Extreme Nocturnal Blood Pressure Dipping is Associated With Increased Arterial Stiffness in Individuals With Components of the Metabolic Syndrome

Background and PurposesThe metabolic syndrome (MS) and abnormal nocturnal blood pressure (BP) dipping are both associated with increased risk of cardiovascular events. An association between MS and arterial stiffness was reported. This study aimed to examine the relationship between arterial stiffness as determined by the Cardio-Ankle Vascular Index (CAVI) and the nocturnal BP dipping pattern in normotensive individuals with one or more risk components of MS.Methods and ResultsA total of 73 normotensive individuals who met at least one of the five National Cholesterol Education Program Adult Treatment Panel III criteria were included. The MS score was calculated according to the GISSI Study. Ambulatory BP was recorded every 30 minutes for a 48-hour period. Individuals with MS and those without MS did not significantly differ in CAVI (p = 0.040) or nocturnal systolic blood pressure (SBP) dipping (p = 0.909). Controlling for age, CAVI was not significantly correlated with the MS score (p = 0.067). CAVI significantly correlated with the magnitude (ρ = 0.29, p = 0.014) and the percentage (ρ = 0.29, p = 0.013) of nocturnal SBP dipping. CAVI independently predicted the magnitude of nocturnal SBP reduction (β = 0.364, p = 0.002) even after adjusting for age and nighttime SBP. The extreme dippers had significantly higher CAVI values than the nondippers (p = 0.012) and a trend toward higher CAVI than the dippers (p = 0.031).ConclusionMS is associated with neither arterial stiffness nor nocturnal dipping pattern in normotensives. However, in normotensive individuals with risk components of the MS, arterial stiffness is related to an extreme dipping pattern.