STEMI and STEMI Equivalents, i.e. Who Needs the Cath Lab Now!

1. The ACC/AHA Criteria (1) (2) 

ST-elevation in 2 contiguous leads that is:

  • Men < 40: 2.5 mm ST-elevation in V2 or V3, 1 mm in any other lead

  • Men > 40: 2.0 mm ST-elevation in V2 or V3, 1 mm in any other lead

  • Women: >1.5 mm ST-elevation in V2 or V3, 1 mm in any other lead

STEMI's have a 90-minute door-to-balloon time mandate from the Center for Medicare Services (CMS). 

  • False positives: left ventricular hypertrophy, left ventricular aneurysm, benign early repolarization, brugada, pericarditis, LBBB, ventricular paced rhythm

  • False negatives: subtle ST-elevation, ST-depression with ongoing symptoms, difficult ECGs, STEMI equivalents.

Anterolateral STEMI, note reciprocal depressions in III and aVF, Culprit artery LAD.

Inferior STEMI, ST-elevation in II, III, aVF, ST-depression in I, aVL.

Lateral STEMI, ST-elevation I, aVL, also V5, V6, ST-depression II, III, aVF, and V1, V2, V3 (posterior extension?).

Tricky case from Dr. Stephen Smith’s ECG blog (5):

M in 40s, CAD w/1 stent, 2 hr CP, radiates to elbows with walking, pain free at presentation, initial Trop .02. Initial ECG is as below:

Interpretation: <1mm ST-elevation inf. leads, ST-depression in aVL!

4 hrs after symptom onset, trop 2 is 0.42, pain free, ECG 2:

6 hrs later, pain returns and the patient gets a 3rd EKG:

Interpretation: ST-elevation II, III, aVF, ST-depression I, aVL, RCA occlusion.

Lesson? Don't fear the repeat EKG.

The ACC/AHA Criteria Summary

  • V2/V3 cut off varies by age/gender

  • Use the T-P segment for measuring ST deviation

  • Only 70% sensitive and 85% specific for acute coronary occlusion

  • aVL ST-depression may occur in inferior MI before inferior ST-elevation

2. New Left Bundle Branch Block (LBBB)

New LBBB alone is no longer an indication for emergent PCI per the 2013 guidelines. You should consider emergent PCI for LBBB in 3 situations:

1.) Unstable patient (hypotension, pulmonary edema, electrical instability) (3

2.) The Sgarbossa criteria satisfied (4) (5) 

  • In LBBB it is normal to have discordant ST changes and T-wave inversions.
  • Concordant ST segment deviation is abnormal.
    • Concordant ST-elevation of 1 mm in atleast 1 lead or
    • Concordant ST-depression of 1 mm in V1 to V3
  • Also excessively discordant ST-deviation (>5 mm) is abnormal

3.) Smith Modified Sgarbossa Criteria Satisfied (6) 

  • Smith et al modified the 3rd criteria so that rather than using a cut off of 5 mm for significant discordance they instead used a discordant ratio of >25%.
  • Increases sensitivity from 52% to 91% while decreasing specificity from 98% to 90%.

Take Home Points for LBBB

  • New LBBB was not specific enough and led to many false positive cath lab activations. 
  • The Sgarbossa criteria are more specific but not as sensitive and may instead lead to false negatives and denial of PCI to some some patients with AMI. 
  • The modified-Sgarbossa criteria are a more sensitive version but has not yet been externally validated.
  • Your cardiologist may not be familiar with these criteria so you need to be the expert and advocate for your patient!

Some example ECGs

Case 1:

Concordant ST-elevation in I and aVL, concordant ST-depression in III and aVF

Case 2

A More Subtle Sgarbossa Positive ECG.

Case 3: 

An approximately 40 yo male, with no known cardiac history, presents with 20 minutes of anginal chest pain

Subtle sgarbossa positive concordant ST-elevation in aVF, modified-sgarbossa positive discordant ST-elevation in III (1 mm ST-elevation / 3 mm QRS amplitude = 0.33 ratio).

1 min later the patient has a V. Fib arrest.  He is successfully, resuscitated and has this post-arrest ECG...

Now obvious sgarbossa positive concordant ST-elevation in III and aVF, and also concordant ST-depression in aVL.

3. de Winter’s Waves (7) (8)

Can be thought of as a subset of hyper acute t-waves characterized by:

De winter RJ, Verouden NJ, Wellens HJ, Wilde AA. A new ECG sign of proximal LAD occlusion. N Engl J Med. 2008;359(19):2071-3.

  • Tall, symmetric, narrow “dagger like” pre-cordial t-waves taking off like “rockets” from a depressed (1-3 mm) ST segment. 
  • Different from HATWs because there is no ST-depression in HATWs.

Suggestive of acute high grade LAD occlusion (in contrast to sub-acute occlusion of Wellen’s syndrome). Although no ST-elevation it may represent an unstable lesion for which emergent PCI should be considered.  These patients are at high risk for decompensation and may progress to STEMI, therefor you should get serial ECGs.

Case 1 -  33 yo M no PMH with CP that radiates into neck and L arm after a jiu-jitsu match. Patient is sweating and looks awful.

Courtesy Dr. Ari Kestler (San Francisco). de Winter T-waves in V3, V4, and V5, 100% LAD occlusion.

Case 2 - 70 yo male presenting with chest pain for the last 30 minutes

Upsloping ST-depression with de Winter t-waves, admitted for NSTEMI. Courtesy Dr. Nicolas Pineda (Chile).

This patient was admitted to the hospital with the diagnosis of NSTEMI.  ECGs were obtained the following morning...

 Initial Repeat ECG showing loss of pre-cordial R wave progression.&nbsp;Courtesy Dr. Nicolas Pineda (Chile)&nbsp;

Initial Repeat ECG showing loss of pre-cordial R wave progression. Courtesy Dr. Nicolas Pineda (Chile)

Now full blown STEMI, R waves are severely diminished lost, irreparable damage has occurred. Courtesy Dr. Nicolas Pineda (Chile)

4. aVR Elevation with Diffuse ST-depression

In the setting of ischemic chest pain this may indicate left main insufficiency (high grade stenosis) or diffuse multi vessel disease.  Often quoted as indicating left main occlusion, but this may not be accurate. If the left main was truly occluded the patient would probably be in profound cardiogenic shock or dead. (9) 

  • The 2013 AHA/ACC STEMI guidelines list aVR ST-elevation as an indication for thrombolytics when PCI cannot be obtained within 2 hours. (10) 
  • The article they reference (11), defines “occlusion” as any stenosis greater than 50%. 
  • Two mechanisms proposed: Diffuse sub-endocardial ischemia with ST-depression in lateral leads producing reciprocal ST-elevation in aVR, or infarction of the basal septum producing aVR STEMI. (12) 
  • If their pain can be medically managed and are HDS then it may be appropriate to cath the next day. But be sure to discuss with your interventionalist.

Case 1 - Elderly man presenting with chest pain and cardiogenic shock who has a brief episode of VF while on cath table

ST-depression I, aVL, II, aVF, V3-V6, and ST-elevation in aVR. 100% left main occlusion. Example 2

Case 2 - Elderly man with known diffuse CAD who how has an acute GI bleed and chest pain

Interpretation: ST-depression in I, II, aVF, V2-V6 (V2-V3 ST-depression is normal in a RBBB).  Proposed cause: Diffuse sub-endocardial ischemia due to acute blood loss causing demand ischemia (type II NSTEMI). Example 8

5. Wellen’s Syndrome (13)

What is it?  Anginal CP that has now resolved with associated ECG changes, normal to minimally elevated cardiac enzymes, and absence of pathologic q-waves or a loss of precordial R-wave progression. Two ECG patterns described by Wellen’s: pattern A and pattern B

  • Pattern A - biphasic t waves (up then down) in the precordial leads
  • Pattern B - deeply inverted symmetric t waves

Verouden NJ, Koch KT, Peters RJ, et al. Persistent precordial "hyperacute" T-waves signify proximal left anterior descending artery occlusion. Heart. 2009;95(20):1701-6.

Why it matters

  • This is a high risk LAD lesion that was occluded at time of pain but now is open.
  • MI within a mean of 6-8.5 days after admission. 
  • MI occurs within a mean of 21.5 days after symptoms. (15)

How to Manage

  • Be cautious with stress testing. Case report data suggests this can be fatal. (16)
  • Less likely to die with early PCI vs medical therapy or delayed PCI (2.6% vs 17.9%). (17)

Case 1 - 45 yo female brought to the ED via EMS, had chest pain earlier, but has now since resolved

Type A Wellen’s waves in V2-V3. Example 5f

Field ECG from 45 minutes prior...

Anterolateral STEMI with reciprocal inferior depressions. Example 5a

Clinical bottom line for Wellen’s Syndrome:

  • Signifies a high grade LAD lesion until proven otherwise, but be sure to consider other causes of these ecg changes
  • ECG changes may be transient
  • Case reports suggest stress testing can induce MI
  • Early PCI has been shown to improve mortality


  • If the history suggests ACS then but the initial ECG is non-diagnostic then repeat the ECG in 10-15 minutes. ACS is a dynamic process.
  • The idea that STEMIs need emergent PCI and NSTEMIs can wait till the next day is a false dichotomy.
  • If objective evidence of ischemia (concerning history, concerning EKG, + trop) and persistent ischemia (persistent pain or persistent concerning EKG) in spite of maximal medical therapy then emergent cath is needed.
  • Don’t settle for basic ECG skills, you need to be the ECG expert.


  1. O'gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;127(4):529-55.

  2. O'gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;127(4):e362-425.

  3. Dr. Scott Weingart, “Who Needs and Acute PCI with Dr. Steve Smith Part I”, EMCRIT Blog, 5/29/2015,

  4. Life In the Fast Lane Educational Blog,

  5. Dr. Stephen Smith, “Unstable Angina Still Exists”, Dr. Smith’s ECG Blog, 6/18/2015, tp://

  6. Neeland IJ, Kontos MC, De lemos JA. Evolving considerations in the management of patients with left bundle branch block and suspected myocardial infarction. J Am Coll Cardiol. 2012;60(2):96-105.

  7. Sgarbossa EB, Pinski SL, Barbagelata A, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators. N Engl J Med. 1996;334(8):481-7.

  8. Cai Q, Mehta N, Sgarbossa EB, et al. The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: from falsely declaring emergency to denying reperfusion in a high-risk population. Are the Sgarbossa Criteria ready for prime time?. Am Heart J. 2013;166(3):409-13.

  9. Smith SW, Dodd KW, Henry TD, Dvorak DM, Pearce LA. Diagnosis of ST-elevation myocardial infarction in the presence of left bundle branch block with the ST-elevation to S-wave ratio in a modified Sgarbossa rule. Ann Emerg Med. 2012;60(6):766-76.

  10. Dr. Amal Mattu, “Case of the Week June 1 2015”, 6/1/2015, ECG Weekly Blog,

  11. Life In the Fast Lane Blog, “Sgarbossa Criteria”,

  12. Dr. Stephen Smith, “Some Cardiologists are Still Not Familiar with Sgarbossa’s Criteria”, Dr. Smith’s ECG Blog, 10/12/2014,

  13. De winter RJ, Verouden NJ, Wellens HJ, Wilde AA. A new ECG sign of proximal LAD occlusion. N Engl J Med. 2008;359(19):2071-3.

  14. Verouden NJ, Koch KT, Peters RJ, et al. Persistent precordial "hyperacute" T-waves signify proximal left anterior descending artery occlusion. Heart. 2009;95(20):1701-6.

  15. Dr. Amal Mattu, “Case of the Week June 29 2015”, 6/29/2015, ECG Weekly Blog,

  16. Dr. Stephen Smith, “The Difference Between Left Main Occlusion and Left Main Insufficiency”, Dr. Smith’s ECG Blog, 8/2/2014,

  17. O’Gara et al, 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction: Executive Summary, AHA Journal, 12/17/2012, section 4.1

  18. Jong et al, Reciprocal Changes in 12-Lead Electrocardiography Can Predict Left Main Coronary Artery Lesion in Patients With Acute Myocardial Infarction, International Heart Journal, 2/15/2006

  19. Life In the Fast Lane Blog, “Left Main Coronary Artery”,

  20. Dr. Salim Rezaie, “ECG of the Week: Wellen’s Syndrome or STEMI”, 8/14/2014, REBEL EM Blog,

  21. De zwaan C, Bär 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):730-6.

  22. Hanna EB, Glancy DL. ST-segment depression and T-wave inversion: classification, differential diagnosis, and caveats. Cleve Clin J Med. 2011;78(6):404-14.

  23. Sowers N. Harbinger of infarction: Wellens syndrome electrocardiographic abnormalities in the emergency department. Can Fam Physician. 2013;59(4):365-6.

  24. De zwaan C, Bär FW, Janssen JH, et al. Angiographic and clinical characteristics of patients with unstable angina showing an ECG pattern indicating critical narrowing of the proximal LAD coronary artery. Am Heart J. 1989;117(3):657-65.

  25. Life in the Fast Lane Blog, “Wellen’s Syndrome”

  26. Body R, Carley S, Wibberley C, Mcdowell G, Ferguson J, Mackway-jones K. The value of symptoms and signs in the emergent diagnosis of acute coronary syndromes. Resuscitation. 2010;81(3):281-6.

  27. Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294(20):2623-9.