SIRT7 and fibrosis: Increased levels of the ketone body β-hydroxybutyrate promoted histone acetylation of the Sirt7 promoter and activated Sirt7 transcription, leading to cardiomyocyte apoptosis and cardiac fibrosis (Xu et al., 2021), suggesting that microbial metabolites served as epigenetic and metabolic regulators of arrhythmogenesis.