NT-proBNP and potential vascular calcification in black and caucasian African men: the SAfrEIC study

Abstract

OBJECTIVE: The N-terminal prohormone B-type natriuretic peptide (NT-proBNP) is a reliable marker of cardiac strain. In hypertensive heart disease, NT-proBNP levels increase and may lose its protective function. Simultaneously, the vasculature is also subject to hemodynamic stress, resulting in vascular matrix remodeling and stiffening which contribute to further cardiac alterations. Alkaline phosphatase (ALP) is a marker of osteoblast activity and is involved in vascular calcification. We explored the link between NT-proBNP and ALP in Black and Caucasian African men. DESIGN AND MAIN OUTCOME MEASURES: This study included 128 Black (mean age, 41.1 years) and 118 Caucasian (mean age, 36.4 years) men. Conventional measurements were acquired along with serum NT-proBNP and ALP. RESULTS: NT-proBNP correlated positively with ALP (r=0.29; p<0.001) in Black Africans, but inversely in Caucasians (r=-0.20; p=0.024). After minimal adjustment (age, body mass index, systolic blood pressure and arterial compliance), the positive significant correlation of NT-proBNP with ALP remained in Black men (r=0.225; p=0.014), whereas significance was lost in Caucasian men. Multiple regression analyses confirmed the independent association of NT-proBNP with ALP in Black men (R2=0.37; beta=0.248; p=0.005), as well as in younger Black men (R2=0.26; beta=0.375; p<0.001; n=96), with no significance in Caucasians. CONCLUSIONS: NT-proBNP is independently and positively associated with ALP in Black African men. This was however not evident in Caucasian men. These results suggest that African men are susceptible to potential early vascular calcification and may develop increased cardiac afterload prematurely.