Ambulatory BP monitoring
Ambulatory BP monitoring (ABPM) was performed with the use of a certified oscillometric device (BPLab, “Piotr Telegin” LLC, Russian Federation). The measurements were performed every 15 min during the day (08:00–22:00), and every 30 min during night (22:00–08:00). The nighttime period was later corrected according to the patient’s diary. The data were considered valid when at least 70% measurements were successful. We assessed average 24-hour BP, daytime and nighttime BP, daytime and nighttime BP load (%), circadian BP profile. According to the ESC/ESH guidelines the following diagnostic thresholds were considered: mean 24-hour BP ≥ 130/80 mm Hg; mean daytime BP ≥ 135/85 mm Hg; and mean nighttime BP ≥ 120/70 mm Hg. Circadian BP profile was assessed separately for systolic and diastolic BP by the equation: 100×(mean BPday-mean BPnight)/mean BPday (values ≥ 10% indicate dippers, while values < 10% indicate non-dippers). For quantitative analysis a circadian coefficient was calculated by formular mean BPnight/mean BPday (values ≥ 0.9 indicate non-dipper profile, while values ≤ 0,8 identify dippers).