Examining Circadian Blood Pressure Patterns: Investigating the Interplay between Dipper Status and Arterial Stiffness Metrics

Background: Compared with dippers, hypertensive individuals with a nondipping nocturnal blood pressure (BP) pattern, often present with heightened target organ damage and a bleaker cardiovascular prognosis, influenced by arterial stiffness. Tonometric pulse wave velocity (PWV) and Augmentation index (AI) have been confirmed as a non-invasive method for arterial stiffness evaluation. The purpose of this study was to assess the relationship between nocturnal blood pressure dipping and arterial stiffness in the hypertensive subjects. Methods: This was a retrospective study of patients underwent ambulatory blood pressure monitoring (ABPM) between April 2021 and April 2022 at our institution. 41 subjects with essential hypertension were included, mean age 55.6 (42% female, 58% male). BP measured by ambulatory monitoring every 20 min between 07:00 am and 23:00 pm and every 30 min at night, throughout 48 hours with a Mobil-o-graph device. Carotid-femoral PWV and AI also measured as an index of aortic stiffness, by using the Mobil-o-graph which uses a validated transfer function. Dipping was defined as a 10-20% fall in nocturnal BP; extreme dipping as greater than 20%, nondipping as less than 10%, and reverse-dipping as 0% at most fall in nocturnal BP. Results: The relationship between PWV and percent of fall in nocturnal SBP (percent of dipping) had negatively related with univariate generalized linear model (coefficient = -0.148, p-value = 0.007). Following multivariate adjustment for age, gender, mean arterial pressure and AI, percent of dipping becomes a variable without significant effect to model (coefficient = -0.408, p-value = 0.110). Age and percent of dipping has significant negative relationship (coefficient = -0.145, p-value = 0.0247) and age is strongly positively related with PWV (coefficient = 0.134, p-value = 0.000001). When multivariate adjustment is made for gender, mean arterial pressure and AI, percent of dipping remains significant variable to model (coefficient = -0.126, p-value = 0.009) Conclusion: Percent of fall in nocturnal SBP has significant negative correlation with PWV. When adjusted with age, percent of fall in nocturnal SBP becomes insignificant variable. This is because age is a confounding variable to multivariate model. Elderly patients have less percent of fall in nocturnal SBP which leads to higher PWV.