Janek Salatzki and co workers (1) present evidence that there may more at work in idiopathic LBBB (ILBBB) than simply dysynchrony. It is generally accepted than LBBB alone can cause heart failure (HF) and myocardial remodeling. Salazki present data using an innovative technique,determination of septal flash volume, which they believe suggests that a contractile impairment is a necessary condition for remodeling while dysynchrony alone may induce heart failure.
The authors state that another explanation for their data is that the LBBB group with remodeling were simply patients who had the LBBB longer. The retrospective nature of their data does not enable them to exclude that alternative.
The first description of ILBBB causing heart failure was in 2005 and one of the speculations at that time was that there was an underlying cardiomyopathy , i.e. it just was not simply the dysynchrony operative in causing HF to develop but a disease process affecting both muscle and conduction fibers.The various case series demonstrating a favorable and often super respond in lone LBBB patients treated with either BiV or conduction system pacing suggests that desynchrony is the dominant problem.
1)Salatski,J et al Presence of contractile impairment appears crucial for structural remodeling in idiopathic left bundle branch block Journal of cardiovascular resonance.2021 april 23
2). Blanc J et al. Evaluation of left bundle branch block as a reversible cause of non-ischemic dilated cardiomyopathy with severe heart failure. A new concept of left ventricular dyssynchrony-induced cardiomyopathy. Europace 2005;7,604
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