Optimal blood pressure values to reduce arterial stiffness, an analysis from UK Biobank

Abstract Introduction Increased arterial stiffness is a powerful independent risk factor for adverse cardiovascular events. While pulse wave velocity has been used extensively as a biomarker of vascular health reflecting functional and structural arterial changes, its use in clinical practice was limited. The Arterial Stiffness Index (ASI) simplifies the assessment of arterial stiffness using a pulse waveform obtained at the finger with an infrared sensor with BP measured using an automated device. Age and raised blood pressure (BP) are major contributors to increased arterial stiffness, but time trajectories of ASI in the general population and optimal BP values to reduce arterial stiffening are scarcely known. Purpose To establish temporal changes of ASI and identify BP values associated with longer-term improvement of arterial stiffness. Methods The study analysed data from UK Biobank (baseline n=154,684, median age 54, interquartile range (IQR) [40-72] years; 52% female; 91% white, 28% hypertension). ASI was measured using PulseTrace PCA2 device (CareFusion, USA) at baseline with measurements repeated in 4617 individuals after a median follow up of 3.0, IQR [2.8-3.3] years. BP was measured during the same time points. Multivariable (adjusted for age, sex, diabetes, and use of BP-lowering drugs) linear regression was used to determine the association of BP with baseline and the association of BP and ASI changes during follow up. ROC analysis was used to determine BP values associated with improvement (reduction) of ASI during follow up. Continuous data are presented as median [IQR] and compared using Wilcoxon test. R software packages were used for analyses. Results At baseline, ASI (m/sec) was higher in those with systolic BP (SBP) >140 mmHg (9.60 [7.15-11.85] vs. 8.67 [6.77-10.70] for SBP ≤140 mmHg, p<0.001) and in those with diastolic BP (DBP) >90 mmHg (9.90 [7.48-12.16] vs 8.81 [6.78-10.90] for DBP ≤90 mmHg, p<0.001). Both SBP and DBP were independently associated with ASI at baseline (B±SE 0.08±0.02 and 0.79±0,29m, respectively; p<0.001 for both). During follow up, the population level SBP remained unchanged (change 0 [-8 - 8] mmHg), with some reduction in DBP (-1.0 [-6.0 - 3.5]) mmHg. SBP reduced in 2234 (48%) and DBP in 2517 (55%). ASI increased by 0.56 [-1.46 - 2.78] m/s, with ASI reduction observed in 1935 (42%). An increase in DBP but not in SBP was independently associated with an increase in ASI (B±SE DBP 0.04±0.01, p<0.001; SBP 0.007±0.006, p=0.22; DBP 0.04±0.007, p<0.001). The baseline BP was predictive of the magnitude of changes in ASI: SBP 132 mmHg (AUC 0.53, p=0.001) and DBP 83 mmHg (AUC 0.54, p<0.001). Conclusions Increased arterial stiffness is associated with higher BP, particularly with higher DBP. Raised ASI is reversible, providing BP is adequately controlled with optimal BP being <132/83 mmHg.