Familialhypercholesterolemia (FH) is one of the most clinically relevant monogenicdisorders contributing to the development of atherosclerotic cardiovasculardisease (ASCVD). The prevalence of FH was estimated to be 1 in 200 to 1 in 250 individualsin studies in which genetic testing was conducted on large community populationsamples.1 However, the disease often remains undetected and thusuntreated, with only 10% of individuals with FH receiving adequate diagnosisand treatment.2

Notingthe recent accumulation of studies on FH, the authors of a Nature ReviewsCardiology article sought tosummarize the key elements of a model of care for the condition that canbe adapted as new evidence emerges.1 Selected points are highlightedbelow.

Screening and detection. A combination of selective, opportunistic (eg, genetic screening of blood donors), systematic, and universal screening approaches is recommended to improve the detection of FH. Universal screening of children and childparent (reverse) cascade testing is potentially a highly effective method for detecting patients with FH at a young age, before they develop ASCVD32 [and] might be particularly relevant to communities with gene founder effects, noted the review authors. All children with FH should ideally be detected from the age of 5 years or earlier if homozygous FH (hoFH) is suspected.

Diagnosis. In the United States, elevated levels of low-density lipoprotein cholesterol (LDL-C) and a family history of FH are the main phenotypic criteria for FH diagnosis in children. Patients with hoFH, heterozygous FH (heFH), and polygenic hypercholesterolemia may also present with overlapping LDL-C levels, posing a challenge for the development of a standardized diagnostic tool for FH.

Genetic testing. Aninternational expert panel recently endorsed genetic testing in the care ofpatients with FH as it would [allow] a definitive diagnosis, improve[e] riskstratification, address the increasing need for more potent therapies, improve[e]adherence to treatments, and increase[e] the precision and cost- effectivenessof cascade testing.1,3 However, genetic testing remains underuseddue to issues such as cost, low access to genetic counseling, and lack ofclinician knowledge in this area.

Clinical risk assessment.Cumulative lifetime exposure to elevated LDL-C is the key factor driving ASCVDrisk in asymptomatic patients with FH, further underscoring the need for timelydiagnosis and risk stratification. In addition to phenotypic and geneticfactors, imaging of subclinical atherosclerosis, might be the most usefulclinical tool for assessing risk in FH.1 For example, imaging ofcoronary artery calcium can be used to predict coronary events in asymptomaticmiddle-aged patients with FH taking statins, and computed tomography coronaryangiography can be used to assess plaque burden and to intensify therapy.

Care of adults.Emerging evidence continues to support aggressive cholesterol-lowering therapyand lifestyle management in patients with FH from as young as 8 years tomaximally mitigate the cumulative cholesterol burden of risk. The review authorsemphasize the importance of patient-centered care and shared decision making,although health literacy is a challenge that may need to be addressed with somepatients.

Whilethere is insufficient evidence to develop strictly defined LDL-C treatmenttargets, current evidence-based recommendations stipulate that in adultpatients with FH, statin therapy and diet should initially be targeted toachieve a 50% reduction in LDL-cholesterol level and an LDL-cholesterol level<1.8 mmol/l (70 mg/dl) or <2.6 mmol/l (100 mg/dl) for primaryprevention, and <1.4 mmol/l (55 mg/dl) or <1.8 mmol/l (70 mg/dl) forsecondary prevention or for patients at very high risk.1

The addition of ezetimibe is indicated in patients who do not achieve the recommended LDL-C levels with statins alone. The use of a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor as a third-line therapy is recommended in those patients or in patients who are intolerant to statins. The addition of a PCSK9 inhibitor in patients with heFH can further reduce LDL-C levels by approximately 60% and lead to recommended treatment targets in more than 80% of patients. However, these agents should not be used during pregnancy, as they cross the placenta and their impact on fetal development has not yet been determined.

Care of children. Extensive evidence supports the treatment of FH starting in childhood, as [m]odest and sustained reductions in LDL- cholesterol levels from early life can have a major effect on reducing mortality associated with ASCVD. Initial therapy is based on lifestyle management in early childhood, with the addition of statins by age 10 years in children with HeFH and upon diagnosis in children with hoFH. Ongoing research is investigating the efficacy and safety of PCSK9 inhibitors in children with heFH or hoFH.4,5

Radical therapies and novel approaches. Lipoprotein apheresis may be required insevere cases of FH, including in pregnant women, and liver transplantationremains the only curative therapy for patients with severe hoFH.

In ongoing studies, an array of novel treatment approaches are being examined, including functional LDL receptor gene transfer therapy in patients with hoFH and targeted RNA-based therapies to lower elevated lipoporotein(a) levels.6-8

Reviewauthors also emphasized the importance of clinical registries, patient supportgroups and networks, and the need for structured research programs that areunderpinned by actionable dissemination and implementation strategies,research skills and training among service providers, and sustainable fundingmodels. They stated that a major challenge is translating new evidence intohealth policy and routine care. Systems approaches for supporting healthorganizations and providers in addressing these gaps in care and serviceprovision are essential.

We spoke with Seth Shay Martin, MD, MHS, associate professor ofmedicine at the Johns Hopkins University School of Medicine in Baltimore,Maryland, and director of the Advanced Lipid Disorders Program of the Ciccarone Center atJohns Hopkins.

Cardiology Advisor: What are examplesof the latest advances in knowledge or practice pertaining to FH?

Dr Martin: A big advance inpractice has been the introduction of PCSK9 inhibitors. When added to statinsand ezetimibe, this class of medications can lower LDL-C by 60% sometimes the reduction can be lower, but inmy experience the effect is commonly approximately 60%. This leads to patientscoming back to clinic really satisfied.

Cardiology Advisor: What is the optimalapproach for the treatment of these patients, and what are some of the toptreatment challenges?

Dr Martin: The optimal approach is to follow the 2018 American Heart Association/American College of Cardiology multi-society guidelines, which recommend a combination approach of lifestyle modification with first-line maximal statin therapy, followed by the addition of ezetimibe and PCSK9 inhibitors. The LDL-C threshold at which additional therapy should be considered is70 mg/dL in high-riskpatients with ASCVD and FH. In patients with isolated FH (termed severe hypercholesterolemia by the guidelines,based on LDL-C levels 190 mg/dL), the LDL-C threshold is 100 mg/dL.

Cardiology Advisor: What are otherrelevant treatment implications for clinicians who treat these patients?

Dr Martin: One of the joys intaking care of a patient with FH is taking care of a family. It is a geneticdisorder with a 50% chance of being passed from parent to child. It is key toperform cascade testing to identify other members of the family; family visitsto the clinic can be beneficial for all.

Cardiology Advisor: What are remaining needs in thisarea?

Dr Martin: There is a great need for increasing awareness and diagnosis rates for FH. This is what our center is working to do as partners of the FH Foundation and as a CASCADE FH Registry site.

References

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Reviewing Evidence on the Screening, Diagnosis, and Care of Familial Hypercholesterolemia - The Cardiology Advisor

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