Prevalence, Clinical Characteristics, and Therapeutic Underachievement in Familial Hypercholesterolemia: Results from the GRegistry-FH Population-Based Study in Greece.

Background and Aim: Familial hypercholesterolemia (FH) is a genetic disorder leading to severely elevated LDL-C and premature atherosclerotic cardiovascular disease (ASCVD). This study, the GRegistry-FH, provides the first population-based estimation of heterozygous FH (HeFH) prevalence and the clinical profile of affected individuals in Greece. Methods: A cross-sectional, questionnaire-based study was conducted on a representative sample of 7704 adults across 22 Greek regions. HeFH was assessed using the Simon Broome and Dutch Lipid Clinic Network (DLCN) criteria. Clinical characteristics and lipid-lowering therapy (LLT) attainment were compared between individuals with the HeFH phenotype and the general population. Results: The prevalence of HeFH was estimated at 1 in 188 individuals (Simon Broome) and 1 in 183 (DLCN). Individuals with the HeFH phenotype were significantly older and exhibited a much higher prevalence of hypertension (48.8% vs. 23.9%). Notably, individuals with the HeFH phenotype experienced myocardial infarction an average of 14 years earlier than non-FH individuals. Although 80.5% of individuals with the HeFH phenotype were on LLT, only 18.2% achieved LDL-C goals. None of the individuals with the HeFH phenotype with established ASCVD reached the target LDL-C of <1.4 mmol/L (55 mg/dL). Conclusions: HeFH is highly prevalent in Greece but remains largely underdiagnosed in younger ages and suboptimally treated. Despite high treatment rates, the vast majority of individuals with the HeFH phenotype fail to reach protective LDL-C targets. These findings emphasize the need for earlier identification and more aggressive combination lipid-lowering strategies.