Nocturnal Hypoxemia and High Circulating TNF-α Levels in Chronic Thromboembolic Pulmonary Hypertension

OBJECTIVE: Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension caused by persistent thromboemboli of the pulmonary arteries, and one of its etiological factors may be inflammation. Sleep disordered breathing (SDB) is reportedly an important complication of pulmonary hypertension. However, the association between SDB and inflammation in CTEPH has been undefined. This prospective observational study analyzed the association between the severity of SDB, pulmonary hemodynamic parameters and the systemic inflammation level in patients with CTEPH. METHODS: CTEPH patients admitted for a right heart catheter (RHC) examination were consecutively enrolled from November 2017 to June 2019 at the pulmonary hypertension center in Chiba University Hospital. Patients with idiopathic pulmonary arterial hypertension (IPAH) were also enrolled as a control group. All patients underwent a sleep study using a WatchPAT 200 during admission. RESULTS: The CTEPH patients showed worse nocturnal hypoxemia, oxygen desaturation index (ODI), and apnea-hypopnea index than the IPAH patients. Among these factors, only the nocturnal mean percutaneous oxygen saturation (SpO(2)) was negatively correlated with the pulmonary hemodynamic parameters. The circulating tumor necrosis factor-alpha (TNF-α) level was also high in the CTEPH group, and a multivariate analysis showed that the nocturnal mean SpO(2) was the most important predictive factor for a high TNF-α level. CONCLUSION: We showed that CTEPH patients had high serum TNF-α levels and that the nocturnal mean SpO(2) was a predictive factor for serum TNF-α levels. Further investigations focused on nocturnal hypoxemia and the TNF-α level may provide novel insight into the etiology and new therapeutic strategies for CTEPH.