Proximal occlusion of the left anterior descending artery can result in new right bundle branch block (RBBB), with or without left anterior fascicular block (LAFB), because the right bundle branch and the anterosuperior fascicle receive the same blood supply. In addition, a patient with chronic RBBB can also have an infarction, and in this scenario the bundle branch block will simply coexist with the infarction.

Electrocardiographic Criteria

  • RBBB does not interfere with the diagnosis of OMI, and the ECG criteria for OMI are the same as for patients without bundle branch block
  • ST elevation in the anterior, inferior, and lateral leads can be easily diagnosed in patients with RBBB

ECG in Infarction With Right Bundle Branch Block

Electrocardiogram showing infarction with right bundle branch block

Acute myocardial infarction with right bundle branch block. New RBBB arising in the setting of infarction indicates greater severity and proximal occlusion of the left anterior descending artery. Note the ST-segment elevation across the extensive anterior wall.

References

  1. Scheffer MK, De Marchi MFN, de Alencar Neto JN, Felicioni SP. Eletrocardiograma de A a Z. São Paulo: Manole, 2024.
  2. Horton CL, Brady WJ. Right bundle-branch block in acute coronary syndrome: diagnostic and therapeutic implications for the emergency physician. Am J Emerg Med. 2009;27(9):1130–41.
  3. Nikus K, Birnbaum Y, Fiol-Sala M, Rankinen J, et al. Conduction Disorders in the Setting of Acute STEMI. Curr Cardiol Rev. 2020;17(1):41–9.
  4. Thygesen K, Alpert JS, Jaffe AS, Chaitman BR, et al. Fourth universal definition of myocardial infarction (2018). Eur Heart J. 2018;40(3):237–69.