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Posterior Electrical Axis Deviation Is Associated With Future Development of Left Bundle Branch Block: A UK Biobank
Mohammad Kayyali1, Ana Mincholé2, Martin Bishop1
1School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.
JACC. Advances
|June 18, 2026
Summary
Posterior electrical axis deviation can help identify individuals at risk for developing left bundle branch block (LBBB). This finding may improve risk stratification for future LBBB development.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Left bundle branch block (LBBB) is a cardiac conduction abnormality linked to cardiovascular dysfunction.
- Current electrocardiogram (ECG)-based definitions of LBBB, primarily using QRS duration (QRSd), have limitations in predicting its development.
Purpose of the Study:
- To investigate if changes in the electrical axis can identify individuals at risk for developing LBBB.
- To assess the electrical axis as a predictor of incident LBBB.
Main Methods:
- Retrospective analysis of 35,749 UK Biobank participants without pre-existing cardiovascular disease.
- Cardiac magnetic resonance imaging and 12-lead ECG data were used to compute electrical axis metrics.
- Kaplan-Meier analysis and adjusted Cox proportional hazards models assessed associations between electrical axis and LBBB development.
Main Results:
- Individuals who developed LBBB were older, more likely to have hypertension, and had a significantly more posterior electrical axis compared to the event-free group.
- A lower electrical axis (posterior deviation) was independently associated with an increased risk of incident LBBB.
- Combined high QRS duration and low electrical axis significantly elevated LBBB risk (4-fold increased hazard).
Conclusions:
- Posterior deviation of the transverse electrical axis is a valuable marker that complements QRS duration in identifying individuals at risk for LBBB.
- The electrical axis appears to reflect early conduction abnormalities, potentially aiding in the risk stratification for future LBBB development.
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