The underlying risks of circadian blood pressure variation for carotid plaque in treated hypertensive patients with normal blood pressure

Objectives The aim of this study was to investigate the relationship between 24 h variation of blood pressure (BP) and carotid plaque in essential hypertensive patients with normal BP under anti-hypertensive treatment. Participants and methods A total of 322 hypertensive patients with systolic BP (SBP) and diastolic BP (DBP) within the normal range after routine treatment were continuously recruited and evaluated by ambulatory BP monitoring from 1 January 2014 to 31 July 2015. The exclusion criteria included participants younger than 18 or older than 90 years of age, pregnancy, night-work employment, and suffering from secondary hypertension. The prevalence of carotid plaque between different circadian BP pattern groups was analyzed using a χ 2 -test. Logistic regression was applied to analyze the relationship between carotid plaque and ambulatory BP monitoring variables. Results All the individuals were divided into a 'carotid plaque' group (n=197) and a 'non-plaque' group (n=125) on the basis of whether the thickness of each plaque was at least 0.5 mm under the carotid ultrasound. In addition, patients were grouped into a dipper (10-20% nocturnal fall of BP in SBP) group and a nondipper (<10% nocturnal fall of BP in SBP) group on the basis of individual SBP variation. In the nondipper group, the number of patients with carotid plaque was higher than the patients without plaque (P=0.017). Logistic analysis showed that the nondipper pattern of BP was significantly associated with the formation of carotid plaque (odds ratio=1.731, P=0.041). Conclusion A nondipper pattern of BP may serve as a risk factor for carotid plaque in treated hypertensive individuals with normal BP.