Key result
Human atrial fibrillation is not associated with nanoscale remodeling of ryanodine receptor (RyR2) clusters, as cluster size, density, and spatial organization remained unaltered compared to non-AF patients.
Why the study?
Remodeling of RyR2 clusters has been observed in pre-clinical models of AF and heart failure, but whether such remodeling occurs in human cardiac disease remained unclear.
Cross-Sectional (n=27)
Single-blind
No
This study provides the first evidence in human tissue that, unlike in preclinical animal models, nanoscale RyR2 cluster remodeling is not an underlying mechanism of altered channel function in atrial fibrillation.
Challenges applicability of RyR2 remodeling from animal models to human AF; leaves open alternative mechanisms for further study.
release in human atrial fibrillation (AF). Clustering properties of RyR2 have been suggested to alter the activity of the channel, with remodeling of RyR2 clusters identified in pre-clinical models of AF and heart failure. Whether such remodeling occurs in human cardiac disease remains unclear. This study aimed to investigate the nanoscale organization of RyR2 clusters in AF patients - the first known study to examine this potential remodeling in diseased human cardiomyocytes. Right atrial appendage from cardiac surgery patients with paroxysmal or persistent AF, or without AF (non-AF) were examined using super-resolution (dSTORM) imaging. Significant atrial dilation and cardiomyocyte hypertrophy was observed in persistent AF patients compared to non-AF, with these two parameters significantly correlated. Interestingly, the clustering properties of RyR2 were remarkably unaltered in the AF patients. No significant differences were identified in cluster size (mean ∼18 RyR2 channels), density or channel packing within clusters between patient groups. The spatial organization of clusters throughout the cardiomyocyte was also unchanged across the groups. RyR2 clustering properties did not significantly correlate with patient characteristics. In this first study to examine nanoscale RyR2 organization in human cardiac disease, these findings indicate that RyR2 cluster remodeling is not an underlying mechanism contributing to altered channel function and subsequent arrhythmogenesis in human AF.
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Munro et al. (2021) conducted a cross-sectional in Atrial Fibrillation (n=27). Atrial Fibrillation (Paroxysmal or Persistent) vs. Non-AF was evaluated on RyR2 cluster size (number of RyR2 channels) (p=0.5719). Human atrial fibrillation is not associated with nanoscale remodeling of ryanodine receptor (RyR2) clusters, as cluster size, density, and spatial organization remained unaltered compared to non-AF patients.
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