Prognostic value of Implantable Defibrillator-computed Respiratory Disturbance Index: the DASAP-HF study

Abstract Background Sleep apnea, as measured by polysomnography, is associated with adverse outcomes in heart failure. The DASAP-HF study previously demonstrated that the Respiratory Disturbance Index (RDI) computed by the ApneaScan™ algorithm (Boston Scientific) accurately identifies severe sleep apnea in implantable cardioverter defibrillator (ICD) patients. Objective The purpose of the long-term study phase was to assess the incidence of clinical events after 24 months and investigate the association with RDI values. Methods Patients with left ventricular ejection fraction ≤35% implanted with an ICD were enrolled and followed-up for 24 months. The RDI calculated at 1 month after implantation was used to stratify patients (below or above 30 episodes/h). The endpoints were all-cause death and a combination of all-cause death or cardiovascular hospitalization. Results 224 out of 265 enrolled patients had usable RDI values. Severe sleep apnea (RDI≥30episodes/h) was diagnosed in 115 (51%) patients. These patients were more frequently male (84% vs. 72%, p=0.030) and had higher creatinine levels. During a median follow-up of 25 months, 19 (8%) patients died. Cardiovascular hospitalizations were reported in 19 (8%) patients. The risk of all-cause death was higher in patients with RDI≥30episodes/h (HR:3.33, 95%CI:1.35-8.21, p=0.023), as well as the risk of all-cause death or cardiovascular hospitalization (HR:1.94, 95%CI:1.01-3.76, p=0.048). At multivariate analysis, independent predictors of death were RDI≥30episodes/h (HR:4.02, 95%CI:1.16-13.97, p=0.029) and creatinine levels (HR:2.36, 95%CI:1.26-4.42, p=0.008). Conclusion In heart failure patients implanted with an ICD, higher RDI values are associated with death and cardiovascular hospitalizations. Device detected severe sleep apnea independently predicts death.