Objectives: We investigated the occurrence of sleep-related breathing disorders (SBDs) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and addressed the effect of pulmonary haemodynamics and SBD indices on the severity of the nocturnal hypoxemia(NH).

Methods: An overnight polysomnography was conducted in patients with CTEPH. Apnoea-hypopnoea-index (AHI) as well as mean pulmonary arterial pressure (mPAP), measured by right-heart catheterisation, were entered into a logistic regression model. Moderate to severe NH was defined as nocturnal oxyhaemoglobin saturation (SpO2) <90% during >20% of total sleep time (TST). SBDs were classified as obstructive sleep apnoea (OSA; AHI ?15 events/h), central sleep apnoea with Cheyne-Stokes respiration (CSA-CSR; CSR pattern ? 50% of TST), obesity-hypoventilation syndrome (OHS), and isolated NH (SpO2 <88% for >5 minutes without OSA,CSA or OHS).

Results: In all, 43 patients (mean age 52.7±15.1 years; mPAP 46.0±16.7mmHg) were included. SBD was observed in 35 (81.4%), of whom 23 had OSA, 2 CSA-CSR, 10 isolated NH, and none OHS. Moderate to severe NH occurred among 28 (65.1%). In a multivariate analysis, mPAP (odds ratio [OR] 1.13; 95% confidence interval [CI] 1.02-1.26, p=0.02) and AHI (OR 1.19; 95% CI 1.01-1.42; p=0.04) were independent determinants of moderate to severe NH, adjusted for age, sex and body-mass-index.

Conclusions: Moderate to severe NH is highly prevalent in patients with CTEPH. Early diagnostic sleep monitoring and intervention with nocturnal supplemental oxygen and/or positive airway pressure as well as pulmonary endarterectomy may reduce adverse outcomes of NH in CTEPH.