Circadian Variation of Blood Pressure and Heart Rate in Normotensives, White-Coat, Masked, Treated and Untreated Hypertensives

Introduction: Ambulatory blood pressure monitoring (ABPM) forms the basis for the diagnosis of masked hypertension, a condition associated with increased target organ damage, and of white-coat hypertension, a common condition among subjects referred to hypertensive centers. The aim of this study was to compare the circadian blood pressure (BP) and heart rate (HR) profiles in 1676 Greek subjects in order to identify the circadian patterns in these two categories of patient. Methods: A total of 1676 subjects underwent 24-hour ABPM. The study population was divided into 5 sub-groups in terms of the clinic and ambulatory BP levels: normotensives (224 subjects), white-coat hypertensives (353 subjects), masked hypertensives (42 subjects), treated (653 subjects) and untreated (404 subjects) hypertensives. Results: The patterns of circadian BP and HR profiles were identical in the 5 groups. A clear nocturnal fall (23:00-04:00), an afternoon nadir (16:00), two daytime peaks (one between 09:00 and 14:00 and the other in the evening at 20:00), and a morning surge in systolic BP, diastolic BP, and HR were observed. Conclusions: The circadian profiles of BP and HR in white-coat and masked hypertension show the same pattern as in normotensive and hypertensive patients (treated and untreated). These findings indicate that factors other than disturbances in BP and HR circadian pattern are likely to be responsible for the pathogenesis of white-coat and masked hypertension. A direct influence of autonomic nervous system activity on the circadian pattern of BP and HR could explain the persistence of a basic circadian profile in normotension, white-coat, masked, and sustained hypertension, independently of 24-hour BP and HR levels.