ASSOCIATION OF SHORT-TERM VARIABILITY INDICES WITH COMMON CAROTID ARTERY INTIMA-MEDIA THICKNESS IN NORMOTENSIVE AND HYPERTENSIVE SUBJECTS

Abstract

Objective: Most studies have demonstrated that increased blood pressure (BP) variability is associated with target-organ damage development and cardiovascular events even after adjusting for average BP levels. Although several BP variability indices have been used for measuring BP variability, the few studies that directly compared the prognostic value of different estimates of BP variability did not provide clear indications as to which index should be preferred. Aim of the study was to compare the association between ambulatory BP variability indices and common carotid artery intima-media thickness (CCA-IMT) in normotensive and hypertensive subjects. Design and method: A total of 977 subjects, referred for evaluation at the Hypertension Unit of our department, underwent 24-h ambulatory blood pressure (BP) monitoring and CCA-IMT ultrasonographic measurements. Short-term BP variability was expressed by standard deviation (SD), time rate of BP variation (TR), average real variability (ARV) and coefficient of variation (CV) of systolic and diastolic BP for both 24-h, daytime and nighttime intervals. All subjects were divided according to the 24-hour BP levels to normotensives (24-hour BP<130/80 mmHg) and hypertensives (24-hour BP>=130/80 mmHg). Statistical analysis was performed by means of bivariate correlations, simple and multiple linear regression analysis. Results: The study population consisted of 464 (47%) normotensive and 513 (53%) hypertensive subjects. In normotensive individuals 24-hour systolic TR (r = 0.184, p < 0.001), 24-hour systolic ARV (r = 0.202, p < 0.001) and diastolic ARV (r = 0.093, p = 0.046) were significantly correlated with CCA-IMT. In hypertensive patients 24-hour systolic TR (r = 0.212, p < 0.001), 24-hour systolic ARV (r = 0.226, p < 0.001) and 24-hour systolic SD (r = 0.088, p = 0.046) significantly correlated with CCA-IMT. The multivariate analysis revealed that 24-hour systolic TR of BP variation and 24-hour systolic ARV were significantly and independently associated with CCA-IMT even after adjustment for 24-hour systolic BP. Conclusions: Systolic ambulatory BP variability indices such as SD, TR and ARV are associated with CCA-IMT in normotensive and hypertensive subjects. 24-hour systolic TR of BP variation and ARV are significantly associated with CCA-IMT independently of average BP levels.