Validation of the ApneaScan Algorithm in Sleep Disordered Breathing

Sleep disordered breathing, in which patients my breath deeply, shallowly or stop breathing for periods whilst asleep, is common in heart failure and associated with a poor prognosis. This study aims to validate a novel function available on certain pacemakers which is designed to detect this condition.The investigators hypothesize that ApneaScan can accurately detect moderate to severe sleep disordered breathing in patients with heart failure as compared against an Embletta sleep study. The investigators will also follow up our patients for 2 years to determine whether the severity of sleep disordered breathing as assessed by ApneaScan correlates with prognosis.

72 patients with heart failure with reduced ejection fraction (HFREF) who have been selected to receive an Implantable Cardioverter-Defibrillator (ICD) or Cardiac Resynchronization Therapy Pacemaker or Defibrillator (CRT-P/D) will undergo pre-implant assessment with an echocardiogram, B-type Natriuretic Peptide (BNP) level, 6 minute walk test, Minnesota living with heart failure and Epworth sleepiness questionnaires. The patients will then have the device implanted. 6 to 8 weeks later the patent will undergo an Embletta home sleep study and download of the ApneaScan data from the device. The mean Apnoea-Hypopnoea Index (AHI) from the ApneaScan download will be compared with that derived from the sleep study. The patients will also have a repeat 6 minute walk test, echocardiogram and BNP level. 2 years after device implantation, all patients will be followed up to document deaths, hospital admissions, Atrial Fibrillation (AF) burden and appropriate therapies from ICD devices.