Impact of obstructive sleep apnea on the global myocardial performance beyond obesity

We aimed to assess the impact of obstructive sleep apnea (OSA) on the left ventricular (LV) function independent of obesity using the myocardial performance index (Tei index) and the global longitudinal LV strain (GLS) and its reversibility after surgery. Twenty-five newly diagnosed OSA patients, normal weight (n = 15) and obese (body mass index [BMI] ≥ 25; n = 20) controls without OSA were enrolled and underwent transthoracic echocardiographic evaluation. The OSA and obese groups had a significantly comparable increased BMI and LV chamber dimension, prolonged isovolumic relaxation time, reduced early mitral filling velocity, and increased late mitral filling velocity and Tei index as compared to the normal weight group. However, GLS was significantly reduced only in the OSA group (-16.5 ± 1.9%) as compared to the normal weight group (-20.6 ± 2.0%, P < 0.001) and obese group (-19.1 ± 2.5%, P < 0.001). As a treatment, 13 of 25 patients underwent surgical modification, and the follow-up echocardiogram revealed significantly improved Tei index and GLS as compared to baseline (0.37 ± 0.06 and -18.9 ± 3.3% vs. 0.42 ± 0.04 and -16.3 ± 2.4%, P = 0.006 and 0.031, respectively), which was comparable to the obese controls. A reduction in the apnea-hypopnea index had a significant effect on the improvement in the GLS (r = 0.73, P < 0.001). LV systolic and diastolic function significantly deteriorated in the patients with OSA beyond obesity, and an improvement in the LV function was observed within 6 months after the surgical modification. GLS is considered to be one of the parameters that can be used in the early detection of LV systolic dysfunction in patients with OSA and a normal ejection fraction.