This research will be one of the first hospital-based studies to comprehensively evaluate the epidemiological characteristics of sleep disordered breathing (SDB) in patients with Congestive Heart Failure (CHF). This prospective, observational cohort, single center study will include all consecutive CHF outpatients from the specialized heart failure clinic in Medical Department, Hospital Taiping, Malaysia irrespective of preserved or depressed Left Ventricular Ejection Fraction (LVEF). All participants will be subjected to an attended in-laboratory polysomnogram (PSG). It is anticipated the frequency and types of SDB to be variable compared to western data as this subject remains understudied in the South East Asian population. This research utilizes PSG rather than Portable Sleep Testing (PST) as seen in preceding studies for the diagnosis of SDB to prevent underdiagnosing SDBs and clearly distinguishing Obstructive Sleep Apnea (OSA) and Central Sleep Apnea (CSA).

The epidemiology of SDB in CHF has not been studied in a South East Asian population. The results from studies conducted in USA and Europe on the prevalence of SDB in CHF may not be applicable to these patients for various reasons. Firstly, a diverse and multi -ethnic population in South East Asia may have an impact on the occurrence of SDB due to varying craniofacial morphological appearances, differences in levels of obesity and respiratory chemosensitivity. Additionally, the disparity in health services and the socio-economic differences between developed countries in the west and developing nations in South East Asia may have an impact on pharmacotherapy of CHF affecting the frequency and severity of SDB in these patients.

This research studies the epidemiological characteristics of SDB in non-selected, consecutive and consenting patients with CHF in the heart failure clinic as studying highly selected patients with clinical characteristics and risk factors of SBD may overestimate the prevalence. As patients with SDB in CHF may lack subjective EDS and assessment tools are unreliable in predicting SDB in CHF patients, the investigators wish to identify clinical predictors in this cohort of patients. It is anticipated there may be differences in this aspect when compared to patients in the western population and the investigators hope to obtain some understanding on the gender differences for SDB that has been reported in prior studies as well. The utility of attended in laboratory PSG as a diagnostic tool for all consecutive patients with CHF will prevent underestimation of AHI and clearly distinguish OSA and CSA based on standard definitions.

The prevalence of SDB in preserved ejection fraction CHF is understudied globally and the investigators wish to include preserved ejection fraction CHF patients apart from depressed ejection fraction CHF patients in this study. SDB presents as a treatment opportunity for patients with CHF but first the disorder has to be suspected and diagnosed. Initiation of nocturnal ventilation following diagnosis may treat the SDB and improve the prognosis of CHF.

Inclusion Criteria:

• All patients with CHF regardless of LVEF Participants need to be older than 18 years old and is able to understand study information and give informed consent

Exclusion Criteria:

• Patients who had been diagnosed with SDB or is treated with any form of Positive Airway Pressure (PAP) therapy prior to this will be excluded from this study.

All consecutive adult patients under follow-up in Heart Failure Clinic, Hospital Taiping during the period 1 April 2022 - 31 December 2024