Short-term beat-to-beat but not ambulatory blood pressure variability is correlated to carotid intima-media thickness.

Abstract

Several studies have shown that blood pressure (BP) variability derived from ambulatory blood pressure monitoring (ABPM) is associated with target organ damage development. However, the use of discontinuous ABPM to assess rapid BP changes is unavoidably limited by the long frequency at which automated measures are scheduled. The aim of our study was to identify whether ABPM-derived variability or short-term beat-to-beat BP variability is better associated with common carotid artery intima-media thickness (CCA-IMT) in untreated hypertensive patients. A total of 85 individuals underwent 24-h ABPM and carotid artery ultrasonographic measurements. Three 5-min recordings of noninvasive beat-to-beat BP were made under standardized conditions. The time rate (TR) of BP variation was defined as the first derivative of the BP values against time. The study population was divided into normotensive and hypertensive participants according to 24-h BP values (130/80 mmHg). Hypertensive patients (n=45) presented significantly higher TR of 24-h BP variation (P<0.05) and beat-to-beat TR of systolic BP variation (P<0.05) than their normotensive counterparts (n=40). The multivariate linear regression analyses in hypertensive patients showed significant and independent associations of CCA-IMT with the following factors: 24-h systolic blood pressure (SBP) (B=0.065, 95% confidence interval: 0.006-0.124; P=0.033) and TR of beat-to-beat SBP (B=0.013, 95% confidence interval: 0.005-0.020; P=0.002). A 10 mmHg/min increase in the TR beat-to-beat SBP variation correlated to an increase of 0.013 mm in the CCA-IMT values. Short-term beat-to-beat TR of BP variation is associated independently with CCA-IMT values and presents a better predictor of target organ damage involvement than BP variability indexes derived from ABPM.