Left anterior fascicular block
Diagnostic criteria include:
- Left axis deviation (-45 or more)
- QRS 80-110ms
- rS in II, III, and aVF
- qR in I and aVL
- Increased QRS voltage in the limb leads
LAFB vs LPFB
|Axis||Left axis deviation||Right axis deviation|
|I and aVL||Upright QRS||Downgoing QRS|
|III||Downgoing QRS||Upright QRS|
- Considered benign finding
- LAFB may increase risk of AF, CHF, and death
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008.
- Mattu A and Brady WJ. ECG's for the Emergency Physician. BMJ Books. Sep 19, 2003.
- Mandyam MC, et al. Long-term outcomes of left anterior fascicular block in the absence of overt cardiovascular disease. JAMA. 2013; 309(15):1587-1588.