The Gut–Heart Axis: A Microbiome-Centered Perspective on Heart Failure

In recent years, gut microbiota has emerged as a central modulator of cardiovascular health and disease. This has led to a transition from the old understanding of cardiovascular pathology as a largely cardiac-centric problem to a systemic, multi-organ process. A growing body of evidence demonstrates that changes in the makeup of gut microbes, generally called dysbiosis, are significant in the development and progression of cardiovascular illnesses, including heart failure. Moreover, there are bidirectional interactions between the failing heart and the gut. In heart failure, impaired hemodynamics and venous congestion further worsen intestinal hypoperfusion and barrier dysfunction in a self-perpetuating cycle that exacerbates dysbiosis and systemic inflammation. The gut-heart axis offers a fresh paradigm for illness progression beyond classical neurohormonal and hemodynamic processes. The gut microbiota acts as an endocrine organ by producing bioactive metabolites such as TMAO (trimethylamine N-oxide), SCFA (short-chain fatty acids) and bile acids, which, via several routes, have a serious impact on host health and disease. This narrative review aims to summarize the current evidence for the gut microbiota as a new cardiovascular risk factor, focusing on biological mechanisms and clinical and epidemiological evidence.