Sgarbossa's criteria

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Sgarbossa's criteria are a set of electrocardiographic findings generally used to identify myocardial infarction (also called acute myocardial infarction) in the presence of a left bundle branch block (LBBB) or a ventricular paced rhythm.[1]

Myocardial infarction (MI) is often difficult to detect when LBBB is present on ECG. A large clinical trial of thrombolytic therapy for MI (GUSTO-1) evaluated the electrocardiographic diagnosis of evolving MI in the presence of LBBB.[2] Among 26,003 North American patients who had a myocardial infarction confirmed by enzyme studies, 131 (0.5%) had LBBB. A scoring system, now commonly called Sgarbossa criteria, was developed from the coefficients assigned by a logistic model for each independent criterion, on a scale of 0 to 5. A minimal score of 3 was required for a specificity of 90%.

Sgarbossa's criteria[edit]

Three criteria are included in Sgarbossa's criteria:[2]

  • ST elevation ≥1 mm in a lead with a positive QRS complex (ie: concordance) - 5 points
  • concordant ST depression ≥1 mm in lead V1, V2, or V3 - 3 points
  • ST elevation ≥5 mm in a lead with a negative (discordant) QRS complex - 2 points

≥3 points = 90% specificity of STEMI (sensitivity of 36%)[2]

Usefulness[edit]

A high take-off of the ST segment in leads V1 to V3 is well-described with uncomplicated LBBB, such as in the setting of left ventricular hypertrophy. In a substudy from the ASSENT 2 and 3 trials, the third criteria added little diagnostic or prognostic value.[3]

A Sgarbossa score of ≥3 was specific but not sensitive (36%) in the validation sample in the original report.[2] A subsequent meta-analysis of 10 studies consisting of 1614 patients showed that a Sgarbossa score of ≥3 had a specificity of 98% and sensitivity of 20%.[4] The sensitivity may increase if serial or previous ECGs are available.[5]

Other methods for detecting AMI in patients with LBBB[edit]

Several other studies have evaluated the usefulness of different ECG findings in diagnosing MI when LBBB is present. Smith et al. modified Sgarbossa's original criteria.[6]

Smith modified Sgarbossa rule:

  • at least one lead with concordant STE (Sgarbossa criterion 1) or
  • at least one lead of V1-V3 with concordant ST depression (Sgarbossa criterion 2) or
  • proportionally excessively discordant ST elevation in V1-V4, as defined by an ST/S ratio of equal to or more than 0.20 and at least 2 mm of STE. (this replaces Sgarbossa criterion 3 which uses an absolute of 5mm)

Wackers et al. correlated ECG changes in LBBB with localization of the infarct by thallium scintigraphy.[7] The most useful ECG criteria were:

  • Serial ECG changes — 67 percent sensitivity
  • ST segment elevation — 54 percent sensitivity
  • Abnormal Q waves — 31 percent sensitivity
  • Cabrera's sign — 27 percent sensitivity, 47 percent for anteroseptal MI
  • Initial positivity in V1 with a Q wave in V6 — 20 percent sensitivity but 100 percent specificity for anteroseptal MI

See also[edit]

References[edit]

  1. ^ Sgarbossa, Elena B.; Pinski, Sergio L.; Gates, Kathy B.; Wagner, Galen S. (1996). "Early Electrocardiographic Diagnosis of Acute Myocardial Infarction in the Presence of Ventricular Paced Rhythm. GUSTO-I investigators". American Journal of Cardiology. 77 (5): 423–424. doi:10.1016/S0002-9149(97)89377-0. ISSN 1062-1458. PMID 8602576. 
  2. ^ a b c d Sgarbossa, Elena B.; Pinski, Sergio L.; Barbagelata, Alejandro; Underwood, Donald A.; Gates, Kathy B.; Topol, Eric J.; Califf, Robert M.; Wagner, Galen S. (1996). "Electrocardiographic Diagnosis of Evolving Acute Myocardial Infarction in the Presence of Left Bundle-Branch Block". New England Journal of Medicine. 334 (8): 481–487. doi:10.1056/NEJM199602223340801. ISSN 0028-4793. PMID 8559200. 
  3. ^ Al-Faleh, Hussam; Fu, Yuling; Wagner, Galen; Goodman, Shaun; Sgarbossa, Elena; Granger, Christopher; Van de Werf, Frans; Wallentin, Lars; W. Armstrong, Paul; et al. (2006). "Unraveling the spectrum of left bundle branch block in acute myocardial infarction: Insights from the Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT 2 and 3) trials". American Heart Journal. 151 (1): 10–15. doi:10.1016/j.ahj.2005.02.043. ISSN 0002-8703. PMID 16368285. 
  4. ^ Tabas, Jeffrey A.; Rodriguez, Robert M.; Seligman, Hilary K.; Goldschlager, Nora F. (2008). "Electrocardiographic Criteria for Detecting Acute Myocardial Infarction in Patients With Left Bundle Branch Block: A Meta-analysis". Annals of Emergency Medicine. 52 (4): 329–336.e1. doi:10.1016/j.annemergmed.2007.12.006. ISSN 0196-0644. PMID 18342992. 
  5. ^ E. B. Sgarbossa (2000). "Value of the ECG in suspected acute myocardial infarction with left bundle branch block". Journal of electrocardiology. 33 Suppl: 87–92. doi:10.1054/jelc.2000.20324. PMID 11265742. 
  6. ^ Smith, Stephen W.; Dodd, Kenneth W.; Henry, Timothy D.; Dvorak, David M.; Pearce, Lesly A. (2012). "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". Annals of Emergency Medicine. 60 (6): 766–776. doi:10.1016/j.annemergmed.2012.07.119. ISSN 0196-0644. PMID 22939607. 
  7. ^ F. J. Wackers (August 1987). "The diagnosis of myocardial infarction in the presence of left bundle branch block". Cardiology clinics. 5 (3): 393–401. PMID 3690603.