation), new left bundle branch block with Sgarbossa criteria, de Winter T waves (upsloping ST depression with tall symmetric T waves in precordial leads), and Wellens syndrome (biphasic or deeply inverted T waves in V2 to V3 indicating critical LAD stenosis). Anatomically, NSTEMI is a subendocardial infarct and STEMI is a transmural infarct, so an occluded coronary that supplies posterior wall can show STEMI physiology with only ST depression on a standard 12-lead.