Comparison of Left Atrial Mechanical Function in Nondipper versus Dipper Hypertensive Patients: A Speckle Tracking Study

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Nondippers are known to carry a high risk of cardiovascular morbidity and mortality. The aim of this study was to investigate the effects of dipper and nondipper status of hypertension on longitudinal systolic and diastolic functions of left atrial (LA) myocardial tissue by means of two-dimensional speckle-tracking echocardiography in treated hypertensive patients. A total of 78 outpatients treated with antihypertensive drugs for at least 1 year were included in the study. The patients were classified as nondippers if their daytime ambulatory systolic and diastolic blood pressure did not decrease by at least 10% during the night. Global longitudinal LA strain/strain rate data were obtained by two-dimensional speckle imaging with automated software and compared between the groups. LA volume index, left ventricular (LV) wall thickness and mass index as well as filling pressure (E/E') were significantly higher in nondippers (all P < 0.001), whereas systolic tissue velocity (S') was significantly lower in nondippers. They also had decreased values of mean peak LA strain (dippers = 27.6 ± 5.5% vs. nondippers = 21.5 ± 4.5%, P < 0.001), strain rate during reservoir (dippers = 1.27 ± 0.4/sec vs. nondippers = 0.98 ± 0.3/sec, P = 0.001), and conduit period (dippers = 1.41 ± 0.4/sec vs. nondippers = 1.06 ± 0.3/sec, P < 0.001). Moreover, we found that LA mechanical dysfunction was closely associated with LV mass, filling pressure, and regional LV contractility. Nondipping in treated hypertensive patients was associated with an adverse cardiac remodeling and impaired LA mechanical function. Further studies are warranted to demonstrate the long-term prognostic significance of these findings.