NT-proBNP, race and endothelial function in the Multi-Ethnic Study of Atherosclerosis

Objective Natriuretic peptides (NPs) are hormones with cardioprotective effects. NP levels vary by race; however, the pathophysiological consequences of lower NP levels are not well understood. We aimed to quantify the association between NPs and endothelial function as measured by flow-mediated dilation (FMD) and the contribution of NP levels to racial differences in endothelial function. Methods In this cross-sectional study of 2938 Multi-Ethnic Study of Atherosclerosis participants (34% Caucasian, 20% African-American, 20% Asian-American and 26% Hispanic) without cardiovascular disease at baseline, multivariable linear regression models were used to examine the association between serum N-terminal pro-B-type NP (NT-proBNP) and natural log-transformed FMD. We also tested whether NT-proBNP mediated the relationship between race and FMD using the product of coefficients method. Results Among African-American and Chinese-American individuals, lower NT-proBNP levels were associated with lower FMD, beta=0.06 (95% CI: 0.03 to 0.09; p<0.001) and beta=0.06 (95% CI: 0.02 to 0.09; p=0.002), respectively. Non-significant associations between NT-proBNP and FMD were found in Hispanic and Caucasian individuals. In multivariable models, endothelial function differed by race, with African-American individuals having the lowest FMD compared with Caucasians, p<0.001. Racial differences in FMD among African-Americans and Chinese-Americans were mediated in part by NT-proBNP levels (African-Americans, mediation effect: -0.03(95% CI: -0.05 to -0.01); Chinese-Americans, mediation effect: -0.03(95% CI: -0.05 to -0.01)). Conclusions Lower NP levels are associated with worse endothelial function among African-Americans and Chinese-Americans. A relative NP deficiency in some racial/ethnic groups may contribute to differences in vascular function.