PP.03.17: SEASONAL DIFFERENCES OF DAYTIME AND CLINICAL BLOOD PRESSURE IN PATIENTS WITH HYPERTENSION AND HIGH NORMAL BLOOD PRESSURE. MASKED HYPERTENSION TENDENCY IN WINTER

Objective: High seasonal (winter [W] vs. summer [S]) differences in cardiovascular mortality and morbidity are the basis for studies of their causes including the blood pressure (BP) values assessment. The aim of this study was to investigate ambulatory BP seasonal changes in hypertensive (H) patients and patients with high normal BP. Design and method: The patients from the general population (Ivanovo, Russian Federation) who attended ambulatory clinics with clinical BP (CBP) < 160/100 mm Hg under antihypertensive treatment (AHT) or without it and the patients with CBP 130–139/85–89 mm Hg without AHT were examined in W and S by ambulatory BP monitoring (ABPM; BPlab device, Nizny Novgorod, Russia). The selection criterion for ABPM records was the quality adequate for sophisticated analyses: duration > = 24 hours, absence of data gaps > 1 hour. The patients were included both in W and in S. Results: The total number of the patients was 498: 36.3% men, 92.4% with H (52.8% with AHT, other with 1 stage H), mean age 51.5 ± 0.4 years, BMI 28.7 ± 0.2 kg/m2, CBP 132.8 ± 0.6/80.2 ± 0.4 mm Hg. The seasonal BP differences are presented in the Table.Conclusions: In our trial the seasonal factor influenced the CBP and the daytime BP only. The absence of nighttime BP seasonal differences may be due to the use of traditional indoor heating systems in W. The ABPM with particular attention to daytime data should be used intensively in W due to the evident masked hypertension tendency (in sites with relatively low ambient temperature in W).