Association Between Long-Term Blood Pressure Variability and 10-Year Progression in Arterial Stiffness: The Multiethnic Study of Atherosclerosis

Abstract

Experimental studies conducted on animal and human endothelium suggested that higher systolic blood pressure (SBP) variability reduces bioavailability of nitric oxide and increases vascular smooth muscle cell proliferation. These vascular wall changes could stiffen the arterial wall. Using data from the Multiethnic Study of Atherosclerosis, we investigated the association between long-term SBP variability and 10-year percent change in arterial stiffness among 1122 individuals (mean age 57 years, 46% males at baseline) who were not taking antihypertensive medications. Within-individual standard deviation, variability independent of the mean, and coefficient of variation of SBP across 5 visits were used to capture long-term SBP variability. Carotid arterial stiffness was measured using distensibility coefficient and Young's elastic modulus at baseline and after a mean of 9.5 years of follow-up (visit 5). In a multivariate linear regression model, individuals in the fifth quintile as compared with those in the first quintile of standard deviation, variability independent of the mean, and coefficient of variation of SBP had a 9.8% (95% confidence interval [CI] -17.0%, -2.7%), 6.4% (95% CI -13.2%, 0.4%), and 8.7% (95% CI -15.4%, -1.9%) higher decline in distensibility coefficient and a 27.5% (95% CI 15.8%, 39.3%), 25.8% (95% CI 14.7%, 36.9%), and 27.9% (95% CI 16.8%, 39.1%) higher progression in Young's elastic modulus, respectively, after 10 years of follow-up. Linear trends in the decline of distensibility coefficient and progression of Young's elastic modulus were observed across the quintiles of SBP variability indices. These findings suggest that higher long-term SBP variability may be a risk factor for arterial stiffness progression independent of mean BP.

Keywords: Young’s elastic modulus; arterial stiffness; blood pressure variability; cohort study; distensibility coefficient; race/ethnicity.

Figure 1

Association between systolic BP variability indices and ten-year percent change in carotid artery DC (A) and YEM (B) by race. Adjusted for age, sex, study center, mean arterial pressure when exposure was SD, DC/YEM, and menopausal status at baseline, and averaged pack years, alcohol intake, physical activity, BMI, heart rate, total cholesterol, HDL, GFR, C-reactive protein, mean arterial pressure when the exposure was SD of systolic BP, and cumulative exposure to systolic BP across visits 1 to 5 when exposures were SD and CV of systolic BP, and diabetes status across visits 1 to 5. Abbreviations: CV, coefficient variation, DC, distensibility coefficient; SBP, systolic blood pressure; SD, standard deviation; VIM, variability independent of the mean; YEM, Young’s elastic modulus. P-value: *<0.05, †<0.01, ‡<0.001.

Figure 2

Association between systolic BP variability indices and ten-year percent change in carotid artery YEM (A) and DC (B) by age. Adjusted for sex, race/ethnicity, study center, mean arterial pressure when exposure was SD, DC/YEM, and menopausal status at baseline, and averaged pack years, alcohol intake, physical activity, BMI, heart rate, total cholesterol, HDL, GFR, C-reactive protein, mean arterial pressure when exposure was SD of systolic BP, cumulative exposure to systolic BP across visits 1 to 5 when exposures were SD and CV of systolic BP, and diabetes status across visits 1 to 5. Abbreviations: CV, coefficient variation, DC, distensibility coefficient; SBP, systolic blood pressure; SD, standard deviation; VIM, variability independent of the mean; YEM, Young’s elastic modulus. P-value: *<0.05, †<0.01, ‡<0.001.