Relations of Arterial Stiffness With Postural Change in Mean Arterial Pressure in Middle-Aged Adults: The Framingham Heart Study

Abstract

Impaired regulation of blood pressure on standing can lead to adverse outcomes, including falls, syncope, and disorientation. Mean arterial pressure (MAP) typically increases on standing; however, an insufficient increase or a decline in MAP on standing may result in decreased cerebral perfusion. Orthostatic hypotension has been reported in older people with increased arterial stiffness, whereas the association between orthostatic change in MAP and arterial stiffness in young- to middle-aged individuals has not been examined. We analyzed orthostatic blood pressure response and comprehensive hemodynamic data in 3205 participants (1693 [53%] women) in the Framingham Heart Study Third Generation cohort. Participants were predominantly middle aged (mean age: 46±9 years). Arterial stiffness was assessed using carotid-femoral pulse wave velocity, forward pressure wave amplitude, and characteristic impedance of the aorta. Adjusting for standard cardiovascular disease risk factors, orthostatic change in MAP (6.9±7.7 mm Hg) was inversely associated with carotid-femoral pulse wave velocity (partial correlation, r_p=-0.084; P<0.0001), forward wave amplitude (r_p=-0.129; P<0.0001), and characteristic impedance (r_p=-0.094; P<0.0001). The negative relation between forward wave amplitude and change in MAP on standing was accentuated in women (P=0.002 for sex interaction). Thus, higher aortic stiffness was associated with a blunted orthostatic increase in MAP, even in middle age. The clinical implications of these findings warrant further study.

Keywords: arterial pressure; blood pressure; hypotension, orthostatic; pulse wave analysis; vascular stiffness.

Figure 1

Orthostatic change in mean arterial pressure as a function of forward wave amplitude in groups defined by sex-specific tertiles of carotid-femoral pulse wave velocity (CFPWV). Values represent estimated differences in change in mean arterial pressure as a function of forward wave amplitude in a model that adjusted for age, sex, height, BMI, total cholesterol, high density lipoprotein cholesterol, triglycerides, fasting glucose, hemoglobin A1c, current smoking, use of medication to treat hypertension or dyslipidemia, and prevalent diabetes or cardiovascular disease. Values for covariates were fixed at the mean value for the cohort and the range of values plotted correspond to the 5^th and 95^th percentiles of forward wave amplitude. Women had a greater increase in mean arterial pressure than men. However, higher stiffness by either measure was associated with a lower increase in mean arterial pressure upon standing; the relation between forward wave amplitude and change in mean arterial pressure was particularly strong in women. P<0.0001 for sex, P=0.01 for forward wave, P=0.002 for interaction between sex and forward wave, and P<0.001 for CFPWV.