Left ventricular diastolic function in patients with obstructive sleep apnoea syndrome and obesity

Abstract

Obstructive sleep apnea syndrome (OSAS) is a chronic disease characterized by recurrent episodes of complete or partial obstruction of the upper airways during sleep and results in sleep fragmentation, night hypoxemia, and daytime sleepiness. The aim of this study was to investigate the state of left ventricular diastolic function in patients with first diagnosed COAS and obesity and to define the determinants of diastolic dysfunction in this category of patients. There were 46 patients (33 men and 13 women) with OSAS and obesity and 52 patients with obesity without OSAS enrolled in the study. The control group included 22 practically healthy individuals. Each patient underwent assessment of body mass index (BMI), 24-hour ambulatory blood pressure monitoring, cardiorespiratory monitoring, transthoracic echocardiography. We found that patients with OSAS and obesity had significant impairment of diastolic function in comparison with patients with obesity without OSAS, which manifested itself in decreasing of E/A ratio, increasing deceleration time and increasing isovolumic relaxation time. Increasing body mass index and increasing level of hypoxia lead to impairment of diastolic dysfunction. Diastolic dysfunction was diagnosed in 4 obese patients without OSAS and in 17 patients with OSAS and obesity. All patients with diastolic dysfunction had second or third stage obesity and severe OSAS. Left ventricular hypertrophy was diagnosed in 9 patients with OSAS and obesity. Patients with concentric hypertrophy had significantly lower E/A in comparison with patients without hypertrophy or with concentric remodeling. We found that the deceleration time has positive correlation with body mass index and desaturation index and negative correlation with min SaO2. Isovolumic relaxation time correlated only with desaturation index. According to the results of univariable regression analysis, five variables were allocated: body mass index, age, desaturation index, index apnea-hypopnea and left ventricular mass index. The multivariate analyses, after adjustment for age and sex and stepwise regression, showed that only the desaturation index was an independent predictor of left ventricular diastolic dysfunction in patients with OSAS and obesity. Obstructive sleep apnea syndrome combined with obesity leads to a deterioration of the diastolic function of the left ventricle even in patients without cardio-vascular diseases. The state of the diastolic function of the left ventricule worsens with an increase in the severity of hypoxic disorders in the syndrome of obstructive sleep apnea and with the degree of obesity. In multivariate regression analysis, the desaturation index was a predictor of left ventricular diastolic dysfunction in patients with obstructive sleep apnea syndrome and obesity.