Impact of left bundle branch block and activation pattern on the heart
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Updated: Jul 4, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Ayman A El-Menyar1, Sayed M Abdou
1Department of Cardiology and Cardiovascular Surgery, HMC, PO Box 3050, Doha, State of Qatar. elmenyar@yahoo.com
Insights
Left bundle branch block (LBBB) impairs left ventricular function and is a risk factor for cardiac mortality. Further research is needed to clarify LBBB
Area of Science:
- Cardiology
- Cardiac Electrophysiology
Background:
- Left bundle branch block (LBBB) is recognized to compromise left ventricular mechanical function.
- Understanding LBBB's impact on cardiac structure, function, and heart failure management is crucial.
Purpose of the Study:
- To review and synthesize existing literature on the implications of LBBB in patients with heart failure.
- To explore the relationship between LBBB, myocardial function, and clinical outcomes.
Main Methods:
- Comprehensive literature review of pertinent articles published between 1950 and 2007.
- Analysis of epidemiological data and clinical studies investigating LBBB's effects.
Main Results:
- LBBB is an independent risk factor for cardiac mortality.
- LBBB adversely affects cardiac perfusion, systolic and diastolic performance, and hemodynamics.
- Clinical implications depend on QRS characteristics, myocardial pathology, ejection fraction, and NYHA class.
Conclusions:
- The precise role of LBBB as a predictor, cause, or consequence of myocardial dysfunction remains unclear.
- Further research is essential to elucidate these relationships.
- Improved understanding will aid patient selection and timing for cardiac resynchronization therapy in LBBB patients.
Abstract:
Left bundle branch block (LBBB) is known to impair the mechanical function of the left ventricle. For a better understanding of the impact of LBBB on the structure and function of the heart and how this influences the management and outcome in patients with heart failure, we reviewed the most pertinent articles published from 1950 to 2007. Epidemiological studies identified LBBB as an independent risk factor for cardiac mortality. It is not only the morphology or duration of QRS but also the underlying myocardial pathology, ejection fraction or New York Heart Association class that may determine the clinical implications of LBBB. Data indicate that LBBB inversely affects the perfusion, systolic, diastolic performance and hemodynamics of the heart. However, there is no solid evidence answering the question of whether LBBB is a predictor, cause or consequence of myocardial dysfunction. Further studies are warranted for better understanding of these relationships, as this will allow better selection of patients and optimal time for resynchronization therapy in patients with LBBB.
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