STEMI Equivalents on ECG: de Winter, Wellens, Posterior MI and aVR
Some acute coronary occlusions never meet the millimetre criteria for ST elevation. Patterns such as posterior MI, de Winter T waves, hyperacute T waves and positive modified Sgarbossa criteria in left bundle branch block or pacing can mark an occluded artery that needs urgent reperfusion. Wellens syndrome is different: it marks a critical LAD stenosis after the artery has reopened.
At a glance
- STEMI criteria miss many acute coronary occlusions, especially of the circumflex artery and the posterior wall.
- Posterior MI: ST depression maximal in V1 to V4, often with tall R waves and upright T waves. ST elevation of 0.5 mm or more in V7 to V9 confirms it.
- de Winter: up-sloping ST depression at the J point in the precordial leads running into tall, symmetric T waves, from proximal LAD occlusion.
- LBBB or a ventricular paced rhythm: use the modified Sgarbossa criteria.
- ST elevation in aVR with ST depression in eight or more leads points to left main or three-vessel disease.
- Wellens: biphasic or deeply inverted T waves in V2 and V3 in a pain-free patient after angina. Arrange early angiography and avoid stress testing.
Criteria
Posterior MI
Horizontal ST depression maximal in V1 to V4, often with tall R waves and upright T waves. ST elevation of 0.5 mm or more in posterior leads V7 to V9, or 1 mm in men under 40, confirms it.
de Winter T waves
Up-sloping ST depression at the J point in the precordial leads, continuing into tall, symmetric T waves, often with slight ST elevation in aVR. Described in proximal LAD occlusion.
Hyperacute T waves
Broad-based, tall, symmetric T waves that are large for the QRS in one coronary territory, often the earliest sign of occlusion.
LBBB or ventricular paced rhythm
A positive modified Sgarbossa rule.
ST elevation in aVR with diffuse ST depression
ST elevation in aVR, often also V1, with ST depression of 1 mm or more in eight or more leads: severe ischemia from left main or three-vessel disease, or a demand state.
Wellens pattern A and B
Pattern A: biphasic T waves in V2 and V3, up then down. Pattern B: deep, symmetric T wave inversion in V2 and V3. Seen in a pain-free interval after angina, with little or no ST elevation and preserved R waves.
What it looks like
de Winter: up-sloping ST depression into a tall T
Wellens A: biphasic T
Wellens B: deep symmetric T inversion
Posterior MI seen in V2: tall R, flat ST depression
How to measure it
- Read ST depression as carefully as ST elevation, and ask where it is greatest.
- ST depression greatest in V1 to V4: record V7 to V9 and look for posterior MI.
- Tall precordial T waves: compare their size with the QRS and with an old ECG.
- LBBB or a paced rhythm: apply the modified Sgarbossa criteria.
- Repeat the ECG every 15 to 30 minutes while pain continues; occlusion comes and goes.
What to do
- Posterior MI, de Winter T waves, hyperacute T waves or a positive modified Sgarbossa rule in a patient with ongoing ischemic symptoms: discuss with interventional cardiology at once. Many centers treat these patterns as STEMI equivalents.
- Wellens pattern: admit, treat as high-risk non-ST-elevation ACS and arrange early angiography. Stress testing can provoke an infarction.
- aVR elevation with diffuse ST depression: urgent cardiology review, and emergency angiography if pain continues or the patient is unstable.
- When the ECG is borderline, serial troponins and a bedside echo looking for a new regional wall motion abnormality help decide.
Pitfalls and mimics
- Waiting for ST elevation to meet millimetre criteria while an occlusion evolves.
- Calling posterior MI anterior ischemia and treating it as non-ST-elevation MI.
- Mixing up the peaked T waves of hyperkalemia and hyperacute T waves.
- Wellens-like T waves have mimics: cocaine, left ventricular hypertrophy with strain, pulmonary embolism, raised intracranial pressure and takotsubo cardiomyopathy.
Key studies
Meyers 2021, J Am Heart Assoc
In 808 high-risk ACS patients, ischemic ST depression greatest in V1 to V4 was 97% specific for occlusion MI. Only 47% of the occlusions it found also met STEMI criteria.
de Zwaan 1982, Am Heart J
Of 145 patients admitted with unstable angina, 26 (18%) had the characteristic precordial T wave pattern. 12 of the 16 who did not have surgery (75%) went on to an extensive anterior MI within weeks.
de Winter 2008, N Engl J Med
Described up-sloping ST depression with tall, symmetric precordial T waves, instead of ST elevation, in patients with acute proximal LAD occlusion.
Thygesen 2018, Fourth Universal Definition of MI
Sets the ECG criteria for ischemia, including posterior leads V7 to V9 and the pattern of aVR elevation with widespread ST depression.
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Questions clinicians ask
What is a STEMI equivalent?
An ECG pattern that signals an acutely occluded coronary artery without meeting the standard ST elevation criteria, such as posterior MI, de Winter T waves or a positive modified Sgarbossa rule in left bundle branch block.
What are de Winter T waves?
Up-sloping ST depression at the J point in the precordial leads that runs into tall, symmetric T waves. They were described in acute occlusion of the proximal left anterior descending artery.
What is Wellens syndrome?
Biphasic or deeply inverted T waves in V2 and V3, found in a pain-free interval after angina, that point to a critical stenosis of the proximal LAD. Without revascularization, many patients go on to an anterior MI.
How do you diagnose a posterior MI on an ECG?
Look for ST depression greatest in V1 to V4, often with tall R waves and upright T waves, then record V7 to V9: ST elevation of 0.5 mm or more there confirms it.
Does ST elevation in aVR mean left main occlusion?
Not always. ST elevation in aVR with widespread ST depression signals severe ischemia, often from left main or three-vessel disease, but it also occurs with tachycardia, anemia and other demand states. Treat it as high risk and involve cardiology urgently.
Sources
- Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Circulation. 2018;138(20):e618-e651. doi.org/10.1161/CIR.0000000000000617
- O'Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction. Circulation. 2013;127(4):e362-e425. doi.org/10.1161/CIR.0b013e3182742cf6
- Rao SV, O'Donoghue ML, Ruel M, et al. 2025 ACC/AHA/ACEP/NAEMSP/SCAI guideline for the management of patients with acute coronary syndromes. Circulation. 2025;151(13):e771-e862. doi.org/10.1161/CIR.0000000000001309
- de Winter RJ, Verouden NJ, Wellens HJ, Wilde AA. A new ECG sign of proximal LAD occlusion. N Engl J Med. 2008;359(19):2071-2073. doi.org/10.1056/NEJMc0804737
- de Zwaan C, Bar FW, Wellens HJ. Characteristic electrocardiographic pattern indicating a critical stenosis high in left anterior descending coronary artery in patients admitted because of impending myocardial infarction. Am Heart J. 1982;103(4 Pt 2):730-736. doi.org/10.1016/0002-8703(82)90480-x
- Meyers HP, Bracey A, Lee D, et al. Ischemic ST-segment depression maximal in V1-V4 (versus V5-V6) of any amplitude is specific for occlusion myocardial infarction (versus nonocclusive ischemia). J Am Heart Assoc. 2021;10(23):e022866. doi.org/10.1161/JAHA.121.022866
Written in our own words by 2 Minute Medicine's physician editors from the sources listed here. The diagrams are schematic drawings made for 2MM, not patient tracings. This page supports, and does not replace, a full ECG reading and clinical judgment.
For health care professionals. Values are for adults unless a page says otherwise.
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