Differential effects of visceral and epicardial adiposity on cardiac remodeling and function in indigenous adults

Background Visceral adiposity is an important contributor to heart failure, especially heart failure with preserved ejection fraction. Adipose tissue distribution differs by sex and ethnicity, which may differentially impact heart failure prevalence in specific populations. However, the effects of visceral and epicardial adiposity on cardiac remodeling and function among Indigenous peoples remain unknown. Purpose To examine the impact of visceral and epicardial adiposity on cardiac remodeling and function among Indigenous adults without diagnosed cardiovascular (CV) disease. Methods As part of the Canadian Alliance for Healthy Hearts and Minds First Nations (CAHHM-FN) study, 1302 Indigenous participants aged 18 years or older from eight Nations across Canada underwent magnetic resonance imaging (MRI) in which cardiac parameters, visceral (VAT) and epicardial adipose tissue (EAT) volumes were measured. Demographic and CV risk factors were collected, along with blood samples. Subclinical cardiac remodeling abnormalities were defined by altered left ventricular (LV) concentricity, as indicated by an increased LV mass-to-volume ratio (LVMV). This analysis focused on the Wendat Nation (n= 157). Results Among participants (61% women) with a mean age of 50 ± 10 years, 43% had a body mass index (BMI) ≥ 30kg/m2. Mean LV ejection fraction and LVMV were 51 ± 9% and 0.78 ± 0.18 g/mL, respectively. Despite comparable BMI between sexes, men had higher VAT (101 mL; 95% CI: 88 to 115 mL) and EAT volumes (11.1 mL; 95% CI: 10.1 to 12.1 mL) compared with women (75 mL; 95% CI: 68 to 81 and 9.8 mL 95% CI: 9.2 to 10.5 mL) adjusted for age and height (all p<0.01). Significant correlations between VAT and abnormal cardiac remodeling (increased LVMV) were observed in both sexes (all p<0.01). In contrast, EAT’s association with increased LVMV was confined to women (p<0.01). Moreover, EAT correlated with diminished LV ejection fraction in both sexes (p<0.01), whereas VAT did not show a significant relationship with cardiac functional impairment (p=0.06). In multiple regression models adjusted for age and CV risk factors, VAT remained significantly associated with adverse cardiac remodeling (R2=0.34, p<0.0001). By contrast, EAT was associated with reduced LV ejection fraction (R2=0.21, p<0.001). Conclusion In middle-aged Wendat adults at high CV risk, visceral adiposity was closely linked to adverse cardiac remodeling, whereas epicardial adiposity was independently associated with impaired cardiac function, regardless of age or other CV risk factors. Further research is needed to elucidate the mechanisms linking visceral and epicardial fat with accelerated cardiac aging.