Cardiac Fibrosis in right Atrial tissue is not different in male Pasifika and Pākehā Cardiac surgery patients in Aotearoa

ABSTRACT

@#Cardiovascular disease (CVD) is the leading cause of death worldwide and in New Zealand. However, a significant inequality in the burden of CVD amongst different ethnic groups exists with a 2 - 3-times higher CVD mortality rate in Pasifika compared to Pākehā. It is unknown whether a difference in cardiac fibrosis might underly this ethnic inequality in CVD mortality. To address this, we determined cardiac fibrosis, myocardial fat infiltration, and the expression of some key miRNAs (miR-15a, miR-15b, miR- 34a and miR-153) in right atrial appendages of Pacific Islanders and New Zealand European patients (n=21) undergoing cardiopulmonary bypass surgery. Cardiac fibrosis was measured by total collagen deposition identified by Picro Sirius Red staining, whereas fat accumulation was determined via Oil-Red-O staining. No differences in cardiac fibrosis were observed between ethnic groups (Collagen Pasifika 23.4±12.5% vs. New Zealand European 29.4±13.2%, one-way ANOVA, p=0.17). Similarly, no differences were observed in accumulation of lipid nor the expression of the miRNAs examined (-15a, - 15b, -34a and -153) between different groups. In conclusion, the earlier requirements for surgical intervention for CVD of Pasifika in Aotearoa might not be explained by differences in miRNAs associated with cardiomyocyte loss, fibrosis or myocardial lipid infiltration. New and Noteworthy Despite the established significant inequality in the burden of CVD amongst the Pasifika compared to the Pākehā (New Zealand European) populations in Aotearoa, we found no difference inhistopathological (cardiac fibrosis, lipid infiltration, or associated pro- or anti-f