Cascade testing for elevated lipoprotein(a) in relatives of probands with familial hypercholesterolaemia and elevated lipoprotein(a)

Lp(a) Levels in Relatives of Patients with Acute Coronary Syndrome and Elevated Lp(a): HER(a) Study

Background: Lipoprotein(a) [Lp(a)] is a proatherogenic particle associated with increased cardiovascular risk. It is mainly genetically determined; so, the aim of our study is to evaluate the levels of Lp(a) in the relatives of a prospective cohort of patients who have suffered from an acute coronary syndrome (ACS) with Lp(a) ≥ 50 mg/dL. Methods: We conducted a multicenter prospective study, in which consecutive patients who had suffered from an ACS and presented Lp(a) ≥ 50 mg/dL and their first-degree relatives were included. Results: We included 413 subjects, of which 56.4% were relatives of the patients. Family history of early ischemic heart disease was present in 57.5%, and only 20.6% were receiving statin treatment. The family cohort was younger (37.5 vs. 59.1 years; p < 0.001), and 4% had ischemic heart disease and fewer cardiovascular risk factors. Mean Lp(a) levels were 64.9 mg/dL, 59.4% had levels ≥ 50 mg/dL, and 16.1% had levels ≥ 100 mg/dL. When comparing the patients with respect to their relatives, the mean level of Lp(a) was lower but without significant differences regarding the levels of LDLc, ApoB, and non-HDL. However, relatives with Lp(a) ≥ 50 mg/dL, had values similar to the group of patients with ACS (96.8 vs. 103.8 mg/dL; p = 0.18). No differences were found in Lp(a) levels in relatives based on the other lipid parameters. Conclusions: Overall, 59.4% of the first-degree relatives of patients who suffered from an ACS with Lp(a) ≥ 50 mg/dL also had elevated levels. Relatives with elevated Lp(a) had similar levels as patients.

Cascade testing of children and adolescents for elevated Lp(a) in pedigrees with familial hypercholesterolaemia

Elevated plasma lipoprotein(a) [Lp(a)] is a common, inherited condition independently causing cardiovascular disease. Recent expert recommendations suggest opportunistically testing for elevated Lp(a) during cascade testing for familial hypercholesterolaemia (FH). We investigated the effectiveness of detecting elevated Lp(a) in 103 children and adolescents who were first-degree relatives of 66 adult index FH cases as part of an established FH cascade screening program. The yield of detection of elevated Lp(a) using a threshold of ≥30 mg/dL in children and adolescents was assessed. Cascade testing from FH index cases with elevated Lp(a) ≥50 mg/dL identified 1 case of Lp(a) ≥30 mg/dL for every 2 children or adolescents tested. In contrast, opportunistic screening from index cases with FH but normal Lp(a) levels demonstrated 1 case of Lp(a) ≥30 mg/dL for every 7.5 children or adolescents tested (p < 0.001). In conclusion, cascade testing for elevated Lp(a) from index cases with FH and elevated Lp(a) is effective in identifying new cases of elevated Lp(a).

Consensus document on Lipoprotein(a) from the Italian Society for the Study of Atherosclerosis (SISA)

AIMS

In view of the consolidating evidence on the causal role of Lp(a) in cardiovascular disease, the Italian Society for the Study of Atherosclerosis (SISA) has assembled a consensus on Lp(a) genetics and epidemiology, together with recommendations for its measurement and current and emerging therapeutic approaches to reduce its plasma levels. Data on the Italian population are also provided.

DATA SYNTHESIS

Lp(a) is constituted by one apo(a) molecule and a lipoprotein closely resembling to a low-density lipoprotein (LDL). Its similarity with an LDL, together with its ability to carry oxidized phospholipids are considered the two main features making Lp(a) harmful for cardiovascular health. Plasma Lp(a) concentrations vary over about 1000 folds in humans and are genetically determined, thus they are quite stable in any individual. Mendelian Randomization studies have suggested a causal role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis and observational studies indicate a linear direct correlation between cardiovascular disease and Lp(a) plasma levels. Lp(a) measurement is strongly recommended once in a patient's lifetime, particularly in FH subjects, but also as part of the initial lipid screening to assess cardiovascular risk. The apo(a) size polymorphism represents a challenge for Lp(a) measurement in plasma, but new strategies are overcoming these difficulties. A reduction of Lp(a) levels can be currently attained only by plasma apheresis and, moderately, with PCSK9 inhibitor treatment.

CONCLUSIONS

Awaiting the approval of selective Lp(a)-lowering drugs, an intensive management of the other risk factors for individuals with elevated Lp(a) levels is strongly recommended.

Detection strategies for elevated lipoprotein(a): will implementation let the genie out of the bottle?

PURPOSE OF REVIEW

Elevated Lp(a) level is an important causal risk factor for atherosclerotic cardiovascular disease (ASCVD), principally coronary artery disease. Selective testing for Lp(a) is highly recommended in patients at intermediate and high risk for ASCVD. Lp(a) levels are predominantly genetically determined, and this has implications for cascade testing.

RECENT FINDINGS

Recent studies show that cascade testing is effective in identifying elevated Lp(a) in close relatives of probands with high Lp(a). Apart from selective testing and cascade testing as detection strategies, some recent guidelines recommend testing of Lp(a) in all adults at least once in their lifetime and various implementation strategies have been suggested.

SUMMARY

Hyper-Lp(a) is an important global health problem that can be easily detected. Hyper-Lp(a) meets all the criteria for universal screening except that there is not yet supportive evidence from clinical interventional trials showing a reduction of ASCVD events. The cost-effectiveness of the various detection and implementation strategies need to be further evaluated.

Lipoprotein(a) levels in children with suspected familial hypercholesterolaemia: a cross-sectional study

AIMS

Familial hypercholesterolaemia (FH) predisposes children to the early initiation of atherosclerosis and is preferably diagnosed by DNA analysis. Yet, in many children with a clinical presentation of FH, no mutation is found. Adult data show that high levels of lipoprotein(a) [Lp(a)] may underlie a clinical presentation of FH, as the cholesterol content of Lp(a) is included in conventional LDL cholesterol measurements. As this is limited to adult data, Lp(a) levels in children with and without (clinical) FH were evaluated.

METHODS AND RESULTS

Children were eligible if they visited the paediatric lipid clinic (1989-2020) and if Lp(a) measurement and DNA analysis were performed. In total, 2721 children (mean age: 10.3 years) were included and divided into four groups: 1931 children with definite FH (mutation detected), 290 unaffected siblings/normolipidaemic controls (mutation excluded), 108 children with probable FH (clinical presentation, mutation not detected), and 392 children with probable non-FH (no clinical presentation, mutation not excluded). In children with probable FH, 32% were found to have high Lp(a) [geometric mean (95% confidence interval) of 15.9 (12.3-20.6) mg/dL] compared with 10 and 10% [geometric means (95% confidence interval) of 11.5 (10.9-12.1) mg/dL and 9.8 (8.4-11.3) mg/dL] in children with definite FH (P = 0.017) and unaffected siblings (P = 0.002), respectively.

CONCLUSION

Lp(a) was significantly higher and more frequently elevated in children with probable FH compared with children with definite FH and unaffected siblings, suggesting that high Lp(a) may underlie the clinical presentation of FH when no FH-causing mutation is found. Performing both DNA analysis and measuring Lp(a) in all children suspected of FH is recommended to assess possible LDL cholesterol overestimation related to increased Lp(a).

Familial Hypercholesterolemia and Lipoprotein(a): A Gordian Knot in Cardiovascular Prevention

Familial hypercholesterolemia (FH) is the most frequent genetic disorder resulting in increased low-density lipoprotein cholesterol (LDL-C) levels from childhood, leading to premature atherosclerotic cardiovascular disease (ASCVD) if left untreated. FH diagnosis is based on clinical criteria and/or genetic testing and its prevalence is estimated as being up to 1:300,000−400,000 for the homozygous and ~1:200−300 for the heterozygous form. Apart from its late diagnosis, FH is also undertreated, despite the available lipid-lowering therapies. In addition, elevated lipoprotein(a) (Lp(a)) (>50 mg/dL; 120 nmol/L), mostly genetically determined, has been identified as an important cardiovascular risk factor with prevalence rate of ~20% in the general population. Novel Lp(a)-lowering therapies have been recently developed and their cardiovascular efficacy is currently investigated. Although a considerable proportion of FH patients is also diagnosed with high Lp(a) levels, there is a debate whether these two entities are associated. Nevertheless, Lp(a), particularly among patients with FH, has been established as a significant cardiovascular risk factor. In this narrative review, we present up-to-date evidence on the pathophysiology, diagnosis, and treatment of both FH and elevated Lp(a) with a special focus on their association and joint effect on ASCVD risk.

Lipoprotein(a) in atherosclerotic cardiovascular disease and aortic stenosis: a European Atherosclerosis Society consensus statement

This 2022 European Atherosclerosis Society lipoprotein(a) [Lp(a)] consensus statement updates evidence for the role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis, provides clinical guidance for testing and treating elevated Lp(a) levels, and considers its inclusion in global risk estimation. Epidemiologic and genetic studies involving hundreds of thousands of individuals strongly support a causal and continuous association between Lp(a) concentration and cardiovascular outcomes in different ethnicities; elevated Lp(a) is a risk factor even at very low levels of low-density lipoprotein cholesterol. High Lp(a) is associated with both microcalcification and macrocalcification of the aortic valve. Current findings do not support Lp(a) as a risk factor for venous thrombotic events and impaired fibrinolysis. Very low Lp(a) levels may associate with increased risk of diabetes mellitus meriting further study. Lp(a) has pro-inflammatory and pro-atherosclerotic properties, which may partly relate to the oxidized phospholipids carried by Lp(a). This panel recommends testing Lp(a) concentration at least once in adults; cascade testing has potential value in familial hypercholesterolaemia, or with family or personal history of (very) high Lp(a) or premature ASCVD. Without specific Lp(a)-lowering therapies, early intensive risk factor management is recommended, targeted according to global cardiovascular risk and Lp(a) level. Lipoprotein apheresis is an option for very high Lp(a) with progressive cardiovascular disease despite optimal management of risk factors. In conclusion, this statement reinforces evidence for Lp(a) as a causal risk factor for cardiovascular outcomes. Trials of specific Lp(a)-lowering treatments are critical to confirm clinical benefit for cardiovascular disease and aortic valve stenosis.

Familial Hypercholesterolemia and Lipoprotein(a): Two Partners in Crime?

PURPOSE OF REVIEW

Familial hypercholesterolemia is a high cardiovascular risk disorder. We will review the role of lipoprotein(a) in cardiovascular risk and in aortic valve stenosis in familial hypercholesterolemia, as well as its association with their phenotype, and strategies to identify this high-risk population.

RECENT FINDINGS

Patients with familial hypercholesterolemia have higher lipoprotein(a) levels mainly due to an increased frequency of LPA variants, and the cardiovascular risk is increased twofolds when both conditions coexist. Also, an increased risk for aortic valve stenosis and valve replacement has been observed with high lipoprotein(a) levels. Assessment of lipoprotein(a) during the cascade screening for familial hypercholesterolemia is a good opportunity to identify this high-risk population. High cardiovascular risk in familial hypercholesterolemia is increased even more when lipoprotein(a) is also elevated. Measurement of lipoprotein(a) in these patients is crucial to identify those subjects who need to intensify LDL-cholesterol reduction pending availability of lipoprotein(a)-specific treatments.

Cascade testing for elevated lipoprotein(a) in relatives of probands with high lipoprotein(a)

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Elevated lipoprotein(a) [Lp(a)] is a common inherited condition associated with atherosclerotic cardiovascular disease.

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Elevated Lp(a) is not routinely tested in clinical practice and most cases remain undiagnosed in the community.

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We identified 124 relatives with elevated Lp(a) (≥50 mg/dL) from 83 affected adult probands who also had dyslipidemia.

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We also demonstrate that follow-up management is effective in lowering low-density lipoprotein-cholesterol levels by 34% as a consequence of initiation of lipid-lowering therapy.

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Cascade testing families for elevated Lp(a) from affected probands with dyslipidemia is an effective and acceptable approach for identifying new cases of elevated Lp(a) who will require management of modifiable risk factors, particularly hypercholesterolemia.

Objective

Elevated lipoprotein(a) [Lp(a)] is a common inherited condition associated with cardiovascular disease. This study investigated whether cascade testing for Lp(a) was effective in detecting new cases of elevated Lp(a) in families.

Methods

Relatives from adult probands with Lp(a) concentration ≥100 mg/dL were tested for elevated Lp(a) (≥50 mg/dL) via a cascade testing program in a tertiary hospital setting. The prevalence and yield of detecting new cases of elevated Lp(a) among the relatives were assessed.

Results

Of the 83 probands, 43.4% had familial combined hyperlipidemia (FCHL) and 34.9% common hypercholesterolemia (CH). Among 182 relatives tested (151 adults and 31 children), elevated Lp(a) was found in 68.1%, with 32.9% having Lp(a) between 50 and 99 mg/dL and 35.2% having Lp(a) ≥100 mg/dL. One new case of elevated Lp(a) ≥50 mg/dL was identified for every 1.5 relatives tested and 1 new case of elevated Lp(a) ≥100 mg/dL for every 2.8 relatives tested. The proportion of relatives detected with elevated Lp(a) was significantly higher when tested from probands with Lp(a) >150 mg/dL compared with those with Lp(a) between 100 and 150 mg/dL (81.1% vs. 55.5%; P = 0.001). The concordance rates (kappa coefficient) for the detection of elevated Lp(a) with FCHL and CH were 34.8% (0.026) and 53.2% (0.099), respectively.

Conclusion

Cascade testing for elevated Lp(a) from affected probands with phenotypic dyslipidemia is highly effective in identifying new cases of high Lp(a) in families. The yield of detecting elevated Lp(a) is greater when probands have higher levels of Lp(a) and exceeds the detection of relatives with FCHL and CH.