ECG of the Week - 26th November 2018 - Interpretation

The following ECG is from a 67 yr old male who presented following an episode of syncope. He had a recent hospital admission for dizziness.

Click to enlarge

Rate:

• 60 bpm

Rhythm:

• Sinus arrhythmia

Axis:

• LAD

Intervals:

• PR - Prolonged (~240ms)
• QRS - Prolonged (130ms)
• QT - 400ms

Additional:

• RBBB Morphology

Interpretation:

• Bifascicular block with pr prolongation
• RBBB
• LAFB

Many people refer to the combination of bifascicular block with a 1st or 2nd degree AV block as a 'trifascicular block', this term is obviously incorrect as a block of all three fascicles should result in complete heart block. 
Further to the inaccurate nature of the term the AHA 2009 Recommendations for the Standardization and Interpretation of the Electrocardiogram specifically recommended the term 'trifascicular block' not be used due to the variation in anatomy and pathology producing the pattern.
On this surface ECG it isn't possible to tell whether all three fascicles are affected as the pr prolongation may be due to disease at the AV node, the left posterior fascicle, or the His bundle.
The AHA 2008 guidelines for PPM insertion are clear that an incidental bifascicular block with pr prolongation in the asymptomatic patient does not warrant PPM insertion (LoE: B, Class III recommendation) but in the setting of syncope are an indication for PPM insertion.
Given history of syncope this patient was admitted under cardiology referral for PPM insertion.

References / Further Reading

Life in the Fast Lane

• 'Trifascicular Block'

Textbook

• Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.