Does arterial stiffness affect orthostatic hypotension among high-altitude Tibetans?

OBJECTIVE: This study aimed to investigate the association between arterial stiffness and orthostatic hypotension (OH) and orthostatic blood pressure (BP) changes among Tibetans living at high altitude. METHODS: A total of 630 high-altitude Tibetans were included (56.53 ± 10.16 years; 246 men). Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV). OH was defined as a decrease in systolic BP (SBP) >20 mmHg or a decrease in diastolic BP (DBP) >10 mmHg after 1 min or 3 min of moving from supine to standing position. RESULTS: The prevalence of OH in this population was 6.3%. Compared with subjects without OH, the subjects with OH had a higher baPWV (P < 0.001). Multiple logistical regression found that baPWV was significantly associated with the occurrence of OH (OR 1.147, CI 95% 1.028-1.280, P = 0.014). Spearman correlation analysis showed that baPWV was negatively associated with orthostatic changes in SBP and DBP(r = -0.256, P < 0.001 and r = -0.194, P < 0.001, respectively). Further multiple stepwise linear regression analysis showed that baPWV was independently correlated with orthostatic BP changes (SBP: β = -0.599, P < 0.001; DBP: β = -0.333, P < 0.001). Moreover, increased baPWV was correlated with attenuation of orthostatic heart rate changes. No significant association was observed between hematocrit or hemoglobin concentration and OH. CONCLUSION: BaPWV was significantly associated with the occurrence of OH and orthostatic changes in the SBP and DBP, which suggests that arterial stiffness may be a potential mechanism of impaired hemodynamic response to orthostatic challenges among high-altitude Tibetans.