RELATIONSHIP OF 24-HOUR AMBULATORY BLOOD PRESSURE VARIABILITY WITH MICRO- AND MACROVASCULAR PARAMETERS AND HYPERTENSION STATUS

Abstract

Objective: Existing evidence shows that increased values of blood pressure variability (BPV) are associated with a higher risk of subclinical organ damage and cardiovascular events, independently of elevated average BP values. We sought to investigate the relation of novel BPV indices with micro- and macrovascular parameters that have not all been previously studied and to identify differences according to hypertension status. Design and method: We evaluated the relationship between BPV indices and micro- and macrovascular parameters in a selected population of 344 individuals (233 never-treated, newly diagnosed hypertensive and 111 normotensive individuals).Using data from 24-h ambulatory blood pressure monitoring device, BPV was assessed by average real variability (ARV) during 24-hours, daytime and nighttime and as systolic weighted standard deviation (wSD). Nonmydriatic retinal photography was used to assess retinal microvascular diameters. Arterial stiffness was evaluated by measurement of pulse wave velocity(PWV) and aortic augmentation index (AIx). Myocardial perfusion was evaluated using subendocardial variability ratio (SEVR).The carotid intima-media thickness (cIMT) was measured by ultrasound. We performed a multiple regression analysis for all the parameters which were statistically significant in the univariate analyses. Results: After adjusting for potential confounders, all vascular parameters [venular retinal diameter (p = 0.036), PWV (p < 0.007), cIMT (p < 0.06)], except for SEVR were independently associated with ARV components in the total population. Further analysis based on hypertension status showed that in hypertensives only macrocirculation indices such as PWV and cIMT were independently associated with ARV (for PWV: 24-h systolic, p = 0.025, nighttime systolic, p = 0.001 and nighttime diastolic, p = 0.012 respectively; and for cIMT, p = 0.001 for both 24-h and daytime systolic). In normotensive individuals, venular diameter was associated with 24-h systolic and diastolic and daytime systolic and diastolic ARV (p = 0.004, p = 0.002, p = 0.001 and p = 0.049 respectively). The arteriovenous ratio was associated with daytime systolic ARV (p = 0.022), and AIx was associated with daytime diastolic ARV (p = 0.022). None of the univariate correlations between vascular parameters and wSD remained significant after adjustment for potential confounders. Conclusions: We concluded that short-term BPV represented by ARV is independently associated with macrovascular parameters in untreated hypertensive patients and microvascular parameters in normotensives.