Effects of blood pressure and heart rate circadian rhythms on left atrial function.

Abstract

We examined the associations among the circadian rhythms of blood pressure (BP), heart rate (HR) and left atrial function in essential hypertensive patients. The study included 237 essential hypertensive patients who completed 24-h ambulatory BP, HR monitoring and two-dimensional speckle tracking echocardiography (2DSTE). The strain and strain rate images were studied, and the following parameters were measured: left atrial reservoir strain and strain rate (LAS-S and LASR-S), left atrial conduit strain and strain rate (LAS-E and LASR-E), and left atrial booster strain and strain rate (LAS-A and LASR-A). The left atrial stiffness index (LASI) was identified as the ratio of E/e' to LAS-S. All participants were divided into three groups according to the percentage of nocturnal BP dipping (dippers, nondippers and reverse dippers). The LASI was significantly higher in BP reverse dippers than in dippers and nondippers. LAS-S, LAS-E and LASR-E were significantly lower in BP reverse dippers than dippers and nondippers. Multivariate logistic regression analysis demonstrated that age, night-time mean SBP and the percentage of nocturnal HR decline were independently related to an increased LASI. Impairment of the left atrial reservoir and conduit functions was correlated with abnormal BP and HR circadian rhythms in hypertension. Increased left atrial stiffness was associated with night-time SBP and the percentage of nocturnal HR decline.