The multiscale dynamics of beat-to-beat blood pressure fluctuation mediated the relationship between frailty and arterial stiffness in older adults.

<bold>Background: </bold>Beat-to-beat blood pressure (BP) is an important cardiovascular output and regulated by neurophysiologic elements over multiple temporal scales. The multiscale dynamics of beat-to-beat BP fluctuation can be characterized by "BP complexity" and has been linked to age-related adverse health outcomes. We here aimed to examine whether BP complexity mediates the association between arterial stiffness and frailty.<bold>Method: </bold>This cross-sectional study was completed between January and October 2021. A total of 350 older adults completed assessments for frailty, arterial stiffness ((i.e., average brachial-ankle pulse wave velocity), and beat-to-beat finger BP. The complexity of beat-to-beat systolic (SBP) and diastolic (DBP) BP series were measured using multiscale entropy. The relationships between frailty, BP complexity and arterial stiffness were examined using ANOVA and linear regression models. The effects of BP complexity on the association between arterial stiffness and frailty were examined using mediation analyses.<bold>Results: </bold>Compared to non-frail, pre-frail and frail groups had significantly elevated lower SBP and DBP complexity (F>11, p<0.001), and greater arterial stiffness (F=16, p<0.001). Greater arterial stiffness was associated with lower BP complexity (β<-0.42, p<0.001). SBP and DBP complexity mediated the association between arterial stiffness and frailty (indirect effects>0.28), account for at least 47% of its total effects on frailty (Mediated proportion: SBP: 50%, DBP: 47%).<bold>Conclusion: </bold>This study demonstrates the association between BP complexity and frailty in older adults, and BP complexity mediates the association between arterial stiffness and frailty, suggesting that this metric would serve as a marker to help characterize important functions in older adults. [ABSTRACT FROM AUTHOR]