Retrograde Conduction in Left Bundle Branch Block: Insights From Left Bundle Branch Pacing
Shunmuga Sundaram Ponnusamy1, William Basil2, Vithiya Ganesan3
1Department of Cardiology, Velammal Medical College, Madurai, India.
JACC. Clinical Electrophysiology
|June 15, 2024
Summary
Left bundle branch pacing (LBBP) for heart failure (HF) with left bundle branch block (LBBB) showed that bidirectional block is linked to worse outcomes, while unidirectional block predicts better results and improved ejection fraction.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Management
Background:
- Biventricular pacing is standard for heart failure (HF), left bundle branch block (LBBB), and left ventricular (LV) dysfunction.
- Left bundle branch pacing (LBBP) offers an alternative to traditional biventricular pacing.
Purpose of the Study:
- To evaluate retrograde conduction properties of the left bundle branch during LBBP.
- To determine the clinical implications of these conduction properties in patients with nonischemic cardiomyopathy and LBBB.
Main Methods:
- Included patients with nonischemic cardiomyopathy, LBBB, and LV ejection fraction (LVEF) ≤35% undergoing LBBP.
- Assessed retrograde conduction using His potential recording, defining unidirectional and bidirectional block.
- Monitored HF hospitalization, ventricular arrhythmias, and mortality.
Main Results:
- Bidirectional block occurred in 82% of patients, associated with advanced HF and wider QRS.
- Unidirectional block occurred in 18%, linked to narrower paced QRS and higher LVEF.
- Unidirectional block predicted significantly better LVEF normalization (OR 4.1) and fewer adverse events (0% vs 12.5%).
Conclusions:
- Bidirectional block in LBBB correlates with more severe HF symptoms.
- Unidirectional block during LBBP is associated with superior clinical outcomes and improved cardiac function.
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