Sleep-related breathing disorders in patients with pulmonary hypertension

Abstract Introduction There are some evidences of sleep-related breathing disorders (SRBD) association with pulmonary hypertension (PH). Only limited information regarding the SRBD prevalence in pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) patients, is available. Purpose To estimate the features of SRBD and the asymmetric dimethylarginine (ADMA) level in PAH and CTEPH patients and their relationship with the severity of PH. Methods There were included 31 patients (45% male; 55% female) with a verified diagnosis of precapillary PH: 22.6% – with PAH; 9,7% with PAH associated with adult congenital heart disease; 64.5% – with CTEPH; 3.2% with PAH associated with connective tissue disease. Patients underwent a general clinical examination, questionnaires, a comprehensive assessment of respiratory function, a complete polysomnographic study, ECG and ECHO studies, assessment of clinical and biochemical blood tests, including an assessment of ADMA and NT-proBNP levels. Results SRBD of a predominantly obstructive nature were found in 74.2% of the examined: 38.7% were mild, 22.6% were moderate, 12.9% were severe. In 35% of patients, episodes of periodic breathing during sleep were recorded. There was no association SRBD with PH functional class and hemodynamic parameters. Moderate correlation was observed between the apnea-hypopnea index and remodeling indices of the heart chambers according to ECHO: for the end-diastolic size of the left ventricle (ρ=0.54; p=0.005); for an indicator of the ratio of the size of the ventricles (RV/LV) (ρ=−0.41, p=0.05). The presence of SRBD wasn't associated with the level of peripheral blood saturation according to pulse oximetry in sleep and during wakefulness. Negative moderate correlation was observed between NT-proBNP level and the average peripheral blood saturation at night in the entire examined group (ρ=−0.40; p=0.035). All patients showed an increase in ADMA, with no association between ADMA and SRBD severity. Conclusions The incidence of SRBD is extremely high in PAH and CTEPH patients. However, there no association between presence and severity of PH, including with right heart remodeling. But the severity of nocturnal hypoxemia is associated with an increase in NT-proBNP level, a proven marker of poor prognosis in PAH and CTEPH groups of patients. SRBD severity indices (apnea-hypopnea index and desaturation index) are associated with ECHO parameters characterizing remode