Left Atrial Volume and Function in Patients With Obstructive Sleep Apnea Assessed by Real-Time Three-Dimensional Echocardiography

Discipline of Sleep Biology and Medicine, Department of Psychobiology, Federal University of São Paulo, Sao Paulo, Brazil.
Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography (Impact Factor: 4.06). 10/2008; 21(12):1355-61. DOI: 10.1016/j.echo.2008.09.007
Source: PubMed


Studies have suggested that obstructive sleep apnea (OSA) contributes to the deterioration of left ventricular diastolic function. This may lead to atrial myocardial overstretching and enlargement, which could be associated with increased cardiovascular risk. The aim of this study was to evaluate left atrial (LA) volume and function in patients with OSA compared with controls without OSA and their associations with any left ventricular diastolic abnormalities using real-time 3-dimensional echocardiography (RT3DE).
Fifty-six patients with mild to severe OSA and 50 controls of similar age and with similar body mass indexes, blood pressure, and frequency of hypertension were analyzed. All subjects underwent polysomnography and RT3DE.
A larger 3-dimensional maximum LA volume indexed for body surface area, larger volume before atrial contraction, and higher active atrial ejection fraction were found in patients with OSA (P < .01 for all). Mitral annular early diastolic velocity (E') was reduced in patients with OSA (P = .03), whereas late diastolic velocity (A') and the ratio of mitral valve early diastolic velocity to mitral annular early diastolic velocity (E/E') were increased in the same group (P < .05 for both). In addition, a lower E'/A' ratio was also found in the OSA group (P = .02). An increase in 3-dimensional maximum LA volume indexed for body surface area was observed, depending on OSA severity. The apnea-hypopnea index and E/E' ratio were independent predictors of an increase in 3-dimensional maximum LA volume in a multiple regression model.
Using RT3DE, this study demonstrates that OSA induces a functional burden on the left atrium, resulting in remodeling. These functional and structural changes are related to the impairment of diastolic function in this population.

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    • "LA analysis using RT3DE has been validated as a prognostic mark of major cardiac events, and shows potential in terms of accuracy, practicability and reproducibility.15 16 This technology has already been used to study LA structure in patients with OSA, and OSA severity was shown to be an independent predictor of LA maximal enlargement.8 "
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    ABSTRACT: Obstructive sleep apnoea (OSA) has been reported as a predictor of left ventricle (LV) diastolic dysfunction and left atrium (LA) remodelling. The aim of this study is to evaluate the impact of OSA treatment with a continuous positive airway pressure device (CPAP) on the LA volume and function, as well as on the LV diastolic function. In total, 56 OSA patients were studied. All patients underwent real-time three-dimensional (RT3DE) and two-dimensional echocardiogram with tissue Doppler evaluation in order to estimate LA volumes, function and LV diastolic performance. A total of 30 patients with an apnoea-hypopnoea index greater than 20 were randomly selected to receive sham CPAP (n = 15) or effective CPAP (n = 15) for 24 weeks. They underwent echo examination on three different occasions: at baseline, after 12 weeks and 24 weeks of CPAP or sham CPAP. In the effective CPAP group we observed the following changes from the baseline to the 24-week echo evaluation: (a) a reduction in the E/E' ratio (10.3 (1.9) to 7.9 (1.3), p = 0.03); (b) an increase in the LA passive emptying fraction (28.8% (11.9%) to 46.8% (9.3%), p = 0.01); and (c) a reduction in the LA active emptying fraction (42.7% (11.5%) to 25.7 (15.7), p<0.01). In the sham group, there were no changes from the baseline to the 24-week echo. We found a positive correlation between 24 week/baseline LA active emptying volume and 24 week/baseline E/E' ratios (r = 0.40, p<0.05) and a negative correlation between 24 week/baseline LA passive emptying volume and 24 week/baseline E/E' ratios (r = -0.53, p<0.05). No significant changes were found on LA total emptying fraction. CPAP improved LV diastolic function and LA passive emptying, but not LA structural variables in OSA patients. NCT00768807.
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