Modified Sgarbossa’s Criteria for MI in Left Bundle Branch Block
An ST/S ratio of 0.20 is also very high and almost as specific as a 0.25 ratio:
In Normal for LBBB and placed rhythm – ST and T waves in opposite direction to QRS main vector:
It’s often difficult to identify an MI for patients with existing left bundle branch blocks (LBBB). About 1 in 200 patients with MI have LBBB. The Modified Sgarbossa’s Criteria is a well accepted approach at determining which LBBB are having an MI.
|Concordant ST elevation >1 mm in leads with a positive QRS complex||No|
|Concordant ST depression > 1 mm in V1-V3||No|
|ST Elevation at the J-point, relative to QRS onset, is at least 1 mm AND has an amplitude at least 25% of the preceding S-wave|
An ST/S ratio of 0.20 is also very high and almost as specific as a 0.25 ratio
Modified Sgarbossa’s Criteria are met if any criteria are positive.
To read Sgarbossa’s Criteria for MI in Left Bundle Branch Block:
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/
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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