Correlation of serum lipoprotein(a) with the angiographic and clinical presentation of coronary artery disease

Impact of ezetimibe on plasma lipoprotein(a) concentrations as monotherapy or in combination with statins: a systematic review and meta-analysis of randomized controlled trials

The aim of this meta-analysis of randomized placebo-controlled clinical trials was to assess the effect of ezetimibe on plasma lipoprotein(a) concentrations. Only randomized placebo-controlled trials investigating the impact of ezetimibe treatment on cholesterol lowering that include lipoprotein(a) measurement were searched in PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases (from inception to February 26th, 2018). A random-effects model and generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. A weighted random-effects meta-regression was performed to evaluate the impact of potential confounders on lipoprotein concentrations. This meta-analysis of data from 10 randomized placebo-controlled clinical trials (15 treatment arms) involving a total of 5188 (3020 ezetimibe and 2168 control) subjects showed that ezetimibe therapy had no effect on altering plasma Lp(a) concentrations (WMD: -2.59%, 95% CI: -8.26, 3.08, p = 0.370; I2 = 88.71%, p(Q) < 0.001). In the subgroup analysis, no significant alteration in plasma Lp(a) levels was observed either in trials assessing the impact of monotherapy with ezetimibe versus placebo (WMD: -4.64%, 95% CI: -11.53, 2.25, p = 0.187; I2 = 65.38%, p(Q) = 0.005) or in trials evaluating the impact of adding ezetimibe to a statin versus statin therapy alone (WMD: -1.04%, 95% CI: -6.34, 4.26, p = 0.700; I2 = 58.51%, p(Q) = 0.025). The results of this meta-analysis suggest that ezetimibe treatment either alone or in combination with a statin does not affect plasma lipoprotein(a) levels.

Impact of Lipoprotein(a) on Long-term Outcomes in Patients With Diabetes Mellitus Who Underwent Percutaneous Coronary Intervention

Patients with diabetes mellitus (DM) are at twofold to fourfold higher cardiovascular risk than those without DM. Serum levels of lipoprotein(a) (Lp(a)) can be risk factors for adverse events. However, the clinical implications of Lp(a) in patients with DM who underwent percutaneous coronary intervention (PCI) is unknown. The aim of the study was to determine the role of Lp(a) in patients with DM who underwent PCI. A total of 3,508 patients were treated by PCI from 1997 to 2011 at our institution. Among them, we analyzed consecutive 1,546 patients with DM. Eligible 1,136 patients were divided into 2 groups (high Lp(a) [n = 575] and low Lp(a) [n = 561]) by the median of Lp(a) levels. The number of chronic kidney disease, multivessel disease, and the level of LDL-C were higher in the group with high Lp(a) than with low Lp(a). The median follow-up period was 4.7 years. Event rate of all-cause death was same between the 2 groups (p = 0.37). However, cumulative incidence of cardiac death and acute coronary syndrome was significantly higher in the high Lp(a) than in the low Lp(a) group (p = 0.03). Multivariable analysis selected a high Lp(a) level as an independent predictor of cardiac death and acute coronary syndrome (hazard ratio 1.20; 95% confidence interval 1.00 to 1.42; p = 0.04). In conclusion, a high Lp(a) value could be associated with advanced cardiac events after PCI for patients with DM.

Impact of lipoprotein(a) as residual risk on long-term outcomes in patients after percutaneous coronary intervention

Cardiovascular risk remains uncertain in patients with cardiovascular disease despite achieving target lipid levels. Serum levels of lipoprotein(a) [Lp(a)] can be risk factors for adverse events. The aim of this study was to determine the role of Lp(a) as a residual risk factor in patients who achieve target lipid levels by the time of treatment by percutaneous coronary intervention (PCI). A total of 3,508 patients were treated by PCI from 1997 to 2011 at our institution. Among them, we analyzed consecutive 569 patients who achieved target lipid levels of low-density lipoprotein cholesterol <100 mg/dl, high-density lipoprotein cholesterol ≥40 mg/dl, and triglycerides <150 mg/dl at PCI. A total of 411 eligible patients were assigned to groups according to Lp(a) levels of ≥30 mg/dl (high Lp(a); n = 119) or <30 mg/dl (low Lp(a); n = 292). The primary outcome was a composite of all-cause death and acute coronary syndrome. The median follow-up period was 4.7 years. Cumulative event-free survival was significantly worse for the group with high Lp(a) than with low Lp(a) group (p = 0.04). Multivariate analysis selected a high Lp(a) level as an independent predictor of primary outcomes (hazard ratio 1.68, 95% confidence interval 1.03 to 2.70, p = 0.04). In conclusion, a high Lp(a) value (≥30 mg/dl) could be associated with a poor prognosis after PCI even for patients who achieved target lipid levels.

Coherent somatic mutation in autoimmune disease

BACKGROUND

Many aspects of autoimmune disease are not well understood, including the specificities of autoimmune targets, and patterns of co-morbidity and cross-heritability across diseases. Prior work has provided evidence that somatic mutation caused by gene conversion and deletion at segmentally duplicated loci is relevant to several diseases. Simple tandem repeat (STR) sequence is highly mutable, both somatically and in the germ-line, and somatic STR mutations are observed under inflammation.

RESULTS

Protein-coding genes spanning STRs having markers of mutability, including germ-line variability, high total length, repeat count and/or repeat similarity, are evaluated in the context of autoimmunity. For the initiation of autoimmune disease, antigens whose autoantibodies are the first observed in a disease, termed primary autoantigens, are informative. Three primary autoantigens, thyroid peroxidase (TPO), phogrin (PTPRN2) and filaggrin (FLG), include STRs that are among the eleven longest STRs spanned by protein-coding genes. This association of primary autoantigens with long STR sequence is highly significant (p<3.0x10(-7)). Long STRs occur within twenty genes that are associated with sixteen common autoimmune diseases and atherosclerosis. The repeat within the TTC34 gene is an outlier in terms of length and a link with systemic lupus erythematosus is proposed.

CONCLUSIONS

The results support the hypothesis that many autoimmune diseases are triggered by immune responses to proteins whose DNA sequence mutates somatically in a coherent, consistent fashion. Other autoimmune diseases may be caused by coherent somatic mutations in immune cells. The coherent somatic mutation hypothesis has the potential to be a comprehensive explanation for the initiation of many autoimmune diseases.

Differential expression of oxidation-specific epitopes and apolipoprotein(a) in progressing and ruptured human coronary and carotid atherosclerotic lesions

The relationships between oxidation-specific epitopes (OSE) and lipoprotein (a) [Lp(a)] and progressive atherosclerosis and plaque rupture have not been determined. Coronary artery sections from sudden death victims and carotid endarterectomy specimens were immunostained for apoB-100, oxidized phospholipids (OxPL), apo(a), malondialdehyde-lysine (MDA), and MDA-related epitopes detected by antibody IK17 and macrophage markers. The presence of OxPL captured in carotid and saphenous vein graft distal protection devices was determined with LC-MS/MS. In coronary arteries, OSE and apo(a) were absent in normal coronary arteries and minimally present in early lesions. As lesions progressed, apoB and MDA epitopes did not increase, whereas macrophage, apo(a), OxPL, and IK17 epitopes increased proportionally, but they differed according to plaque type and plaque components. Apo(a) epitopes were present throughout early and late lesions, especially in macrophages and the necrotic core. IK17 and OxPL epitopes were strongest in late lesions in macrophage-rich areas, lipid pools, and the necrotic core, and they were most specifically associated with unstable and ruptured plaques. Specific OxPL were present in distal protection devices. Human atherosclerotic lesions manifest a differential expression of OSEs and apo(a) as they progress, rupture, and become clinically symptomatic. These findings provide a rationale for targeting OSE for biotheranostic applications in humans.

Oxidized phospholipids on apoB-100-containing lipoproteins: a biomarker predicting cardiovascular disease and cardiovascular events

Oxidative stress is a well-known etiologic factor in the development of cardiovascular disease. Oxidation of lipoproteins, and in particular of low density lipoprotein, is a necessary if not obligatory mechanism for the generation of macrophage-derived foam cells, the first major initiating factor in the development of an atherosclerotic plaque. Oxidation of lipoproteins does not result in the generation of a single, defined molecular species, but of a variety of oxidation-specific epitopes, such as oxidized phospholipids and malondialdehyde-lysine epitopes. Unique monoclonal antibodies have been developed to bind these well-defined epitopes, and have been used in in vitro assays to detect them on circulating lipoproteins present in plasma. This article will summarize the accumulating clinical data of one oxidation-specific biomarker, oxidized phospholipids (OxPL) on apoB-100 lipoproteins. Elevated levels of OxPL/apoB predict the presence and progression of coronary, femoral and carotid artery disease, are increased following acute coronary syndromes and percutaneous coronary intervention, and predict the development of death, myocardial infarction, stroke and need for revascularization in unselected populations. OxPL/apoB levels are independent of traditional risk factors and the metabolic syndrome, and enhance the risk prediction of the Framingham Risk Score. The OxPLs measured in this assay reflect the biological activity of the most atherogenic lipoprotein(a) (Lp(a)) particles, reflected in patients with high plasma Lp(a) levels with small apo(a) isoforms. The predictive value of OxPL/apoB is amplified by Lp(a) and phospholipases such as lipoprotein-associated phospholipase A(2) and secretory phospholipase A(2), which are targets of therapy in clinical trials. This assay has now been validated in over 10,000 patients and efforts are underway to make it available to the research and clinical communities.

Lp(a)-cholesterol is associated with HDL-cholesterol in overweight and obese African American children and is not an independent risk factor for CVD

BACKGROUND

The role of lipoprotein (a) cholesterol {Lp(a)-C}as an additional and/or independent risk factor for cardiovascular disease (CVD) is not clear. We evaluated the associations between Lp(a)-C and other CVD risk factors including plasma lipoprotein concentrations and body fatness in overweight and obese African American children.

METHODS

A cross-sectional analysis was carried out using data from a sample of 121 African American children aged 9-11 years with body mass index (BMI)'s greater than the 85th percentile. Body height, weight and waist circumference (WC) were measured. Fasting plasma concentrations of Lp(a)-C, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), very low density lipoprotein cholesterol (VLDL-C), intermediate density lipoprotein cholesterol (IDL-C), low density lipoprotein cholesterol (LDL-C), and triacylglycerides (TAG) were analyzed using the vertical auto profile (VAP) cholesterol method.

RESULTS

After adjusting for child age, gender, and pubertal status, Lp(a)-C was positively associated with both HDL-C and TC, and negatively associated with VLDL-C and TAG. Including BMIz and WC as additional covariates did not alter the direction of the relationships between Lp(a)-C and the other lipoproteins. Finally, after adjusting for the other plasma lipoproteins, Lp(a)-C remained strongly associated with HDL-C, whereas the associations of Lp(a)-C with the other lipoproteins were not significant when HDL-C was simultaneously included in the regression models.

CONCLUSIONS

Lp(a)-C was positively associated with HDL-C and this association is not influenced by other lipoprotein subclasses or by the degree of obesity. We conclude that Lp(a) cholesterol is not an independent risk factor for CVD in African American children.

Combined effects of small apolipoprotein (a) isoforms and small, dense LDL on coronary artery disease risk

BACKGROUND AND AIMS

Lipoprotein (a) [Lp(a)] consists of low-density lipoprotein (LDL) and apolipoprotein (a) [apo(a)]. Both Lp(a) constituents are well-recognized risk factors for coronary artery disease (CAD). This study investigates the interrelationship of apo(a) and LDL size, as well as their possible synergistic effect on the increase of CAD risk.

METHODS

One hundred nine CAD patients and 102 apparently healthy subjects were included in the study. Lp(a) concentration was measured using immunoturbidimetry. The sizes of apo(a) isoforms were determined by SDS-agarose gel electrophoresis followed by immunoblotting. LDL particle size was determined by gradient gel electrophoresis.

RESULTS

We found an inverse correlation between apo(a) size and Lp(a) concentration (r(2) = 31%, p <0.001 in the control group and r(2) = 35%, p <0.001 in the CAD group). Individuals with smaller apo(a) isoforms and small, dense LDL (sdLDL) >50% had the highest risk of CAD development (OR = 4.23, p = 0.017). The synergy index (SIM) for the combination of smaller apo(a) isoforms and sdLDL >50% was 1.2. Adjustment for Lp(a) and triacylglycerol concentrations eliminated smaller apo(a)/sdLDL >50% related risk (p = 0.233 and p = 0.09, respectively).

CONCLUSIONS

Smaller apo(a) isoforms appear to be superior to sdLDL for the assessment of CAD risk. Their combined effect is synergistic.

Lipoprotein(a) is related to the extent of lesions in the coronary vasculature and to unstable coronary syndromes

BACKGROUND

Lp(a) is a highly atherogenic particle with a prothrombotic effect. Until now its relation to the extent and severity of the atheromatic lesions had not been established by standard procedures.

HYPOTHESIS

This study examined the correlation of Lp(a) to the extent and severity of coronary artery disease (CAD) and its relation to unstable clinical events (not including sudden death).

METHODS

In 202 patients undergoing coronary angiography, plasma lipids were measured with the usual procedures and Lp(a) with the enzyme-linked immunosorbent assay. The extent of CAD was expressed in the number of diseased vessels and its severity in terms of the severity coefficient and the obstruction coefficient.

RESULTS

A very strong relationship between LP(a) and the number of diseased vessels (p = 0.0007) signifying diffuse atherosclerosis, but no relation with the severity of the lesions. was found. However, it was the only lipid that correlated significantly with the number of totally occluded vessels (p = 0.0003). The thrombogenic ability of Lp(a) was manifested by increased incidence of myocardial infarction and unstable angina episodes in patients with elevated Lp(a) (p = 0.0157).

CONCLUSION

Elevated Lp(a) predisposes to the extent of CAD and total occlusions but not to the severity of lesions. Patients with increased Lp(a) levels and unstable angina are at increased danger of suffering myocardial infarction. Thus, Lp(a) may predispose to plaque destabilization and thrombosis of noncritical lesions.

Ginkgo biloba (EGb 761) in arteriosclerosis prophylaxis

The prevention or deceleration of atherogenesis is one of the most significant anti-aging objectives since this is a matter of avoidance of myocardial infarction and stroke. To approach this prophylactic aim, phytochemical nutrition counteracting peroxidation of blood lipids based on their scavenger qualities for reactive oxygen species (ROS) can possibly serve. For example, oxidized LDL particles are highly atherogenic. Against this background, we investigated in a pilot study the effect of Ginkgo biloba (EGb 761: Rökan novo), the free oxygen radical scavenging properties of which are well-documented, on the atherosclerotic nanoplaque formation in cardiovascular high-risk patients. In eight patients who had undergone an aortocoronary bypass operation, the reduction of atherosclerotic nanoplaque formation amounted to 11.9 +/- 2.5% (p < 0.0078) and of nanoplaque size to 24.4 +/- 8.1% (p < 0.0234), respectively, after a 2-month therapy with Ginkgo biloba extract (EGb 761, 2 x 120 mg daily, Rökan novo, Spitzner Arzneimittel, Ettlingen, Germany). Additionally, superoxide dismutase (SOD) activity was upregulated by 15.7 +/- 7.0% (p < 0.0391), the quotient oxLDL/LDL lowered by 17.0 +/- 5.5% (p < 0.0234) and lipoprotein(a) concentration decreased by 23.4 +/- 7.9% (p < 0.0234) in the patients' blood after the 2-month medication regimen. The concentration of the vasodilating substances cAMP and cGMP was augmented by 37.5 +/- 9.1% (p < 0.0078) and 27.7 +/- 8.3% (p < 0.0156), respectively. A multimodal regression analysis reveals a basis for a mechanistic explanation of nanoplaque reduction under ginkgo treatment. The atherosclerosis inhibiting effect is due to an upregulation in the body's own radical scavenging enzymes and an attenuation of the risk factors oxLDL/LDL and Lp(a). Furthermore, the significant increase in the vasodilator cAMP and cGMP concentration powerfully supports the maintenance of an open bypass.

Comparison of Lipoprotein(a) levels between elderly and middle-aged men with coronary artery disease

Lipoprotein(a) [Lp(a)] is known to be a risk factor for atherosclerotic disease in middle-aged men, but the role of Lp(a) in women and in the elderly is less clear. In most studies, excess Lp(a) is not associated with increased risk for persons >65 years of age. This study examined the strength of association of a number of risk factors to coronary artery disease (CAD) in groups of men <65 years (n = 108) and >65 of age (n = 66) with angiographically documented significant narrowing of coronary arteries. Serum Lp(a) concentrations were determined; elevated Lp(a) is positively associated with CAD for men <65 years (adjusted OR: 2.45, P <0.05) but not for men >65 of age (adjusted OR: 0.56, P = NS). For middle-aged men, elevated Lp(a) appears to be an independent risk factor for premature CAD, and the importance of Lp(a) as a risk factor appears to decrease with age. These data suggest that the utility of Lp(a) lipoprotein levels in predicting the risk of CAD in older men is limited. Factors, such as age; sex; levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides; carotid-wall thickness; smoking status; the presence or absence of diabetes and systolic and diastolic hypertension; body mass index (BMI); and other traditional risk factors, must be evaluated together to determine the risk of CAD for the entire population.

Towards biosensing of arteriosclerotic nanoplaque formation using femtosecond spectroscopy

The ultrafast dynamics of proteoheparan sulfate (HS-PG) in Krebs blood substitute solution was measured using femtosecond transient absorption spectroscopy after UV excitation. Interacting with blood lipoproteins and Ca(2+) ions, the proteoglycan HS-PG is the key component of the so-called nanoplaque, the earliest stage in atherogenesis. Since tryptophan (Trp) residues are the main optically active parts of HS-PG, analogous measurements were performed on bare Trp in Krebs solution. The comparison reveals distinct differences to main characteristics of the HS-PG broadband absorption spectra. Analyzing the Trp spectra, we show that the results from transient absorption spectroscopy resemble the time constants of the chromophore ultrafast solvation dynamics that have been found by another group using fluorescence up-conversion techniques. Yet, the broadband transient absorption provides more details about the molecular dynamics, including stimulated emission, excited state absorption and resonant energy transfer. Furthermore, the absorption long time dynamics upon adding Ca(2+) to the HS-PG probe were investigated by transient absorption spectroscopy and by surface force and ellipsometry investigations. Notably, a Ca(2+)-induced conformational change responsible for arteriosclerotic nanoplaque formation was detected. Slight differences, which are only visible as broad spectral features in the sub-picosecond time scale, provide a first insight into the molecular formation of nanoplaques in blood vessels, which may yield a better understanding of the genesis of arteriosclerosis.

Predictors of coronary artery disease in the Lebanese population

BACKGROUND

Coronary artery disease (CAD) is one of the major causes of morbidity and mortality in the world. The disease is determined by many risk factors such as age, gender, diabetes, dyslipidemia, smoking, as well as elevated serum levels of lipoprotein (a) (Lp(a)), homocysteine, C-reactive protein (CRP) and uric acid. In this study, we evaluated the association of biologic and metabolic parameters with CAD in a group of Lebanese patients.

METHODS

Three hundred patients were recruited for the study. Biologic and blood metabolic parameters were measured. Patients were then divided into 3 groups according to their catheterization result: 0% stenosis (controls), <50% stenosis and >or=50% stenosis.

RESULTS

Hyperlipidemias, CRP, homocysteine and uric acid levels in CAD patients were not different from those of the controls. However, age, elevated fasting blood glucose (FBG) and elevated serum Lp(a) levels were found to be strong independent predictors of CAD in our study population. Association with CAD was also shown for gender, hypertension, diabetes and family history of CAD.

CONCLUSION

We report the importance of serum Lp(a) levels and FBG in the prediction and prevention of CAD in our population.

Significance of apolipoprotein(a) phenotypes in acute coronary syndromes: relation with clinical presentation

BACKGROUND

High lipoprotein(a) [Lp(a)] levels and small-sized apolipoprotein(a) [apo(a)] phenotypes have been linked to acute coronary syndromes (ACS). We sought to determine whether Lp(a) concentrations and apo(a) phenotypes may be related to the clinical syndrome of presentation among ACS patients.

METHODS

Two hundred ten ACS patients and 105 controls were enrolled. One hundred thirteen patients presented with acute myocardial infarction (AMI) and 97 with unstable angina pectoris (UAP). Lp(a) concentrations were determined by ELISA and apo(a) isoforms were detected with a high-resolution immunoblotting method.

RESULTS

Lp(a) levels and the percentage of subjects with at least one small-sized apo(a) isoform were significantly higher both in AMI patients and in UAP subjects as compared with controls. Among ACS patients, the percentage of subjects with at least one small apo(a) phenotype was significantly higher in patients who presented with AMI than in those with UAP (p<0.001). Multivariate logistic regression analysis showed that the presence of at least one small-sized apo(a) isoform was associated with AMI as the patient's clinical syndrome of presentation (OR=2.51, 95% CI: 1.38-4.58, p<0.01).

CONCLUSIONS

Among ACS patients, apo(a) isoforms of low molecular weight were associated with AMI onset. High-resolution apo(a) phenotyping might be helpful to identify individuals at high risk for developing AMI.

Association of serum total homocysteine with the extent of ischemic heart disease in a Mediterranean cohort

High total homocysteine (tHcy) concentrations increase coronary disease risk. Therefore, the authors examined the relation between tHcy concentrations and the number of stenotic arteries in patients with ischemic heart disease (IHD). They enrolled 155 patients with IHD (135 men) who had undergone selective coronary angiography during the previous 2 years. These patients were divided into 4 groups according to the number of vessels (0, 1, 2, and 3) with > or = 70% stenosis. They also reviewed the major coronary risk factors for each patient (age, gender, hypertension, diabetes mellitus, dyslipidemia, cigarette smoking, obesity), and measured serum concentrations of tHcy, folate, vitamin B12 and lipids. There was a significant positive correlation (rs = 0.19; p = 0.017; n = 155) between tHcy serum concentration and the extent of coronary atherosclerosis, expressed by the number of coronary arteries with significant stenosis. Moreover, the number of affected vessels displayed a significant positive correlation with the presence of diabetes mellitus (rs = 0.30; p < 0.0001; n = 155) and serum concentrations of lipoprotein (a) (rs = 0.25; p < 0.05; n = 67) and a negative correlation with apolipoprotein A-I serum concentration (rs = -0.27; p < 0.01; n = 67). In this study, the serum concentrations of tHcy correlated with the extent of coronary atherosclerosis, independently of other classical risk factors, with the exception of diabetes mellitus.

Percutaneous coronary intervention results in acute increases in oxidized phospholipids and lipoprotein(a): short-term and long-term immunologic responses to oxidized low-density lipoprotein

BACKGROUND

This study was performed to assess whether oxidized low-density lipoprotein (OxLDL) levels are elevated after percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Patients (n=141) with stable angina pectoris undergoing PCI had serial venous blood samples drawn before PCI, after PCI, and at 6 and 24 hours, 3 days, 1 week, and 1, 3, and 6 months. Plasma levels of OxLDL-E06, a measure of oxidized phospholipid (OxPL) content on apolipoprotein B-100 detected by antibody E06, lipoprotein(a) [Lp(a)], autoantibodies to malondialdehyde (MDA)-LDL and copper-oxidized LDL (Cu-OxLDL), and apolipoprotein B-100-immune complexes (apoB-IC) were measured. OxLDL-E06 and Lp(a) levels significantly increased immediately after PCI by 36% (P<0.0001) and 64% (P<0.0001), respectively, and returned to baseline by 6 hours. In vitro immunoprecipitation of Lp(a) from selected plasma samples showed that almost all of the OxPL detected by E06 was bound to Lp(a) at all time points, except in the post-PCI sample, suggesting independent release and subsequent reassociation of OxPL with Lp(a) by 6 hours. Strong correlations were noted between OxLDL-E06 and Lp(a) (r=0.68, P<0.0001). MDA-LDL and Cu-OxLDL autoantibodies decreased, whereas apoB-IC levels increased after PCI, but both returned to baseline by 6 hours. Subsequently, IgM autoantibodies increased and peaked at 1 month and then returned to baseline, whereas IgG autoantibodies increased steadily over 6 months.

CONCLUSIONS

PCI results in acute plasma increases of Lp(a) and OxPL and results in short-term and long-term immunologic responses to OxLDL. OxPL that are released or generated during PCI are transferred to Lp(a), suggesting that Lp(a) may contribute acutely to a protective innate immune response. In settings of enhanced oxidative stress and chronically elevated Lp(a) levels, the atherogenicity of Lp(a) may stem from its capacity as a carrier of proinflammatory oxidation byproducts.

Response of lipoprotein(a) levels to therapeutic life-style change in obese African-Americans

Lipoprotein(a) (Lp(a)) is regarded as an independent risk factor for Atherosclerotic cardiovascular disease. The objectives of this study were: to determine the effects of diet and exercise on Lp(a) and to evaluate the relation of Lp(a) with the lipid profile (total serum cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol). Baseline Lp(a), body mass index (BMI) and the lipid profiles were measured in 343 Obese (BMI >30kg/m(2)) African-Americans. After a 3-month intervention of diet and exercise by 105 participants, their lipids were re-measured. Baseline Lp(a) levels ranged from 1.2 to 280mg/dl. Lp(a) was inversely associated with triglyceride (P<0.05). After the intervention, Lp(a) and HDL increased by a mean of 20 and 5%, respectively. Total cholesterol, triglycerides, LDL and BMI decreased by 7, 10, 11 and 8%, respectively. Women taking estrogen replacement had a negligible change in Lp(a) while participants taking HMG-CoA reductase inhibitors had an increase in Lp(a) levels by 30%.

The role of risk factors in the development of atherosclerosis

Our understanding of risk factors for atherogenesis has changed significantly over the last decade. In addition to better grasp of the mechanism of action of the "classic" (causal) risk factors, a number of potentially important new factors has emerged. In this review we briefly summarize the evidence of the relation between atherosclerosis and the currently recognized causal risk factors, namely, age, smoking, LDL cholesterol, HDL cholesterol, hypertension, and diabetes. More emphasis has been put on description of the emerging entities such as atherogenic profile of plasma lipoproteins with discussion of LDL and HDL subclasses, Lp(a), homocysteine, and, last but not least, on the role of infection and inflammation in atherogenesis. Whenever possible, we tried to summarize the relevant lines of evidence such as epidemiological, pathological, genetic, and clinical trial data linking the specific factor with atherosclerosis.

Hyperinsulinemia, lipoprotein (a), and Chlamydia pneumoniae antibodies--are they risk factors or serologic predictors for progression of coronary artery disease?

The authors studied 134 patients with unstable angina pectoris symptoms and 32 subjects without coronary artery disease (CAD) for the presence of classical risk factors such as hypercholesterolemia, smoking, and family history of CAD. In addition they analyzed plasma insulin levels, lipoprotein (a) (Lp [a]) levels, and antibody titers against Chlamydia pneumoniae. All patients had a heart catheterization. Patients with diabetes mellitus were excluded from the study. Fasting insulin, low-density lipoprotein (LDL) cholesterol and Chlamydia pneumoniae immunoglobulin G (IgG) and IgA antibody titers did not show any difference in CAD from healthy control subjects, whereas Lp(a) was increased and high-density lipoprotein (HDL) decreased in CAD patients. These data indicate that lipoprotein (a), low HDL cholesterol, and smoking, but neither hyperinsulinemia nor elevated Chlamydia pneumoniae titers, are risk factors or predictors for CAD.

[Lipoprotein (a) as a predictor of severity of coronary artery stenosis documented by angiography in male coronary patients under 50 years old]

OBJECTIVE

To determine the relationship between lipoprotein (a) seric levels with the age of coronary artery disease debut and the severity of coronary lesions in a group of male patients less than 50 years old.

PATIENTS AND METHODS

We studied a group of 230 male patients, younger than 50 who were consecutively admitted to the hospital because of an ischemic coronary event. During hospitalization, the lipoprotein (a) in plasma was measured in all patients. They were distributed in two groups according to age at time of coronary disease clinical presentation with a cut off age of 40. A group of 142 patients underwent a cardiac catheterism and coronariography due to clinical or electrical unstability.

RESULTS

The lipoprotein (a) levels were related with the number of diseased vessels. In this way lipoprotein (a) levels were 12 mg/dl (1.5-75) in those patients showing a normal coronariography; 27 mg/dl (2. 5-96) in those with one vessel disease; 34 mg/dl (7-90) in those with two vessels affected and 63 mg/dl (2-116) in the case of three-vessel disease, with statistical significance of p = 0.003. No significant differences in lipoprotein (a) levels were found when the age of coronary artery disease presentation was taken into account. In this way lipoprotein (a) levels were 31 mg/dl (2-97) in patients younger than 40 years of age, in comparison to 33 mg/dl (2-94) in those older than 40.

CONCLUSIONS

In our community male patients with a diagnosis of coronary artery disease and less than 50 years old showed a relationship between lipoprotein (a) levels and the severity and number of coronary vessel diseases. However, an association between lipoprotein (a) levels with the age of coronary disease presentation was not evident.

The role of lipoprotein[a] in atherosclerosis

Recent studies confirm and extend previous evidence that lipoprotein (Lp) plays a significant role in atherosclerosis and is one of the top five or six risk factors for cardiovascular disease. In Japanese patients, Lp levels and apo phenotypes are significant predictors for myocardial infarction. Lp levels are significantly higher in ischemic stroke patients than in controls. However, plasma concentrations of Lp are not predictive of ischemic cerebral infarction in either men or women. Serum Lp levels are significantly higher in patients with carotid plaques or measurable intima-media thickness than in controls without. Despite these associations, there is no significant relationship between Lp level and arterial endothelial function, smooth muscle response, or carotid wall thickness, even though other lipid risk factors like low-density lipoprotein cholesterol (LDL-C) and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio are correlated with abnormal arterial function and structure. There is new evidence that the association of Lp with extracellular matrix (ECM) secreted by arterial smooth muscle cells increases two- to threefold the subsequent specific binding of LDL. Alpha-defensins released from activated or senescent neutrophils stimulate the binding of Lp to ECM of endothelial cells. Several factors that affect the accumulation of Lp and oxidized LDL in the arterial intima have been identified. Several recent studies have provided new insights into the physiologic role that Lp might play in compromising fibrinolysis. The interaction of Lp with cells is clearly distinct from that with ECM and with fibrinogen; the regulation sites within Lp and plasminogen for these regulatory molecules are not identical. These recent advances bring us significantly closer to understanding how Lp exerts its atherogenic and thrombogenic properties.