Abstract 8955: Cardiopulmonary Phenotyping of Sex-Based Differences in a Feline Model of HFpEF

Abstract

Introduction: Approximately 50% of all heart failure (HF) diagnoses can be classified as HF with preserved ejection fraction (HFpEF), which has no FDA approved therapies. HFpEF is more prevalent in females compared to males, but the underlying mechanisms for the development as a sex-based disorder are unknown. We previously described how slow progressive pressure overload (PO) in male felines recapitulates the HFpEF phenotype but have not investigated the female phenotype. Hypothesis: Females will develop a less severe HFpEF phenotype compared to males under the same pathological stress. Methods & Results: Male (m) and female (f) domestic short felines (age 2mo) underwent aortic constriction (m: n=11; f: n=10) using a customized pre-shaped band or a sham procedure (m: n=7; f: n=7). Before surgery (baseline), there was no difference in body weight (BW) between groups and lung compliance was not different. Echocardiography revealed no significant difference in the ratio of left atrium to aortic root (LA/Ao), LA ejection fraction (LA EF), left ventricle (LV) ejection fraction, LV wall-thickness, and E/A ratio. By 4mo post-surgery, both males and females had developed cardiac dysfunction and decreased lung compliance. At this time, females had significantly smaller BWs than males. Despite the difference in BW, LV wall thickness and changes in E/A ratio were similar in both sexes in banded vs. shams. Importantly, LV EF did not change in any group. There was a decrease in LA EF and increased LA/Ao in all banded animals. Invasive hemodynamics at 4mo post-surgery showed no differences between sexes for the systolic pressure gradient generated by aortic banding. Banded males had higher LV end-diastolic pressure vs. banded females (m: 15.0±2.7mmHg; f: 8.1±1.9mmHg). However, there was a trend towards prolongation of tau and lower dp/dt min in banded females, suggestive of abnormal relaxation. There were no differences between banded males and females in heart weight/BW or cardiomyocyte cross-sectional area and both developed fibrosis. Conclusions: Exposure of male and female felines to PO resulted in similar cardiac hypertrophy, fibrosis, and decreased lung compliance. Females had lower LVEDP than males suggesting they may be protected from diastolic dysfunction.