Gut dysbiosis and heart failure: navigating the universe within

Alternations in gut microbial composition (i.e. loss of microbial diversity or 'gut dysbiosis') have been associated with heart failure with reduced ejection fraction (HFrEF). It has also been suggested that increased chronic low-level inflammation and immune system dysregulation seen in patients with HFrEF could be related to gut dysbiosis and increased intestinal permeability. Hence, the concept of modulating gut microbial composition with the goal of reducing systemic inflammation and controlling HFrEF progression has generated a substantial interest in the scientific community. However, several challenges to the gut dysbiosis theory remain as the exact gut microbial composition in HFrEF patients in these studies is not the same and a common microbiome linked to HFrEF is not yet established. With the advances in culture independent sequencing techniques it has also become evident that the gut microbiome may be much more diverse than previously believed. Further, various 'omic' technologies have enabled us to appreciate the potential role of gut microbial metabolites in various physiological processes in the host. Hence, identification of specific gut microbial metabolites may offer an alternative approach at solving this gut microbiome-HFrEF puzzle. In the current review, we evaluate the concept of gut symbiosis, the potential role of gut dysbiosis in systemic inflammation and HFrEF, and finally highlight the challenges faced by the gut dysbiosis theory in HFrEF and provide a framework for the possible solutions.