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Lesson

STEMI Equivalents

12 min Cardiac & ECG Skip to quiz

Objective: Transmit a concerning pattern in one territory even without textbook ST elevation. A closed artery can show up without meeting a millimeter rule for ST elevation.

Why this matters

Get and read a 12-lead within about 10 minutes of first medical contact when ACS (acute coronary syndrome, a heart-attack workup) is possible. Do not wait for textbook ST elevation only because a look-alike once fooled you. A STEMI (ST-elevation myocardial infarction) millimeter rule is not the only way a closed artery shows up. Transmit a concerning pattern in one territory and choose a PCI-capable (cath-lab) hospital. You are not the cath-lab reader. Do not hold the tracing.

Key points
  • Get the 12-lead early. Repeat it if symptoms continue. Lead II is not a STEMI call.
  • Transmit it. Use STEMI-alert language: “possible occlusion MI or STEMI equivalent versus a mimic. We need a PCI-capable evaluation.”
  • You do not need to name de Winter (upsloping ST depression into a tall anterior T) perfectly. Say “territorial ST depression with a tall T wave” or “concerning anterior pattern,” then transport.

Clinical sequence

  1. Protect the airway, breathing, and circulation. If ACS is possible, get a 12-lead within about 10 minutes of first medical contact. Do not delay life-saving care to get the tracing.
  2. Look for a territorial story: hyperacute T waves; ST depression with a tall T (de Winter-style anterior occlusion); biphasic or deeply inverted T waves in the precordial leads after pain (Wellens-style proximal LAD warning); or isolated posterior MI (anterior depression and a tall R from the back).
  3. If this is LBBB (left bundle-branch block) or a paced rhythm, do not let uncertainty cancel a STEMI-alert call. Transmit it. Modified Sgarbossa (concordant ST elevation rules) is advanced. “Possible equivalent” is enough.
  4. Give aspirin and choose the hospital per protocol. Repeat the ECG if pain continues. Give oxygen if the sat is under about 90%, not as a default non-rebreather at 98%.

Teaching points

  • Hyperacute T waves: broad, tall T waves in one territory, in a sick patient, can be the first ECG of an occlusion. Transmit it.
  • de Winter-style: upsloping ST depression at the J point into tall, peaked anterior T waves. Talk about it as a possible anterior occlusion. Do not call it only strain.
  • Wellens-style: deep inverted or biphasic T waves in V2–V3, in a patient who is now pain-free or was just in pain, are a high-risk proximal LAD (left anterior descending) warning. They are not “nonspecific T-wave changes.” Transmit and transport. It is not an automatic STEMI alert unless your system lists it.
  • Posterior: anterior ST depression may be a posterior STEMI. Add right-sided or posterior leads if protocol includes them. See the right and posterior lesson.
Verbalize
  • ACS is possible. Get the 12-lead now.
  • This is a concerning pattern in one territory. I am transmitting it as a possible occlusion or STEMI equivalent.
  • LBBB or a paced rhythm still gets a STEMI-alert conversation if the story is ACS.
  • Go to a PCI-capable hospital.

Common errors

  • Waiting for 2 mm of elevation in two leads while an anterior de Winter pattern is already on the paper.
  • Calling Wellens “nonspecific” and staying on scene for another set of vitals.
  • Skipping transmission because the hospital will repeat it.

Practice

One-minute check

Your partner gives you three tracings. First, broad tall T waves in V2–V4 and pain 8/10. Second, a biphasic T wave in V2–V3 and the pain is gone. Third, left bundle-branch block, sweating, and pressure. For each, say the radio sentence. Then practice the same patterns in CardioStrip 12-Lead (Wellens-style, de Winter-style, hyperacute T).

Related: 12-Lead STEMI Recognition, Right-Sided & Posterior MI.

Sources & Further Study

Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.

Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.

Check Your Understanding

Questions drawn only from this lesson. After you check, the key is highlighted. Education practice — not a certification exam.

1. A 12-lead with fat hyperacute T waves in V2–V4 in a diaphoretic patient:
2. Anterior ST depression with tall, peaked T waves (de Winter-style) is best treated as:
3. Deep inverted or biphasic T waves in V2–V3 after chest pain (Wellens-style) mean:
4. LBBB or a paced rhythm with an ACS story:
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