Serum lipids, lipoprotein(a) level, and apolipoprotein(a) isoforms as prognostic markers in patients with coronary heart disease

Lipoprotein(a) and the Risk for Recurrent Atherosclerotic Cardiovascular Events Among Adults With CKD: The Chronic Renal Insufficiency Cohort (CRIC) Study

Rationale & Objective

Many adults with chronic kidney disease (CKD) and atherosclerotic cardiovascular disease (ASCVD) have high lipoprotein(a) levels. It is unclear whether high lipoprotein(a) levels confer an increased risk for recurrent ASCVD events in this population. We estimated the risk for recurrent ASCVD events associated with lipoprotein(a) in adults with CKD and prevalent ASCVD.

Study Design

Observational cohort study.

Setting & Participants

We included 1,439 adults with CKD and prevalent ASCVD not on dialysis enrolled in the Chronic Renal Insufficiency Cohort study between 2003 and 2008.

Exposure

Baseline lipoprotein(a) mass concentration, measured using a latex-enhanced immunoturbidimetric assay.

Outcomes

Recurrent ASCVD events (primary outcome), kidney failure, and death (exploratory outcomes) through 2019.

Analytical Approach

We used Cox proportional-hazards regression models to estimate adjusted HR (aHRs) and 95% CIs.

Results

Among participants included in the current analysis (mean age 61.6 years, median lipoprotein(a) 29.4 mg/dL [25th-75th percentiles 9.9-70.9 mg/dL]), 641 had a recurrent ASCVD event, 510 developed kidney failure, and 845 died over a median follow-up of 6.6 years. The aHR for ASCVD events associated with 1 standard deviation (SD) higher log-transformed lipoprotein(a) was 1.04 (95% CI, 0.95-1.15). In subgroup analyses, 1 SD higher log-lipoprotein(a) was associated with an increased risk for ASCVD events in participants without diabetes (aHR, 1.23; 95% CI, 1.02-1.48), but there was no evidence of an association among those with diabetes (aHR, 0.99; 95% CI, 0.88-1.10, P comparing aHRs = 0.031). The aHR associated with 1 SD higher log-lipoprotein(a) in the overall study population was 1.16 (95% CI, 1.04-1.28) for kidney failure and 1.02 (95% CI, 0.94-1.11) for death.

Limitations

Lipoprotein(a) was not available in molar concentration.

Conclusions

Lipoprotein(a) was not associated with the risk for recurrent ASCVD events in adults with CKD, although it was associated with a risk for kidney failure.

Circulating lipoprotein (a) and all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis

AIMS

To investigate the association between circulating lipoprotein(a) (Lp(a)) and risk of all-cause and cause-specific mortality in the general population and in patients with chronic diseases, and to elucidate the dose-response relations.

METHODS AND RESULTS

We searched literature to find prospective studies reporting adjusted risk estimates on the association of Lp(a) and mortality outcomes. Forty-three publications, reporting on 75 studies (957,253 participants), were included. The hazard ratios (HRs) and 95% confidence intervals (95%CI ) for the top versus bottom tertile of Lp(a) levels and risk of all-cause mortality were 1.09 (95%CI: 1.01-1.18, I²: 75.34%, n = 19) in the general population and 1.18 (95%CI: 1.04-1.34, I²: 52.5%, n = 12) in patients with cardiovascular diseases (CVD). The HRs for CVD mortality were 1.33 (95%CI: 1.11-1.58, I²: 82.8%, n = 31) in the general population, 1.25 (95%CI: 1.10-1.43, I²: 54.3%, n = 17) in patients with CVD and 2.53 (95%CI: 1.13-5.64, I²: 66%, n = 4) in patients with diabetes mellitus. Linear dose-response analyses revealed that each 50 mg/dL increase in Lp(a) levels was associated with 31% and 15% greater risk of CVD death in the general population and in patients with CVD. No non-linear dose-response association was observed between Lp(a) levels and risk of all-cause or CVD mortality in the general population or in patients with CVD (P_nonlinearity > 0.05).

CONCLUSION

This study provides further evidence that higher Lp(a) levels are associated with higher risk of all-cause mortality and CVD-death in the general population and in patients with CVD. These findings support the ESC/EAS Guidelines that recommend Lp(a) should be measured at least once in each adult person's lifetime, since our study suggests those with higher Lp(a) might also have higher risk of mortality.

Time-resolved fluorescence immunoassay (TRFIA) for the simultaneous detection of hs-CRP and lipoprotein(a) in serum

Elevated serum high-sensitivity C-reactive protein (hs-CRP) and lipoprotein(a) (Lp(a)) levels are associated with the development of native coronary atherosclerosis. We aimed to establish a new method for the simultaneous detection of hs-CRP and Lp(a) to predict the development of atherosclerosis. A one-step time-resolved fluorescence immunoassay (TRFIA) with europium(III) (Eu³⁺ ) or samarium(III) (Sm³⁺ ) labels was established, and the performance of this TRFIA (in terms of sensitivity, specificity, accuracy, and cutoff values) was evaluated using clinical serum samples and compared with those of registered kits. The sensitivity was 0.052 μg/ml for hs-CRP and 0.64 μg/ml for Lp(a). The intra-assay and inter-assay cross-reactivities (CVs) were very low, ranging from 2.05% to 4.67% for hs-CRP and from 2.42% to 6.43% for Lp(a). The CVs were very low (<0.34% and <2.65%, respectively) with five interferents. Additionally, there was a high Pearson coefficient between the present TRFIA method and the registered kits (R² = 0.9967 and 0.9906, respectively). These data indicate that this study developed a TRFIA method that can be used for the quantitative detection of hs-CRP and Lp(a) in serum with high sensitivity, specificity, and accuracy. This TRFIA provides a new method for predicting the development of atherosclerosis.

Assessing Atherosclerotic Cardiovascular Disease Risk with Advanced Lipid Testing: State of the Science

Cardiovascular disease is the number one cause of death and disability worldwide. While substantial gains have been made in reducing cardiovascular mortality, future projections suggest that we have reached a nadir and may be at an inflection point, given the rising tide of obesity and diabetes. Evaluation and management of plasma lipids is central to the prevention of atherosclerotic cardiovascular disease. Although the standard lipid panel represents a well-established platform to assess risk, this test alone can be insufficient and/or misleading. Advances in our understanding of atherosclerosis have led to the development of lipid-based biomarkers that help to discriminate the risk of cardiovascular disease when it is unclear. While these biomarkers provide novel information, their implementation into clinical medicine remains difficult given discrepancies in the literature, lack of assay standardisation, poor accessibility and high cost. However, additional measures of atherogenic lipoproteins or their surrogates may offer insight beyond the standard lipid panel, providing a more precise assessment of risk and more accurate assessment of lipid-lowering therapy.

Lipoprotein(a): An independent, genetic, and causal factor for cardiovascular disease and acute myocardial infarction

Lipoprotein(a) [Lp(a)] is a circulating lipoprotein, and its level is largely determined by variation in the Lp(a) gene (LPA) locus encoding apo(a). Genetic variation in the LPA gene that increases Lp(a) level also increases coronary artery disease (CAD) risk, suggesting that Lp(a) is a causal factor for CAD risk. Lp(a) is the preferential lipoprotein carrier for oxidized phospholipids (OxPL), a proatherogenic and proinflammatory biomarker. Lp(a) adversely affects endothelial function, inflammation, oxidative stress, fibrinolysis, and plaque stability, leading to accelerated atherothrombosis and premature CAD. The INTER-HEART Study has established the usefulness of Lp(a) in assessing the risk of acute myocardial infarction in ethnically diverse populations with South Asians having the highest risk and population attributable risk. The 2018 Cholesterol Clinical Practice Guideline have recognized elevated Lp(a) as an atherosclerotic cardiovascular disease risk enhancer for initiating or intensifying statin therapy.

Association of the HNF1A polymorphisms and serum lipid traits, the risk of coronary artery disease and ischemic stroke

BACKGROUND

Hepatocyte nuclear factor-1α gene (HNF1A) single nucleotide polymorphisms (SNPs) have been associated with serum lipid traits in several previous genome-wide association studies. However, little is known about such associations in the Chinese populations. The present study aimed to determine the association of the HNF1A rs1169288, rs2259820, rs2464196 and rs2650000 SNPs and serum lipid traits, the risk of coronary artery disease (CAD) and ischemic stroke (IS).

METHODS

The genotypes of the four SNPs in 562 CAD and 521 IS patients, as well as 594 healthy controls, were detected using the Snapshot technology.

RESULTS

The genotype and allele distribution of the four SNPs was not different between controls and CAD or IS patients (p > 0.05 for all). rs1169288, rs2259820 and rs2464196 SNPs were significantly associated with serum lipid levels in both controls and CAD patients (p < 0.004-0.009). rs2259820 and rs2464196 SNPs were significantly associated with a lower risk of CAD [odds ratio (OR) = 0.64, 95% confidence interval (CI) = 0.44-0.91, p = 0.015 and OR =0.62, 95% CI = 0.43-0.89, p = 0.010, respectively]. Significant linkage disequilibrium was noted among the four SNPs (r²  > 0.5, D' > 0.8). The haplotype of rs1169288A-rs2259820C-rs2464196G-rs2650000A was associated with an increased risk of CAD (OR =1.95, 95% CI: 1.13-3.37, p = 0.015). Interactions of SNP-SNP (rs1169288-rs2464196-rs2650000) and haplotype-environment on the risk of CAD (A-C-G-A-smoking) or IS (A-C-G-A-sex and A-T-A-C-alcohol consumption) were also observed among these SNPs.

CONCLUSIONS

These findings suggest that the HNF1A polymorphisms may be the genetic risk factors for CAD and IS.

Exploring the expression bar code of SAA variants for gastric cancer detection

We reported an integrated platform to explore serum protein variant pattern in cancer and its utility as a new class of biomarker panel for diagnosis. On the model study of serum amyloid A (SAA), we employed nanoprobe-based affinity mass spectrometry for enrichment, identification and quantitation of SAA variants from serum of 105 gastric cancer patients in comparison with 54 gastritis patients, 54 controls, and 120 patients from other cancer. The result revealed surprisingly heterogeneous and most comprehensive SAA bar code to date, which comprises 24 SAA variants including SAA1- and SAA2-encoded products, polymorphic isoforms, N-terminal-truncated forms, and three novel SAA oxidized isotypes, in which the variant-specific peptide sequence were also confirmed by LC-MS/MS. A diagnostic model was developed for dimension reduction and computational classification of the 24 SAA-variant bar code, providing good discrimination (AUC = 0.85 ± 3.2E-3) for differentiating gastric cancer group from gastritis and normal groups (sensitivity, 0.76; specificity, 0.81) and was validated with external validation cohort (sensitivity, 0.71; specificity, 0.74). Our platform not only shed light on the occurrence and modification extent of under-represented serum protein variants in cancer, but also suggested a new concept of diagnostic platform by serum protein variant profile.

Primary risk factors influence risk of recurrent myocardial infarction/death from coronary heart disease: results from the Stockholm Heart Epidemiology Program (SHEEP)

Background

Prognosis after a first myocardial infarction (MI) is influenced by primary risk factors as well as secondary risk factors. There is still a lack of follow-up studies of well-characterized patient cohorts assessing the relative importance of these factors.

Design

A cohort of 1635 patients (aged 45-70 years) surviving at least 28 days after a first MI were followed for 6-9 years with regard to recurrent MI/fatal coronary heart disease (CHD). Data were collected through questionnaires, physical examinations, and medical records.

Methods

Hazard ratios (HR) with 95% confidence intervals (CI) for different risk factors were calculated using the Cox proportional hazard model.

Results

Of the primary risk factors, diabetes in both sexes was the most important predictor of recurrent MI/fatal CHD, multivariate-adjusted HR in men 1.6 (95% CI; 1.0-2.4) and in women 2.5 (95% CI; 0.9-6.9). Other primary risk factors with prognostic influence were job strain, HR 1.5 (95% CI; 1.0-2.1), and central obesity, HR 1.4 (95% CI; 1.0-2.0), in men and a low level of apolipoprotein A1, HR 2.3 (95% CI; 1.1-5.0), and high-density lipoprotein cholesterol, HR 1.9 (95% CI; 0.9-4.1), in women. The secondary risk factors most detrimental for prognosis were heart failure in men, HR 2.2 (95% CI; 1.2-4.0), and a high peak acute cardiac enzyme level in women, HR 4.4 (95% CI; 2.0-9.7).

Conclusions

Long-term follow-up of patients who survived at least 28 days after a first MI shows that several primary cardiovascular risk factors, particularly diabetes, contribute to the increased risk of recurrent MI/fatal CHD.

Menopausal hormone treatment cardiovascular disease: another look at an unresolved conundrum

Cardiovascular disease (CVD) is the most common cause of death in women. Before the Women's Health Initiative (WHI) hormone trials, evidence favored the concept that menopausal hormone treatment (MHT) protects against CVD. WHI studies failed to demonstrate CVD benefit, with worse net outcomes for MHT versus placebo in the population studied. We review evidence regarding the relationship between MHT and CVD with consideration of mechanisms and risk factors for atherogenesis and cardiac events, results of observational case-control and cohort studies, and outcomes of randomized trials. Estrogen effects on CVD risk factors favor delay or amelioration of atherosclerotic plaque development but may increase risk of acute events when at-risk plaque is present. Long-term observational studies have shown ∼40% reductions in risk of myocardial infarction and all-cause mortality. Analyses of data from randomized control trials other than the WHI show a ∼30% cardioprotective effect in recently menopausal women. Review of the literature as well as WHI data suggests that younger and/or more recently menopausal women may have a better risk-benefit ratio than older or remotely menopausal women and that CVD protection may only occur after >5 years; WHI women averaged 63 years of age (12 years postmenopausal) and few were studied for >6 years. Thus, a beneficial effect of long-term MHT on CVD and mortality is still an open question and is likely to remain controversial for the foreseeable future.

Lipoprotein(a) levels, apo(a) isoform size, and coronary heart disease risk in the Framingham Offspring Study

The aim of this study was to assess the independent contributions of plasma levels of lipoprotein(a) (Lp(a)), Lp(a) cholesterol, and of apo(a) isoform size to prospective coronary heart disease (CHD) risk. Plasma Lp(a) and Lp(a) cholesterol levels, and apo(a) isoform size were measured at examination cycle 5 in subjects participating in the Framingham Offspring Study who were free of CHD. After a mean follow-up of 12.3 years, 98 men and 47 women developed new CHD events. In multivariate analysis, the hazard ratio of CHD was approximately two-fold greater in men in the upper tertile of plasma Lp(a) levels, relative to those in the bottom tertile (P < 0.002). The apo(a) isoform size contributed only modestly to the association between Lp(a) and CHD and was not an independent predictor of CHD. In multivariate analysis, Lp(a) cholesterol was not significantly associated with CHD risk in men. In women, no association between Lp(a) and CHD risk was observed. Elevated plasma Lp(a) levels are a significant and independent predictor of CHD risk in men. The assessment of apo(a) isoform size in this cohort does not add significant information about CHD risk. In addition, the cholesterol content in Lp(a) is not a significant predictor of CHD risk.

LDL-associated apolipoprotein J and lysozyme are associated with atherogenic properties of LDL found in type 2 diabetes and the metabolic syndrome

OBJECTIVES

Exchangeable low-density lipoprotein (LDL)-associated proteins can affect the atherogenic properties of LDL. Our aim was to analyse the protein composition of LDL from individuals with or without type 2 diabetes and the metabolic syndrome (T2DM) in relation to other LDL particle characteristics, to assess whether certain proteins associate more with certain subclasses of LDL typical for T2DM, such as small, apoCIII-rich LDL.

DESIGN

Low-density lipoprotein from two cohorts of 61-year-old men (n = 19 and 64) with or without T2DM was isolated using size-exclusion chromatography or deuterium oxide-based ultracentrifugation. LDL-associated proteins were identified using mass spectrometry and quantified using two-dimensional gel electrophoresis or enzyme-linked immunosorbent assay. Differently expressed LDL-associated proteins apolipoprotein (apo)J and lysozyme were also measured in serum from a third cohort of women (n = 71) with or without T2DM. Lysozyme binding to advanced glycation end product (AGE)-LDL was examined in vitro.

RESULTS

ApoJ and lysozyme were increased in LDL particles with increased apoCIII content and decreased cholesterol content. When isolated with size-exclusion chromatography, LDL from individuals with T2DM contained more apoJ and lysozyme and less apoA1 than LDL from control individuals. LDL content of apoJ correlated with a smaller LDL particle size. Serum levels of lysozyme, but not apoJ, were increased in individuals with T2DM. In vitro, lysozyme associated more with AGE-LDL than with unmodified LDL.

CONCLUSIONS

Our results indicate that apoJ and lysozyme are increased in LDL with characteristics of small dense LDL in T2DM. Small dense LDL is easily glycated, and the increased affinity of lysozyme for AGE-LDL provides a possible partial explanation for an increase lysozyme in LDL from those with type 2 diabetes.

Usefulness of serum high-density lipoprotein cholesterol level as an independent predictor of one-year mortality after percutaneous coronary interventions

Low levels of high-density lipoprotein (HDL) cholesterol are a marker of coronary artery disease progression and are associated with cardiovascular events. However, whether low HDL cholesterol is a useful prognostic indicator after percutaneous coronary intervention (PCI) is not known. In a sample of 4,088 patients who underwent PCI we evaluated 1-year mortality and repeat revascularization as a function of baseline HDL levels classified into approximate quartiles of very low (<35 mg/dl), low (35 to 40 mg/dl), medium (41 to 47 mg/dl) and high (48 to 120 mg/dl) HDL cholesterol. Decreasing levels of HDL cholesterol were associated with younger age, male gender, smoking, diabetes mellitus, and a history of bypass surgery (p <0.0001 for all). One-year mortality and coronary revascularization were significantly higher in the very low HDL cholesterol group compared with the other groups (very low HDL cholesterol 6.5% and 25.4%, respectively; low HDL cholesterol 3.1% and 20.8%; medium HDL cholesterol 4.3% and 22.7%; high HDL cholesterol 3.1% and 20.6%, p = 0.0001 and p = 0.007). One-year mortality was significantly higher in men with an HDL cholesterol level <33 mg/dL and in women with an HDL cholesterol level <38 mg/dL. In multivariable analysis, very low HDL was associated with nearly twofold the risk of death after adjusting for other independent predictors of outcome. In conclusion, in patients with coronary artery disease undergoing PCI, a baseline HDL cholesterol level <35 mg/dl is an important prognostic indicator. Baseline HDL cholesterol levels <33 mg/dl for men and <38 mg/dl were associated with higher one-year mortality after PCI.

Elevated Lp(a) with a small apo(a) isoform in children: risk factor for the development of premature coronary artery disease

BACKGROUND

levels of Lp(a) and low-molecular-weight apolipoprotein(a) isoform are strongly associated with the development of early cardiovascular disease. Certain types of apo(a) isoforms in combination with elevated levels of Lp(a) may be important in the determining of premature coronary artery disease. Therefore, we investigated the association of familial history of premature coronary artery disease and apo(a) size and Lp(a) levels in children and adolescents with hypercholesterolemia using a novel method determining apo(a) isoforms.

METHODS AND RESULTS

Isoforms were classified in six phenotype patterns: S1-S4, B, F and according to their K-IV repeats. Apo(a) isoforms were divided into two groups: low-molecular- and high-molecular apo(a) isoforms. In subjects with double-banded apo(a) isoforms containing a small- and a large-isoform Lp(a) each contribution was based on the intensity of staining of the two bands. The percentage of patients with elevated levels of Lp(a) and a small apo(a) isoform (i.e. elevated small-isoform Lp(a)) was 46% in the risk group and 20% in the control group, p < 0.05. The percentage number of children and adolescents with elevated Lp(a) levels was higher in the risk group, reaching statistical significance (p < 0.05).

CONCLUSION

Elevated levels of small-isoform Lp(a) might be a strong and independent risk factor for the development of premature coronary artery disease in children and adolescents with hypercholesterolemia.

Lipoprotein(a): an independent risk factor for ischemic heart disease that is dependent on triglycerides in subjects with type 2 diabetes mellitus

Lipoprotein(a) is an independent risk factor for Ischaemic Heart Disease (IHD) in the general population. There are conflicting reports in the extent of its association with IHD among subjects with Type 2 diabetes mellitus (T2DM).

The aim was to determine the concentration of Lp(a) and its relationship with other lipids parameters among Omani T2DM subjects with and without IHD. An over-night fasting blood sample from 221 T2DM subjects (86 females and 135 males) and 156 non-diabetics (69 females and 87 males) aged 30–70 years (as control) was taken for lipid profile studies.

Lp(a) was significantly lower (p = 0.012) among T2DM subjects 0.123(1.12) g/L compared to non-diabetics 0.246 (1.18)g/L, irrespective of gender.

A significant correlation (Spearman correlation, P = 0.047) was revealed between Lp(a) and IHD among Omani T2DM subjects. The proportions of T2DM subjects with IHD and an Lp(a) >0.3 g/L was higher compared to T2DM without IHD irrespective of gender, for women 42% vs. 27% and for men 17.5 vs. 8%, respectively.

A significant negative correlation existed between Lp(a) and triglycerides (r = 0.41, P = 0.002) among T2DM subjects. In contrast, a significant positive correlation existed between Lp(a) and LDL-chol among the non-diabetic subjects.

Women had significantly higher Lp(a) concentration compared to men ( 0.30 Vs. 0.16 g/L, P < 0.0001) irrespective of the diabetic status.

Lp(a) is an independent risk factor for IHD among Omani T2DM subjects. Lp(a) concentration was significantly lower and negatively correlated with triglycerides among Omani diabetic compared to non-diabetic subjects.

Role of inflammation in nonrheumatic, regurgitant heart valve disease. A comparative, descriptive study regarding apolipoproteins and inflammatory cells in nonrheumatic heart valve disease

BACKGROUND

Nonrheumatic aortic stenosis is the predominant cause of heart valve surgery in the Western world. Aortic and mitral regurgitation account for a lesser amount of the heart valve surgery. During the 1990s, inflammatory cell infiltrates have been demonstrated in nonrheumatic stenotic aortic valves. These findings suggest an inflammatory component in the pathogenesis of nonrheumatic aortic valve stenosis. However, nonrheumatic regurgitant aortic and mitral valves have not been investigated in this respect. The aim of this study was to compare nonrheumatic regurgitant aortic and mitral valves with stenotic aortic valves regarding the presence of T lymphocytes, macrophages, apolipoprotein B, and apolipoprotein A-I.

METHODS

Valve specimens were obtained from 42 patients referred to hospital for surgery because of significant heart valve disease. From these patients, 29 aortic stenotic valves, 9 aortic regurgitant, and 6 mitral regurgitant valves, all nonrheumatic, were obtained for the study. Fourteen valves collected from subjects undergoing clinical/medicolegal autopsy were used as control. In order to identify mononuclear inflammatory cells and apolipoproteins, sections were investigated with immunohistochemical analyses and then categorized semiquantitatively.

RESULTS

Regurgitant and control valves showed a significantly lower degree of inflammatory cell infiltrate and a lower degree of apolipoprotein deposition as compared to stenotic aortic valves.

CONCLUSIONS

The signs of inflammation seen in nonrheumatic aortic stenosis are not prominent features in the nonrheumatic, regurgitant valves. This is consistent with the multi-factorial pathogenesis of these conditions.

Differential impact of plasma triglycerides on HDL-cholesterol and HDL-apo A-I in a large cohort

OBJECTIVES

To examine the relationship between plasma triglycerides (TG) to HDL-cholesterol (HDL-C) or HDL apo A-I.

DESIGN AND METHODS

Bivariate and multiple linear regression analyses in a large cohort of 1886 subjects.

RESULTS

Higher plasma TG levels were associated with lower concentrations of both HDL-C and HDL-apo A-I. However, the HDL-C/HDL-apo A-I ratio was inversely correlated with plasma TG indicating that the overall composition of the HDL changed as plasma TG changed. Plasma TG levels contributed to 15.9% of the variance of the HDL-C/HDL-apo A-I ratio, whereas gender, HDL-TG, LDL-TG, body mass index and plasma apo B levels represented between 0.15% and 2.21% of this variance.

CONCLUSIONS

These results indicate that increasing levels of plasma TG result in greater reduction in HDL-C levels than in HDL-apo A-I and this might explain, at least in part, the differences that have been observed in the magnitude of the association of HDL-C versus HDL-apo A-I with the risk of cardiovascular disease.

Lipoprotein(a), type 2 diabetes and vascular risk in coronary patients

BACKGROUND

Lipoprotein(a) [Lp(a)] is an important cardiovascular risk factor in the general population. However, prospective data on the vascular risk conferred by Lp(a) in patients with diabetes mellitus are scarce and controversial. It is not known whether the diabetic state affects the association of Lp(a) with vascular events among coronary patients.

DESIGN

We measured Lp(a) in 587 consecutive patients undergoing coronary angiography for the evaluation of coronary artery disease. The incidence of vascular events was recorded over 4 years.

RESULTS

At baseline, Lp(a) was significantly lower in patients with type 2 diabetes (T2DM) (n = 136) than in nondiabetic individuals (11 (0.8-30) mg dL(-1) vs. 16 (0.8-51) mg dL(-1); P = 0.025). Prospectively, Lp(a) was a strong and independent predictor of vascular events in nondiabetic patients (standardized adjusted hazard ratio (HR) = 1.461 (1.121-1.904); P = 0.005), but not in patients with T2DM [HR = 0.812 (0.539-1.223); P = 0.320]. An interaction term diabetes x Lp(a) was significant (P = 0.008), indicating that Lp(a) was a significantly stronger predictor of vascular events in nondiabetic patients than in patients with T2DM.

CONCLUSIONS

Lp(a) in diabetic coronary patients is low and not associated with the incidence of vascular events. Although measurement of Lp(a) provides useful information in nondiabetic coronary patients, it is of little value in coronary patients with T2DM.

Prognostic value of lipoproteins and their relation to inflammatory markers among patients with coronary artery disease

BACKGROUND

Lipoproteins and their subfractions are associated with the incidence of atherosclerotic diseases. In patients with coronary artery disease (CAD), low serum concentrations of high density lipoprotein (HDL) and high low-density lipoproteins (LDL) are correlated to myocardial infarction and cardiovascular death. There is growing evidence indicating that those lipoprotein factors are related to the inflammatory process in atherogenesis.

METHODS

We investigated in a median follow up of 3.9 years the association of HDL, apolipoprotein A-I (apoA-I), LDL, apolipoprotein B (apoB), and triglycerides with the incidence of a combined endpoint (myocardial infarction and cardiovascular death) and their relation to markers of inflammation in 1298 patients with angiographically documented CAD.

RESULTS

In univariate analysis, serum concentrations of apoA-I were significantly and inversely related to the combined endpoint, whereas serum concentrations of LDL, apoB, and triglycerides were not. HDL was not significantly related to the endpoint in univariate analyses (p=0.057). Multivariate analyses showed that only apoA-I is an independent predictor. ApoA-I (and HDL) was significantly related to markers of inflammation.

CONCLUSION

Serum apoA-I levels were an independent predictor for fatal and non-fatal cardiovascular events in patients with CAD. This may be related to its anti-inflammatory effect.

Apoprotein(a) phenotypes and plasma lipoprotein(a) concentration in patients with diabetes mellitus

OBJECTIVES

To determine whether apo(a) isoforms and plasma Lp(a) concentrations in association with some lipid parameters increase the relative risk for the development of atherosclerosis in patients with diabetes mellitus (IDDM and NIDDM).

DESIGN AND METHODS

Apo (a) isoforms, Lp(a) and plasma lipids were determined in 40 IDDM and 65 NIDDM patients and in 182 healthy individuals. Apo(a) isoforms were separated by 3 to 15% gradient SDS-PAGE followed by immunoblotting.

RESULTS

Logistical analysis showed that: Lp(a) levels >30 mg/dL (RR = 0.25, p < 0.000001; RR = 0.18, p < 0.00002), HTA (RR = 0.212, p < 0.00001; RR = 0.30, p < 0.00001), LMW-S1 apo(a) isoform (RR = 6.86, p < 0.0131; RR = 7.04, p < 0.0057) play a significant role in aterogenecity in both groups of patients with DM (IDDM and NIDDM). The 6.50-fold increase in risk was found in NIDDM patients with high Lp(a) levels (>30 mg/dL) and plasma total/HDL cholesterol ratio (4.5-5.8).

CONCLUSION

Elevated Lp(a) levels, LMW S1 apo(a) isoform, HTA and combination of increased Lp(a) levels and total/HDL cholesterol ratio increase the risk for the development of atherosclerosis in patients with DM (IDDM and NIDDM).

Apolipoprotein(a) size and lipoprotein(a) concentration and future risk of angina pectoris with evidence of severe coronary atherosclerosis in men: The Physicians' Health Study

BACKGROUND

The relationship of lipoprotein (a) [Lp(a)] concentrations with risk of coronary heart disease needs clarification, especially for threshold values for increased risk and for possible interactions with LDL-cholesterol concentrations and apolipoprotein (a) [apo(a)] size polymorphism. This study was designed to examine the ability of baseline Lp(a) concentration and apo(a) size to predict future severe angina pectoris in apparently healthy men.

METHODS

Baseline Lp(a) concentration and apo(a) size were determined in 195 men who subsequently developed angina and in 195 men who remained free of cardiovascular disease for 5 years.

RESULTS

Cases had higher median Lp(a) concentrations than did controls (30.6 vs 22.5 nmol/L; P = 0.02). Lp(a) concentration was predictive of angina [relative risk (RR) from lowest to highest quintiles: 1.0, 1.5, 1.0, 1.8, and 2.6; P for trend = 0.015]. The increased risk was approximately 4-fold (95% confidence interval, 1.4- to 11-fold) among men who had Lp(a) above the 95th percentile (>158 nmol/L). Men with Lp(a) concentrations in the highest quintile and LDL-cholesterol concentrations >1600 mg/L had a 12-fold increased risk (95% confidence interval, 1.5- to 43-fold). Small apo(a) size isoforms also significantly predicted risk of angina (RR for lowest quintile = 4.1; P for trend = 0.004). When the independent effect of Lp(a) concentration and apo(a) size was assessed by including them in the same multivariate model, only the association between apo(a) size and risk remained significant.

CONCLUSIONS

High Lp(a) predicts risk of angina, and the risk is substantially increased with high concomitant LDL-cholesterol. Small apo(a) size predicts angina with greater strength and independence than Lp(a) concentration.

Apolipoprotein B and apolipoprotein A-I: risk indicators of coronary heart disease and targets for lipid-modifying therapy

Although LDL cholesterol (LDL-C) is associated with an increased risk of coronary heart disease, other lipoproteins and their constituents, apolipoproteins, may play an important role in atherosclerosis. Elevated levels of apolipoprotein (apo) B, a constituent of atherogenic lipoproteins, and reduced levels of apo A-I, a component of anti-atherogenic HDL, are associated with increased cardiac events. Apo B, apo A-I and the apo B/apo A-I ratio have been reported as better predictors of cardiovascular events than LDL-C and they even retain their predictive power in patients receiving lipid-modifying therapy. Measurement of these apolipoproteins could improve cardiovascular risk prediction.

Relationship between apolipoprotein(a) size polymorphism and coronary heart disease in overweight subjects

BACKGROUND

Overweight is associated with an increased cardiovascular risk which is only partially explained by conventional risk factors. The objective of this study was to evaluate lipoprotein(a) [Lp(a)] plasma levels and apolipoprotein(a) [apo(a)] phenotypes in relation to coronary heart disease (CHD) in overweight subjects.

METHODS

A total of 275 overweight (BMI > or = 27 kg/m2) subjects, of which 155 had experienced a CHD event, 337 normal weight subjects with prior CHD and 103 CHD-free normal weight subjects were enrolled in the study. Lp(a) levels were determined by an ELISA technique and apo(a) isoforms were detected by a high-resolution immunoblotting method.

RESULTS

Lp(a) levels were similar in the three study groups. Overweight subjects with CHD had Lp(a) concentrations significantly higher than those without [median (interquartile range): 20 (5-50.3) versus 12.6 (2.6-38.6) mg/dl, P < 0.05]. Furthermore, overweight subjects with CHD showed a higher prevalence of low molecular weight apo(a) isoforms than those without (55.5% versus 40.8%, P < 0.05) and with respect to the control group (55.5% versus 39.8%, P < 0.05). Stepwise regression analysis showed that apo(a) phenotypes, but not Lp(a) levels, entered the model as significant independent predictors of CHD in overweight subjects.

CONCLUSIONS

Our data indicate that small-sized apo(a) isoforms are associated with CHD in overweight subjects. The characterization of apo(a) phenotypes might serve as a reliable biomarker to better assess the overall CHD risk of each subject with elevated BMI, leading to more intensive treatment of modifiable cardiovascular risk factors.

Evaluation of a fully-automated particle-enhanced turbidimetric immunoassay for the measurement of plasma lipoprotein(a). population-based reference values in an area with low incidence of cardiovascular disease

OBJECTIVES

Lipoprotein(a) has been proposed as an independent risk factor for cardiovascular disease. This lipoprotein possesses a marked size polymorphism that makes difficult to measure accurately its concentration in plasma. The International Federation of Clinical Chemistry recently recommended to carefully evaluate new commercial methods for lipoprotein(a) measurement to discard the possible influence of lipoprotein(a) isoforms on immunoreactivity. They also recommended to perform population-based studies for different ethnic and geographic groups. Therefore, in the evaluation of a fully automated, particle-enhanced turbidimetric immunoassay for the measurement of lipoprotein(a) we have determined its reference interval in the Spanish population, an area with the lowest incidence of cardiovascular disease in Europe.

DESIGN AND METHOD

We evaluated a commercial kit of reagents calibrated against the Proposed Reference Material and determined the effect of lipoprotein(a) size polymorphism on the measurements. A population-based study was carried out in two different villages on the Mediterranean coast of Spain.

RESULTS

Imprecision at different lipoprotein(a) concentrations ranged between 3.0 and 15.4%. Recovery was 98.5 +/- 2.1. Detection limit was 4.8 nmol/L. There were no significant interferences from lipemia, jaundice, hemolysis, paraproteinemia, apolipoprotein B or plasminogen. We did not observe any effect of the lipoprotein(a) size polymorphism on the measurements. Mean (and SD) values for plasma lipoprotein(a) (n = 369) were 53.6 (65.3) nmol/L, the median was = 25.3 nmol/L and range varied between <4.8 and 356.0 nmol/L.

CONCLUSION

The present article presents an accurate and practical assay for measuring plasma lipoprotein(a) concentrations and describes its reference values in a population of Spanish Caucasians. Our results are similar to those obtained in other Caucasian populations (between 10 and 25% higher than in participants of the CARDIA study).