Longitudinal changes in excess pressure independently predict declining renal function among healthy individuals - A pilot study

Background: Aortic reservoir function independently predicts end-organ damage in cross-sectional analyses. However, longitudinal associations are more important regarding causation, but this has never been examined at rest or in response to light-moderate intensity exercise. The aim of this study was to determine the association between the change in aortic reservoir characteristics, in particular excess pressure integral (P_excess) at rest and in response to exercise and the change in kidney function among healthy individuals followed over time.

Methods: Aortic reservoir function (P_excess and reservoir pressure), aortic stiffness, brachial and central blood pressure (BP), and renal function (estimated glomerular filtration rate [eGFR]) were recorded among 33 healthy individuals (57 ± 9 years; 55% male) at baseline and after an average 3.0 ± 0.3 years.

Results: Over the follow up period, there was a significant increase in resting brachial BP, central BP, P_excess, and aortic stiffness (P < 0.05 all). The change over time in resting P_excess (but not aortic stiffness) was significantly related to the change in eGFR (r = -0.38, P = 0.038) and remained independent of age at follow up, change in 24-hour ambulatory systolic BP and body mass index (β = -0.0300, P = 0.043). There was no association between the change in aortic pulse wave velocity and the change eGFR (P = 0.46) nor were there any associations with exercising hemodynamics.

Conclusions: P_excess is independently associated with a decline in renal function among healthy people followed over 3 years. These novel findings indicate the need to determine the underlying physiological determinants of aortic reservoir function.