Elevated Lipoprotein(a) does not promote early atherosclerotic changes of the carotid arteries in young, healthy adults

Lipoprotein(a) levels and carotid intima-media thickness in children: A 20-year follow-up study

Elevated lipoprotein(a) [Lp(a)] is independently associated with cardiovascular disease (CVD). In a recent long-term follow-up study involving children with familial hypercholesterolemia (FH), Lp(a) levels contributed significantly to early atherosclerosis, as measured by carotid intima-media thickness (cIMT). To determine if this holds true for children without FH, we conducted a 20-year follow-up study, examining 88 unaffected siblings (mean age: 12.9 years) of children with FH. No significant association was found between Lp(a) and cIMT during follow-up (ß-adjusted [95% confidence interval] = 0.0001 [-0.008 to 0.008] mm per 50 nmol/L increase Lp(a), p = 0.97). In conclusion, our findings suggest that elevated levels of Lp(a) do not play a significant role in arterial wall thickening among children without FH during the 20-year follow-up period. This leads us to consider the possibility that cIMT may not be a suitable marker for detecting potential subtle changes in the arterial wall mediated by Lp(a) in the young, general population. However, it could also be that elevated Lp(a) is only a significant risk factor for atherosclerosis in the presence of other risk factors such as FH.

Lipoprotein(a) distribution and its association with carotid arteriopathy in the Chinese population

BACKGROUND AND AIMS

The distribution of lipoprotein(a) [Lp(a)] has not been well-studied in a large population in China. The relationship between Lp(a) and carotid atherosclerosis remains undefined. In this study, we aimed to investigate the distribution of Lp(a) levels and to assess their association with carotid arteriopathy in China.

METHODS

In this cross-sectional study, 411,634 adults with Lp(a) measurements from 22 health check-up centers were used to investigate Lp(a) distribution in China. Among participants with Lp(a) data, carotid ultrasound was performed routinely at seven health check-up centers covering 75,305 subjects. Carotid intima-media thickness (cIMT) and carotid plaque were used as surrogate biomarkers of carotid arteriopathy. The multivariate logistic regression model was applied to evaluate the association of increased Lp(a) levels with carotid arteriopathy.

RESULTS

The distribution of Lp(a) concentrations was right-skewed, with a median concentration of 10.60 mg/dL. The proportions of Lp(a) levels ≥30 mg/dL and ≥50 mg/dL were 16.75% and 7.10%, respectively. The median Lp(a) level was higher in females individuals in northern China, and increased with age. Spearman's analysis revealed weak correlations between the Lp(a) concentration as a continuous variable and other lipid profiles. The multiple logistic regression analysis showed that participants with Lp(a) levels ≥50 mg/dL had an increased risk of cIMT ≥1.0 mm (OR = 1.138, 95% CI, 1.071-1.208) and carotid plaque (OR = 1.296, 95% CI, 1.219-1.377) compared with those with Lp(a) levels <50 mg/dL.

CONCLUSIONS

This is the first study of the Lp(a) distribution in a large population in China. Our findings revealed a positive association between elevated Lp(a) levels (≥50 mg/dL) and increased prevalence of carotid atherosclerosis, which implies an increased risk of cardiovascular disease in the future.

Lipoprotein(a) in Youth and Prediction of Major Cardiovascular Outcomes in Adulthood

BACKGROUND

Elevated lipoprotein(a) [Lp(a)] is a common risk factor for cardiovascular disease outcomes with unknown mechanisms. We examined its potential role in identifying youths who are at increased risk of developing adult atherosclerotic cardiovascular disease (ASCVD).

METHODS

Lp(a) levels measured in youth 9 to 24 years of age were linked to adult ASCVD and carotid intima-media thickness in the YFS (Cardiovascular Risk in Young Finns Study), in which 95 of the original 3596 participants (2.7%) recruited as children have been diagnosed with ASCVD at a median of 47 years of age. Results observed in YFS were replicated with the use of data for White participants from the BHS (Bogalusa Heart Study). In BHS, 587 White individuals had data on youth Lp(a) (measured at 8-17 years of age) and information on adult events, including 15 cases and 572 noncases. Analyses were performed with the use of Cox proportional hazard regression.

RESULTS

In YFS, those who had been exposed to high Lp(a) level in youth [defined as Lp(a) ≥30 mg/dL] had ≈2 times greater risk of developing adult ASCVD compared with nonexposed individuals (hazard ratio, 2.0 [95% CI, 1.4-2.6]). Youth risk factors, including Lp(a), low-density lipoprotein cholesterol, body mass index, and smoking, were all independently associated with higher risk. In BHS, in an age- and sex-adjusted model, White individuals who had been exposed to high Lp(a) had 2.5 times greater risk (95% CI, 0.9-6.8) of developing adult ASCVD compared with nonexposed individuals. When also adjusted for low-density lipoprotein cholesterol and body mass index, the risk associated with high Lp(a) remained unchanged (hazard ratio, 2.4 [95% CI, 0.8-7.3]). In a multivariable model for pooled data, individuals exposed to high Lp(a) had 2.0 times greater risk (95% CI, 1.0-3.7) of developing adult ASCVD compared with nonexposed individuals. No association was detected between youth Lp(a) and adult carotid artery thickness in either cohort or pooled data.

CONCLUSIONS

Elevated Lp(a) level identified in youth is a risk factor for adult atherosclerotic cardiovascular outcomes but not for increased carotid intima-media thickness.

Similar Myocardial Perfusion and Vascular Stiffness in Children and Adolescents with High Lipoprotein (a) Levels, in Comparison with Healthy Controls

Background and Aims

This study investigated the possible correlation between elevated lipoprotein (a) (Lp(a)) levels and early vascular aging biomarkers in healthy children and adolescents.

Methods

Twenty-seven healthy children/adolescents, mean age 9.9 ± 3.7 years, with high Lp(a) levels without other lipid abnormalities and 27 age- and sex-matched controls with normal Lp(a) levels, were included in the study. The investigation of possible early vascular aging was assessed by measuring vascular function indices: carotid intima-media thickness (c-IMT), pulse wave velocity (PWV), augmentation index (AIx), and subendocardial viability ratio (SEVR).

Results

Although serum lipid values were within normal levels, mean values of total cholesterol and apolipoprotein B were higher in the group of children with high Lp(a) levels than controls (p = 0.006 and p < 0.001, respectively). Vascular function indices did not show significant differences, neither between the 2 groups nor in the subgroups of children with increased Lp(a) levels. These subgroups were defined by the presence or absence of family history of premature coronary artery disease. Lp(a) levels did not show a significant correlation with the other parameters studied, both regarding the whole sample (patients and controls), as well as in the subgroups of elevated Lp(a) levels. However, in the group of children with high Lp(a) levels, c-IMT and PWV were positively correlated with diastolic blood pressure (r = 0.427, p = 0.026 and r = 0.425, p = 0.030, respectively), while SEVR was negatively correlated with AIx (r = -0.455, p = 0.017).

Conclusions

Healthy children and adolescents with high Lp(a) levels do not yet have impaired vascular indices, compared to controls. However, in order to prevent early atherosclerosis, it is crucial to early identify and follow up children with high Lp(a) levels and positive family history of premature coronary disease or other cardiovascular risk factors.

Elevated Lp(a) (Lipoprotein[a]) Levels Increase Risk of 30-Day Major Adverse Cardiovascular Events in Patients Following Carotid Endarterectomy

Background and Purpose:

General population studies have shown that elevated Lp(a) (lipoprotein[a]) levels are an emerging risk factor for cardiovascular disease and subsequent cardiovascular events. The role of Lp(a) for the risk of secondary MACE in patients undergoing carotid endarterectomy (CEA) is unknown. Our objective is to assess the association of elevated Lp(a) levels with the risk of secondary MACE in patients undergoing CEA.

Methods:

Lp(a) concentrations were determined in preoperative blood samples of 944 consecutive patients with CEA included in the Athero-Express Biobank Study. During 3-year follow-up, major adverse cardiovascular events (MACE), consisting of myocardial infarction, stroke, and cardiovascular death, were documented.

Results:

After 3 years follow-up, Kaplan-Meier cumulative event rates for MACE were 15.4% in patients with high Lp(a) levels (>137 nmol/L; >80th cohort percentile) and 10.2% in patients with low Lp(a) levels (≤137 nmol/L; ≤80th cohort percentile; log-rank test: P =0.047). Cox regression analyses adjusted for conventional cardiovascular risk factors revealed a significant association between high Lp(a) levels and 3-year MACE with an adjusted hazard ratio of 1.69 (95% CI, 1.07–2.66). One-third of MACE occurred within 30 days after CEA, with an adjusted hazard ratio for the 30-day risk of MACE of 2.05 (95% CI, 1.01–4.17). Kaplan-Meier curves from time point 30 days to 3 years onward revealed no significant association between high Lp(a) levels and MACE. Lp(a) levels were not associated with histological carotid plaque characteristics.

Conclusions:

High Lp(a) levels (>137 nmol/L; >80th cohort percentile) are associated with an increased risk of 30-day MACE after CEA. This identifies elevated Lp(a) levels as a new potential risk factor for secondary cardiovascular events in patients after carotid surgery. Future studies are required to investigate whether Lp(a) levels might be useful in guiding treatment algorithms for carotid intervention.

Serum lipoprotein (a) predicts acute coronary syndromes in patients with severe carotid stenosis

BACKGROUND

Different cut-off values of serum lipoprotein (a) [Lp (a)] were recently identified to better stratify cardiovascular risk categories. Both pathophysiological and prognostic values of Lp (a) remain unclear.

MATERIALS AND METHODS

Here, the prognostic value of Lp (a) and its correlation with intraplaque features were assessed in patients with severe carotid artery stenosis undergoing endarterectomy (n = 180). The cut-off value of 10 mg/dL for serum Lp (a) was selected to predict 24-month follow-up acute coronary syndrome (ACS). In addition, the association between serum Lp (a) and intraplaque lipids, collagen, inflammatory and vascular cells was assessed. Serum Lp (a) levels were measured by nephelometric assay.

RESULTS

Patients with high Lp (a) had similar comorbidities, medications and laboratory parameters as compared to low Lp (a) levels. At 24-month follow-up, patients with high Lp (a) had more ACS as compared to low levels. Histological parameters within plaques were comparable in the study groups. No significant correlation between Lp (a) serum levels and intraplaque parameters was found, except for a weak positive association with smooth muscle cells in upstream plaque portions. When adjusted for gender, the presence of dyslipidaemia and chronic coronary artery disease, Lp (a) ≥10 mg/dL remained predictive for ACS.

CONCLUSIONS

Lp (a) determination could be a useful tool to predict ACS in patients with severe carotid stenosis.

Carotid artery plaques and intima medial thickness in familial hypercholesteraemic patients on long-term statin therapy: A case control study

BACKGROUND AND AIMS

Statins reduce subclinical atherosclerosis and premature atherosclerotic cardiovascular disease (ASCVD) in patients with familial hypercholesterolemia (FH). However, some FH patients still develop ASCVD despite statin therapy. We compared subclinical atherosclerosis assessed by carotid plaque presence and intima media thickness (C-IMT), in long-term statin-treated FH patients and healthy controls. Furthermore, we analysed whether carotid ultrasonography findings associated with subclinical coronary atherosclerosis.

METHODS

We assessed the presence of carotid plaques and C-IMT in 221 asymptomatic heterozygous FH patients (48% men; 46 ± 15 years) on long-term (10.0 ± 7.8 years) statin treatment and 103 controls (32% men, 47 ± 16 years).

RESULTS

The frequency of carotid plaques and C-IMT did not differ significantly between the FH patients and controls (69 (31%) versus 24 (23%), p = 0.1 and 0.58 ± 0.13 versus 0.58 ± 0.12 mm, p = 0.9, respectively). In a subgroup of 49 FH patients who underwent cardiac computed tomography, coronary artery calcification correlated with carotid plaque presence (R = 0.47; p = 0.001), but not with C-IMT (R = 0.20; p = 0.2).

CONCLUSIONS

Carotid plaques and C-IMT did not differ between long-term statin-treated heterozygous FH patients and healthy controls. This shows that long-term statin treatment in these FH patients reduces carotid atherosclerosis to a degree of a healthy population. These findings strongly suggests that sonography of the carotid arteries during follow-up of statin-treated FH patients has limited value.

Lipoprotein (a) as a cause of cardiovascular disease: insights from epidemiology, genetics, and biology

Human epidemiologic and genetic evidence using the Mendelian randomization approach in large-scale studies now strongly supports that elevated lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular disease, that is, for myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis. The Mendelian randomization approach used to infer causality is generally not affected by confounding and reverse causation, the major problems of observational epidemiology. This approach is particularly valuable to study causality of Lp(a), as single genetic variants exist that explain 27-28% of all variation in plasma Lp(a). The most important genetic variant likely is the kringle IV type 2 (KIV-2) copy number variant, as the apo(a) product of this variant influences fibrinolysis and thereby thrombosis, as opposed to the Lp(a) particle per se. We speculate that the physiological role of KIV-2 in Lp(a) could be through wound healing during childbirth, infections, and injury, a role that, in addition, could lead to more blood clots promoting stenosis of arteries and the aortic valve, and myocardial infarction. Randomized placebo-controlled trials of Lp(a) reduction in individuals with very high concentrations to reduce cardiovascular disease are awaited. Recent genetic evidence documents elevated Lp(a) as a cause of myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis.

Lipoprotein (a) levels are not associated with carotid plaques and carotid intima media thickness in statin-treated patients with familial hypercholesterolemia

BACKGROUND

Lipoprotein (a), also called Lp(a), is a cardiovascular disease (CVD) risk factor. Statins do not lower Lp(a), this may at least partly explain residual CVD risk in statin-treated patients with familial hypercholesterolemia (FH). We investigated the association of Lp(a) levels with atherosclerosis in these patients.

METHODS AND RESULTS

We performed ultrasonography in 191 statin-treated FH patients (50% men; 48 ± 15 years) to detect carotid plaques and determine carotid intima-media thickness (C-IMT). Patients with high versus low Lp(a) levels (≤0.3 g/L) had similar plaque prevalence (36 and 31%, p = 0.4) and C-IMT (0.59 ± 0.12 and 0.59 ± 0.13 mm, p = 0.8). Patients with and without plaques had similar Lp(a) levels (median 0.35 (IQR: 0.57) and 0.24 (0.64) g/L, respectively, p = 0.4).

CONCLUSIONS

The Lp(a) levels were not associated with atherosclerosis in the carotid arteries of statin-treated FH patients. This suggests that adequate statin treatment delays carotid atherosclerosis in FH independently of Lp(a) levels.

Carotid Intima-Media Thickness in Asymptomatic Subjects With Low Lipoprotein(a) Levels

Background

Elevated and extreme circulating levels of lipoprotein(a) (Lp(a)) are considered to be an atherosclerotic risk factor, although additional studies on the low levels of Lp(a) are necessary to provide confirmation. The carotid intima-media thickness (CIMT) is known as a surrogate index of atherosclerosis. The aim of the present study was to investigate the correlation between the serum Lp(a) and CIMT in asymptomatic subjects with a relatively low Lp(a) level.

Methods

The study included 65 asymptomatic female Japanese subjects (mean age: 60 years) with a serum Lp(a) level < 30 mg/dL. Clinical data including the serum Lp(a) and CIMT were measured, and their correlations were examined.

Results

The median Lp(a) level was 18.6 mg/dL and the mean CIMT level was 0.8 mm. There was a significant and inverse correlation between the CIMT and Lp(a) (r = - 0.24, P ≤ 0.05), in addition to a significant and positive correlation between the CIMT and subject age and systolic blood pressure. A stepwise multiple linear regression analysis identified the Lp(a) to be correlated independently, significantly and inversely with the CIMT.

Conclusions

The Lp(a) levels were inversely correlated with the CIMT in this population, suggesting that subjects with a low Lp(a) level may have a predisposition to carotid atherosclerosis. This finding was preliminary and should be investigated further in larger studies and in additional settings.

Keywords

Lp(a); Carotid artery; IMT; Atherosclerosis

Lipoprotein (a) and carotid atherosclerosis in young patients with stroke

BACKGROUND AND PURPOSE

Elevated lipoprotein (a) concentration is associated with carotid atherosclerosis in middle-aged and older patients with ischemic stroke. This association has not been explored in young patients with stroke.

METHODS

A retrospective analysis of data from patients aged 16 to 54 years consecutively treated for acute ischemic stroke in a tertiary stroke unit during 4.5 years was performed. We graded carotid atherosclerosis using carotid duplex as: no atherosclerosis (A); plaque without stenosis (B); or stenosis≥50% (C).

RESULTS

One hundred ninety-six patients were included (male/female: 119/77; mean age±SD: 44.3±8.6 years): 115 in Group A; 67 in Group B; and 14 in Group C. Multivariate analysis using polynomial logistic regression showed a graded association of lipoprotein (a) plasma concentration with carotid atherosclerosis (P<0.001).

CONCLUSIONS

Our results showed a positive association of lipoprotein (a) plasma concentration with carotid atherosclerosis in young adults with ischemic stroke. This association was strong, graded, and independent of traditional risk factors including cholesterol.

Lipoprotein(a) Genetic Variants Associated With Coronary and Peripheral Vascular Disease but Not With Stroke Risk in the Heart Protection Study

Background—

Genetic studies have identified 2 single-nucleotide polymorphisms (SNPs) at the LPA locus (rs3798220 and rs10455872) that are strongly and independently related to lipoprotein(a) levels and to coronary disease risk, but their relevance for other atherothrombotic disease is uncertain.

Methods and Results—

These 2 LPA SNPs were examined together as an LPA genotype score for associations with vascular outcomes among participants in the Heart Protection Study. The LPA score was examined first in 12 236 participants with prevalent vascular disease (9277 coronary disease cases, and 1326 ischemic stroke and 2011 peripheral vascular disease cases with no history of coronary disease) and 3687 vascular disease-free controls and, subsequently, in 3251 participants who had incident major vascular events during follow-up (2106 coronary disease, 507 ischemic stroke, and 707 peripheral vascular disease events). For prevalent disease, the LPA score was strongly associated with coronary disease (odds ratio [OR] per variant allele, 1.19; 95% CI, 1.08 to 1.30) and peripheral vascular disease (OR, 1.18; 95% CI, 1.04 to 1.34) but not with ischemic stroke (OR, 1.03; 95% CI, 0.89 to 1.20). Similarly, for incident disease, the LPA score was strongly associated with coronary disease (hazard ratio [HR], 1.19; 95% CI, 1.09 to 1.30) and peripheral vascular disease (HR, 1.20; 95% CI, 1.02 to 1.40) but not with ischemic stroke (HR, 0.83; 95% CI, 0.67 to 1.03).

Conclusions—

The comparable strength of associations of the LPA score with coronary disease and peripheral vascular disease but not with stroke suggest that lipoprotein(a) may have effects on atherothrombotic vascular disease that are only relevant at specific sites.

Clinical Trial Registration—

URL: http://isrctn.org . Unique identifier: ISRCTN48489393.

Conventional and Mendelian randomization analyses suggest no association between lipoprotein(a) and early atherosclerosis: the Young Finns Study

BACKGROUND

Lipoprotein(a) [Lp(a)] is an established risk factor for coronary disease and stroke, but mechanisms underlying this association are unknown. We examined the association of Lp(a) with early atherosclerosis by using conventional epidemiologic analysis and a Mendelian randomization analysis. The latter utilized genetic variants that are associated with Lp(a) to estimate causal effect.

METHODS

A prospective population-based cohort study of 939 men and 1141 women was conducted. Lp(a) was measured repeatedly at mean ages 17 and 38 years. Measurements of carotid intima-media thickness (IMT) and brachial flow-mediated dilation (FMD) at mean ages 32 and 38 years were used to determine the level and 6-year progression of subclinical atherosclerosis. Lp(a)-related genetic variant, rs783147, was identified by a genome wide association analysis (P = 3.1 × 10⁻⁵⁸), and a genetic score was constructed based on 10 Lp(a)-related variants. Mendelian randomization test was performed using a two-stage instrumental variables analysis.

RESULTS

rs783147 and the genetic score were strong instruments for nonconfounded Lp(a) levels (F-statistics 269.6 and 446.0 in the first-stage instrumental variable analysis). However, Lp(a) levels were not associated with the levels of or change in IMT or FMD in any of the conventional and instrumental variables tests. The null finding was observed both with rs783147 and the genetic score as instruments and remained unchanged after adjustment for clinical characteristics, such as age, sex, HDL and LDL cholesterol, ApoB, systolic and diastolic blood pressure, diabetes and smoking.

CONCLUSIONS

Data from conventional and Mendelian randomization analyses provide no support for early atherogenic effects of increased Lp(a) levels.

Metabolic syndrome and carotid intima media thickness in the Health 2000 Survey

BACKGROUND AND PURPOSE

Metabolic syndrome has been associated with increased carotid intima-media thickness (CIMT) and cardiovascular disease (CVD). The objective of this study was to examine metabolic syndrome as a determinant of CIMT in men and women and to compare the Framingham risk score (FRS) and metabolic syndrome as risk factors for increased carotid atherosclerosis.

METHODS

The study population consisted of 1353 Finnish men and women aged 45 years and above who participated in Finnish population-based Health 2000 Survey. CIMT was used as a marker of subclinical atherosclerosis. The National Cholesterol Education Program Adult Treatment Panel III criterion was used to define the presence of metabolic syndrome.

RESULTS

In multivariable models, metabolic syndrome was an independent determinant of CIMT in both sexes (p</=0.001 for both). When metabolic syndrome was included in the regression models along with its components, it was an independent determinant of CIMT in women but not in men. After dividing the population into risk categories according to FRS and the presence of metabolic syndrome, FRS predominantly determined CIMT regardless of the presence of metabolic syndrome in men. In women, however, CIMT was significantly higher in subjects with metabolic syndrome than in those without it, independently of the FRS.

CONCLUSIONS

Metabolic syndrome is an independent determinant of CIMT in both sexes. In women but not in men, metabolic syndrome is associated with CIMT independently of its components. Metabolic syndrome provides additional information on a person's risk for early atherosclerosis beyond FRS in women but not in men.

Hyperlipoproteinaemia(a) is a common cause of autosomal dominant hypercholesterolaemia

Autosomal dominant hypercholesterolaemia (ADH) are a heterogeneous group of monogenic lipid disorders. The plasma level of lipoprotein(a) (Lp(a)) is a heritable trait associated with increased coronary heart disease (CHD) risk.

OBJECTIVE

To evaluate the frequency of elevated Lp(a) as a cause of ADH and the characteristics of subjects with high Lp(a) (hyperLp(a)).

MATERIAL AND METHODS

200 healthy subjects and 933 unrelated Spanish subjects with a clinical diagnosis of ADH who were screened for low-density lipoprotein receptor (LDLR) and apolipoprotein B (APOB) gene mutations. Standard cardiovascular risk factors and blood lipid levels, including Lp(a), were evaluated. HyperLp(a) was defined as Lp(a) levels >or=95th centile of control values.

RESULTS

Lp(a) was higher in 263 subjects without LDLR or APOB mutations (nonLDLR/nonAPOB group) than in 670 subjects with mutations (FH group): 40.0 mg/dl (interquartile range (IR) 15.0-89.0) versus 31.0 mg/dl (IR 11.0-73.7) respectively, p = 0.002. HyperLp(a) was present in 23% of ADH subjects (odds ratio (OR) 5.6 (95% CI, 2.9 to 10.7) versus controls) and 29% of nonLDLR/nonAPOB subjects (OR 7.7; 3.9 to 15.4). After adjusting for Lp(a), LDL cholesterol levels were <95th centile in 28 (10.6%) nonLDLR/nonAPOB subjects and in 9 (1.3%) FH subjects. Lp(a) levels were nonsignificantly higher in ADH subjects with early-onset CHD than in those without (43.5 mg/dl, (IR, 12.0-82.0) versus 31.7 mg/dl (11.8-76.5), respectively).

CONCLUSIONS

HyperLp(a) is responsible for ADH in approximately 6% of nonLDLR/nonAPOB subjects. HyperLp(a) would not appear to be a risk factor for early-onset CHD in ADH, independently of whether genetic defects have or have not been demonstrated.