Risk factors for cardiovascular events in patients with heterozygous familial hypercholesterolaemia: protocol for a systematic review

INTRODUCTION

Heterozygous 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 ANALYSIS

Our 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 DISSEMINATION

All 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 NUMBER

CRD42022304273.

A resilient type of familial hypercholesterolaemia: case-control follow-up of genetically characterized older patients in the SAFEHEART cohort

AIMS 

Knowledge of the features of patients with familial hypercholesterolaemia (FH) who are protected from atherosclerotic cardiovascular disease (ASCVD) is important for the clinical and prognostic care of this apparently high-risk condition. Our aim was to investigate the determinant and characteristics of patients with FH who are protected from ASCVD and have normal life expectancy, so-called 'resilient' FH (R-FH).

METHODS AND RESULTS 

Spanish Familial Hypercholesterolaemia cohort study (SAFEHEART) is an open, multicentre, nation-wide, long-term prospective cohort study in genetically defined patients with heterozygous FH in Spain. Patients in the registry who at the time of analysis were at least 65 years or those who would have reached that age had they not died from an ASCVD event were analysed as a case-control study. Resilient FH was defined as the presence of a pathogenic mutation causative of FH in a patient aged ≥65 years without clinical ASCVD. Nine hundred and thirty registrants with FH met the study criteria. A defective low-density lipoprotein (LDL)-receptor mutation, higher plasma level of high-density lipoprotein cholesterol (HDL-C), younger age, female gender, absence of hypertension, and lower plasma lipoprotein (a) [Lp(a)] concentration were independently predictive of R-FH. In a second model, higher levels of HDL-C and lower 10-year score in SAFEHEART-RE were also independently predictive of R-FH.

CONCLUSION 

Resilient FH may be typified as being female and having a defective LDL-receptor mutation, higher levels of plasma HDL-C, lower levels of Lp(a), and an absence of hypertension. The implications of this type of FH for clinical practice guidelines and the value for service design and optional care of FH remains to be established.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT02693548.