Nocturnal Hypoxemic Burden Predicts Mortality in Patients Awaiting Heart Transplantation

Risk stratification for patients with end-stage heart failure (HF) awaiting heart transplantation (HTX) is crucial. Sleep-disordered breathing (SDB) is a prevalent comorbidity, yet the impact of its resultant hypoxemic burden remains unclear in this population. We investigated the prognostic impact of nocturnal hypoxemic burden in patients with end-stage HF awaiting HTX. We prospectively enrolled 101 patients with end-stage HF listed for HTX at a single centre. Baseline polygraphy quantified nocturnal hypoxemic burden (time with SpO2 < 90%; t90). The primary endpoint was a 5-year composite of all-cause mortality or left ventricular assist device (LVAD) implantation. Multivariable Cox proportional hazards models were used for adjustment. During 5-year follow-up, 24 patients reached the primary endpoint. The primary finding was a significant, dose-response relationship between t90 (analysed as a continuous variable) and the primary endpoint (p < 0.001). In a multivariable Cox model adjusted for glomerular filtration rate (GFR) and left ventricular ejection fraction (LVEF), each 30-min increase in t90 was associated with a 29% increase in hazard (Adjusted HR: 1.29, 95% CI: 1.14-1.47, p < 0.001). A t90 of ≥ 180 min was identified as a clinical threshold of high risk, conferring a > 5-fold increase in hazard (Adjusted HR: 5.18, 95% CI: 1.69-15.81, p = 0.004). The cumulative duration of nocturnal hypoxemic burden is a powerful, independent predictor of death or LVAD implantation in patients with end-stage HF. Routine assessment of hypoxemic burden should be considered for risk stratification in patients awaiting heart transplantation. Trial Registration: ClinicalTrials.gov: NCT03026634.