STEMI vs NSTEMI
How to tell STEMI and NSTEMI apart when a board question makes them look alike.
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ST elevation in at least two contiguous leads on the first ECG is the immediate branch point to emergent reperfusion.
Side by side
Persistent ST-segment elevation of at least 1 mm in two contiguous leads or a STEMI equivalent requires immediate reperfusion activation.
Ischemic symptoms with elevated troponin but without diagnostic ST elevation supports NSTEMI and early risk-stratified invasive strategy.
Acute complete coronary occlusion causes transmural ischemia that is time-critical for myocardial salvage.
Subtotal coronary occlusion causes subendocardial necrosis and biomarker rise without classic ST elevation criteria.
STEMI diagnosis is ECG-based first; troponin may be initially normal but typically rises above assay cutoff such as troponin I over 0.04 ng/mL within 3 to 6 hours.
NSTEMI has dynamic troponin elevation above the 99th percentile with ischemic symptoms and ECG changes such as ST depression or T-wave inversion without persistent ST elevation.
The trap
A common error is waiting for troponin confirmation before cath lab activation when clear ST elevation is already present. Another miss is posterior STEMI misread as NSTEMI when V1 to V3 show horizontal ST depression and tall R waves, which should prompt posterior leads V7 to V9.
The repair move
Next best step: activate PCI immediately with door-to-balloon goal under 90 minutes and give aspirin 325 mg chewed plus a P2Y12 inhibitor and anticoagulation unless contraindicated. If PCI cannot be achieved within 120 minutes and symptom onset is within 12 hours, give fibrinolysis when no contraindication exists, then transfer for early invasive care.
Try a free question
CoreA 58-year-old man has crushing substernal chest pain for 40 minutes. BP 100/62 mm Hg, HR 106/min, oxygen saturation 95% on room air. ECG shows 2 mm ST elevation in V2 to V4. What is the next best step in management?
Show answer and explanation
Answer: A. Activate emergent PCI pathway immediately. Diagnostic ST elevation with ischemic pain requires immediate reperfusion and should not wait for serial biomarkers.
Why the other choices are tempting
- B. Wrong because delaying for troponin confirmation risks avoidable myocardial loss.
- C. Wrong because unstable acute coronary occlusion is not managed as an outpatient.
- D. Wrong because analgesia without reperfusion fails to treat the culprit occlusion.
- E. Wrong because focal contiguous ST elevation with classic ischemic pain is not typical pericarditis.
Flashcards
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Which ECG finding mandates immediate STEMI reperfusion rather than NSTEMI observation?
At least 1 mm ST elevation in two contiguous leads or a STEMI equivalent requires emergent reperfusion strategy.
How does NSTEMI usually appear on ECG compared with STEMI?
NSTEMI lacks persistent diagnostic ST elevation and may show ST depression or T-wave inversion with positive troponin.
Quick answers
What is the fastest way to tell STEMI from NSTEMI?
ST elevation in at least two contiguous leads on the first ECG is the immediate branch point to emergent reperfusion.
What is the key clue for STEMI?
Persistent ST-segment elevation of at least 1 mm in two contiguous leads or a STEMI equivalent requires immediate reperfusion activation.
What is the key clue for NSTEMI?
Ischemic symptoms with elevated troponin but without diagnostic ST elevation supports NSTEMI and early risk-stratified invasive strategy.
What is the common trap with STEMI vs NSTEMI?
A common error is waiting for troponin confirmation before cath lab activation when clear ST elevation is already present. Another miss is posterior STEMI misread as NSTEMI when V1 to V3 show horizontal ST depression and tall R waves, which should prompt posterior leads V7 to V9.