Severe obstructive sleep apnea increases left atrial volume independently of left ventricular diastolic impairment

Abstract

Purpose: Severe obstructive sleep apnea (OSA) directly impairs left ventricular (LV) diastolic function. Left atrial volume index (LAVI), an independent predictor of future cardiovascular events, is also related to OSA severity. This study aimed to assess whether OSA is associated with an increase in LAVI independently of LV diastolic function.

Methods: Two hundred six OSA patients (apnea hypopnea index, AHI ≥ 5/h) without cardiac disease, hypertension, and diabetes were enrolled. They underwent overnight fully attended polysomnography and 2-dimensional echocardiography in order to estimate LA volumes and LV diastolic function which was assessed by the ratio of transmitral early diastolic flow velocity to late diastolic flow velocity (E/A), deceleration time, and mitral annular velocity (e') which was derived from tissue Doppler imaging. Patients were divided into two groups based on AHI, namely, group M (5 ≤ AHI < 30/h) and group S (AHI ≥ 30/h).

Results: The LAVI value in group S was significantly larger than that in group M (20 ± 5 vs. 23 ± 5 mL/m(2), P < 0.001). E/A in group S was significantly lower than that in group M (P < 0.001), whereas the ratio of E to e' (E/e') in group S was significantly higher than that in group M (P < 0.001). AHI showed a statistically significant correlation with LAVI (P < 0.001). On multivariate linear regression analysis, severe OSA was independently related with LAVI even after adjusting for age, sex, systolic blood pressure, body mass index, and measurements of LV diastolic function (P = 0.04).

Conclusions: Severe OSA itself might directly increase LAVI, independently of LV diastolic function.

Keywords: Diastolic function; Echocardiography; Left atrial volume; Obstructive sleep apnea.