Relationship of short-term blood pressure variability with carotid intima-media thickness in hypertensive patients

Abstract

Background: High blood pressure (BP) is among significant risk factor for stroke and other vascular occurrences, it experiences nonstop fluctuations over time as a result of a complex interface among cardiovascular control mechanisms. Large blood pressure variability (BPV) has been proved to be promising in providing potential regulatory mechanisms of the cardiovascular system. Although the previous studies also showed that BPV is associated with increased carotid intima-media thickness (IMT) and plaque, whether the correlation between variability in blood pressure and left common carotid artery-intima-media thickness (LCCA-IMT) is stronger than right common carotid artery-intima-media thickness (RCCA-IMT) remains uncertain in hypertension.

Methods: We conduct a study (78 hypertensive subjects, aged 28-79) to evaluate the relationship between BPV and carotid intima-media thickness in Shenzhen. The blood pressure was collected using the 24 h ambulatory blood pressure monitoring, and its variability was evaluated using standard deviation (SD), coefficient of variation (CV), and average real variability (ARV) during 24 h, daytime and nighttime. All the IMT measurements are collected by ultrasound.

Results: As the results showed, 24 h systolic blood pressure variability (SBPV) evaluated by SD and ARV were significantly related to LCCA-IMT (r(1) = 0.261, P = 0.021; r(1) = 0.262, P = 0.021, resp.). For the daytime diastolic blood pressure variability (DBPV), ARV indices were significantly related to LCCA-IMT (r(1) = 0.239, P = 0.035), which differed form BPV evaluated by SD and CV. For the night time, there is no significant correlation between the BPV and IMT. Moreover, for all the subjects, there is no significant correlation between the BPV and RCCA-IMT/number of plaques, whereas, the SD, CV, and ARV of daytime SBP showed a positive correlation with LCCA-IMT (r(1) = 0.312, P = 0.005; r(1) = 0.255, P = 0.024; r(1) = 0.284, P = 0.012, resp.). Moreover, the ARV of daytime SBPV, 24 h SBPV and nighttime DBPV showed a positive correlation with the number of plaques of LCCA (r(1) = 0.356, P = 0.008; r(1) = 0.297, P = 0.027; r(1) = 0.278, P = 0.040, resp.). In addition, the number of plaques in LCCA had higher correlation with pulse pressure and diastolic blood pressure than that in RCCA. And multiple regression analysis indicated LCCA-IMT might not only be influenced by age or smoking but also by the SD index of daytime SBPV (p = 0.035).

Conclusions: The results show that SBPV during daytime and 24 h had significant correlation with IMT, for the hypertensive subjects from the southern area of China. Moreover, we also found the daytime SBPV to be the best predictor for the progression of IMT in multivariate regression analysis. In addition, the present study suggests that the correlation between BPV and left common carotid artery-intima-media thickness/number of plaques is stronger than right common carotid artery-intima-media thickness/number of plaques.

Fig. 1

The correlation of the blood pressure variability and carotid intima-media thickness in all subjects. BPV blood pressure variability, IMT intima-media thickness, CV coefficient of variation, ARV average real variability, SBPV systolic blood pressure variability, DBPV diastolic blood pressure variability.

Fig. 2

Changes in mean CCA-IMT in association with stepwise increases in SBPV (evaluated with SD, CV, and ARV) in hypertensives. Values are means ± S.E.M. a Variability of 24 h SBP. b Variability of daytime SBP. *P < 0.05 vs the <6.9 mmHg group. ^†P < 0.05 vs the <8.1 mmHg group. c Variability of nighttime SBP.