Association of Prolonged Nocturnal Hypoxemia with Clinical Worsening in Patients with Chronic Thromboembolic Pulmonary Hypertension Undergoing Pulmonary Endarterectomy

Abstract

Background: Obstructive sleep apnea (OSA) is common in patients with chronic thromboembolic pulmonary hypertension (CTEPH), but the pathological determinants of adverse outcomes remain unknown. This study aimed to investigate the prognostic significance of various sleep parameters in patients with CTEPH undergoing pulmonary endarterectomy. Methods: 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 (e.g., 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 the 71 patients with operable CTEPH who underwent overnight cardiorespiratory polygraphy, 36 (50.7%) had OSA (AHI of 5) and 32 (45.1%) had nocturnal hypoxemia (T90 of 30%). A 10% increase in T90 was associated with a 27% greater risk of worse hemodynamics, as quantified by mean pulmonary artery pressure of 46 mmHg (odds ratio: 1.27, 95% confidence interval [CI]: 1.07–1.50, p = 0.006). Clinical worsening (CW) was experienced by 19 (26.8%) patients over a median follow-up of 26.8 months. AHI did not predict a higher risk of CW (hazard ratio [HR]: 1.00, 95% CI: 0.93–1.06, p = 0.906). A higher cumulative incidence of CW was seen in patients with nocturnal hypoxemia than in those with normoxemia (43.8% vs . 12.8%, log -rank p = 0.017). Cox regression analysis revealed the association between nocturnal hypoxemia and an increased risk of CW (HR: 3.27, 95% CI: 1.17–9.13, p = 0.024), and these associations persisted after covariate adjustment. Conclusions: Nocturnal hypoxemia quantified by T90 was a risk predictor of short- and long-term CW events among patients with operable CTEPH.