Impact of obstructive sleep apnea on left atrial functional and structural remodeling beyond obesity

Abstract

Background: To evaluate the left atrial (LA) volume and function of obese patients with/without obstructive sleep apnea (OSA) and its association with left ventricular (LV) diastolic function independent of obesity.

Methods: LA volumetric and functional parameters were measured by 2-dimensional and strain echocardiography in 49 obese (body mass index ≥ 25 kg/m(2)) subjects (24 non-OSA and 25 OSA).

Results: OSA group showed larger maximal LA volume indexed for body surface area, larger volume before atrial contraction, a reduction in the LA passive emptying fraction, and an increase in the LA active emptying fraction with no significant change in LA total emptying fraction. Mitral annular early diastolic velocity (Ea) was significantly reduced, whereas the ratio of mitral valve early diastolic velocity (E) to Ea (E/Ea) and late diastolic velocity (Aa) were significantly increased in OSA group. Although the mean peak late diastolic strain rate had not shown any differences, the LA mean peak systolic strain/strain rate, and mean peak early diastolic strain rate were significantly lower in the OSA group. Apnea-hypopnea index (AHI) of the OSA patients was significantly correlated with E/Ea (r=0.67, p<0.001). There is a significant correlation between LA active emptying volume index and E/Ea (r=0.77, p<0.001), and between LA passive emptying volume index and E/Ea (r=-0.51, p=0.009).

Conclusion: LA structural and functional remodeling was significantly correlated with the severity of OSA and LV diastolic filling pressure. OSA impaired LA wall compliance and passive contraction independent of obesity.