The POACH study is part of the Cardiosleep research program. It is a prospective, observational, multicentre study conducted in Singapore. The recruitment target is 1365 patients. Eligible patients with AF and high cardiovascular risk will be recruited for a home-based sleep study using a FDA-approved portable device. The patients will be divided into 2 groups based on the presence or absence of OSA using apnoea-hypopnoea index ≥ 15 events/hour. The AF will be treated as per local standard practice. Participation in the POACH study will not affect the management of AF. Follow-up will be conducted every 6 months until the median follow-up duration has reached 2 years. The primary endpoint is a four-component composite of all-cause mortality, myocardial infarction, stroke and heart failure hospitalisation. Antecubital venous blood samples will be taken from the patients in the morning after the sleep study for targeted mass spectrometry which will measure 83 circulating metabolites. Sparse Principal Component Analysis will be used for data reduction. Identification of distinct associations between metabolic perturbations and OSA will be performed.