Abstract
ObjectiveThe effects of seasonality on blood pressure (BP) and cardiovascular (CV) events are well established, while the influence of seasonality and other environmental factors on arterial stiffness and wave reflection has never been analyzed. This study evaluated whether seasonality (daily number of hours of light) and acute variations in outdoor temperature and air pollutants may affect carotid-femoral pulse wave velocity (PWV) and pressure augmentation.Design and method731 hypertensive patients (30–88 years, 417 treated) were enrolled in a cross-sectional study during a 5-year period. PWV, central BP, Augmentation Index (AIx) and Augmentation Pressure (AP) were measured in a temperature-controlled (22–24°C) room. Data of the local office of the National Climatic Data Observatory were used to estimate meteorological conditions and air pollutants (PM10, O3, CO, N2O) exposure on the same day.ResultsPWV (mean value 8.5±1.8 m/s) was related to age (r = 0.467, p<0.001), body mass index (r = 0.132, p<0.001), central systolic (r = 0.414, p<0.001) and diastolic BP (r = 0.093, p = 0.013), daylight hours (r = -0.176, p<0.001), mean outdoor temperature (r = -0.082, p = 0.027), O3 (r = -0.135, p<0.001), CO (r = 0.096, p = 0.012), N2O (r = 0.087, p = 0.022). In multiple linear regression analysis, adjusted for confounders, PWV remained independently associated only with daylight hours (β = -0.170; 95% CI: -0.273 to -0.067, p = 0.001). No significant correlation was found between pressure augmentation and daylight hours, mean temperature or air pollutants. The relationship was stronger in untreated patients and women. Furthermore, a positive, independent association between O3 levels and PWV emerged in untreated patients (β: 0.018; p = 0.029; CI: 0.002 to 0.034) and in women (β: 0.027; p = 0.004; CI: 0.009 to 0.045).ConclusionsPWV showed a marked seasonality in hypertensive patients. Environmental O3 levels may acutely reduce arterial stiffness in hypertensive women and in untreated patients.
Highlights
The seasonality of cardiovascular (CV) disease is well known, with acute events occurring more frequently during winter months than in the summertime [1,2,3,4,5,6]
Pulse Wave Velocity (PWV) showed a marked seasonality in hypertensive patients
The climate-related variations of arterial stiffness and central blood pressure (BP) augmentation, which are key parameters for cardiovascular risk stratification in hypertensive patients and in the general population [15,16,17], have never been investigated. This issues could be of importance since aortic Pulse Wave Velocity (PWV), an indirect measure of large artery stiffness, has a functional component that varies in response to acute stimuli [18] and an increase in Augmentation Index (AIx), and central BP after acute cold exposure has been described [19]
Summary
The seasonality of cardiovascular (CV) disease is well known, with acute events occurring more frequently during winter months than in the summertime [1,2,3,4,5,6]. The climate-related variations of arterial stiffness and central BP augmentation, which are key parameters for cardiovascular risk stratification in hypertensive patients and in the general population [15,16,17], have never been investigated. This issues could be of importance since aortic Pulse Wave Velocity (PWV), an indirect measure of large artery stiffness, has a functional component that varies in response to acute stimuli [18] and an increase in Augmentation Index (AIx), and central BP after acute cold exposure has been described [19]. Seasonal variations in PWV and central BP augmentation might play a role in determining the higher rate of CV events during winter
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