Prolonged nocturnal hypoxemia predicts worse prognosis in patients with chronic thromboembolic pulmonary hypertension undergoing pulmonary endarectomy

Objective: Obstructive sleep apnea (OSA) and/or nocturnal hypoxemia is prevalent in patients with chronic thromboembolic pulmonary hypertension (CTEPH), yet the pathological determinants of adverse outcomes remain ambiguous. We aimed to investigate the prognostic significance of various sleep parameters for poor prognosis in patients with CTEPH undergoing pulmonary endarterectomy (PEA). Design and method: Consecutive patients diagnosed with CTEPH who underwent overnight cardiorespiratory polygraphy for the assessment of OSA were enrolled. Time-to-event analysis was performed investigating cardiorespiratory indices (eg, apnea-hypopnea index [AHI], time percentage with oxygen saturation below <90% [T90]) and clinical worsening using the log-rank test and multivariable Cox proportional hazard models adjusted for multiple confounders. Results: Of 71 operable CTEPH patients, 36 (50.7%) had OSA (AHI = 5 or above) and 32 (45.1%) had nocturnal hypoxemia (T90 no less than 30%). A 10% increase in T90 was associated with a nearly 27% greater risk of being classified as a high-risk group (odds ratio: 1.27, 95% confidence interval [CI] 1.07-1.50, P = 0.006), as quantified by mean pulmonary artery pressure over 46 mmHg. Over a median follow-up of 39.0 months, 19 (26.8%) patients experienced CW events. AHI did not predict a higher risk of incident CW (hazard ratio [HR]: 1.00, 95% CI: 0.93-1.06, P = 0.906). By contrast, Compared with normoxemic patients, patients with nocturnal hypoxemia had a higher cumulative incidence of CW (43.8% vs. 12.8%, log-rank P = 0.017). Notably, nocturnal hypoxemia was associated with an increased risk of CW events (HR: 3.27, 95% CI 1.17-9.13, P = 0.024), and these associations persisted even after covariate adjustment. Conclusions: Among patients with operable CTEPH, nocturnal hypoxemia quantified by T90 was a robust risk predictor of both short-term and long-term CW events. Investigation of nocturnal hypoxemic burden in CTEPH may aid in the early risk-stratification.