Nondipping Pattern and Carotid Atherosclerosis in a Middle-Aged Population: OPERA Study

Abstract

BACKGROUND The lack of dropping in night-time blood pressure of 10% or more (nondipping) seems to associate with cardiovascular risk factors. The relationship between the dipping pattern and atherosclerosis is not clear. The night-time systolic blood pressure (SBP) determines the dipping status. We investigated the connection between intima-media thickness (IMT) and dipping status (dipper, nondipper) taking into account covariates known to associate with hypertension and early atherosclerosis. 900 middle-aged (446 men, 454 women) were studied, 51% of them using blood pressure lowering medication. IMT was measured by a duplex ultrasound from the common carotid artery (CCA), the internal carotid artery (ICA) and the bifurcation enlargement (BIF). The mean IMT was defined as the mean of ICA, BIF, and the 3 highest CCA measurements. Ambulatory blood pressure (ABP) was recorded using the fully automatic SpaceLabs90207 oscillometric unit. Nondippers had lower high-density lipoprotein cholesterol (P = 0.02), higher triglycerides (P < 0.01), body mass index (P < 0.0001) and higher night-time blood pressure (P < 0.0001) than dippers and they were more often nonsmokers (P = 0.01). Increased mean IMT in carotid artery was associated with ABP nondipping pattern (P < 0.01) regardless of conventional cardiovascular risk factors, antihypertensive or lipid lowering medications. Nocturnal blood pressure elevation was independently associated with IMT (P < 0.01). When sexes were analysed separately, the association was seen in men but was only a trend among women. Nondipping status in ABP monitoring is independently associated with early atherosclerosis. Whether nondipping pattern is a predictor of atherosclerosis remains to be explored in a future prospective follow-up of this cohort.