The ambulatory arterial stiffness index is not a measure of arterial stiffness in a selected group of children at risk of secondary hypertension

The ambulatory arterial stiffness index (AASI) has emerged as an ambulatory blood pressure monitoring (ABPM) measure of stiffness and is supposedly useful in younger subjects. The objective of our study was to evaluate the relationships between the AASI and indices of arterial stiffness in a pediatric population at risk of hypertension. Cross-sectional study of children/adolescents (8–18 years) whose pulse wave velocity (PWV: carotid-to-femoral cf-PWV and heart-finger hf-PWV), augmentation index (AIx; normalized at 75 bpm: AIx75), systemic arterial stiffness (aortic pulse pressure/stroke volume, measured via pulse contour analysis), and ABPM were measured. At-risk populations were potential vascular remodeling (preterm birth, n = 44 and chronic kidney diseases, n = 7) and potential hyperkinetic causes (congenital central hypoventilation syndrome, n = 14 and psychostimulant treatment, n = 10). The mean age of the 75 participants was 12.3 ± 2.5 years (34 girls), and their mean AASI was 0.33 ± 0.17. AASI did not correlate with cf-PWV, hf-PWV, AIx, or systemic arterial stiffness. In contrast, the AASI correlated with both systolic and diastolic BP dipping at night (R = − 0.23; p = 0.048 and R = − 0.33; p = 0.004, respectively). Systemic arterial stiffness correlated with hf-PWV and AIx75 (R = 0.35; p = 0.004 and R = − 0.34; p = 0.013, respectively). Based on ABPM, 15/75 (20%) participants had hypertension, and they had higher cf-PWV than participants without hypertension (5.64 ± 0.70 vs 4.92 ± 0.78 m/s, p = 0.002) and not different AASI values (0.34 ± 0.14 vs 0.32 ± 0.18, p = 0.756). Conclusion: AASI is not a measure of arterial stiffness in children at risk of secondary hypertension. What is Known: • The ambulatory arterial stiffness index (AASI) has emerged as an ambulatory blood pressure monitoring measure of stiffness and is supposedly useful in younger subjects. Few adult studies validated the concept of AASI as a marker of arterial stiffness, and recent studies suggested the need for AASI measurement in pediatric subjects. What is New: • Our cross-sectional study, which used different methods for the assessment of vascular remodeling, shows that the AASI is not a reliable marker of arterial stiffness in children at risk of secondary hypertension. Graphical Abstract