Relationship between echocardiographic assessment and plasma endothelin-1 levels in obese patients with or without obstructive sleep apnea

Abstract

Background: OSA and obesity are increasingly prevalent disease which promote vascular dysfunction, contributing to systemic and pulmonary hypertension over time. Among a wide spectrum of circulating factors, 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 possible association between plasma ET-1 levels and echocardiographic findings in obese with or without OSA, as well as in non-obese OSA subjects.

Methods: Ninety-seven subjects (56 males) were enrolled into the study. They underwent the following tests: venous endothelin-1 levels, pulmonary function testing and arterial blood gas analysis. All patients except controls underwent transthoracic echocardiography, and polysomnographic study.

Results: ET-1 levels were significantly higher in obese patients, both with and without OSA (respectively, n=30, mean value 268.06 ± 49.56 pg/ml, and n=32, mean value 263,12 ± 65.26 pg/ml), compared to patients affected by OSA with a normal body mass index (BMI), and to healthy controls (respectively, n=20, mean value 149,8 ± 23,09 pg/ml, and n=15, mean value 152,3 ± 27,64 pg/ml) (p<0.0001). Plasma ET-1 levels significantly correlated with systolic pulmonary artery pressure (PAPs) in obese patients with or without OSA (respectively, n=30, r=0.385, p=0.03567; n=32, , r=0.3497, p=0.0497) while this relationship was not found in OSA patients with normal BMIs.

Conclusions: Obesity is more important risk factor than OSA for the development of endothelial dysfunction and consequent PH. Further studies are needed to identify subjects who may benefit of new treatments for PH.