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Modified Sgarbossa Criteria: Ready for Primetime?


Modified Sgarbossa Criteria TitleThe recognition of ST-segment elevation myocardial infarction (STEMI) in the presence of left bundle-branch block (LBBB) remains difficult and frustrating to both emergency medicine physicians and cardiologists. According to the 2004 STEMI guidelines, emergent reperfusion therapy was recommended to patients with suspected ischemia and new LBBB however, the new 2013 STEMI guidelines made a drastic change by removing this recommendation. Several papers have recently been published discussing a modified Sgarbossa’s criteria and a new algorithm to help decrease false cath lab activation and/or fibrinolytic therapy, but are they ready for primetime?

What were the old guidelines for LBBB and STEMI activation?

  • 1996 and 2004 American College of Cardiology/American Heart Association (ACC/AHA): Class I indication if symptoms < 12 hours1,2
  • 2012 European Society of Cardiology (ESC): Class Ia indication if symptoms < 12 hours3

Original Sgarbossa Criteria

  • Concordant ST-segment elevation ≥ 1 mm in any lead (5 points)
  • Concordant ST-segment depression ≥ 1 mm in lead V1 – V3 (3 points)
  • Discordant ST-segment elevation ≥ 5 mm in any lead (2 points)
Sgarbossa Criteria

Image from 4

How accurate are the old Sgarbossa Criteria? 

In detecting culprit coronary occlusion on angiography, the rate of false activation with STEMI and presumed new LBB was:

  • Larson et al: 44%5
  • Chang et al: 80.8%6
  • Jain et al: 86%7

Ideally, diagnostic tests for life-threatening conditions (i.e. AMI) need to be highly sensitive.  The reason the original Sgarbossa criteria are limited in clinical practice is the low sensitivity (20%).  This is why a new LBBB alone is no longer a criteria for emergent cath lab activation. Recently, Steven Smith, MD from Dr. Smith’s ECG Blog published a new criterion to replace the third component of the original Sgarbossa Criteria using the ST/S ratio instead of discordant ST-elevation ≥ 5mm. 

 What are the new modified Sgarbossa Criteria?

  • Concordant ST-segment elevation ≥ 1 mm in any lead
  • Concordant ST-segment depression ≥ 1 mm in lead V1 – V3
  • Discordant ST/S Ratio ≤ -0.25

ST-S Ratio 2

How should the modified Sgarbossa Criteria be used in initial evaluation of patients with suspected AMI with LBBB?4

  • Suspected patient with AMI with LBBB should have emergent primary PCI or fibrinolysis if:
    • Hemodynamic instability or acute heart failure (Validated), or
    • Sgarbossa score ≥ 3 (Validated), or
    • ST/S ratio ≤ -0.25 (Proposed, NOT Validated)
AMI & LBBB Algorithm 2

Image from 4

Limitations of the modified Sgarbossa Criteria and the proposed new algorithm

  • The ST/S ratio study is a very small study (33 vs 129 ECGs)
  • More complex, making the modified criteria and algorithm harder to remember
  • Need a prospective, externally validated study to confirm clinical application of the modified Sgarbossa Criteria

Take Home Point

The Modified Sgarbossa Criteria is more sensitive than the original Sgarbossa Criteria for predicting AMI in the presence of LBBB, but needs an external validation study before we can begin to apply it.

Antman E, Anbe D, Armstrong P, et al. ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction–executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1999 guidelines for the management of patients with acute myocardial infarction). J Am Coll Cardiol. 2004;44(3):671-719. [PubMed]
Ryan T, Anderson J, Antman E, et al. ACC/AHA guidelines for the management of patients with acute myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction). J Am Coll Cardiol. 1996;28(5):1328-1428. [PubMed]
Task F, Steg P, James S, et al. ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J. 2012;33(20):2569-2619. [PubMed]
Cai Q, Mehta N, Sgarbossa E, 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):409-413. [PubMed]
Larson D, Menssen K, Sharkey S, et al. “False-positive” cardiac catheterization laboratory activation among patients with suspected ST-segment elevation myocardial infarction. JAMA. 2007;298(23):2754-2760. [PubMed]
Chang A, Shofer F, Tabas J, Magid D, McCusker C, Hollander J. Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients. Am J Emerg Med. 2009;27(8):916-921. [PubMed]
Jain S, Ting H, Bell M, et al. Utility of left bundle branch block as a diagnostic criterion for acute myocardial infarction. Am J Cardiol. 2011;107(8):1111-1116. [PubMed]
Salim Rezaie, MD

Salim Rezaie, MD

ALiEM Associate Editor
Clinical Assistant Professor of EM and IM
University of Texas Health Science Center at San Antonio
Founder, Editor, Author of R.E.B.E.L. EM and REBEL Reviews
  • Graham Walker

    I’ve tried to include some of this in the MDCalc Sgarbossa’s Criteria calculator after emailing with Stephen about it. Did you make those graphics yourself, Salim?

    • Christopher

      They look to be derived from the figures in reference #7.

    • Salim R. Rezaie

      Hello Graham,

      The images with the QRS Complexes are derived from: #7 on the reference list by Q Cai et al. I have modified the images with some text at the bottom to explain them a little bit better.


  • VinceD

    I love to see that Sgarbossa’s criteria is evolving and they’re including Dr. Smith’s research, but to really make my dreams come true I hope they drop the scoring system on their next iteration. That box could be replaced by a simple “Concordant ST-elevation or depression present?” decision and still have almost the same results, while also making the whole thing a bit more clinically useful and less likely to scare folks away.

    • Salim R. Rezaie

      Hey Vince,
      I agree with the numbers not being part of the Sgarbossa Criteria. A more simplified way may be:

      Concordant = “Bad”
      Disconcordant = ST/S Ratio if < or = -0.25 = "Bad"


  • NICE post by Salim. To follow-up on Salim’s title – What IS “ready for prime time” – are the following concepts:
    i) The majority of patients with LBBB who present to an ED for evaluation of chest discomfort do not have acute coronary occlusion. The patients we want to identify are the less than 10% of LBBB patients who DO have acute occlusion – since these are the ones who clearly benefit from acute reperfusion.

    ii) The ECG may help to identify a surprising number of these patients with acute occlusion. Primary ST elevation (= concordant ST elevation – or ST elevation in leads that shouldn’t have ST elevation) is the best predictor of acute occlusion.

    iii) The benefit of the Smith-Modified Sgarbossa Criteria of excessive discordance by abnormal ratio – is that it provides a method to account for excessive ST deviation when QRS amplitude is increased (the original Sgarbossa criteria did not do this). When assessed in conjunction with History and the overall pattern of the ECG – there will often be suggestive clues despite LBBB in those patients who do have acute occlusion.

    iv) Remember that most LBBB patients who present to an ED are not having an acute STEMI. If they are hemodynamically stable and chest pain is controlled – then acute reperfusion offers little. This is why the simple finding of LBBB should NO LONGER be indication to activate the cath lab.

    v) As stated by Vince and others – the point score adds little …. I find it counterproductive – since so many interpreters seem obsessed with counting points rather than attending to the overall pattern of the 12 lead.

    • Salim R. Rezaie

      Hello Ken,
      Thank you as always for the pearls of ECG wisdom. I agree the big reason LBBB was removed from the guidelines was because the majority were not true STEMIs, but the 10 – 20% that are still need early reperfusion. Finally, your next to last point is key…STEMI = ECG changes + symptoms + CE positive. If a patient is not having symptoms and not hemodynamcally unstable it most likely not a STEMI.


  • Ken

    Do you know if you can use the criteria in the setting of a ventricularly paced rhythm?

    • Salim R. Rezaie

      Hey Ken,
      Great question. The article makes no mention of ventricularly paced rhythms. As a matter of fact there is no mention if these patients were included or excluded from the study. I know that the original Sgarbossa Criteria could be used with paced rhythms. I have actually emailed the primary author of the article to see if I can get a more definitive answer on the modified Sgarbossa Criteria and paced rhythms. When I get an answer I will be sure to comment on this post.


    • Salim R. Rezaie

      Hello Ken,
      So I talked with Amal Mattu and Stephen Smith and both agreed that pacers were not tested with the new ST/S ratio. That being said, probably could be used with pacers, but as far as EBM goes has not been studied. Hope this helps.