LBBB poses a major challenge for ECG interpretation in emergency department patients with chest pain suspected to be ischemic. The secondary ventricular repolarization abnormalities it causes can confound the analysis of ST-segment deviation.

Electrocardiographic Criteria

Sgarbossa Criteria

  • ST elevation ≥ 1 mm concordant with the QRS in any lead
  • ST depression ≥ 1 mm in leads V1, V2 or V3
  • ST elevation ≥ 5 mm discordant with the QRS in any lead

Modified Sgarbossa Criteria

  • ST elevation ≥ 1 mm concordant with the QRS in any lead
  • ST depression ≥ 1 mm in leads V1, V2 or V3
  • ST/S or ST/R amplitude ratio ≥ 0.25 in any lead

Barcelona Algorithm

  • ST deviation ≥ 1 mm concordant with QRS polarity in any lead: ST depression ≥ 1 mm concordant with QRS polarity in any lead or ST elevation ≥ 1 mm concordant with QRS polarity in any lead
  • ST deviation ≥ 1 mm discordant with QRS polarity in any lead with maximal voltage (RS) ≤ 6 mm

New or Presumably New Left Bundle Branch Block

Currently, LBBB in the clinical setting of acute chest pain in the emergency department should not be considered a STEMI equivalent.

ECG in Myocardial Infarction with Left Bundle Branch Block

Coming soon…

References

  1. Scheffer MK, De Marchi MFN, de Alencar Neto JN, Felicioni SP. Eletrocardiograma de A a Z. São Paulo: Manole, 2024.
  2. Antman EM, Anbe DT, Armstrong PW, Bates ER, et al. ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction – Executive summary: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to revise the 1999 guidelines for the management of patients with acute myocardial infarction). Vol. 110, Circulation. 2004. 588–636 p.
  3. Sgarbossa EB, Pinski SL, Barbagelata A, Underwood DA, et al. Electrocardiographic Diagnosis of Evolving Acute Myocardial Infarction in the Presence of Left Bundle-Branch Block. N Engl J Med. 1996;334(8):481–7.
  4. Smith SW, Dodd KW, Henry TD, Dvorak DM, et al. 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;60(6):766–76.
  5. Marco A Di, Rodriguez M, Cinca J, Bayes-Genis A, et al. New electrocardiographic algorithm for the diagnosis of acute myocardial infarction in patients with left bundle branch block. J Am Heart Assoc. 2020;9(14).