Incomplete reverse remodeling in pulmonary hypertension-induced right ventricular dysfunction in aged mice.

Right ventricular (RV) function is the strongest predictor of survival in pulmonary hypertension (PH) and age-related heart disease; however, no therapies improve RV function. Understanding how the RV undoes pathological remodeling (reverse remodeling) might aid in identifying therapies, particularly in aging populations in which RV failure is significant. Our objective was to determine if the aged RV can undergo reverse remodeling following the resolution of pathological afterload by pulmonary hypertension (PH). We exposed male and female aged (18-21 months) C57BL/6 mice to hypobaric hypoxia (HH) for 4 weeks to model PH before returning the mice to normoxia for three (WK3RR) or six (WK6RR) weeks. HH stimulated RV hypertrophy and fibrosis which were attenuated with WK3RR and WK6RR. Activation of autophagy and anti-fibrotic pathways likely underlie morphological reverse remodeling. However, HH decreased RV systolic function as assessed by fractional area change (FAC) and stroke volume (SV) that were not rescued with normoxia re-exposure. The aged RV can undergo morphological reverse remodeling following the removal of pathological load; however, RV function does not improve. Further investigation into the mechanisms of reverse remodeling may identify potential drug therapies for maladaptive RV remodeling with aging.