Sgarbossa’s Criteria for MI in Left Bundle Branch Block
Criteria to diagnose acute MI in patients with prior LBBB.
No
Yes
No
Yes
In proportion to the preceding S-wave (or R-wave) as determined by 1) at least 1 mm of ST elevation (or depression) AND 2) an ST/S ratio ≤-0.25:
No
Yes
| Patient’s score | Range | Clinical advice |
|---|---|---|
| 0 | 0 | 0 |
In Normal for LBBB and placed rhythm – ST and T waves in opposite direction to QRS main vector:
In some cases it is often difficult to identify an MI for patients with existing left bundle branch blocks (LBBB). About 1 in 200 patients with MI have LBBB. Sgarbossa’s is a well accepted approach at determining which LBBB are having an MI.
| Patient’s score | Range | Clinical advice |
| 0-2 points | In the original Sgarbossa criteria, a score of <3 typically is not considered diagnostic of acute MI, but also does not rule out MI. In concerning patients, repeating ECGs and cardiac enzymes may be helpful, along with cardiology consultation. NOTE! the Modified Sgarbossa Criteria (which changes the third criteria) does not use the points system, it is positive if any criteria are met. | |
| ≥3 points | A score of 3 or more is 90% specific for MI. NOTE! the Modified Sgarbossa Criteria (which changes the third criteria) does not use the points system, it is positive if any criteria are met. |
Addition of the assigned points.
| Concordant ST elevation > 1mm in leads with a positive QRS complex | Yes | +5 |
| Concordant ST depression > 1 mm in V1-V3 | Yes | +3 |
| Excessively discordant ST elevation (or depression) in leads with a negative QRS In proportion to the preceding S-wave (or R-wave) as determined by 1) at least 1 mm of ST elevation (or depression) AND 2) an ST/S ratio ≤-0.25 | Yes | +2 |
A score of 3 or more is 90% specific for MI, but not sensitive (36%). Therefore a positive score should be acted upon, but a lower score can not by itself rule out MI – maintain a high index of suspicion if the presentation is consistent with MI.
0-2 points. In the original Sgarbossa criteria, a score of <3 typically is not considered diagnostic of acute MI, but also does not rule out MI. In concerning patients, repeating ECGs and cardiac enzymes may be helpful, along with cardiology consultation.
NOTE: the Modified Sgarbossa Criteria (which changes the third criteria) does not use the points system, it is positive if any criteria are met.
As mentioned, Sgarbossa’s criteria does not rule out myocardial infarction in patients with pre-existing Left Bundle Branch Block (it is not sufficiently sensitive), but in patients with ≥ 3 points, it is specific for MI.
Literature:
1. Sgarbossa EB, Pinski SL, Barbagelata A, Underwood DA, Gates KB, Topol EJ, Califf RM, Wagner GS. 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 Feb 22;334(8):481-7. Erratum in: N Engl J Med 1996 Apr 4;334(14):931. PubMed PMID: 8559200. https://pubmed.ncbi.nlm.nih.gov/8559200/?dopt=Abstract
2. 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 Dec;60(6):766-76. doi: 10.1016/j.annemergmed.2012.07.119. Epub 2012 Aug 31. Erratum in: Ann Emerg Med. 2013 Oct;62(4):302. PubMed PMID: 22939607. https://pubmed.ncbi.nlm.nih.gov/22939607/
3. Cai Q, Mehta N, Sgarbossa EB, Pinski SL, Wagner GS, Califf RM, Barbagelata A. 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 Sep;166(3):409-13. doi: 10.1016/j.ahj.2013.03.032. Epub 2013 Aug 6. PubMed PMID: 24016487. https://pubmed.ncbi.nlm.nih.gov/24016487/
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