Abstract 12632: Relationships Between Circadian Ambulatory Systolic Blood Pressure Variability With Subclinical Atherosclerosis in Healthy Middle-Aged Individuals

Abstract

<p><strong>Background:</strong> Short-term fluctuations in blood pressure (BP) as measured by 24-hr ambulatory BP monitoring (ABPM) is associated with subclinical atherosclerosis in the general population. However, whether short-term blood pressure variability (BPV) in the day versus night-time has differential effects on the development of subclinical atherosclerosis is uncertain.</p><p><strong>Methods and Results:</strong> We investigated the relationship between mean 24-hr BP and BPV parameters with common carotid artery intima-media thickness (CIMT) in 305 middle-aged Chinese (mean age 54±7years, 45% male) free from hypertension, hyperlipidaemia, diabetes or cardiovascular diseases. Subclinical atherosclerosis with elevated CIMT was defined as >75th percentile of CIMT of the overall study cohort. Linear regression models adjusted for age, sex, body mass index and smoking status revealed significant associations between office, day- and night-time mean SBP, day-time SBP standard deviation (SD) and coefficient of variation (CV) with elevated CIMT (all p<0.05). As shown in the <em>Table</em>, logistic regression analysis demonstrated that only ABPM day-time mean SBP (odds ratio [OR]:2.54, 95% confidence interval [95%CI]:1.29-5.00), night-time mean SBP (OR:3.23, 95%CI:1.67-6.22), night-time mean DBP (OR:2.27, 95%CI:1.16-4.42), day-time SBP CV (OR:0.47, 95%CI:0.26-0.86) and night-time SBP SD (OR1.94, 1.05-3.58) predicted the occurrence of subclinical atherosclerosis (all p<0.05).</p><p><strong>Conclusions:</strong> In healthy middle-age individuals without known hypertension, mean day and night-time SBP as measured using ABPM provided the strongest positive predictive value for elevated CIMT. Interestingly, increase day-time SBP CV versus night-time SBP SD have opposite effects on CIMT, suggesting circadian changes in SBP might have distinct contributions to the development of subclinical atherosclerosis.</p>