Literature search and data sources
This systematic review and meta-analysis were executed using a preplanned protocol. The results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines(5). An electronic search with the assistance of a librarian was conducted. We searched the databases including Ovid MEDLINE, Ovid Embase Scopus, Web of Science, Google Scholar, and EBSCO CINAHL from inception up to December 26th, 2020 were queried. The search was not restricted to time, publication status or language. Moreover, the references as well as studies related to first author and corresponding author of included studies were hand-searched for other relevant studies. We used Medical Subject Headings (MeSH) terms with keywords sleep apnea, sleep-disordered breathing, hypoventilation disorder/disease, DD and heart failure with preserved/normal ejection fraction. (Figure 1) shows details. We included randomized and quasi-randomized designs, pre-post trials, cross-sectional studies, and observational studies.