Intermittent Fasting Enhances Right Ventricular Function in Preclinical Pulmonary Arterial Hypertension

BACKGROUND: Intermittent fasting (IF) confers pleiotropic cardiovascular benefits including restructuring of the gut microbiome and augmentation of cellular metabolism. Pulmonary arterial hypertension (PAH) is a rare and lethal disease characterized by right ventricular (RV) mitochondrial dysfunction and resultant lipotoxicity and microbiome dysbiosis. However, the effects of IF on RV function in PAH are unexplored. Therefore, we investigated how IF altered gut microbiota composition, RV function, and survival in the monocrotaline model of PAH. METHODS AND RESULTS: Male Sprague Dawley rats were randomly allocated into 3 groups: control, monocrotaline‐ad libitum feeding, and monocrotaline‐IF (every other day feeding). Echocardiography and invasive hemodynamics showed IF improved RV systolic and diastolic function despite no significant change in PAH severity. IF prevented premature mortality (30% mortality rate in monocrotaline‐ad libitum versus 0% in monocrotaline‐IF rats, P=0.04). IF decreased RV cardiomyocyte hypertrophy and reduced RV fibrosis. IF prevented RV lipid accrual on Oil Red O staining and ceramide accumulation as determined by metabolomics. IF mitigated the reduction in jejunum villi length and goblet cell abundance when compared with monocrotaline‐ad libitum. The 16S ribosomal RNA gene sequencing demonstrated IF changed the gut microbiome. In particular, there was increased abundance of Lactobacillus in monocrotaline‐IF rats. Metabolomics profiling revealed IF decreased RV levels of microbiome metabolites including bile acids, aromatic amino acid metabolites, and gamma‐glutamylated amino acids. CONCLUSIONS: IF directly enhanced RV function and restructured the gut microbiome. These results suggest IF may be a non‐pharmacological approach to combat RV dysfunction, a currently untreatable and lethal consequence of PAH.