Sgarbossa's Criteria for MI in Left Bundle Branch Block
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. Sgarbossa's is a well accepted approach at determining which LBBB are having an MI.
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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.
Addition of the assigned points.
Facts & Figures
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.
Recently, Stephen Smith modified Sgarbossa Criteria looking at excessively discordant ST elevation and changing this slightly. This has been references by Dr. Sgarbossa herself (see third reference) and should now be included in Sgarbossa criteria.
Original/Primary ReferenceSgarbossa 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.
ValidationSmith 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.
Other ReferencesCai 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.
About the Creator
Elena Sgarbossa, MD, is a board certified cardiologist and works as an independent medical and scientific writer/editor/translator. She is also a member of Editorial Board of the Journal of Electrocardiology. Dr. Sgarbossa previously worked in clinical cardiology and research at Rush-Presbyterian Medical Center and Cleveland Clinic.
To view Dr. Elena Sgarbossa's publications, visit PubMed