Neurological Institute Outcomes

A progressive and often fatal condition, group 1 pulmonary arterial hypertension (PAH) is defined by right ventricular (RV) failure. There are poorer outcomes in connective tissue disease (CTD). The objective was to investigate whether obstructive sleep apnea, defined by the apnea-hypopnea index (AHI), and sleep-related hypoxia, defined by percentage time oxygen saturation <90% (T90), contribute to RV dysfunction and survival.

Patients included in this study were participants of the Pulmonary Vascular Disease Phenomics (National Heart, Lung, and Blood Institute) cohort. Patients with group 1 PAH were compared to comparators and healthy controls. Models for RV function with AHI and T90 were constructed and adjusted for demographics, oxygen use, diffusing capacity of the lungs for carbon monoxide, and pulmonary hypertension medications. Adjusted time-to-event models were constructed for transplant-free survival.

N=186 participants with group 1 PAH were included with a mean age of 52.6 ± 14.1 years; 71.5% women, 80.8% Caucasian, and there were 43 events (transplant or death). AHI and T90 were associated with decreased RV ejection fraction by 2.18% (-2.18; 95% CI: -4.00 to -0.36, p=0.019) and 0.93% (-0.93; 95% CI: -1.47 to -0.40, p<0.001), respectively. T90 was associated with increased RV systolic pressure by 2052 mmHg (2.52; 95% CI: 1.61 to 3.43; p<0.001), increased mean pulmonary artery pressure by 0.27 mmHg (0.27; 95% CI: 0.05 to 0.49; p=0.019), and RV hypertrophy by 1.24 mm (1.24; 95% CI: 1.10 to 1.40; p<0.001). T90, but not AHI, was associated with a 17% increased 5-year risk for transplant or death (HR: 1.17; 95% CI: 1.07 to 1.28). In non-CTD-associated PAH, T90 was associated with a 21% increased risk for transplant or death (HR: 1.21; 95% CI: 1.08 to 1.34). In CTD-associated PAH, T90 was associated with RV dysfunction, but not transplant or death.

The association between sleep-related hypoxia and RV functional measures, transplant, and death was greater in magnitude than that of AHI. Interestingly, T90 was only associated with RV dysfunction in CTD-associated PAH. Hypoxia contributes to PAH severity.