Increased nocturnal heart rate andwave reflection are earlymarkers of cardiovascular disease in Williams-Beuren syndrome children

Objective: Williams-Beuren syndrome (WBS) is a genetic disorder that involves elastin gene causing cardiovascular abnormalities and increased risk. However, data on arterial function in these patients are only few and conflicting. Aim of this study was to evaluate dynamic behaviour of central and peripheral blood pressure (BP) and arterial stiffness parameters early in the course of WBS. Methods: We enrolled 19 WBS paediatric patients (age 13-4 years) and 23 age, height and BP-matched controls (10±4 years). We evaluated 24-h ambulatory BP values via an ambulatory blood pressure monitoring (ABPM) system (Mobil-O-Graph) also capable to calculate 24-h central BP and 24-h arterial stiffness parameters. Carotid-femoral PWV (cf-PWV) was assessed in all WBS individuals (Complior). Results: BP values were similar in WBS and control, during the daytime and the night-time. The same behaviour applies to 24-h central BP. However, during the night, WBS showed heart rate values (HR; 78-10 vs. 71-9 bpm; P<0.03), augmentation index (Aix; 24.6±13.5% vs. 16.5±8.9%; P=0.03) and reflection magnitude (68 5.8 vs. 63.5 8.1; P=0.02) higher than controls. The HR, Aix and reflection magnitude reduction in the day-night shift was lower in WBS than in controls. Cf-PWV in WBS children did not differ when compared with their normalized expected value. Conclusion: In WBS children, the higher night-time HR, Aix and reflection magnitude and their impaired physiological reduction in the day-night shift suggests an abnormal sympathetic cardiovascular control, an augmented wave reflection and an increase in small arteries resistance. These alterations possibly due to a sympathetic overactivity can be regarded as earlier hallmarks of cardiovascular dysfunction in these patients.