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

Abstract

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.