Synonyms and Keywords: Sgarbossa criteria; Original Sgarbossa Criteria
Acute myocardial infarction is often difficult to detect when LBBB is present on the electrocardiogram (ECG). A large clinical trial of thrombolytic therapy for AMI (GUSTO-1) evaluated the electrocardiographic diagnosis of evolving acute MI in the presence of LBBB. Among 26,003 North American patients who had an acute myocardial infarction confirmed by enzyme studies, 131 (0.5%) had LBBB. A scoring system, now commonly called Sgarbossa's 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 Calculator
Shown below is the calculator for Sgarbossa's criteria (check all the boxes that apply):
- Score < 3: Not diagnostic of acute MI but does not rule out it
- Score ≥ 3: Diagnostic of acute MI (90% specificity and a 36% sensitivity for STEMI)
Validation and Usefulness
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.
A Sgarbossa's score of ≥ 3 was specific but not sensitive (36%) in the validation sample in the original report. A subsequent meta-analysis of 10 studies consisting of 1614 patients showed that a Sgarbossa's score of ≥ 3 had a specificity of 98% and sensitivity of 20%. The sensitivity may increase if serial or previous ECGs are available.
Other Methods for Detecting AMI in Patients With LBBB
Several other studies have evaluated the usefulness of different ECG findings in diagnosing AMI when LBBB is present. Wackers et al. correlated ECG changes in LBBB with localization of the infarct by thallium scintigraphy. 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
- 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.
- Al-Faleh, Hussam; Fu, Yuling; Wagner, Galen; Goodman, Shaun; Sgarbossa, Elena; Granger, Christopher; Van de Werf, Frans; Wallentin, Lars; W. Armstrong, Paul (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.
- 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.
- 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. PMID 11265742.
- F. J. Wackers (1987). "The diagnosis of myocardial infarction in the presence of left bundle branch block". Cardiology clinics. 5 (3): 393–401. PMID 3690603.