Left Bundle Branch Block

Definition:

Conduction abnormality of the left ventricle, causing wide QRS complexes and ST changes mimicking STEMI.

History/Physical Exam:

History of CAD, hypertension, previous MI.

Key 12-Lead Features:

• QRS > 120ms
• Prominent S (V1-3) / prominent R (V5/6, I/aVL)
• ST Elevation common in V1-4
• See Sgarbossa Criteria for Diagnosing MI in the presence of LBBB

12 Lead Sample

References

1. Da Costa D, et al. Bradycardias and atrioventricular conduction block. 2002. [Link]