Circadian blood pressure variation: relationship between dipper status and measures of arterial stiffness


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Abstract

BackgroundCompared with dippers, hypertensive individuals with a nondipping nocturnal blood pressure (BP) profile have more target organ damage and a worse cardiovascular prognosis, potentially mediated through arterial stiffness.ObjectiveTo examine arterial stiffness and dipping in a population of 314 untreated hypertensive individuals, mean age 48 ± 8 years, 55% men.MethodsDipping 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. Aortic pulse wave velocity (PWV) (Complior) and augmentation index (Sphygmocor) were measured.ResultsGroups did not differ by age, gender, 24-h or daytime mean BP, body mass index, smoking, cholesterol, glucose, renin or aldosterone. The relationship between PWV and dipper-status was J-shaped, with extreme-dippers and reverse-dippers having the highest PWV. Nondippers and reverse-dippers had significantly higher age and sex-adjusted PWV compared with dippers. Following multivariate adjustment for age, gender, mean arterial pressure, heart rate and smoking, reverse-dippers had significantly higher PWV than either dippers or nondippers (P = 0.005 and P = 0.006, respectively). Dipper status was not associated with augmentation index.ConclusionsA reverse-dipper pattern, corresponding to the 95% percentile of the night: day BP ratio on ambulatory BP monitoring, identifies a population group with increased PWV. This difference could not be explained by the measured risk factors. Reverse-dippers had significantly less day: night variability in heart rate and wider pulse pressures at night than any of the other groups, suggesting altered sympathetic tone at night as a potential mechanism

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