Sex differences in the association between aortic stiffness and orthostatic blood pressure changes

Background: Orthostatic blood pressure (BP) changes are associated with cardiovascular disease. Aortic stiffness could affect BP responses to postural changes, but the influence of sex differences on the pressure dependency of arterial stiffness is unclear. Aim: To investigate the relationship between aortic stiffness and orthostatic-BP changes, as well as the influence of sex, which is a moderator of aortic stiffness. Methods: Duplicate BP and aortic stiffness measures were recorded whilst supine and after 2-minutes standing in 271 patients with uncomplicated hypertension (50% female; aged 60 [range 23–73] years). Orthostatic-BP and aortic stiffness changes were determined as the differences from supine to standing. BP was measured by a validated oscillometric device and aortic stiffness was measured by carotid-to-femoral pulse-wave-velocity (XCEL, AtCor Medical, Australia). Results: Orthostatic-systolic BP (SBP) changes averaged –5.4±11.0 (mean±SD) mmHg, with no differences between sexes. However, the orthostatic change in aortic stiffness was higher in men compared with women (1.9±1.2 vs. 1.3±1.2 m/s; P < 0 .05). There were only weak or non-significant associations between supine aortic stiffness and changes in BP for women and men. However, in multivariate analyses, orthostatic change in aortic stiffness was negatively associated with orthostatic-BP change in women, but positively associated in men (B=–1.97 [95%CI: –3.57, –0.37], P=0.02 and B=1.71 [95%CI: 0.34, 3.07], P=0.01, respectively) (Figure). Conclusions: Orthostatic change in aortic stiffness is associated with orthostatic change in SBP among patients with uncomplicated hypertension. However, the direction of this association differs by sex, suggesting that the underlying pressure-dependent mechanisms of arterial stiffness may also differ. A better understanding of these interactions may have relevance to the new approaches of BP treatment and arterial stiffness as a marker of cardiovascular disease.