The relationship between circadian rhythm of blood pressure and vascular dysfunction in essential hypertension.

Objective: This study aimed to explore whether circadian rhythm of blood pressure is associated with brachial-ankle pulse wave velocity (baPWV) and brachial artery flow-mediated dilation (FMD) in patients with essential hypertension.
Method: This cross-sectional study included 4,217 patients with essential hypertension who completed 24-hour ambulatory blood pressure monitoring, baPWV, and FMD. BaPWV and FMD were measured to evaluate arterial stiffness and endothelial dysfunction. Participants were divided into dipper, non-dipper, and reverse dipping groups according to the nocturnal systolic blood pressure dipping percentage.
Results: In this study, baPWV was highest in the reverse dipping groups, followed by non-dipper and dipper groups (1667.11 ± 327.90 vs. 1613.88 ± 325.11 vs. 1577.45 ± 306.15 cm/s, P  < .001) and FMD gradually increased (4.41 ± 2.87 vs. 4.70 ± 2.84 vs. 4.92 ± 2.79%, P  = .001). baPWV and FMD were significantly associated with declining nocturnal systolic blood pressure (SBP). Interestingly, FMD (β = 0.042, P  = .014) was only positively associated with a drop in nocturnal SBP decline in patients <65 years of age. Whereas baPWV was consistently negatively associated with nocturnal SBP decline regardless of age (β = -0.065, P  < .001, age <65 years; β = -0.149, P  = .002, age ≥ 65). Receiver operating characteristics (ROC) curves analysis showed areas under the curve (AUC) of baPWV/FMD for predicting circadian rhythm of blood pressure are 0.562/0.554 with a sensitivity of 51.7%/53.9% and specificity of 56.4%/53.4.
Conclusion: Impairment of baPWV and FMD were correlated with abnormal circadian rhythm of blood pressure in essential hypertension, suggesting a decrease in nighttime SBP may associate with endothelial function and arterial stiffness.