Investigating the gut microbiota in advanced heart failure and cardiac cachexia.

Cardiac cachexia (CC) is associated with advanced heart failure (AHF), characterized by unintentional weight loss (UWL) of fat/muscle. It is exacerbated by right ventricular systolic dysfunction (RVSD). The potential pathogenic role of gut microbiota (GM) changes has not been investigated in CC. We aimed to explore this. Patients with AHF with or without CC/UWL, stable chronic heart failure (HF), and healthy controls (HCs) were recruited following national ethical approval. Fecal bacterial DNA was extracted, quantified, and 16S rRNA gene sequencing was performed. GM composition, alpha, and beta diversity were compared between CC/UWL-AHF and the rest of the cohort (ROC). The secondary analyses compared AHF, HF, and HCs, and patients with and without RVSD. Sixty-seven patients returned samples, including 14 with CC/UWL-AHF. No taxonomic differences were observed between CC/UWL-AHF and ROC. A weak trend toward compositional differences was observed (beta diversity R²  =  0.016, p  =  0.071). No differences were observed in RVSD. Numerous significant GM alterations were observed across the HF spectrum, including changes to Streptococcus spp., Alistipes, and Bacteroides. CC/UWL-AHF may be associated with subtle GM compositional changes. Larger studies are required to investigate this further.