Echocardiographic findings and plasma endothelin-1 levels in obese patients with and without obstructive sleep apnea.

Abstract

Obstructive sleep apnea (OSA) and obesity are increasingly prevalent worldwide. Both promote endothelial dysfunction contributing to systemic and pulmonary hypertension over time. Endothelin-1 (ET-1) plays a pivotal role in the development of pulmonary hypertension (PH). The aim of the present study was to assess the association between plasma ET-1 and echocardiographic findings in obese individuals with and without OSA, as well as in non-obese patients with OSA. Ninety-seven subjects (56 males) were enrolled in the study. All subjects underwent the following tests: venous endothelin-1 levels, pulmonary function testing, and arterial blood gas analysis. All patients except controls underwent transthoracic echocardiography and portable testing for sleep-disordered breathing. Plasma ET-1 levels were significantly higher in obese patients, both with and without OSA (respectively, n = 30 (mean value, 268.06 ± 49.56pg/ml) and n = 32 (mean value, 263.12 ± 65.26pg/ml)), compared with non-obese patients with OSA or to healthy controls (respectively, n = 20 (mean value, 149.8 ± 23.09pg/ml) and n = 15 (mean value, 152.3 ± 27.64pg/ml); p < 0.0001). Pulmonary artery pressure (PAPs) in obese patients with OSA were significantly higher than in obese patients without OSA (p < 0.0001), while there was no statistical difference between PAPs of obese patients without OSA, compared with the group of non-obese OSA patients. Plasma ET-1 levels significantly correlated with systolic PAPs in obese patients both with and without OSA (respectively, n = 30, r = 0.385, p = 0.03567; n = 32, r = 0.3497, p = 0.0497). Our study suggests that endothelin levels are more strongly associated with weight than the presence of sleep-disordered breathing, but pulmonary artery hypertension is associated with both weight and OSA.