Ideal cardiovascular health influences cardiovascular disease risk associated with high lipoprotein(a) levels and genotype: The EPIC-Norfolk prospective population study

BACKGROUND AND AIMS

Lipoprotein(a) (Lp[a]) is a strong genetic risk factor for cardiovascular disease (CVD). The American Heart Association has prioritised seven cardiovascular health metrics to reduce the burden of CVD: body mass index, healthy diet, physical activity, smoking status, blood pressure, diabetes and cholesterol levels (together also known as ideal cardiovascular health). Our objective was to determine if individuals with high Lp(a) levels could derive cardiovascular benefits if characterized by ideal cardiovascular health.

METHODS

A total of 14,051 participants of the EPIC-Norfolk study were stratified according to the cardiovascular health score (based on the number of health metrics with an ideal, intermediate or poor status). Of them, 1732 had a CVD event during a mean follow-up of 11.5 years. Cox proportional hazards models were used to describe the association between the cardiovascular health score and Lp(a) level or genotype (as estimated by the rs10455872 variant) with the risk of CVD.

RESULTS

We observed little or no differences in serum Lp(a) levels across the seven cardiovascular health metric categories. Among participants with high serum Lp(a) levels ≥50 mg/dl), those in the highest (i.e. healthiest) cardiovascular health score category (10-14) had an adjusted hazard ratio for cardiovascular disease of 0.33 (95% CI = 0.17-0.63, p = 0.001) compared to participants in the lowest (i.e. unhealthiest) cardiovascular health score category(0-4). Similar results were obtained when we replaced Lp(a) with rs10455872.

CONCLUSIONS

Although Lp(a) levels are only slightly influenced by cardiovascular health metrics, an ideal cardiovascular health could substantially reduce CVD risk associated with high Lp(a) levels or genotype.

Lipoprotein(a) in postmenopausal women: assessment of cardiovascular risk and therapeutic options

INTRODUCTION

Lipoprotein(a) [Lp(a)], a low-density lipoprotein (LDL)-like particle, has been independently associated with increased cardiovascular disease (CVD) risk in various populations, such as postmenopausal women. The purpose of this narrative review is to present current data on the role of Lp(a) in augmenting CVD risk in postmenopausal women and focus on the available therapeutic strategies.

METHODS

PubMed was searched for English language publications until November 2015 under the following terms: "therapy" OR "treatment" AND ["lipoprotein (a)" OR "Lp(a)"] AND ("postmenopausal women" OR "menopausal women" OR "menopause").

RESULTS

Only hormone replacement therapy (mainly oral estrogens) and tibolone have been specifically studied in postmenopausal women and can reduce Lp(a) concentrations by up to 44%, although evidence indicating a concomitant reduction in CVD risk associated with Lp(a) is lacking. As alternative treatments for women who cannot, or will not, take hormonal therapies, niacin and the upcoming proprotein convertase subtilisin / kexin type 9 (PCSK-9) inhibitors are effective in reducing Lp(a) concentrations by up to 30%. Statins have minimal or no effect on Lp(a). However, data for these and other promising Lp(a)-lowering therapies including mipomersen, lomitapide, cholesterol-ester-transfer protein inhibitors and eprotirome are derived from studies in the general, mainly high CVD risk, population, and include only subpopulations of postmenopausal women.

CONCLUSIONS

Past, present and emerging therapies can reduce Lp(a) concentrations to a varying extent. Overall, it remains to be proven whether the aforementioned reductions in Lp(a) by these therapeutic options are translated into CVD risk reduction in postmenopausal women.

Lipoprotein(a) and lipid profiles of patients awaiting coronary artery bypass graft; a cross sectional study

Background

Lipoprotein(a) (Lp(a)) excess is an independent risk factor of coronary artery disease (CAD) and have shown wide ethnic variations. Further, lipid parameters used in the assessment and management of risk factors for CAD may not reflect accurately the disease or severity if the patients are on pharmacological interventions when compared to Lp(a). Lp(a) levels of Sri Lankan CAD patients awaiting coronary artery bypass graft are not documented.

Methods

A cross sectional study was carried out with patients (n = 102) awaiting coronary artery bypass graft at a tertiary healthcare institution in Sri Lanka. Lp(a) was determined by immunoturbidimetric method (Konelab 20XT) and information on risk factors collected using a standardized questionnaire. The severity of CAD was determined by Gensini score. Lipid parameters and pharmacological treatment data were obtained from the Medical Records. Data were analysed using independent sample t-test, Pearson and Spearman tests respectively.

Results

Total cholesterol (TC), LDL cholesterol (LDLc) and HDL cholesterol (HDLc) of the total study sample (average ± SD) were, 150 ± 36 mg/dL, 92 ± 36 mg/dL and 34 ± 9 mg/dL respectively with no significant difference irrespective of being on pharmacological treatment or not. All lipid parameters were significantly high (p < 0.05) in females. The average Lp(a) was 50 ± 38 (SD) mg/dL with no significant difference in males or females independent of being on treatment (50 ± 39 mg/dL) or not (49 ± 39 mg/dL) and above the cut off value (30 mg/dL).

Conclusions

Despite pharmacological interventions 27 % of the study population had high LDLc and majority low HDLc. Mean Lp(a) was in excess irrespective of risk factors or being on treatment or not and is confirmed as an independent, potential marker for assessing the susceptibility for CAD especially in those with other intermediate risk factors but considered non-hyperlipidemic by conventional methods.

Elevated lipoprotein(a) levels predict cardiovascular disease in type 2 diabetes mellitus: a 10-year prospective cohort study

BACKGROUND/AIMS

Elevated lipoprotein(a) (Lp[a]) level is known to be a risk factor for cardiovascular disease (CVD). However, the data that has been reported on the association between the Lp(a) level and CVD in type 2 diabetes has been limited and incoherent. The aim of this study was to investigate the relationship between the Lp(a) concentration and new onset CVD in type 2 diabetes.

METHODS

From March 2003 to December 2004, patients with type 2 diabetes without a prior history of CVD were consecutively enrolled. CVD was defined as the occurrence of coronary artery disease or ischemic stroke. Cox proportional hazards models were used to identify the associations between the Lp(a) and CVD after adjusting for confounding variables.

RESULTS

Of the 1,183 patients who were enrolled, 833 participants were evaluated with a median follow-up time of 11.1 years. A total of 202 participants were diagnosed with CVD (24.2%). The median Lp(a) level for 1st and 4th quartile group was 5.4 (3.5 to 7.1) and 55.7 mg/dL (43.1 to 75.3). Compared with patients without CVD, those with CVD were older, had a longer duration of diabetes and hypertension, and used more insulin and angiotensin converting enzyme inhibitors/angiotensin receptor blockers at baseline. A Cox hazard regression analysis revealed that the development of CVD was significantly associated with serum Lp(a) level (hazard ratio, 1.92; 95% confidence interval [CI], 1.26 to 2.92; p < 0.001, comparing the 4th vs. 1st quartile of Lp[a]).

CONCLUSIONS

Elevated Lp(a) level was an independent predictable risk factor for CVD in type 2 diabetes. Other cardiovascular risk factors should be treated more intensively in type 2 diabetic patients with high Lp(a) levels.

Effect of extended-release niacin on plasma lipoprotein(a) levels: A systematic review and meta-analysis of randomized placebo-controlled trials

AIM

Lipoprotein(a) (Lp(a)) is a proatherogenic and prothrombotic lipoprotein. Our aim was to quantify the extended-release nicotinic acid Lp(a) reducing effect with a meta-analysis of the available randomized clinical trials.

METHODS

A meta-analysis and random-effects meta-regression were performed on data pooled from 14 randomized placebo-controlled clinical trials published between 1998 and 2015, comprising 17 treatment arms, which included 9013 subjects, with 5362 in the niacin arm.

RESULTS

The impact of ER niacin on plasma Lp(a) concentrations was reported in 17 treatment arms. Meta-analysis suggested a significant reduction of Lp(a) levels following ER niacin treatment (weighted mean difference - WMD: -22.90%, 95% CI: -27.32, -18.48, p<0.001). Results also remained similar when the meta-analysis was repeated with standardized mean difference as summary statistic (WMD: -0.66, 95% CI: -0.82, -0.50, p<0.001). When the studies were categorized according to the administered dose, there was a comparable effect between the subsets of studies with administered doses of <2000mg/day (WMD: -21.85%, 95% CI: -30.61, -13.10, p<0.001) and ≥2000mg/day (WMD: -23.21%, 95% CI: -28.41, -18.01, p<0.001). The results of the random-effects meta-regression did not suggest any significant association between the changes in plasma concentrations of Lp(a) with dose (slope: -0.0001; 95% CI: -0.01, 0.01; p=0.983), treatment duration (slope: -0.40; 95% CI: -0.97, 0.17; p=0.166), and percentage change in plasma HDL-C concentrations (slope: 0.44; 95% CI: -0.48, 1.36; p=0.350).

CONCLUSION

In this meta-analysis of randomized placebo-controlled clinical trials, treatment with nicotinic acid was associated with a significant reduction in Lp(a) levels.

Lipoprotein(a)-cholesterol levels estimated by vertical auto profile correlate poorly with Lp(a) mass in hyperlipidemic subjects: Implications for clinical practice interpretation of Lp(a)-mediated risk

BACKGROUND

Lipoprotein(a) [Lp(a)] is generally measured as total mass of the entire particle or as apolipoprotein(a) particle number.

OBJECTIVE

The cholesterol content of Lp(a) [Lp(a)-C)] can be estimated by the vertical auto profile (VAP) method. We assessed whether this is an accurate surrogate measurement of Lp(a) mass.

METHODS

VAP-Lp(a)-C and VAP-high density lipoprotein cholesterol (HDL-C) estimated by the VAP technique, Lp(a) mass, oxidized phospholipids on apolipoprotein B-100 (OxPL-apoB) that primarily reflect OxPL on Lp(a), and HDL-C measured by enzymatic methods were measured in 552 hypercholesterolemic patients at baseline and 24 weeks after therapy with niacin monotherapy (N = 118), ezetimibe/simvastatin monotherapy (n = 155), or ezetimibe/simvastatin (10/20 mg) + niacin (to 2 g) (N = 279) in a randomized, double-blind trial.

RESULTS

VAP-Lp(a)-C correlated only modestly with Lp(a) mass at baseline (r = 0.56, P < .001) and 24 weeks (r = 0.56, P < .001), explaining only 31% of the association. VAP-Lp(a)-C correlated with HDL-C at baseline (r = 0.34, P < .001) and 24 weeks (r = 0.30, P < .001) and with VAP-HDL-C at baseline (r = 39, P < .001) and 24 weeks (r = 0.33, P < .001). In contrast, Lp(a) mass did not correlate with HDL-C at baseline (r = 0.06, P = .12) and 24 weeks (r = -0.01 P = .91). Lp(a) mass correlated strongly with oxidized phospholipids on apolipoprotein B-100 at baseline (r = 0.81, P < .001) and 24 weeks (r = 0.79, P < .001). VAP-Lp(a)-C levels increased linearly with HDL-C and VAP-HDL-C quartiles (P < .001 for both) but Lp(a) mass did not. Quantitating the percent of cholesterol present on Lp(a) by dividing VAP-Lp(a)-C by Lp(a) mass revealed that 25% of patients had a percentage >100, which is not possible.

CONCLUSIONS

VAP-Lp(a)-C is a poor estimate for Lp(a) mass and likely reflects the content of HDL-C in the overlapping density spectrum of Lp(a) and HDL. These data suggest that patients with prior VAP-Lp(a)-C measurements may have misclassification of Lp(a)-related risk.

Correlation between serum levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) and atherogenic lipoproteins in patients with coronary artery disease

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of serum low-density lipoprotein (LDL) cholesterol levels. Recently, PCSK9 has additionally been related to metabolic risk factors such as the levels of triglycerides, apolipoprotein B (apoB), insulin, and glucose, as well as body mass index. The purpose of this study was to investigate correlations between serum levels of PCSK9 and apoB-containing atherogenic lipoproteins in patients with coronary artery disease (CAD).

Methods

Serum levels of PCSK9 and lipoprotein(a) [Lp(a)]; small, dense LDL; and oxidized LDL were measured in 101 patients with CAD who were not receiving lipid-lowering therapy.

Results

Serum hetero-dimer PCSK9 levels were positively correlated with serum levels of Lp(a) (r = 0.195, p = 0.05); small, dense LDL (r = 0.336, p = 0.0006); and oxidized LDL (r = 0.268, p = 0.008). Multivariate regression analyses showed that serum hetero-dimer PCSK9 was a significant predictor of serum levels of Lp(a) (β = 0.235, p = 0.01); small, dense LDL (β = 0.143, p = 0.03); and oxidized LDL (β = 0.268, p = 0.008).

Conclusions

Serum PCSK9 levels were positively correlated with serum levels of Lp(a); small, dense LDL; and oxidized LDL in patients with CAD. This suggests that the interaction between serum PCSK9 and apoB-containing lipoproteins plays a role in establishing the atherosclerotic status of patients.

Trial registration

UMIN Clinical Trials Registry, UMIN ID: C000000311.

[Increased lipoprotein(a) in a paediatric patient associated with nephrotic syndrome]

A common complication in paediatric patients with nephrotic syndrome (NS) is hyperlipidaemia. About 20% of children do not respond to treatment with corticosteroids, presenting with a cortico-resistant NS (CRNS), which can progress to kidney failure. It has been observed that paediatric patients with CRNS have an elevated low density lipoprotein cholesterol (LDL-c), very low density lipoprotein cholesterol (VLDL-c), and triglycerides levels, as well as elevated Lipoprotein-a [Lp (a)] levels. The case is presented of a 5 year old boy, diagnosed with CRNS, presenting with dyslipidaemia with increased LDL-c, Apo-B100, and Lp(a) levels. After the poor prognosis of the renal function, immunosuppressant treatment was started with tacrolimus and atorvastatin to control dyslipidaemia. Although tacrolimus causes an elevation of total cholesterol and LDL-c, the significant alterations of the children lipid profile suggest the existence of a high cardiovascular risk. In these cases, it would be interesting to have reference values in children in our health area.

The re-emergence of lipoprotein(a) in a broader clinical arena

Lipoprotein(a) [Lp(a)] is a genetic, independent and likely causal risk factor for cardiovascular disease (CVD) and calcific aortic valve stenosis (CAVS). Lp(a) levels are primarily genetically determined and tend to fluctuate only mildly around a pre-determined level. In primary care settings, one Lp(a) measurement can reclassify up to 40% of patients in intermediate risk score categories. In secondary care settings, recent data from the JUPITER and AIM-HIGH trials demonstrate that elevated Lp(a) remains part of the "residual risk" despite achievement of low-density lipoprotein cholesterol levels <70 mg/dL. Recent reports suggest that statins can increase Lp(a) levels, potentially further contributing to this residual risk. Current therapies to lower Lp(a) are limited to niacin, mipomersen and proprotein convertase subtilisin kexin-type 9 inhibitors, but these drugs are limited by weak efficacy and not specifically approved for Lp(a) lowering. Emerging therapies to lower Lp(a) may shed new light into the potential clinical benefit of lowering Lp(a) in CVD and CAVS.

Analysis of the association between plasma PCSK9 and Lp(a) in Han Chinese

PURPOSE

It has been reported that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors can significantly reduce lipoprotein(a) [Lp(a)], and the mechanism for Lp(a) reduction remains unclear. Recently an interesting clinical research with a small sample showed a positive correlation between plasma PCSK9 and Lp(a) levels in diabetes. Here we aimed to use a relatively large sample to investigate whether such an association exists in Han Chinese.

METHODS

A total of 783 inpatients were consecutively enrolled and composed of 172 patients with type 2 diabetes mellitus (T2DM) and 611 non-T2DM subjects. Plasma PCSK9 level was measured by ELISA, and its association with Lp(a) was assayed by Spearman's correlation and multiple regression. Clinical and biochemical parameters were determined in all subjects studied.

RESULTS

No significant differences in PCSK9 and Lp(a) levels were found between T2DM and non-T2DM patients. PCSK9 level was not related to Lp(a) level either in T2DM or non-T2DM group in bivariate correlation and multiple linear regression analysis. Additionally, no association between the levels of PCSK9 and Lp(a) was found in well, poorly controlled T2DM patients or in T2DM patients with or without coronary artery disease (CAD). Besides, no difference was found among the PCSK9 values across tertiles of Lp(a) level.

CONCLUSION

We found no association of plasma PCSK9 levels with Lp(a) level in Han Chinese with or without T2DM, suggesting that Lp(a) reduction by PCSK9 inhibitors may not be achieved simply through PCSK9 pathway at least in Chinese.

Increased risk of coronary artery calcification progression in subjects with high baseline Lp(a) levels: The Kangbuk Samsung Health Study

BACKGROUND

Results from previous studies support the association of lipoprotein(a) [Lp(a)] levels and coronary artery disease risk. In this study, we analyzed the association between baseline Lp(a) levels and future progression of coronary artery calcification (CAC) in apparently healthy Korean adults.

METHODS

A total of 2611 participants (mean age: 41years, 92% mend) who underwent a routine health check-up in 2010 and 2014 were enrolled. Coronary artery calcium score (CACS) were measured by multi-detector computed tomography. Baseline Lp(a) was measured by high-sensitivity immunoturbidimetric assay. Progression of CAC was defined as a change in CACS >0 over four years.

RESULTS

Bivariate correlation analyses with baseline Lp(a) and other metabolic parameters revealed age, total cholesterol, HDL-C, LDL-C and CACS to have a significant positive correlation, while body weight, fasting glucose level, blood pressure and triglyceride level were negatively correlated with baseline Lp(a) level. After four years of follow-up, 635 subjects (24.3%) had CAC progression. The participants who had CAC progression were older, composed of more men, more obese, and had higher fasting glucose levels and worse baseline lipid profiles compared to those who did not have CAC progression. The mean serum Lp(a) level was significantly higher in subjects who had CAC progression compared to those who did not (32.5 vs. 28.9mg/dL, p<0.01). When the risk for CAC progression according to baseline Lp(a) was calculated, those with Lp(a) level≥50mg/dL had an odds ratio of 1.333 (95% CI 1.027-1.730) for CAC progression compared to those with Lp(a)<50mg/dL after adjusting for confounding factors.

CONCLUSIONS

In this study, the subjects who had higher Lp(a) were at significantly higher risk for CAC progression after four years of follow-up, suggesting the role of high Lp(a) in CAC progression.

Ischemic stroke in a young adult with extremely elevated lipoprotein(a): A case report and review of literature

Lipoprotein(a) [Lp(a)] is an apolipoprotein(a) molecule bound to 1 apolipoprotein B-100. Elevated levels of Lp(a) are thought to be an independent risk factor for atherosclerosis and to promote thrombosis through incompletely understood mechanisms. We report a 34-year-old man with an ischemic stroke in the setting of an extremely high Lp(a) level-212 mg/dL. He developed severe carotid artery stenosis over a 6-year period and had thrombus formation post-carotid endarterectomy. To our knowledge, this case is unique because the Lp(a) is the highest reported level in a patient without renal disease. Moreover, this is the first reported case of the youngest individual with a stroke presumably related to development of carotid plaque over a 6-year period. The thrombotic complication after endarterectomy may have been related to the prothrombotic properties of Lp(a). Of note, the Lp(a) level did not respond to atorvastatin but did decrease 15% after aspirin 325 mg was added although his Lp(a) levels were variable, and it is not clear that this was cause and effect. This case highlights the need to better understand the relation between Lp(a) and vascular disease and the need to screen family members for elevated Lp(a). We also review treatment options to lower Lp(a) and ongoing clinical trials of newer lipid-lowering drugs that can also lower Lp(a).

Association between lipoprotein(a) and nonalcoholic fatty liver disease among Korean adults

BACKGROUND

Lipoprotein(a) [Lp(a)] and nonalcoholic fatty liver disease (NAFLD) are risk factors for cardiovascular diseases. We investigated the relationship between Lp(a) concentrations and NAFLD among Korean adults.

METHODS

A total of 2242 nondiabetic subjects undergoing routine health screening examination were enrolled. Anthropometric and biochemical parameters, including Lp(a) were measured. NAFLD were assessed by ultrasonography. Adjusted Odds ratios for the presence of NAFLD according to Lp(a) tertiles were estimated using logistic regression.

RESULTS

Subjects were grouped according to the severity of NAFLD and Lp(a) concentrations. Lp(a) concentrations were decreased across the severity of NAFLD and the prevalence of NAFLD decreased with the Lp(a) tertiles. Compared with subjects in the lowest tertile of Lp(a), those in the highest tertile had higher total cholesterol and LDL-C concentrations and lower body mass index, blood pressure, fasting glucose, triglyceride, ALT, and HOMA-IR concentrations. In the logistic regression analysis after adjusting for multiple risk factors, the relationship between Lp(a) concentrations and the presence of NAFLD remained significant. However, this association was attenuated after adjusting for insulin resistance.

CONCLUSIONS

Lp(a) was inversely associated with the presence of NAFLD, but it was not an independent risk factor for NAFLD among Korean adults.

Serum lipoprotein(a) levels and diabetic nephropathy among Japanese patients with type 2 diabetes mellitus

AIMS

We aimed to evaluate the association between serum lipoprotein(a) [Lp(a)] levels and diabetic nephropathy among Japanese patients with type 2 diabetes mellitus.

METHODS

This study included 581 patients with type 2 diabetes mellitus. Serum Lp(a) levels were divided into four groups; the cut-off points were at the 30th, 60th, and 90th percentile values on the basis of the distribution for all subjects. Diabetic nephropathy was defined as present when the urinary albumin-creatinine ratio was ≥33.9mg/mmol creatinine and/or the estimated glomerular filtration rate was <30ml/min/1.72m(2). Adjustment was made for age, sex, body mass index, hemoglobin A1c, duration of diabetes mellitus, current drinking, current smoking, hypertension, dyslipidemia, coronary heart disease, and stroke.

RESULTS

Higher serum Lp(a) levels were significantly associated with a higher prevalence of diabetic nephropathy: the adjusted odds ratios (95% confidence intervals) for diabetic nephropathy in relation to serum Lp(a) levels of ≤6, 7-15, 16-38, and ≥39mg/dl were 1.00 (reference), 2.74 (1.08-7.00), 3.31 (1.28-8.54), and 4.80 (1.57-14.60), respectively (P for trend=0.004).

CONCLUSIONS

The results suggest that serum Lp(a) levels may be positively associated with diabetic nephropathy among Japanese patients with type 2 diabetes mellitus.

Lipoprotein(a) and risk of sudden cardiac death in middle-aged Finnish men: A new prospective cohort study

BACKGROUND

Lipoprotein(a) [Lp(a)] is an established and independent risk factor for cardiovascular outcomes. However, the relationship of Lp(a) with risk of sudden cardiac death (SCD) is unknown. We aimed to assess the association of Lp(a) with risk of SCD in the Kuopio Ischemic Heart Disease prospective cohort study of 1881 men aged 42-61years at recruitment.

METHODS AND RESULTS

Plasma Lp(a) concentration was assessed at baseline and repeat measurements made several years apart. After a median follow-up of 24.7years, 141 SCDs were recorded. Hazard ratios (HRs) (95% confidence intervals [CI]) were assessed and were corrected for within-person variability in Lp(a) levels. The regression dilution ratio of loge Lp(a) adjusted for age was 0.84 (95% CI: 0.81-0.88). Lipoprotein(a) levels were log-linearly associated with risk of SCD. In analyses adjusted for established risk factors, the HR (95% CI) for SCD per 1 standard deviation (3.56-fold) higher baseline loge Lp(a) was 1.24 (1.05-1.47; P=0.013). This remained consistent on further adjustment for alcohol consumption, resting heart rate, lipids, and C-reactive protein 1.23 (1.04-1.46; P=0.018). HRs remained unchanged after accounting for incident coronary events and did not vary importantly in several relevant clinical subgroups. Adding Lp(a) to a SCD risk prediction model did not significantly improve risk discrimination beyond established risk factors, but improved the continuous net reclassification 30.2% (1.1 to 59.2%, P=0.042).

CONCLUSIONS

Available evidence shows a continuous and independent association between Lp(a) levels and risk of SCD. Further research is needed to replicate these findings.

The role of lipoprotein(a) in clotting reactions during lipoprotein apheresis--A case report

In individuals with familial hypercholesterolemia (FH) who are unable to reach a target low-density lipoprotein level on a drug regimen, lipoprotein apheresis (LA) may be the treatment of choice. Severe reactions involving clotting during LA are not well described in the literature. We report a case of a 63-year-old woman with FH and markedly elevated lipoprotein(a) (Lp[a]) levels who experienced such a reaction while undergoing LA with a dextran-sulfate cellulose column on the Kaneka MA-01 Liposorber system. Owing to the clotting as well as a blood pressure drop to <100 mm Hg systolic, the procedure was stopped early. Before her second procedure, she was given an increased loading dose of unfractionated heparin. She did not develop clotting during this second procedure. A growing body of literature on the role of Lp(a) in atherothrombotic complications and hemostasis supports a possible mechanism by which clotting in the instrument could occur during apheresis. Our patient's initial pretreatment Lp(a) was 3.5 times greater than the mean Lp(a) levels in patients with FH. This theory is consistent with our case in that the patient's Lp(a) levels progressively declined with each procedure, and she had no subsequent clotting.

Distinct metabolism of apolipoproteins (a) and B-100 within plasma lipoprotein(a)

OBJECTIVES

Lipoprotein(a) [Lp(a)] is mainly similar in composition to LDL, but differs in having apolipoprotein (apo) (a) covalently linked to apoB-100. Our purpose was to examine the individual metabolism of apo(a) and apoB-100 within plasma Lp(a).

MATERIALS AND METHODS

The kinetics of apo(a) and apoB-100 in plasma Lp(a) were assessed in four men with dyslipidemia [Lp(a) concentration: 8.9-124.7nmol/L]. All subjects received a primed constant infusion of [5,5,5-(2)H3] L-leucine while in the constantly fed state. Lp(a) was immunoprecipitated directly from whole plasma; apo(a) and apoB-100 were separated by gel electrophoresis; and isotopic enrichment was determined by gas chromatography/mass spectrometry.

RESULTS

Multicompartmental modeling analysis indicated that the median fractional catabolic rates of apo(a) and apoB-100 within Lp(a) were significantly different at 0.104 and 0.263 pools/day, respectively (P=0.04). The median Lp(a) apo(a) production rate at 0.248nmol/kg·day(-1) was significantly lower than that of Lp(a) apoB-100 at 0.514nmol/kg·day(-1) (P=0.03).

CONCLUSION

Our data indicate that apo(a) has a plasma residence time (11days) that is more than twice as long as that of apoB-100 (4days) within Lp(a), supporting the concept that apo(a) and apoB-100 within plasma Lp(a) are not catabolized from the bloodstream as a unit in humans in the fed state.

Effects of Lipoprotein apheresis on the Lipoprotein(a) levels in the long run

BACKGROUND

Lipoprotein(a) (Lp(a)) is a low density lipoprotein-like particle to which apolipoprotein(a) is bound. It is recognized as an atherosclerosis-inducing risk factor. Up to now a detailed description of the effect of Lipoprotein apheresis (LA) on Lp(a) levels in the long run is lacking.

METHODS

We studied 59 patients with elevated Lp(a) levels who were treated with LA at the Lipoprotein Apheresis Center at the University Hospital Dresden. We analyzed Lp(a) concentrations before the start of the LA treatment and during this extracorporeal therapy.

RESULTS

Comparing the Lp(a) levels before the start of LA therapy and pre-apheresis (measured before the LA sessions) Lp(a) levels, we observed a reduction of the Lp(a) levels of about 22.8% in all patients. Lp(a) levels were acutely (comparing post-apheresis with pre-apheresis concentrations) reduced by all 6 available LA methods (by about 70%). A linear regression analysis was performed to differentiate the long term course of pre-apheresis Lp(a) levels. In 30 patients we saw an increase of the pre-apheresis Lp(a) levels over the time, in 15 patients a constancy and in 14 patients a decrease. Patients with a decrease of pre-apheresis Lp(a) levels over the time had significantly higher initial (before the start of the extracorporeal treatment) and pre-apheresis values and they were significantly older. These patients had significantly more severe peripheral arterial disease as well as cardiac valve and carotid stenosis. The patients with the lowest initial Lp(a) levels and an increase of the pre-apheresis Lp(a) levels over the time had the highest percentage of intake of Tredaptive(®)/Niaspan(®) though after stopping the intake of these nicotinic acid preparations no clear increase of Lp(a) concentrations was observed. The applied LA systems did not seem to have a significant influence on the course of pre-apheresis Lp(a) levels. In all patients there was a high variability of Lp(a) concentrations between LA sessions which may in part be due to the inaccuracy of the method used to measure Lp(a) concentrations.

CONCLUSION

Pre-apheresis Lp(a) levels (before the LA sessions) are lower than those before the start of a LA treatment but they behave differently among patients during LA treatment.

Supplementation with coenzyme Q10 reduces plasma lipoprotein(a) concentrations but not other lipid indices: A systematic review and meta-analysis

Plasma lipoprotein(a) [Lp(a)] elevations are associated with increased cardiovascular risk. Coenzyme Q10 (CoQ10) is a member of the mitochondrial respiratory chain with a prominent role as a potent gene regulator. The Lp(a)-lowering efficacy of CoQ10 has been investigated in different clinical settings with contrasting results. A systematic literature search in Medline, SCOPUS, Web of Science and Google Scholar databases was conducted to identify controlled trials investigating the efficacy of CoQ10 supplementation on plasma Lp(a) levels. Inverse variance-weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated for net changes in Lp(a) levels using a random-effects model. Random-effects meta-regression was performed to assess the effect of putative confounders on plasma Lp(a) levels. Seven randomized controlled trials with a total of 409 subjects (206 in the CoQ10 arm and 203 in the control arm) met the eligibility criteria. Overall, CoQ10 supplementation was paralleled by a slight but significant reduction of plasma Lp(a) levels (WMD: -3.54 mg/dL, 95% CI: -5.50, -1.58; p<0.001), this effect being more robust in those trials with higher baseline Lp(a) levels (slope: -0.44; 95% CI: -0.80, -0.08; p=0.018). Reduction of plasma Lp(a) levels was consistent across different CoQ10 doses, with an inverse association between administered CoQ10 dose and Lp(a) lowering (slope: 0.04; 95% CI: 0.01, 0.07; p=0.004). Neither total cholesterol and cholesterol subfractions, nor triglyceride levels were affected by CoQ10 supplementation. In conclusion, CoQ10 supplementation, in the tested range of doses, reduces plasma Lp(a) concentrations, particularly in patients with Lp(a)≥ 30 mg/dL. Other lipid indices were not altered by CoQ10 supplementation.

Longer duration of statin therapy is associated with decreased carotid plaque vascularity by magnetic resonance imaging

OBJECTIVE

Plaque neovasculature is a major route for lipoprotein and leukocyte ingress into plaques, and has been identified as a risk factor for carotid plaque disruption. Vp, a variable derived from pharmacokinetic modeling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), correlates with plaque neovasculature density. Because lipid-lowering therapy has been associated with regression of neovasculature in animal models, we sought to determine clinical correlates of carotid plaque neovasculature (as assessed by Vp) in participants on statin therapy for established cardiovascular disease.

METHODS

98 participants from an AIM-HIGH sub-study underwent DCE-MRI of their carotid arteries. Expert readers who were blinded to all clinical variables analyzed the MR images to measure carotid plaque Vp in all participants. Associations between Vp and duration of statin therapy and other clinical risk factors were analyzed.

RESULTS

Prior duration of statin treatment at enrollment ranged from <1 year (21%) 1-5 years (40%) and >5 years (39%). In univariate analyses, shorter duration of statin therapy (P = 0.01), the presence of metabolic syndrome (P = 0.02), and higher body mass index (P = 0.01) and lipoprotein(a) (P = 0.01) were all significantly associated with higher baseline Vp values. In multivariate analyses, significant associations remained between shorter duration of statin therapy (P = 0.004) and lipoprotein(a) (P = 0.04).

CONCLUSIONS

These are the first human, in vivo findings suggesting a relationship between duration of statin therapy and regression of carotid plaque neovasculature. Future longitudinal studies are warranted both to confirm this finding and to address whether changes in neovasculature may translate into change in risk for plaque disruption. CLINICALTRIALS.

GOV IDENTIFIERS

NCT00880178, NCT01178320 and NCT00120289.

Association of Elevated Serum Lipoprotein(a), Inflammation, Oxidative Stress and Chronic Kidney Disease with Hypertension in Non-diabetes Hypertensive Patients

Hypertension is the most common cardiovascular risk factor. Lipoprotein(a) [Lp(a)], inflammation, oxidative stress and chronic kidney disease (CKD) exacerbate the response to tissue injury and acts as markers of the vascular disease, especially in glomerulosclerosis. We compared the clinical characteristics of 138 non-diabetes hypertensive women (ndHT) patients with 417 non-diabetes normotensive subjects and tested the association of hypertension with Lp(a), inflammation, CKD and oxidative stress by using multiple logistic regression. BP, BMI, waist circumference, creatinine, Lp(a), inflammation and malondialdehyde levels were significantly higher and CKD state in the ndHT patients (p < 0.05). Multiple logistic regression showed hypertension associated with increased Lp(a), inflammation, ORs and 95 % CIs were 2.52 (1.33, 4.80), 2.75 (1.44, 5.27) after adjusting for their covariates. Elevated serum Lp(a) and inflammation levels concomitants with increased oxidative stress and CKD were the major risk factors associated with hypertension and implications for the increased risk of HT and vascular disease.

Lipoprotein (a) is related to coronary atherosclerotic burden and a vulnerable plaque phenotype in angiographically obstructive coronary artery disease

BACKGROUND

Lipoprotein Lp(a) has been shown to be an independent risk factor for coronary artery disease (CAD). However, its association with CAD burden in patients with ACS is largely unknown, as well as the association of Lp(a) with lipid rich plaques prone to rupture.

AIM

We aim at assessing CAD burden by coronary angiography and plaque features including thin cap fibroatheroma (TCFA) by optical coherence tomography (OCT) in consecutive patients presenting with acute coronary syndrome (ACS) and obstructive CAD along with serum Lp(a) levels.

METHODS

This study comprises an angiographic and an OCT cohort. A total of 500 ACS patients (370 men, average age 66 ± 11) were enrolled for the angiographic cohort and 51 ACS patients (29 males, average age 65 ± 11) were enrolled for the OCT cohort. Angiographic CAD severity was assessed by Sullivan score and by Bogaty score including stenosis score and extent index. OCT plaque features were evaluated at the site of the minimal lumen area and along the culprit segment.

RESULTS

In the angiographic cohort, at multivariate analysis, Lp(a) was a weak independent predictor of Sullivan score (p < 0.0001), stenosis score (p < 0.0001) and extent index (p < 0.0001). In the OCT cohort, patients with higher Lp(a) levels (≥ 30 md/dl) compared to patients with lower Lp(a) levels (<30 md/dl) exhibited a higher prevalence of lipidic plaque at the site of the culprit stenosis (67% vs. 27%; P = 0.02), a wider lipid arc (135 ± 114 vs 59 ± 111; P = 0.03) and a higher prevalence of TCFA (38% vs. 10%; P = 0.04).

CONCLUSIONS

Among patients with ACS, raised Lp(a) levels are associated with an increased atherosclerotic burden and it identifies a subset of patients with features of high risk coronary atherosclerosis.

Plasma lipoprotein(a) predicts major cardiovascular events in patients with chronic kidney disease who undergo percutaneous coronary intervention

BACKGROUND

Chronic kidney disease (CKD) is associated with increased risk for cardiovascular disease. The predictive power of traditional risk factors for cardiovascular disease is diminished in patients with CKD. The serum level of lipoprotein(a) [Lp(a)] can be a risk factor for adverse events, but the clinical implications of Lp(a) in patients with CKD who have been treated by percutaneous coronary intervention (PCI) remain uncertain. We aimed to determine the role of Lp(a) on long-term outcomes in patients with CKD after PCI.

METHODS

We analyzed data from 904 patients with CKD among 3508 patients who underwent a first PCI between 1997 and 2011 at our institution. We divided patients into 2 groups [high (n=454) or low (n=450)] according to median levels of Lp(a). The primary outcome was a composite of all-cause death and acute coronary syndrome (ACS).

RESULTS

The baseline characteristics of the groups were similar and the median follow-up period was 4.7 years. Cumulative event-free survival was significantly worse for the group with high, than low Lp(a) (P=0.01). Multivariable analysis indicated a high Lp(a) level as an independent predictor of primary outcomes (hazard ratio, 1.35; 95% CI, 1.01-1.82; P=0.04).

CONCLUSIONS

A high Lp(a) value is associated with a poor prognosis after PCI for patients with CKD.

Lipoprotein(a) and Arterial Stiffness Parameters

BACKGROUND

Circulating lipoprotein(a) [Lp(a)] and arterial stiffness are markers associated with the atherosclerotic processes. With regard to cardiovascular outcomes, the relationship between Lp(a) and arterial stiffness has not been sufficiently summarized. The present review focuses on the existing association between Lp(a) and arterial stiffness parameters.

SUMMARY

This review included human clinical studies that were published between 1980 and 2015. The metrics of arterial stiffness parameters, 'pulse wave velocity' (PWV) and 'cardio-ankle vascular index' (CAVI), were used for this search, which yielded only 4 cross-sectional studies on this topic. Of these 4 studies, 3 reports were based on the use of PWV, while 1 study was based on the use of CAVI. Three studies (including the study using CAVI) reported that high Lp(a) levels were positively associated with arterial stiffness.

CONCLUSION

The present review indicates a positive association between Lp(a) and arterial stiffness, as assessed by PWV and CAVI. To definitively establish these findings, there is a need for further prospective outcome studies that simultaneously measure Lp(a) and the oxidative form of Lp(a) (as a pathological marker) as well as PWV and CAVI.

Lipoprotein(a): Its relevance to the pediatric population

Lipoprotein(a) (Lp(a)) is a highly atherogenic and heterogeneous lipoprotein that is inherited in an autosomal codominant trait. A unique aspect of this lipoprotein is that it is fully expressed by the first or second year of life in children, a pattern that is distinctly different from other lipoproteins, which typically only reach adult levels after adolescence. Despite decades of research, Lp(a) metabolism is still poorly understood but what is abundantly clear is that it is an independent risk factor for atherosclerotic cardiovascular disease (ASCVD). The Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents does not recommend measuring Lp(a) levels as part of routine screening except in youth with an ischemic or hemorrhagic stroke or youth with a parental history of ASCVD not explained by classical risk factors. One of the reasons that both the pediatric and adult guidelines fail to include this lipoprotein as part of routine lipid screening is the absence of data to show that lowering Lp(a) will reduce current or future ASCVD risk independently of low-density lipoprotein cholesterol (LDL-C) lowering. The cholesterol carried by Lp(a) is included in the low-density lipoprotein cholesterol measurement, but a separate test is used to measure the lipoprotein mass and/or cholesterol carried only by Lp(a). Because levels seem to be largely under genetic control, studies of lifestyle modification have been inconclusive although one study in obese children showed a decrease in the Lp(a) level comparable with the favorable effect on other lipids. The most compelling data regarding the importance of Lp(a) in the pediatric population are the increased risk associated with arterial ischemic stroke, a risk that is comparable with that associated with antiphospholipid antibodies or protein C deficiency. Although no specific pharmaceutical treatments are recommended to lower Lp(a) levels in youth, it is vitally important to educate youth and their parents about the excessive risk associated with this lipoprotein and the need to avoid the acquisition of other lifestyle-related risk factors such as smoking, excess weight, and physical inactivity to preserve more ideal cardiovascular health in adulthood.

Effect of garlic on plasma lipoprotein(a) concentrations: A systematic review and meta-analysis of randomized controlled clinical trials

OBJECTIVES

Garlic can play an essential role in the prevention of atherosclerosis, but the research addressing the effect of garlic on the concentration of lipoprotein(a) [Lp(a)] has not been fully demonstrated. The aim of this study was to assess the effect of garlic on plasma Lp(a) concentrations through systematic review of literature and meta-analysis of available randomized controlled trials.

METHODS

The literature search included SCOPUS, PubMed-Medline, ISI Web of Science, and Google Scholar databases up to March 10, 2015 to identify randomized controlled trials investigating the effect of garlic on plasma Lp(a) concentrations. Two independent reviewers extracted data on study characteristics, methods, and outcomes. Overall, the effect of garlic on plasma Lp(a) levels was reported in six trials.

RESULTS

Meta-analysis did not suggest a significant alteration in plasma Lp(a) levels after garlic consumption (weighted mean difference [WMD] = 16.86%; 95% confidence interval, -4.59 to 38.31; P = 0.124). This result was robust in the leave-one-out sensitivity analysis. When the studies were categorized according to the duration of supplementation, there was no effect in the subgroup of trials lasting ≤12 wk (WMD = 2.01%; 95% CI, -14.67 to 18.68; P = 0.813) but a significant elevation of plasma Lp(a) concentrations was found in trials lasting >12 wk (WMD = 54.59%; 95% CI, 30.47-78.71; P < 0.001). Random-effects meta-regression suggested an inverse association between the changes in plasma concentrations of Lp(a) and duration of supplementation (slope 1.71; 95% CI, 0.46-2.97; P = 0.007).

CONCLUSIONS

The present meta-analysis did not suggest a significant effect of garlic supplementation on the reduction of Lp(a) levels.

Lack of association of rs3798220 with small apolipoprotein(a) isoforms and high lipoprotein(a) levels in East and Southeast Asians

OBJECTIVE

The variant allele of rs3798220 in the apolipoprotein(a) gene (LPA) is used to assess the risk for coronary artery disease (CAD) in Europeans, where it is associated with short alleles of the Kringle IV-2 (KIV-2) copy number variation (CNV) and high lipoprotein(a) (Lp(a)) concentrations. No association of rs3798220 with CAD was detected in a GWAS of East Asians. Our study investigated the association of rs3798220 with Lp(a) concentrations and KIV-2 CNV size in non-European populations to explain the missing association of the variant with CAD in Asians.

METHODS

We screened three populations from Africa and seven from Asia by TaqMan Assay for rs3798220 and determined KIV-2 CNV sizes of LPA alleles by pulsed-field gel electrophoresis (PFGE). Additionally, CAD cases from India were analysed. To investigate the phylogenetic origin of rs3798220, 40 LPA alleles from Chinese individuals were separated by PFGE and haplotyped for further SNPs.

RESULTS

The variant was not found in Africans. Allele frequencies in East and Southeast Asians ranged from 2.9% to 11.6%, and were very low (0.15%) in CAD cases and controls from India. The variant was neither associated with short KIV-2 CNV alleles nor elevated Lp(a) concentrations in Asians.

CONCLUSION

Our study shows that rs3798220 is no marker for short KIV-2 CNV alleles and high Lp(a) in East and Southeast Asians, although the haplotype background is shared with Europeans. It appears unlikely that this SNP confers atherogenic potential on its own. Furthermore, this SNP does not explain Lp(a) attributed risk for CAD in Asian Indians.

Early renal failure as a cardiovascular disease: Focus on lipoprotein(a) and prothrombotic state

Patients with renal failure are at increased risk of cardiovascular events even at the earliest stages of disease. In addition to many classic cardiovascular risk factors, many conditions that are commonly identified as emerging risk factors might contribute to occurrence of cardiovascular disease. Changes in circulating levels of many of these emerging risk factors have been demonstrated in patients with early stages of renal failure caused by different types of renal disease and have been associated with detection of cardiovascular complications. However, for most of these factors evidence of benefits of correction on cardiovascular outcome is missing. In this article, we comment on the role of lipoprotein(a) and prothrombotic factors as potential contributors to cardiovascular events in patients with early renal failure.

Role of lipoprotein(a) in predicting the severity of new on-set coronary artery disease in type 2 diabetics: A Gensini score evaluation

The objective of the study was to investigate the usefulness of serum lipoprotein(a) level in predicting the severity of new on-set coronary artery disease in type 2 diabetics. A total of 1254 new on-set, consecutive coronary artery disease patients were classified into two groups: diabetes group (n = 380) and non-diabetes group (n = 874). The relationship between serum lipoprotein(a) levels and the severity of coronary artery disease assessed by Gensini score was analysed. Data showed that the diabetes group had higher serum triglyceride and high sensitivity C-reactive protein levels but lower high-density lipoprotein cholesterol levels (all p < 0.05). The multivariate logistic regression analysis suggested that lipoprotein(a) was an independent predictor for high Gensini score (odds ratio = 1.82, 95% confidence interval: 1.10-3.12, p = 0.029) after adjusting for traditional cardiovascular risk factors. Additionally, lipoprotein(a) levels were positively correlated with Gensini score (rho = 0.15, p = 0.014) and significantly elevated according to the tertiles of Gensini score (p = 0.008) in diabetics. However, no such results were observed in non-diabetics. Our data indicate that lipoprotein(a) is an independent predictor for the severity of new on-set coronary artery disease patients accompanied by type 2 diabetes, suggesting that these patients may benefit from lipoprotein(a) management in clinical assessment.

Monocyte subset distribution in patients with stable atherosclerosis and elevated levels of lipoprotein(a)

Background

Lipoprotein(a) (Lp(a)) is a proatherogenic plasma lipoprotein currently established as an independent risk factor for the development of atherosclerotic disease and as a predictor for acute thrombotic complications. In addition, Lp(a) is the major carrier of proinflammatory oxidized phospholipids (OxPL). Today, atherosclerosis is considered to be an inflammatory disease of the vessel wall in which monocytes and monocyte-derived macrophages are crucially involved. Circulating monocytes can be divided according to their surface expression pattern of CD14 and CD16 into at least 3 subsets with distinct inflammatory and atherogenic potential.

Objective

The aim of this study was to examine whether elevated levels of Lp(a) and OxPL on apolipoprotein B-100–containing lipoproteins (OxPL/apoB) are associated with changes in monocyte subset distribution.

Methods

We included 90 patients with stable coronary artery disease. Lp(a) and OxPL/apoB were measured, and monocyte subsets were identified as classical monocytes (CMs; CD14++CD16−), intermediate monocytes (IMs; CD14++CD16+), and nonclassical monocytes (NCMs; CD14+CD16++) by flow cytometry.

Results

In patients with elevated levels of Lp(a) (>50 mg/dL), monocyte subset distribution was skewed toward an increase in the proportion of IM (7.0 ± 3.8% vs 5.2 ± 3.0%; P = .026), whereas CM (82.6 ± 6.5% vs 82.0 ± 6.8%; P = .73) and NCM (10.5 ± 5.3 vs 12.8 ± 6.0; P = .10) were not significantly different. This association was independent of clinical risk factors, choice of statin treatment regime, and inflammatory markers. In addition, OxPL/apoB was higher in patients with elevated Lp(a) and correlated with IM but not CM and NCM.

Conclusions

In conclusion, we provide a potential link between elevated levels of Lp(a) and a proatherogenic distribution of monocyte subtypes in patients with stable atherosclerotic disease.

•

Lipoprotein(a) serves as an independent risk factor in atherosclerotic disease.

•

Monocyte subsets exhibit distinct inflammatory and atherogenic properties.

•

Patients with elevated levels of Lp(a) show a shift towards intermediate monocytes.

•

This association was independent of clinical properties and inflammatory markers.

•

Those patients also exhibited higher OxPL/apoB concentrations.

Hypoascorbemia induces atherosclerosis and vascular deposition of lipoprotein(a) in transgenic mice

Lipoprotein(a), a variant of LDL carrying the adhesive glycoprotein apo(a), is a leading risk factor for cardiovascular disease. Lipoprotein(a) (Lp(a)) is found in humans and subhuman primates but rarely in lower mammals. Better understanding of the evolutionary advantage of this molecule should elucidate its physiological role. We developed a new mouse model with two characteristics of human metabolism: the expression of Lp(a) and the lack of endogenous ascorbate (vitamin C) production. We show that dietary deficiency of ascorbate increases serum levels of Lp(a). Moreover, chronic hypoascorbemia and complete depletion of ascorbate (scurvy) leads to Lp(a) accumulation in the vascular wall and parallels atherosclerotic lesion development. The results suggest that dietary ascorbate deficiency is a risk factor for atherosclerosis independent of dietary lipids. We provide support for the concept that Lp(a) functions as a mobile repair molecule compensating for the structural impairment of the vascular wall, a morphological hallmark of hypoascorbemia and scurvy.

Lipoprotein(a) catabolism is regulated by proprotein convertase subtilisin/kexin type 9 through the low density lipoprotein receptor

Elevated levels of lipoprotein(a) (Lp(a)) have been identified as an independent risk factor for coronary heart disease. Plasma Lp(a) levels are reduced by monoclonal antibodies targeting proprotein convertase subtilisin/kexin type 9 (PCSK9). However, the mechanism of Lp(a) catabolism in vivo and the role of PCSK9 in this process are unknown. We report that Lp(a) internalization by hepatic HepG2 cells and primary human fibroblasts was effectively reduced by PCSK9. Overexpression of the low density lipoprotein (LDL) receptor (LDLR) in HepG2 cells dramatically increased the internalization of Lp(a). Internalization of Lp(a) was markedly reduced following treatment of HepG2 cells with a function-blocking monoclonal antibody against the LDLR or the use of primary human fibroblasts from an individual with familial hypercholesterolemia; in both cases, Lp(a) internalization was not affected by PCSK9. Optimal Lp(a) internalization in both hepatic and primary human fibroblasts was dependent on the LDL rather than the apolipoprotein(a) component of Lp(a). Lp(a) internalization was also dependent on clathrin-coated pits, and Lp(a) was targeted for lysosomal and not proteasomal degradation. Our data provide strong evidence that the LDLR plays a role in Lp(a) catabolism and that this process can be modulated by PCSK9. These results provide a direct mechanism underlying the therapeutic potential of PCSK9 in effectively lowering Lp(a) levels.

Lipoprotein(a): an important cardiovascular risk factor and a clinical conundrum

Elevated plasma concentrations of lipoprotein(a) (Lp[a]) are an emerging risk factor for the development of coronary heart disease (CHD). Recent genetic and epidemiologic data have provided strong evidence for a causal role of Lp(a) in CHD. Despite these developments, which have attracted increasing interest from clinicians and basic scientists, many unanswered questions persist. The true pathogenic mechanism of Lp(a) remains a mystery. Significant uncertainty exists concerning the appropriate use of Lp(a) in the clinical setting. No therapeutic intervention remains that can specifically lower plasma Lp(a) concentrations, although the list of compounds that lower Lp(a) and LDL continues to expand.

Relationships of plasma lipoprotein(a) levels with insulin resistance in hypertensive patients

BACKGROUND

Lipoprotein(a) [Lp(a)] is an emergent cardiovascular risk factor that is related to the presence and severity of cardiovascular damage in hypertensive patients. In these patients, insulin resistance is frequently detected but its relationship with plasma Lp(a) is not clear. The aim of this study was to examine the relationships between Lp(a) and variables of glucose metabolism in hypertension.

METHODS

In 527 consecutive, non-diabetic, middle-aged hypertensive patients we measured anthropometric indexes, 24-hour creatinine clearance, lipid profile including Lp(a) levels, fasting glucose, insulin and C-peptide, and calculated the Homeostatic Model Assessment (HOMA) index.

RESULTS

Lp(a) levels were significantly and progressively lower with increasing HOMA-index values. Lp(a) was inversely related to fasting glucose, insulin, and C-peptide, HOMA-index, and creatinine clearance and directly related to LDL-cholesterol. Multiple regression analysis adjusted for age, sex, body mass index, blood pressure, smoking habit, alcohol intake, renal function, lipid profile, history of cardiovascular events, and drug use showed that HOMA-index and creatinine clearance were inversely and independently associated to Lp(a) levels.

CONCLUSIONS

Insulin resistance and higher fasting insulin levels are associated with lower plasma Lp(a) in hypertensive patients. This association might be relevant in the assessment of cardiovascular risk in these patients.

Serum lipoprotein(a) concentrations do not change significantly in the immediate seven-day period post myocardial infarction

BACKGROUND

Lipoprotein(a) is an independent predictor of cardiovascular disease and its variability after myocardial infarction was assessed in this study.

METHODS

Lipoprotein(a) was analysed by a size insensitive latex immunoturbidimetric end point assay in samples from days 0 to 7 in 31 patients admitted with myocardial infarction.

RESULTS

Median lipoprotein(a) changed by -0.9%, -0.1% and 9.6% on days 1, 2-3 and 4-7, respectively, and was not statistically significant. Median total cholesterol reduced by 8.7%, 9.1%, 14.5% and C-reactive protein increased by 68.4%, 510%, 502% over days 1, 2-3, 4-7, respectively.

CONCLUSIONS

Unlike total cholesterol and C-reactive protein, lipoprotein(a) does not demonstrate significant variability for up to seven days after myocardial infarction and measurements made during this period after myocardial infarction are physiologically meaningful.

Copy number variation of the Lipoprotein(a) (LPA) gene is associated with coronary artery disease in a southern Han Chinese population

Copy number variations (CNVs), genomic duplication or deletion events occurring at larger than 1 kb scale, contribute to the complex diseases substantially. Lipoprotein(a) [Lp(a)] is a major inherited risk factor for atherosclerosis and coronary artery disease (CAD). We investigated the association between a CNV of the Lp(a) (LPA) gene and CAD. The case-control study included 271 CAD patients and 207 controls diagnosed by coronary angiography. A taqman real-time fluorescence PCR based technique was developed according to the 2 × 2(-ΔΔCt±SD) calculation method. We detected LPA CNVs with a range of 1, 2 and 3. The 1 copy number carriers had a significantly reduced risk of CAD compared with those with 2 copy number after adjusting for the confounding factors (P < 0.001, OR = 0.38, 95% CI 0.23-0.64). Further stratified analyses suggested a significant protective effect of the 1 copy number in the elderly population (P = 0.008), females (P = 0.007) as well as in populations with non-hyperlipidemia (P = 0.003), hypertension (P = 0.001), non-smoking (P < 0.001) and high Lp(a) (≥ 0.3 g/L) levels (P = 0.001). The 1 copy number of the LPA gene may be an independent protective factor of CAD in a southern Han Chinese population, particularly in females and the elderly.

Virtually same oxidizability of LDL but higher Lp(a) levels in arterial compared to venous plasma

Plaque formation is confined to the arterial trunk. We assumed that due to the higher aeration of arterial compared to venous blood, higher levels of the atherogenic agent oxidized LDL might be present in arteries, contributing to plaque formation. We aimed to compare (i) the basal oxidative status of LDL in arterial and venous blood and (ii) the susceptibility of arterial and venous LDL to oxidation. The basal oxidative status of LDL was determined by measuring lipid hydroperoxide (LPO) concentrations, plasma levels of auto-antibodies against oxidized LDL, and by measuring oxidation-specific epitopes on LDL particles. The oxidizability of arterial vs. venous LDL (catalyzed by copper) was estimated by monitoring the time-course of conjugated dienes formation. Interestingly, we found the same basal oxidative status of LDL in arterial and venous plasma. LPO concentrations and levels of auto-antibodies against oxidized LDL were similar in arterial and venous plasma and amounts of oxidation-specific epitopes were similar on the respective LDL particles. Moreover, we found similar susceptibilities of arterial and venous LDL to (copper-mediated) oxidation. Lag-times until the onset of conjugated diene formation were slightly shorter in arterial compared to venous LDL in the presence of 5 μM, but not in the presence of 1 μM CuCl2. Additionally, we found significantly higher levels of the atherogenic lipoprotein(a) in arterial plasma. We conclude that not higher oxidizability of arterial LDL but higher arterial lipoprotein(a) levels might help to explain why sclerosis is confined to the arterial trunk.

Lipoprotein(a) mass: a massively misunderstood metric

The importance of lipoprotein (a)-Lp(a)-as a cardiovascular (CV) risk marker has been underscored by recent findings that CV risk is directly related to baseline Lp(a) levels, even in well-treated patients. Although there is currently little that can be done pharmacologically to lower Lp(a) levels, knowledge of its serum concentration is important in overall risk assessment. This review focuses on 1 aspect of Lp(a) that is rarely discussed directly: how to express its levels in serum. There is considerable confusion on this point, and a fuller understanding of what the concentration units mean will help improve study-to-study comparisons and thereby advance our understanding of the pathobiology of this lipoprotein particle. As discussed here, the term Lp(a) mass refers to the entire mass of the particle: lipids, proteins, and carbohydrates combined. At present, there are no commercially available assays that are completely insensitive to the variability in particle mass, which arises not only from differences in apo(a) isoform mass but also from variations in lipid mass. Because lipoprotein "particle number" (molar concentration) has been found to be superior to component-based metrics (ie, low-density lipoprotein particle vs cholesterol concentrations) for CV disease risk prediction, the development of a mass-insensitive Lp(a) assay should be a high priority.

Inflammation, lipid metabolism and cardiovascular risk in rheumatoid arthritis: A qualitative relationship?

Life expectancy in patients with rheumatoid arthritis (RA) is reduced compared to the general population owing to an increase in cardiovascular diseases (CVD) not fully explained by traditional cardiovascular risk factors. In recent years, interest has been focused on the alterations in lipid metabolism in relation to chronic inflammation as one of the possible mechanisms involved in the pathogenesis of atherosclerosis of RA patients. Research regarding this issue has revealed quantitative alterations in lipoproteins during the acute-phase reaction, and has also demonstrated structural alterations in these lipoproteins which affect their functional abilities. Although many alterations in lipid metabolism have been described in this regard, these structural changes associated with inflammation are particularly important in high-density lipoproteins as they affect their cardioprotective functions. In this respect, excessive oxidation in low-density lipoprotein (LDL) and increased lipoprotein(a) with a predominance of smaller apolipoprotein(a) isoforms has also been reported. This article will discuss proinflammatory high-density lipoproteins (piHDL), oxidized LDL and lipoprotein(a). Elevated concentrations of these lipoproteins with marked pro-atherogenic properties have been observed in RA patients, which could help to explain the increased cardiovascular risk of these patients.

Lipoprotein(a) level and apolipoprotein(a) phenotype as predictors of long-term cardiovascular outcomes after coronary artery bypass grafting

OBJECTIVE

To evaluate the relationships of lipoprotein(a) (Lp(a)) concentration and apolipoprotein(a) (apo(a)) phenotype to major adverse cardiovascular events after coronary artery bypass grafting (CABG) in long-term follow-up.

METHODS

This single-center study included 356 patients with stable coronary heart disease (CHD) who underwent successful CABG. At baseline, we assessed the patient's risk factor profile for atherosclerosis, Lp(a) concentration and apo(a) phenotype. The primary endpoint was the composite of cardiovascular death and non-fatal myocardial infarction (MI). The secondary endpoint also included hospitalization for recurrent or unstable angina and repeat revascularization.

RESULTS

Over a mean of 8.5 ± 3.5 years (range 0.9-15.0 years), the primary and secondary endpoints were registered in 46 (13%) and 107 (30%) patients, respectively. Patients with Lp(a) ≥30 mg/dL were at significantly greater risk for the primary endpoint (hazard ratio (HR) 2.98, 95% confidence interval (CI) 1.76-5.03, p < 0.001) and secondary endpoint (HR 3.47, 95% CI 2.48-4.85, p < 0.001) than patients with Lp(a) values <30 mg/dL. The low molecular-weight apo(a) phenotype was also associated with higher risk of both primary and secondary endpoints (3.57 (1.87-6.82) and 3.05 (2.00-4.62), respectively; p < 0.001 for both), regardless of conventional risk factors and statins use.

CONCLUSION

In stable CHD patients Lp(a) concentration and low molecular-weight apo(a) phenotype are independently associated with three-fold increase in risk of major adverse cardiovascular events within 15 years after CABG. Lp(a) levels may provide an additional information for postoperative cardiovascular risk assessment.

[Effect of biliary obstruction on lipoprotein(a) concentration]

OBJECTIVES

This study was appointed to determine the correlation between the concentration of lipoprotein(a) [Lp(a)], apolipoproteins and lipids with biochemical parameters of liver function in a group of patients with reversible cholestasis. We have also determined the concentration of these parameters once solved the biliary obstruction process.

MATERIAL AND METHODS

Eighteen adults over 17 years with extrahepatic cholestasis were included in the study on a prospective basis, and we determined in them biochemical liver function parameters and lipoprotein metabolism parameters, particularly Lp(a) before and after unblocking.

RESULTS

The concentration of Lp(a) prior to desobstruction was inverse and statistically significantly correlated with the concentration of gamma glutamyl transpeptidase (correlation coefficient [r] = -0.757, P = .018). The concentration of Lp(a) (median = 2.66 mg/dL, interquartile range = 5,62) showed a statistically significant increase (median = 9.72 mg/dL, interquartile range = 28.76, P < .001), once the unblocking was performed. Concentrations of total cholesterol and triglycerides had a statistically significant decrease, and HDL cholesterol and apolipoprotein A-1 showed a statistically significant increase once the unblocking was carried out.

CONCLUSIONS

The concentration of Lp(a) is decreased during cholestasis, although there is a significant simultaneous hypercholesterolemia. Cholestasis has a causal role in lowering Lp(a), because the unblocking of bile duct recovers Lp(a) concentration. Our study supports the concept that bile acids exert a controlling effect on the synthesis of Lp(a) and open a mechanism for the treatment of hyper Lp(a).

Effect of Nicotinic acid/Laropiprant in the lipoprotein(a) concentration with regard to baseline lipoprotein(a) concentration and LPA genotype

BACKGROUND

Lipoprotein(a) [Lp(a)] is a lipoprotein in which apolipoproteinB-100 is linked to apolipoprotein(a) [apo(a)]. Significant variation in Lp(a) concentration is specific to LPA gene, which codes for apo(a). Nicotinic acid (NA) is used for treatment of dyslipidemias, and the lowering effect of NA on Lp(a) has been previously reported.

OBJECTIVE

To evaluate the Lp(a) lowering effect of 1g/20mg and 2g/40mgday of Nicotinic acid/Laropiprant in subjects with different baseline Lp(a) concentrations and depending on the LPA genotype.

METHODS

In an open-label, 10-week study, 1g/20mgday of NA/Laropiprant for 4weeks followed by 6weeks of 2g/40mgday conducted at 3 centers in Spain, 82 subjects were enrolled. Patients were studied at baseline and at the end of both treatment periods and were enrolled in three groups: normal Lp(a) (<50mg/dL), high Lp(a) (50-120mg/dL) and very high Lp(a) (>120mg/dL). The LPA genetic polymorphism was analyzed by a real-time PCR.

RESULTS

There was a significant difference in LPA genotypes among Lp(a) concentration groups and an inverse and significant correlation between baseline Lp(a) concentration and LPA genotype was found (R=-0.372, p<0.001). There were a significant decrease in total cholesterol, triglycerides, LDL cholesterol, apo B and Lp(a), and a significant increase in HDL cholesterol after NA/Laropiprant treatment, without changes in BMI. However, there were no statistical differences in percentage variation of analyzed variables depending on LPA genotype.

CONCLUSION

LPA genotype is a major determinant of Lp(a) baseline concentration. However, the lipid lowering effect of NA is not related to LPA genotype.

[Lipoprotein(a) is associated to atherosclerosis in primary hypercholesterolemia]

INTRODUCTION

Several studies have suggested that Lp(a) could be a risk factor mainly in hypercholesterolemic patients.

METHODS

A total of 909 individuals were selected for this study. 307 were diagnosed of familiar hypercholesterolemia with a pathogenic mutation in LDLR or APOB genes (FH+), 291 of familiar combined hyperlipidemia (FCH) and 311 of familial hypercholesterolemia without a pathogenic mutation in LDLR nor APOB genes (FH-). Main risk factor were studied, included statin treatment. Plasma lipids, Lp(a), HbA1c and C-reactive protein. Intima-media thickness (IMT) of common and bulb carotid in both sides were measured in all subjects.

RESULTS

Lp(a) values (median, interquartile range) were 21.9mg/dL (9.24-50.5) in FH+, 22.4mg/dL (6.56-51.6) in FCH and 32.7 (14.6-71.5) in FH- (P<.001). Regression analysis including age, gender, HDL cholesterol, LDL cholesterol corrected for Lp(a), Lp(a), C-reactive protein, packs of cigarettes/day per year, systolic blood pressure and glucose as independent variables, demonstrate that Lp(a) was associated with carotid IMT in FH- subjects. Cardiovascular disease was more frequent in subjects with Lp(a) >50mg/dL (17.9%) than in subjects with Lp(a) <15mg/dL (9.6%), and between 15-50mg/dL (10.1%), and it was concentrated mostly in FH-group (6.7, 11.3, and 23.4% for the groups of Lp(a) <15mg/dL 15-50mg/dL, and >50mg/dL, respectively).

CONCLUSIONS

Our results indicate that Lp(a) is associated with atherosclerosis burden especially in subjects with FH- and concentrations of Lp(a)>50mg/dL.

The expanding role of lipoprotein apheresis in the treatment of raised lipoprotein(a) in ischaemic heart disease and refractory angina

It is increasingly recognised that lipoprotein(a) [Lp(a)], an inherited, genetically-determined form of LDL-cholesterol, is an independent cardiovascular risk factor and predictor of adverse cardiovascular outcomes. Lp(a) is felt to increase cardiovascular risk via its pro-thrombotic effect and by enhancing intimal lipoprotein deposition. Lipoprotein apheresis is currently the most effective treatment for raised Lp(a). There is a growing body of evidence suggesting that aggressively lowering raised Lp(a) may improve cardiovascular and clinical outcomes, although much more research is required in this field.

Angina which is refractory to conventional medical therapy and revascularisation, is extremely challenging to manage. Treatment options for such patients remain very limited. We describe the case of a patient with refractory angina and raised lipoprotein(a) in whom aggressive reduction of Lp(a) with lipoprotein apheresis successfully ameliorated the progression of coronary stenosis and provided effective and durable relief of angina symptoms. In our centre, we are currently conducting a prospective, randomised controlled cross-over study of patients with refractory angina and raised Lp(a), randomised to undergoing lipoprotein apheresis or ‘sham’ apheresis with assessment of myocardial perfusion, carotid atherosclerosis, endothelial vascular function, thrombogenesis, oxidised phospholipids and their antibodies, exercise capacity, angina symptoms and quality of life at the beginning and end of treatment.

Lipoprotein (a), LPA Ile4399Met, and fibrin clot properties

INTRODUCTION

Elevated lipoprotein(a) (Lp(a)) levels were reported to be associated with dense fibrin clots. The apo(a) component of Lp(a) is encoded by LPA, and the Met allele of the LPA Ile4399Met polymorphism is associated with elevated Lp(a) levels and cardiovascular disease risk. We investigated whether Ile4399Met was associated with fibrin clot properties.

MATERIALS AND METHODS

We determined plasma Lp(a) levels, fibrin clot permeability and lysis time for 64 LPA 4399Met carriers and 128 noncarriers matched for age, sex, ethnicity, and enrollment site.

RESULTS

Elevated Lp(a) levels were associated with reduced clot permeability and prolonged lysis time (P<0.0001). Carriers of 4399Met had higher Lp(a) levels compared with noncarriers (P=0.0003). However, this association differed by ethnicity (P=0.003 for interaction between genotype and ethnicity): compared with noncarriers, 4399Met carriers had 2.89 fold higher Lp(a) levels among Caucasians while no difference was observed among non-Caucasians (primarily East Asians and Hispanics). Among all subjects, no association was observed between Ile4399Met and clot properties, but this relationship also differed by ethnicity: among non-Caucasians, 4399Met carriers had increased clot permeability and shorter lysis time; whereas among Caucasians, the trend was for decreased permeability and longer lysis time (P<0.01 for interactions between genotype and ethnicity).

CONCLUSIONS

We confirmed that elevated Lp(a) levels are associated with dense fibrin clots, and found that the association of LPA 4399Met carriers and clot permeability as well as lysis time differ by ethnicity.

Assessment of adipokines relationships with cardiovascular risk markers in relation to body indices in normoglycemic males

OBJECTIVES

To evaluate the phenotypic relationship between obesity indices, resistin, adiponectin and cardiovascular risk markers in normoglycemic healthy individuals.

METHODOLOGY

This cross-sectional study was conducted in the Department of Physiology College of Medicine, King Saud University, Riyadh. A total of 120 male subjects were selected for the study. All subjects underwent analysis of body composition, glucose, glycosylated hemoglobin (HbA1c), lipids, adiponectin, resistin, lipoprotein(a) and high sensitivity C reactive protein (hsCRP).

RESULTS

Body mass index (BMI) (r=0.326, p < 0.001), body fat mass (BFM) (r=0.377, p < 0.001), body fat percentage (BF%) (r=0.326, p < 0.001), waist hip ratio (WHR) (r=0.402, p < 0.001) and basal Insulin levels (r=0.217, p=0.018) were positively correlated with hsCRP. However, serum adiponectin levels (r=0.189, p=0.0391) were negatively correlated with hsCRP. Adiponectin levels were significantly lower in obese compared to non obese subjects (p=0.0551). Keeping hsCRP as dependant variable we observed that WHR, BFM, BF%, BMI and adiponectin were significant predictors in univariate analysis. In multiple regression analysis WHR and adiponectin were independent predictors of hsCRP.

CONCLUSION

Obese individuals have significantly higher levels of hsCRP levels and lower adiponectin levels than non obese subjects. Serum adiponectin levels and WHR are independant predictors of hsCRP levels in normoglycemic subjects.

Apolipoprotein(a) acts as a chemorepellent to human vascular smooth muscle cells via integrin αVβ3 and RhoA/ROCK-mediated mechanisms

Lipoprotein(a) (Lp(a)) is an independent risk factor for the development of cardiovascular disease. Vascular smooth muscle cell (SMC) motility and plasticity, functions that are influenced by environmental cues, are vital to adaptation and remodelling in vascular physiology and pathophysiology. Lp(a) is reportedly damaging to SMC function via unknown molecular mechanisms. Apolipoprotein(a) (apo(a)), a unique glycoprotein moiety of Lp(a), has been demonstrated as its active component. The aims of this study were to determine functional effects of recombinant apo(a) on human vascular SMC motility and explore the underlying mechanism(s). Exposure of SMC to apo(a) in migration assays induced a potent, concentration-dependent chemorepulsion that was RhoA and integrin αVβ3-dependent, but transforming growth factor β-independent. SMC manipulation through RhoA gene silencing, Rho kinase inhibition, statin pre-treatment, αVβ3 neutralising antibody and tyrosine kinase inhibition all markedly inhibited apo(a)-mediated SMC migration. Our data reveal unique and potent activities of apo(a) that may negatively influence SMC remodelling in cardiovascular disease. Circulating levels of Lp(a) are resistant to lipid-lowering strategies and hence a greater understanding of the mechanisms underlying its functional effects on SMC may provide alternative therapeutic targets.

Lipoprotein(a) in type 2 diabetic subjects and its relationship to diabetic microvascular complications

AIM: To estimate the level of serum lipoprotein (a) [Lp (a)] in type 2 diabetes mellitus patients and to determine the relationship between Lp(a) in type 2 diabetes mellitus patients and micro-vascular complications.

METHODS: A cross sectional study was performed that enrolled 144 subjects with type 2 diabetes mellitus above the age of 25 years attending outpatient clinic of Government Medical College, Kozhikode. Lp(a) levels were measured quantitatively in venous samples using Turbidimetric Immunoassay in all subjects. Each patient was evaluated for micro vascular complications, namely diabetic retinopathy, nephropathy and neuropathy. The relationship between Lp(a) levels and the micro vascular complications was assessed by univariate analysis.

RESULTS: Mean age of cases was 53.93 ± 10.74 years with a male to female ratio of 1.3:1. Mean duration of diabetes was 9.53 ± 7.3 years. Abnormal Lp(a) levels (≥ 30 mg/dL) were observed in 38 (26.4%) diabetic subjects. Seventy-eight (54.16%) cases had diabetic nephropathy and significantly higher Lp(a) levels were found among these cases [Median 28.2 mg/dL (Interquartile range; IQR 24.4-33.5) vs 19.3 mg/dL (IQR 14.7-23.5); P < 0.05]. Retinopathy was present among 66 (45.13%) cases and peripheral neuropathy was detected among 54 (37.5%) cases. However, Lp(a) levels were not significantly different among those with or without retinopathy and neuropathy. Positive correlation was found between higher Lp(a) levels and duration of diabetes (r = 0.165, P < 0.05) but not with HbA1c values (r = – 0.083).

CONCLUSION: Abnormal Lp(a) levels were found among 26.4% of diabetic subjects. Patients with diabetic nephropathy had higher Lp(a) levels. No association was found between Lp(a) levels and diabetic retinopathy or neuropathy. Longer duration of diabetes correlated with higher Lp(a) levels.