THE RELATIONSHIP BETWEEN CIRCADIAN RHYTHM OF BLOOD PRESSURE AND LEFT ATRIAL PHASIC FUNCTION IN HYPERTENSION

Abstract

Objective: Objective: We used two dimensional speckle tracking echocardiography (2DSTE)-based strain and strain rate imaging to evaluate left atrial (LA) mechanics and investigated its correlation with circadian rhythm of blood pressure in essential hypertension (HT). Design and method: Design and Methods: We enrolled 249 HT patients. All subjects were evaluated by ambulatory 24-hour blood pressure monitoring and 2D-STE. According to blood pressure (BP) patterns, these patients were divided into three groups. Group I (dipper, n = 91), patients with a 10%-20% reduction in BP at nighttime; Group II (non-dipper, n = 129), patients with a < 10% reduction in BP at nighttime; Group III (reverse dipper, n = 29), patients with higher BP at nighttime compared with daytime. The strain and strain rate images were studied, and the following parameters were measured: LA reservoir strain and strain rate (LAS-S, LASR-S), LA conduit strain and strain rate (LAS-E and LASR-E), LA booster strain and strain rate (LAS-A and LASR-A). LA stiffness index (LASI) was defined as the ratio of E/e‘ to LAS-S. In the present study, we also explored the correlation between LASI and cardiovascular risk factors as well as ambulatory blood pressure indexes. The factors related to LASI were evaluated by multivariate regression analysis to find the independent factors. Results: Results: LASI was significantly higher in Group III than Group I (p < 0.05). LAS-E and LASR-E were significantly lower in Group III than Group I and II (p < 0.05 for both). However, there were no significant differences between the Group I and II (p > 0.05). Otherwise, LAS-S, LASR-S, LAS-A and LASR-A were not significantly different among these three groups. We also found LASI was correlated with ages, diabetes, courses of HT, 24-hour mean systolic blood pressure (24h-mSBP), 24-hour mean diastolic blood pressure (24h-mDBP), daytime mean SBP (d-SBP), nighttime mean SBP (n-SBP) and nighttime mean DBP (n-DBP). Multivariate regression analysis revealed that age, n-SBP and n-DBP were independent factors related to LASI. Conclusions: Conclusions: Left atrial function is associated with circadian rhythm of blood pressure. Nocturnal blood pressure may have more influence on left atrial stiffness and conduit function.