Night time blood pressure and cardiovascular structure in a middle-aged general population in northern Italy: the Vobarno Study

The aim was to determine, in a cross-sectional study, the relation between structural alterations in the heart and carotid arteries, and blood pressure (BP) changes from day to night time, measured by ambulatory BP (ABP). In 225 untreated subjects (107 F, 118 M, age range 48-64 years) and 59 treated subjects (24 M, 35 F, age range 50-64), living in a small town of northern Italy (Vobarno, Brescia) carotid intima media thickness as well as the occurrence of plaque, were evaluated by ultrasound. Echocardiographic left ventricular (LV) mass was measured according to the Penn Convention. BP was determined by clinic measurement and by 24-h non-invasive ABP monitoring. Subjects were divided in two groups, according to the decrease of nighttime systolic BP (SBP) 'dippers' (SBP decreased by at least 10% during night time) and 'non-dippers' (decrease of night time SBP <10%). The intima-media thickness in the common carotid, in the carotid bifurcation, in the internal carotid artery and average intima-media thickness were significantly greater in untreated non-dippers as compared with dipper subjects (ANOVA P<0.05). A significantly higher prevalence of plaque was observed in untreated non-dippers as compared with dippers (P=0.002). After adjusting for age, sex, 24-h SBP, and smoking, IMT in the carotid bifurcation and average intima-media thickness remained significantly greater in non-dipper subjects (P<0.05 for all comparisons). No significant differences in LV mass were observed between dippers and non-dipper subjects. In conclusion, in a general population of unselected middle-aged subjects, night time BP values, among other risk factors, seem to represent an important determinant of carotid wall structure.