IntroductionHeterozygous familial hypercholesterolaemia (heFH) is the most common monogenic cause of premature atherosclerotic cardiovascular disease. The precise diagnosis of heFH is established by ...genetic testing. This systematic review will investigate the risk factors that predict cardiovascular events in patients with a genetic diagnosis of heFH.Methods and analysisOur literature search will cover publications from database inception until June 2023. We will undertake a search of CINAHL (trial), clinicalKey, Cochrane Library, DynaMed, Embase, Espacenet, Experiments (trial), Fisterra, ÍnDICEs CSIC, LILACS, LISTA, Medline, Micromedex, NEJM Resident 360, OpenDissertations, PEDro, Trip Database, PubPsych, Scopus, TESEO, UpToDate, Web of Science and the grey literature for eligible studies. We will screen the title, abstract and full-text papers for potential inclusion and assess the risk of bias. We will employ the Cochrane tool for randomised controlled trials and non-randomised clinical studies and the Newcastle–Ottawa Scale for assessing the risk of bias in observational studies. We will include full-text peer-reviewed publications, reports of a cohort/registry, case–control and cross-sectional studies, case report/series and surveys related to adults (≥18 years of age) with a genetic diagnostic heFH. The language of the searched studies will be restricted to English or Spanish. The Grading of Recommendations, Assessment, Development and Evaluation approach will be used to assess the quality of the evidence. Based on the data available, the authors will determine whether the data can be pooled in meta-analyses.Ethics and disseminationAll data will be extracted from published literature. Hence, ethical approval and patient informed consent are not required. The findings of the systematic review will be submitted for publication in a peer-reviewed journal and presentation at international conferences.PROSPERO registration numberCRD42022304273.
