The retrospectively enrolled subjects were 151 patients with PAH in the Nice Classification group 1 who were admitted for routine hemodynamic follow-up and were screened for SDB from April 2008 through February 2010 (37 males, 114 females 44☑6 years old). The objective of the present study, therefore, was to determine whether nocturnal hypoxemia and/or SA is associated with prognosis in PAH patients. Many studies show that the presence of SA is associated with a poor prognosis in patients with left-sided heart failure, 15, 16īut the effect of nocturnal hypoxemia and SA on the outcome of patients with PAH is unknown. Sleep-disordered breathing (SDB) in patients with pulmonary arterial hypertension (PAH), which comprises not only SA, but also periodic breathing and nocturnal hypoxemia, is common. Pulmonary vasoconstriction occurs in response to alveolar hypoxia, then increased pulmonary vascular resistance (PVR), contributing to an increase in PAP and resulting in pulmonary vascular remodeling. Sleep apnea (SA) can cause repeated nocturnal arterial oxygen desaturation, sleep fragmentation, increased sympathetic activity, oxidative stress, inflammation and endothelial dysfunction, negative swings in intrathoracic pressure, and acute increase in pulmonary arterial pressure (PAP). SA in patients with PAH was not associated with worse prognosis, unlike left ventricular heart failure, but nocturnal hypoxemia was related to poor prognosis. On the other hand, the mortality in patients with lower averaged SpO 2 was significantly higher than in those with higher averaged SpO 2 (χ 2=14.7, P<0.001) and that was the only independent variable related to death in multivariate Cox proportional hazards analysis. By Kaplan-Meier analysis, there was no significant difference in deaths of patients with and without SA (χ 2=2.82, P=0.093).

Over an average follow-up of 1,170☗63 days, 32 patients died. SA was noted in 58 patients (obstructive SA/central SA: 29/29). Averaged percutaneous oxygen saturation (SpO 2) during sleep was measured and an apnea-hypopnea index >5 was defined as SA. They underwent right-heart catheterization and a sleep study with simplified polysomnography. They were all in the Nice Classification group 1 (idiopathic PAH/associated PAH=52/48%, mean PAP of 46☑6 mmHg). We enrolled 151 patients with PAH (44☑6 years old, male/female=37/114). The presence of SA is associated with a poor prognosis in patients with chronic left-sided heart failure, but little is known for patients with pulmonary arterial hypertension (PAH). Sleep apnea (SA) can cause repeated nocturnal arterial oxygen desaturation and result in acute increase in pulmonary arterial pressure (PAP).

Nocturnal hypoxemia