Assessing low levels of high-density lipoprotein cholesterol as a risk factor in coronary heart disease

Biologic risk markers for coronary heart disease: nonlinear associations with income

BACKGROUND

It is unclear whether a linear relationship is an appropriate description of the association between income and biologic markers of coronary heart disease risk. Stronger associations at certain levels of income would have implications for underlying mechanisms.

METHODS

The study is based on a healthy sample of 25-64 year olds (n = 14,022) from a nationally representative cross-sectional study (the 1988-1994 United States Third National Health and Nutrition Examination Survey). We use regression splines to model the shape of the association between income and 8 biologic markers for coronary heart disease risk, controlling for age, race/ethnicity, marital status, and education.

RESULTS

Substantial income-biomarker associations were found for 5 outcomes among women (HDL cholesterol, triglycerides, C-reactive protein, systolic blood pressure, and venous blood lead) and for 3 outcomes among men (HDL cholesterol, triglycerides, and venous blood lead). The most common shapes of association were a stronger association at lower income levels and a greater risk level of biomarker near median income.

CONCLUSIONS

We find that the associations of income with biologic risk markers are often nonlinear. The differences in the shape of association suggest there are multiple pathways through which income is associated with coronary heart disease risk.

The genetics of high-density lipoprotein metabolism: clinical relevance for therapeutic approaches

The risk for coronary artery disease (CAD) is inversely correlated with high-density lipoprotein (HDL) cholesterol plasma levels. These plasma HDL cholesterol levels are influenced by the activity of a number of enzymes and receptors, and therefore, variations in the genes encoding for these proteins may consequently result in an altered CAD risk. Identification of such pivotal players in HDL cholesterol metabolism that are also strongly associated with CAD risk is crucial for the materialization of novel therapeutic modalities. A large amount of knowledge has been obtained by studies involving families with extreme HDL phenotypes specific to molecular defects. In fact, thus far, monogenetic defects have been described in the genes coding for apolipoprotein A-I, adenosine triphosphate-binding cassette transporter A1, cholesterol ester transfer protein, the lack of endothelial lipase (LIPG), phospholipid transfer protein, and lecithin-cholesterol acyltransferase. Despite the fact that the total number of carriers of such mutations is rather small, much can be gained by extensively studying the metabolic and vascular consequences of these mutations. Surrogate markers for atherosclerosis have proved to be useful to overcome this sample size limitation and have been widely exploited to study families with decreased or increased HDL cholesterol levels in order to correlate HDL cholesterol phenotypes to atherosclerotic burden in cases and controls. Apart from such extreme phenotype approaches, novel population-based genome-wide association studies have been used to decipher the link between genetic loci and HDL cholesterol levels, and the identification of novel HDL cholesterol-related genes is eagerly awaited. These might be instrumental in the ongoing fight against atherosclerosis.

Longevity: potential life span and health span enhancement through practice of the basic yoga meditation regimen

This chapter briefly reviews recent psychological, physiological, molecular biological, and anthropological research which has important implications, both direct and indirect, for the recognition and understanding of the potential life span and health span enhancing effects of the basic yoga meditational regimen. This regimen consists of meditation, yogic breath control practices, physical exercises (of both a postural- and movement-based, including aerobic nature), and dietary practices. While each of these component categories exhibit variations in different schools, lineages, traditions, and cultures, the focus of this chapter is primarily on basic forms of relaxation meditation and breath control, as well as postural and aerobic physical exercises (e.g., yogic prostration regimens, see below), and a standard form of yogic or ascetic diet, all of which constitute a basic form of regimen found in many if not most cultures, though with variations.

Concentration polarization of high-density lipoprotein and its relation with shear stress in an in vitro model

The purpose of this study was to determine the concentration polarization of high-density lipoprotein (HDL) at the surface of the carotid artery under conditions of steady flow and to establish its relationship with shear stress using an in vitro vascular simulation model of carotid bifurcation. Shear stress, HDL concentration at the surface, and the ratio of HDL concentration at the surface to concentration in bulk flow were measured at different locations within the model under high-speed (1.451 m/s) and low-speed (0.559 m/s) flow. HDL showed concentration polarization at the surface of the carotid artery model, particularly in the internal carotid artery sinus. With decreasing flow velocity, the shear stress at the surface also decreased, and HDL concentration polarization increased. The concentration polarization of HDL was negatively and strongly correlated with shear stress at both low- (r = −0.872, P < .001) and high-speed flow (r = −0.592, P = .0018).

Genome-wide linkage scan for plasma high density lipoprotein cholesterol, apolipoprotein A-1 and triglyceride variation among American Indian populations: the Strong Heart Family Study

BACKGROUND

Recent studies have identified chromosomal regions linked to variation in high density lipoprotein cholesterol (HDL-C), apolipoprotein A-1 (apo A-1) and triglyceride (TG), although results have been inconsistent and previous studies of American Indian populations are limited.

OBJECTIVE

In an attempt to localise quantitative trait loci (QTLs) influencing HDL-C, apo A-1 and TG, we conducted genome-wide linkage scans of subjects of the Strong Heart Family Study.

METHODS

We implemented analyses in 3484 men and women aged 18 years or older, at three study centres.

RESULTS

With adjustment for age, sex and centre, we detected a QTL influencing both HDL-C (logarithm of odds (LOD) = 4.4, genome-wide p = 0.001) and apo A-1 (LOD = 3.2, genome-wide p = 0.020) nearest marker D6S289 at 6p23 in the Arizona sample. Another QTL influencing apo A-1 was found nearest marker D9S287 at 9q22.2 (LOD = 3.0, genome-wide p = 0.033) in the North and South Dakotas. We detected a QTL influencing TG nearest marker D15S153 at 15q22.31 (LOD = 4.5 in the overall sample and LOD = 3.8 in the Dakotas sample, genome-wide p = 0.0044) and when additionally adjusted for waist, current smoking, current alcohol, current oestrogen, lipid treatment, impaired fasting glucose, and diabetes, nearest marker D10S217 at 10q26.2 (LOD = 3.7, genome-wide p = 0.0058) in the Arizona population.

CONCLUSIONS

The replication of QTLs in regions of the genome that harbour well known candidate genes suggest that chromosomes 6p, 9q and 15q warrant further investigation with fine mapping for causative polymorphisms in American Indians.

Marked high density lipoprotein deficiency due to apolipoprotein A-I Tomioka (codon 138 deletion)

We report a novel apolipoprotein A-I (apoA-I) mutation identified in a 64-year-old patient with marked plasma high density lipoprotein (HDL) cholesterol (4 mg/dl) and apoA-I (5mg/dl) deficiency, prior myocardial infarction, and moderate corneal opacities. Coronary angiography revealed extensive atherosclerosis in all three major vessels. Genomic DNA sequencing of the proband revealed a homozygous novel deletion of two successive adenine residues in codon 138 in the apoA-I gene, resulting in a frameshift mutation at amino acid residues 138-178, which we have designated as apoA-I Tomioka. His elder brother was also homozygous for apoA-I Tomioka with marked HDL cholesterol and apoA-I deficiency, but had no clinical evidence of coronary heart disease. Other family members including three siblings and two sons were heterozygous for the mutation, and had approximately 50% of normal plasma HDL cholesterol, and apoA-I. Analysis of apoA-I-containing HDL particles by two-dimensional gel electrophoresis revealed undetectable apoA-I HDL particles in the homozygotes, while in heterozygotes, the mean concentrations of apoA-I in large alpha-1 and very small prebeta-1 HDL subpopulations were significantly decreased at about 35% of normal. Thus, apoA-I Tomioka, a novel deletion mutation in codon 138 of the apoA-I gene, is the causative defect in this case of HDL deficiency.

The hypertension peril: lessons from CETP inhibitors

Pharmacologic inhibitors of the cholesteryl ester transfer protein (CETP) are capable of increasing HDL cholesterol by 50% to 100% in humans. Despite intriguing antiatherogenic effects of CETP inhibition in animal models of atherosclerosis, the Investigation of Lipid Level Management to Understand its Impact in Atherosclerotic Events trial investigators observed an excess of cardiovascular and noncardiovascular morbidity and mortality associated with the use of the CETP inhibitor torcetrapib. This review summarizes available clinical and experimental data about potential underlying mechanisms.

Novel therapies for increasing serum levels of HDL

The protectiveness of elevated HDL-C against CHD and its long-term sequelae is a subject of intense investigation throughout the world. HDL has the capacity to modulate a large number of atherogenic mechanisms, such as inflammation, oxidation, thrombosis, and cell proliferation. Among lipoproteins, HDL is also unique, in that it promotes the mobilization and clearance of excess lipid via the series of reactions collectively termed "reverse cholesterol transport." Numerous therapeutic agents are being developed in an attempt to modulate serum levels of HDL-C as well as its functionality. This article discusses the development of newer treatments targeted at raising HDL-C and HDL particle numbers to reduce residual risk in patients at risk for CHD.

Polymorphism in the CETP gene region, HDL cholesterol, and risk of future myocardial infarction: Genomewide analysis among 18 245 initially healthy women from the Women's Genome Health Study

BACKGROUND

Recent trial data have challenged the hypothesis that cholesteryl ester transfer protein (CETP) and high-density lipoprotein cholesterol (HDL-C) have causal roles in atherothrombosis. One method to evaluate this issue is to examine whether polymorphisms in the CETP gene that impact on HDL-C levels also impact on the future development of myocardial infarction.

METHODS AND RESULTS

In a prospective cohort of 18 245 initially healthy American women, we examined over 350 000 singe-nucleotide polymorphisms (SNPs) first to identify loci associated with HDL-C and then to evaluate whether significant SNPs within these loci also impact on rates of incident myocardial infarction during an average 10-year follow-up period. Nine loci on 9 chromosomes had 1 or more SNPs associated with HDL-C at genome-wide statistical significance (P<5x10(-8)). However, only SNPs near or in the CETP gene at 16q13 were associated with both HDL-C and risk of incident myocardial infarction (198 events). For example, SNP rs708272 in the CETP gene was associated with a per-allele increase in HDL-C levels of 3.1 mg/dL and a concordant 24% lower risk of future myocardial infarction (age-adjusted hazard ratio, 0.76; 95% CI, 0.62 to 0.94), consistent with recent meta-analysis. Independent and again concordant effects on HDL-C and incident myocardial infarction were also observed at the CETP locus for rs4329913 and rs7202364. Adjustment for HDL-C attenuated but did not eliminate these effects.

CONCLUSIONS

In this prospective cohort of initially healthy women, SNPs at the CETP locus impact on future risk of myocardial infarction, supporting a causal role for CETP in atherothrombosis, possibly through an HDL-C mediated pathway.

Phenolic antioxidants and antiatherogenic effects of Marula (Sclerocarrya birrea Subsp. caffra) fruit juice in healthy humans

Antioxidant activity and composition of Israeli-grown marula ( Sclerocarrya birrea subsp. caffra) fruit juice and health-promoting aspects of juice consumption on serum lipids and lipoproteins pattern in healthy volunteers were studied. Marula juice was found to contain high vitamin C and potassium levels and low sugar concentration (267 mg dL (-1), 328 mg dL (-1), and 7.3 g dL (-1), respectively). The juice contains a significant level of phenolics (56 mg of pyrogallol equiv dL (-1)) and was found to be a potent antioxidant (382 mg of vitamin C equiv dL (-1)). The antioxidant activity was resistant to pasteurization regimens and long-term freezing and slowly decreased during refrigeration, losing up to 14% of its capacity after 4 weeks. Three-week administration of the juice as a food supplement to healthy subjects significantly reduced their serum total cholesterol (by 8%), LDL-cholesterol concentration (by 17%), and triglyceride level (by 7%), increased their serum HDL-cholesterol level (by 10%), and attenuated serum oxidative stress. Upon a 4 week "washout" period, most of these parameters returned toward baseline values. Separation of the juice soluble phenolics by HPLC produced potent antioxidant fractions, tentatively containing hydrolyzable tannins, catechins, and hydroxycinnamic acid derivatives, which could be responsible for the observed protection against atherosclerosis risk factors following marula fruit juice consumption.

Multiple actions of high-density lipoprotein

PURPOSE OF REVIEW

The most accepted property of high-density lipoprotein is reverse cholesterol transport. However, other beneficial actions may contribute to the antiatherogenic role of high-density lipoprotein. This review addresses the action of high-density lipoprotein beyond reverse cholesterol transport.

RECENT FINDINGS

High-density lipoprotein cholesterol levels are inversely associated with coronary heart disease and other forms of vascular disease. Apart from transferring excess cholesterol to the liver, high-density lipoprotein exhibits favorable effects on oxidation, inflammation, thrombosis and endothelial function. Some of these actions are at least in part attributed to high-density lipoprotein-associated enzymes, such as paraoxonase and platelet-activating factor acetylhydrolase. However, high-density lipoprotein can become dysfunctional and proatherogenic under certain circumstances.

SUMMARY

Current data suggest that high-density lipoprotein possesses various properties beyond reverse cholesterol transport. However, many issues on the exact role of high-density lipoprotein remain unknown. Future research is needed.

Low HDL cholesterol, smoking and IL-13 R130Q polymorphism are associated with myocardial infarction in Greek Cypriot males. A pilot study

This study was carried out in Greek Cypriot males to identify risk factors that predispose to myocardial infarction (MI). Genetic and lipid risk factors were investigated for the first time in a Greek Cypriot male case-control study.Contrary to other studies, mean low density lipoprotein cholesterol did not differ between cases and controls. High density lipoprotein cholesterol on the other hand, although within normal range in cases and controls, was significantly higher in the control population. In agreement with many other studies, smoking was significantly more prevalent in cases compared with controls. In pooled cases and controls, smokers had a significantly lower HDL-C level compared with non-smokers. The frequency of the IL-13 R130Q homozygotes for the mutation (QQ), as well as the mutant allele were significantly higher in cases compared with controls. The IL-13 R130Q variant, or another locus, linked to it, may increase the risk of MI.

Variants in the CD36 gene associate with the metabolic syndrome and high-density lipoprotein cholesterol

A region along chromosome 7q was recently linked to components of the metabolic syndrome (MetS) in several genome-wide linkage studies. Within this region, the CD36 gene, which encodes a membrane receptor for long-chain fatty acids and lipoproteins, is a potentially important candidate. CD36 has been documented to play an important role in fatty acid metabolism in vivo and subsequently may be involved in the etiology of the MetS. The protein also impacts survival to malaria and the influence of natural selection has resulted in high CD36 genetic variability in populations of African descent. We evaluated 36 tag SNPs across CD36 in the HyperGen population sample of 2020 African-Americans for impact on the MetS and its quantitative traits. Five SNPs associated with increased odds for the MetS [P = 0.0027-0.03, odds ratio (OR) = 1.3-1.4]. Coding SNP, rs3211938, previously shown to influence malaria susceptibility, is documented to result in CD36 deficiency in a homozygous subject. This SNP conferred protection against the MetS (P = 0.0012, OR = 0.61, 95%CI: 0.46-0.82), increased high-density lipoprotein cholesterol, HDL-C (P = 0.00018) and decreased triglycerides (P = 0.0059). Fifteen additional SNPs associated with HDL-C (P = 0.0028-0.044). We conclude that CD36 variants may impact MetS pathophysiology and HDL metabolism, both predictors of the risk of heart disease and type 2 diabetes.

Apolipoprotein A-I versus HDL cholesterol in the prediction of risk for myocardial infarction and stroke

PURPOSE OF REVIEW

To compare the potential of high-density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I, the major protein in HDL particles, in predicting cardiovascular risk. Pros and cons for using these risk markers are discussed.

RECENT FINDINGS

Both HDL cholesterol and apoA-I are in most clinical conditions antiatherogenic - the higher the values, the lower the cardiovascular risk. Methodological and physiological factors speak in favour of using apoA-I rather than HDL cholesterol as a marker of risk. In prospective risk studies and in lipid-lowering trials it has been shown that the apoB/A-I ratio, which reflects the cholesterol balance between all potentially atherogenic (apoB) and antiatherogenic lipoproteins (apoA-I), is a better risk marker than low-density lipoprotein cholesterol, HDL cholesterol and lipid ratios in predicting cardiovascular risk and response to lipid lowering induced by statins. Practical advantages speak in favour of using apoB and apoA-I - fasting is not needed to analyze and interpret the values of apoB and apoA-I.

SUMMARY

New guidelines should be developed in which target values for apoB and apoA-I are defined to enable the use of these new strong risk markers/factors in clinical practice.

Newly identified loci that influence lipid concentrations and risk of coronary artery disease

To identify genetic variants influencing plasma lipid concentrations, we first used genotype imputation and meta-analysis to combine three genome-wide scans totaling 8,816 individuals and comprising 6,068 individuals specific to our study (1,874 individuals from the FUSION study of type 2 diabetes and 4,184 individuals from the SardiNIA study of aging-associated variables) and 2,758 individuals from the Diabetes Genetics Initiative, reported in a companion study in this issue. We subsequently examined promising signals in 11,569 additional individuals. Overall, we identify strongly associated variants in eleven loci previously implicated in lipid metabolism (ABCA1, the APOA5-APOA4-APOC3-APOA1 and APOE-APOC clusters, APOB, CETP, GCKR, LDLR, LPL, LIPC, LIPG and PCSK9) and also in several newly identified loci (near MVK-MMAB and GALNT2, with variants primarily associated with high-density lipoprotein (HDL) cholesterol; near SORT1, with variants primarily associated with low-density lipoprotein (LDL) cholesterol; near TRIB1, MLXIPL and ANGPTL3, with variants primarily associated with triglycerides; and a locus encompassing several genes near NCAN, with variants strongly associated with both triglycerides and LDL cholesterol). Notably, the 11 independent variants associated with increased LDL cholesterol concentrations in our study also showed increased frequency in a sample of coronary artery disease cases versus controls.

Niacin for stroke prevention: evidence and rationale

Low levels of high-density lipoprotein (HDL) cholesterol are associated with increased atherothrombotic events, including stroke. Niacin is a safe and effective means of raising HDL, yet its role in stroke prevention is not well characterized. The purpose of the study is to determine the role of niacin in stroke prevention. A search of the PUBMED database using the keywords niacin, stroke, atherosclerosis, and/or carotid artery was undertaken to identify studies for review. National guidelines from the American Heart Association and National Cholesterol Education Program were reviewed. Treatment of low serum HDL (<40 mg/dL) is an identified goal of dyslipidemic therapy. Niacin is effective in raising HDL levels and reducing cardiovascular events in individuals with high vascular risk and can be used for treatment of stroke patients with low serum HDL. Niacin can be used safely in combination with statins, the first-line dyslipidemic treatment for secondary stroke risk reduction, with increased efficacy. Studies are needed to better define the role for niacin in secondary stroke prevention. Treatment of stroke patients with extended-release (ER) of niacin, alone or in combination with statins, should be considered in stroke patients with atherosclerotic mechanisms with low serum HDL-C levels.

Correction of low HDL cholesterol to reduce cardiovascular risk: practical considerations relating to the therapeutic use of prolonged-release nicotinic acid (Niaspan)

BACKGROUND

Substantial residual cardiovascular risk persists despite effective LDL lowering treatment in populations at elevated risk for adverse cardiovascular outcomes. Low HDL cholesterol is an independent cardiovascular risk factor and occurs in about one-third of patients treated for dyslipidaemia in Europe. Moreover, randomised intervention studies have shown that increasing HDL cholesterol improves cardiovascular outcomes. Correcting low HDL cholesterol therefore presents a rational and proven strategy for intervention to produce further reductions in cardiovascular risk beyond those possible with a statin alone. Nicotinic acid (niacin in the USA) is the most effective agent currently available for increasing levels of HDL cholesterol.

OVERALL STUDY RESULTS

A once-daily, prolonged-release formulation of nicotinic acid (Niaspan) is as effective on HDL cholesterol as the immediate-release formulation, and is equally effective at increasing HDL cholesterol whether or not patients are already taking a statin. Niaspan also shares the antiatherogenic benefit of nicotinic acid, and induced regression of atherosclerosis in patients with cardiovascular disease during a period of treatment of up to 2 years. The incidence of flushing, the principal side effect of nicotinic acid, is lower with Niaspan than with immediate-release nicotinic acid. Simple practical measures are available to minimise the incidence and impact of flushing, including careful dose titration and avoiding hot or spicy foods near the time of ingestion of Niaspan. The potential for hepatotoxicity, muscle toxicity or marked exacerbation of hyperglycaemia in diabetes with Niaspan is very low, with or without concomitant statin treatment.

CONCLUSION

Niaspan provides a practical means of delivering the cardioprotective benefits associated with correction of low HDL cholesterol.

Screening for cardiovascular risk factors in a dental setting

BACKGROUND

The authors assessed the utilization of oral health care professionals (OHCPs) as a resource for identifying patients who were unaware of their increased risk of developing cardiovascular disease (CVD).

METHODS

OHCPs administered a CVD risk-screening questionnaire, measured blood pressure and tested cholesterol levels, high-density lipoprotein levels and hemoglobin A1c (HgA1c) levels using "finger-stick" blood testing in 100 patients treated in a dental school clinic who were unaware of their CVD risk status. The authors determined the prevalence of specific risk factors (that is, smoking and abnormal levels of systolic blood pressure, lipids, body mass index and HgA1c) and calculated Framingham 10-year coronary heart disease (CHD) risk scores.

RESULTS

Seventeen percent of the 100 patients (35 percent of men, 5 percent of women) had an increased global risk of experiencing a CHD event within 10 years (Framingham risk score>10 percent). Seventy-three percent of participants had one or more risk factors and 31 percent had two or more risk factors present. More men than women had low levels of high-density lipoprotein (45 percent [18/40] of men versus 3.3 percent [2/60] of women; P<.0001). The mean Framingham CHD risk score increased with increasing risk factor burden.

CONCLUSIONS

OHCPs identified patients with an increased CHD risk who could benefit from primary prevention activities. A substantial proportion of study patients who were unaware of their risk status were at an increased risk of experiencing a CHD event within 10 years. OHCPs could contribute to public health CHD control efforts.

Total cholesterol content of erythrocyte membranes is increased in patients with acute coronary syndrome: a new marker of clinical instability?

OBJECTIVES

We hypothesized that cholesterol content is increased in the circulating erythrocytes of patients with acute coronary syndrome (ACS) and may be a marker of clinical instability. We therefore sought to investigate whether cholesterol content differs in erythrocyte membranes of patients presenting with ACS compared to patients with chronic stable angina (CSA).

BACKGROUND

Plaque rupture in ACS depends at least partly on the volume of the necrotic lipid core. Histopathologic studies have suggested that cholesterol transported by erythrocytes and deposited into the necrotic core of atheromatous plaques contributes to lipid core growth.

METHODS

Consecutive angina patients were prospectively assessed; 120 had CSA (83 men, age 64 +/- 11 years) and 92 ACS (67 men, 66 +/- 11 years). Total cholesterol content in erythrocyte membranes (CEM) was measured using an enzymatic assay, and protein content was assessed by the Bradford method.

RESULTS

The CEM (median and interquartile range) was higher (p < 0.001) in ACS patients (184 microg/mg; range 130.4 to 260.4 microg/mg) compared with CSA patients (81.1 microg/mg; range 53.9 to 109.1 microg/mg) (analysis of covariance). Total plasma cholesterol concentrations did not correlate with CEM levels (r = -0.046, p = 0.628).

CONCLUSIONS

This study shows, for the first time, that CEM is significantly higher in patients with ACS compared with CSA patients. These findings suggest a potential role of CEM as a marker of atheromatous plaque growth and vulnerability. Large ad hoc studies are required to establish the clinical importance and pathogenic significance of CEM measurement.

Genotypic variation in ATP-binding cassette transporter-1 (ABCA1) as contributors to the high and low high-density lipoprotein-cholesterol (HDL-C) phenotype

The ATP-binding cassette transporter-1 (ABCA1) mediates cholesterol efflux and genotypic variation in ABCA1 and may impact reverse cholesterol transport and influence cardiovascular disease (CVD) risk. However, although mutations in ABCA1 have generally been identified with low HDL-C, few have undertaken a comparative evaluation between high and low high-density lipoprotein-cholesterol (HDL-C). Therefore, to evaluate for potential gain-of-function polymorphisms/mutations in ABCA1, 56 consecutive subjects were screened presenting with high (60-99 mg/dL [1.6-2.6 mmol/L]) or very high HDL-C (>100 mg/dL [2.6 mmol/L]) and were compared with subjects with average or low HDL-C (n = 68). Carrier frequencies of common ABCA1 polymorphisms, R219K, V771M, V825I, I883M, E1172D, and R1587K were also assessed. All 50 exons and exon-intron boundaries of ABCA1 were screened using single-stranded conformation polymorphism (SSCP). DNA samples with SSCP-shifts or differing band patterns were sequenced. For the 6 common polymorphisms, genotyping was determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism. Overall, 5 novel nonsynonymous mutations were identified, all of which were associated with low HDL-C. Of the 6 common ABCA1 polymorphisms, very high HDL-C was associated with a higher genotype frequency for R219K (P(trend) = 0.04) and higher genotype and allelic frequency for E1172D (P(trend) = 0.0004, P(trend) = 0.0002, respectively) compared with lower HDL-C. These data reaffirm that rare mutations in ABCA1 are associated with low HDL-C. However, at least 1 ABCA1 polymorphism (eg, E1172D) may contribute to the high HDL-C phenotype.

Low HDL-cholesterol is common in European Type 2 diabetic patients receiving treatment for dyslipidaemia: data from a pan-European survey

AIMS

To measure the prevalence of low high-density lipoprotein (HDL)-cholesterol (men < 1.03 mmol/l; women < 1.29 mmol/l) in European Type 2 diabetic patients receiving treatment for dyslipidaemia.

METHODS

The pan-European Survey of HDL-cholesterol measured lipids and other cardiovascular risk factors in 3866 patients with Type 2 diabetes and 4436 non-diabetic patients undergoing treatment for dyslipidaemia in 11 European countries.

RESULTS

Diabetic patients were more likely to be obese or hypertensive than non-diabetic patients. Most patients received lifestyle interventions (87%) and/or a statin (89%); treatment patterns were similar between groups. Diabetic patients had [means (SD)] lower HDL-cholesterol [1.22 (0.37) vs. 1.35 mmol/l (0.44) vs. non-diabetic patients, P < 0.001] and higher triglycerides [2.32 (2.10) vs. 1.85 mmol/l (1.60), P < 0.001]. More diabetic vs. non-diabetic patients had low HDL-cholesterol (45% vs. 30%), high triglycerides (> or = 1.7 mmol/l; 57% vs. 42%) or both (32% vs. 19%). HDL-cholesterol < 0.9 mmol/l was observed in 18% of diabetic and 12% of non-diabetic subjects. Differences between diabetic and non-diabetic groups were slightly greater for women. LDL- and total cholesterol were lower in the diabetic group [3.02 (1.05) vs. 3.30 mmol/l (1.14) and 5.12 (1.32) vs. 5.38 mmol/l (1.34), respectively, P < 0.001 for each].

CONCLUSIONS

Low HDL-cholesterol is common in diabetes: one in two diabetic women has low HDL-cholesterol and one diabetic man in four has very low HDL-cholesterol. Management strategies should include correction of low HDL-cholesterol to optimize cardiovascular risk in diabetes.

High-Density Lipoprotein Cholesterol

Background and Purpose— This review characterizes the current state of knowledge of high-density lipoprotein (HDL) in relation to stroke.

Summary of Review— HDL has anti-atherosclerotic and anti-inflammatory properties and is an important component in atherosclerosis. Serum HDL-cholesterol levels are inversely related to heart disease and stroke risk. There are various established and experimental treatments which can raise serum HDL cholesterol and improve its function.

Conclusion— HDL is an emerging target for atherosclerotic stroke treatment with the potential to dramatically impact the care of stroke patients.

Reconstituted high-density lipoprotein stimulates differentiation of endothelial progenitor cells and enhances ischemia-induced angiogenesis

BACKGROUND

Plasma high-density lipoprotein (HDL) levels have an inverse correlation with incidence of ischemic heart disease as well as other atherosclerosis-related ischemic conditions. However, the molecular mechanism by which HDL prevents ischemic disease is not fully understood. Here, we investigated the effect of HDL on differentiation of endothelial progenitor cells and angiogenesis in murine ischemic hindlimb model.

METHODS AND RESULTS

Intravenous injection of reconstituted HDL (rHDL) significantly augmented blood flow recovery and increased capillary density in the ischemic leg. rHDL increased the number of bone marrow-derived cells incorporated into the newly formed capillaries in ischemic muscle. rHDL induced phosphorylation of Akt in human peripheral mononuclear cells. rHDL (50 to 100 microg apolipoprotein A-I/mL) promoted differentiation of peripheral mononuclear cells to endothelial progenitor cells in a dose-dependent manner. The effect of rHDL on endothelial progenitor cells differentiation was abrogated by coadministration of LY294002, an inhibitor of phosphatidylinositol 3-kinase. rHDL failed to promote angiogenesis in endothelial NO-deficient mice.

CONCLUSIONS

rHDL directly stimulates endothelial progenitor cell differentiation via phosphatidylinositol 3-kinase/Akt pathway and enhances ischemia-induced angiogenesis. rHDL may be useful in the treatment of patients with ischemic cardiovascular diseases.

Update on PPAR agonists: The clinical significance of FIELD and PROACTIVE

The peroxisome proliferator-activated receptor (PPAR) family of genes plays a major role in metabolic regulation. Unfortunately, the results of two recent, large event trials of PPAR agonists have been mixed. High rates of crossover to statin use confound the interpretation of the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial, which found a less than expected reduction in coronary and stroke events with fenofibrate. Of concern, nonsignificant increases in coronary and sudden deaths, thrombotic events, and pancreatitis occurred in the fenofibrate group. The PROspective pioglitAzone Clinical Trial In macroVascular Events (PROACTIVE) also found a reduction in coronary and stroke events with pioglitazone compared with placebo in a population with diabetes and cardiovascular disease, but this benefit was counterbalanced by an increase in congestive heart failure as well as symptomatic edema. Further research is needed to determine the role of PPAR agonists in the prevention of cardiovascular disease.

The relationship of percent body fat by bioelectrical impedance analysis with blood pressure, and glucose and lipid parameters

The objective of this study was to clarify the clinical significance and usefulness of measuring percent body fat (PBF) when compared with body mass index (BMI) in the Japanese population. A total of 2,483 Japanese individuals (1,380 men and 1,103 women) who underwent a medical checkup from 1999-2002 were employed. PBF was determined using bioelectrical impedance analysis (BIA). Relationships of age, BMI and PBF with several metabolic parameters, including blood pressure, lipids and plasma glucose levels were assessed in both genders separately. In men, PBF was a stronger determinant of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C) and triglycerides (TG) compared with age and BMI, whereas in women, age was the strongest determinant of TC and LDL-C. In both genders, BMI was the strongest determinant of serum HDL-C among age, PBF and BMI. Based on these data, we suggest that measuring PBF by BIA is superior to BMI for predicting TC, LDL-C and TG in Japanese men.

Functionally defective high-density lipoprotein: a new therapeutic target at the crossroads of dyslipidemia, inflammation, and atherosclerosis

High-density lipoproteins (HDL) possess key atheroprotective biological properties, including cellular cholesterol efflux capacity, and anti-oxidative and anti-inflammatory activities. Plasma HDL particles are highly heterogeneous in physicochemical properties, metabolism, and biological activity. Within the circulating HDL particle population, small, dense HDL particles display elevated cellular cholesterol efflux capacity, afford potent protection of atherogenic low-density lipoprotein against oxidative stress and attenuate inflammation. The antiatherogenic properties of HDL can, however be compromised in metabolic diseases associated with accelerated atherosclerosis. Indeed, metabolic syndrome and type 2 diabetes are characterized not only by elevated cardiovascular risk and by low HDL-cholesterol (HDL-C) levels but also by defective HDL function. Functional HDL deficiency is intimately associated with alterations in intravascular HDL metabolism and structure. Indeed, formation of HDL particles with attenuated antiatherogenic activity is mechanistically related to core lipid enrichment in triglycerides and cholesteryl ester depletion, altered apolipoprotein A-I (apoA-I) conformation, replacement of apoA-I by serum amyloid A, and covalent modification of HDL protein components by oxidation and glycation. Deficient HDL function and subnormal HDL-C levels may act synergistically to accelerate atherosclerosis in metabolic disease. Therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and quality of HDL particles is the target of innovative pharmacological approaches to HDL raising, including inhibition of cholesteryl ester transfer protein, enhanced lipidation of apoA-I with nicotinic acid and infusion of reconstituted HDL or apoA-I mimetics. A preferential increase in circulating concentrations of HDL particles possessing normalized antiatherogenic activity is therefore a promising therapeutic strategy for the treatment of common metabolic diseases featuring dyslipidemia, inflammation, and premature atherosclerosis.

QTL mapping for genetic determinants of lipoprotein cholesterol levels in combined crosses of inbred mouse strains

To identify additional loci that influence lipoprotein cholesterol levels, we performed quantitative trait locus (QTL) mapping in offspring of PERA/EiJxI/LnJ and PERA/EiJxDBA/2J intercrosses and in a combined data set from both crosses after 8 weeks of consumption of a high fat-diet. Most QTLs identified were concordant with homologous chromosomal regions that were associated with lipoprotein levels in human studies. We detected significant new loci for HDL cholesterol levels on chromosome (Chr) 5 (Hdlq34) and for non-HDL cholesterol levels on Chrs 15 (Nhdlq9) and 16 (Nhdlq10). In addition, the analysis of combined data sets identified a QTL for HDL cholesterol on Chr 17 that was shared between both crosses; lower HDL cholesterol levels were conferred by strain PERA. This QTL colocalized with a shared QTL for cholesterol gallstone formation detected in the same crosses. Haplotype analysis narrowed this QTL, and sequencing of the candidate genes Abcg5 and Abcg8 confirmed shared alleles in strains I/LnJ and DBA/2J that differed from the alleles in strain PERA/EiJ. In conclusion, our analysis furthers the knowledge of genetic determinants of lipoprotein cholesterol levels in inbred mice and substantiates the hypothesis that polymorphisms of Abcg5/Abcg8 contribute to individual variation in both plasma HDL cholesterol levels and susceptibility to cholesterol gallstone formation.

Therapeutic elevation of HDL-cholesterol to prevent atherosclerosis and coronary heart disease

Innovative pharmacological approaches to raise anti-atherogenic high-density lipoprotein-cholesterol (HDL-C) are currently of considerable interest, particularly in atherogenic dyslipidemias characterized by low levels of HDL-C, such as type 2 diabetes, the metabolic syndrome, and mixed dyslipidemia, but equally among individuals with or at elevated risk for premature cardiovascular disease (CVD). Epidemiological and observational studies first demonstrated that HDL-C was a strong, independent predictor of coronary heart disease (CHD) risk, and suggested that raising HDL-C levels might afford clinical benefit. Accumulating data from clinical trials of pharmacological agents that raise HDL-C levels have supported this concept. In addition to the pivotal role that HDL-C plays in reverse cholesterol transport and cellular cholesterol efflux, HDL particles possess a spectrum of anti-inflammatory, anti-oxidative, anti-apoptotic, anti-thrombotic, vasodilatory and anti-infectious properties, all of which potentially contribute to their atheroprotective nature. Significantly, anti-atherogenic properties of HDL particles are attenuated in common metabolic diseases that are characterized by subnormal HDL-C levels, such as type 2 diabetes and metabolic syndrome. Inhibition of cholesteryl ester transfer protein (CETP), a key player in cholesterol metabolism and transport, constitutes an innovative target for HDL-C raising. In lipid efficacy trials, 2 CETP inhibitors-JTT-705 and torcetrapib-induced marked elevation in HDL-C levels, with torcetrapib displaying greater efficacy. Moreover, both agents attenuate aortic atherosclerosis in cholesterol-fed rabbits. Clinical trial data demonstrating the clinical benefits of these drugs on atherosclerosis and CHD are eagerly awaited.

Low high-density lipoprotein cholesterol and cardiovascular disease: risk reduction with statin therapy

A low level of high-density lipoprotein cholesterol (HDL-C) is a major risk factor for cardiovascular disease; however, patients with low levels of HDL-C without raised low-density lipoprotein cholesterol (LDL-C) levels are not currently eligible for lipid-lowering therapy. Many individuals with low levels of HDL-C have a combination of cardiovascular risk factors that include high LDL particle concentrations. Lowering LDL particle concentration and its surrogate measure, LDL-C, is an important approach to reducing cardiovascular risk. Statins are the most effective agents for lowering levels of LDL and can significantly increase levels of HDL-C. Extending statin therapy to patients with low levels of HDL-C but with LDL-C levels below target may have benefits for cardiovascular disease reduction in these patients.

The role of exercise in modulating the impact of an ultralow-fat diet on serum lipids and apolipoproteins in patients with or at risk for coronary artery disease

BACKGROUND

Ultralow-fat diets are known to reduce high-density lipoprotein cholesterol (HDL-C) levels. In the setting of a multicomponent lifestyle intervention program, relationships between exercise variables and HDL-C levels were examined to determine whether exercise moderates this dietary effect on serum lipids and apolipoproteins.

METHODS

We performed a 3-month, prospective, nonrandomized lifestyle intervention study (< or = 10% dietary fat; aerobic exercise [180 min/wk], group support, and yoga [60 min/day]) in 120 subjects with or at risk for coronary artery disease.

RESULTS

After 3 months, dietary fat intake was reduced to 8.7% +/- 2.6% of total intake and the median weekly exercise time was 194 minutes. High-density lipoprotein cholesterol levels decreased by 8.3 +/- 11.3 mg/dL (P < .001), and triglyceride levels increased by 17.6 +/- 102.7 mg/dL (P = .026). A small dense low-density lipoprotein cholesterol (LDL-C) phenotype emerged indicated by a 13.8% LDL-C reduction accompanied by only a 2.3% reduction in apolipoprotein B levels (P = .064). Among subjects with exercise amounts less than those of the group median, HDL-C reductions were greater in those with more than (-13.5 +/- 16.0 mg/dL) versus less than (-2.5 +/- 7.5 mg/dL) the median reductions in fat intake (P = .026). Even among subjects who exercised > 194 min/wk, HDL-C was reduced compared with baseline (-7.4 +/- 7.9 mg/dL, P < .001).

CONCLUSIONS

An ultralow-fat diet as a component of a comprehensive lifestyle intervention induces reductions in HDL-C and the emergence of a dyslipidemic lipid profile. Aerobic exercise only partially mitigates this effect.

Targeting cholesteryl ester transfer protein for the prevention and management of cardiovascular disease

Epidemiologic studies have shown that the concentration of high-density lipoprotein cholesterol (HDL-C) is a strong, independent, inverse predictor of coronary heart disease risk. This identifies HDL-C as a potential therapeutic target. Compared with low-density lipoprotein cholesterol (LDL-C)-lowering agents, however, currently available HDL-raising drugs are relatively ineffective. Consequently, recent years have seen considerable efforts expended on identifying new drugs that can raise HDL-C. Cholesteryl ester transfer protein (CETP) plays an important role in cholesterol metabolism, being responsible for the transfer of cholesteryl esters from HDL to very low-density lipoproteins and LDLs. The observation that Japanese populations with CETP deficiency exhibited high levels of HDL-C has led to the concept that drugs targeting CETP activity may elevate HDL-C levels and potentially decrease cardiovascular risk. Support of this proposition has been obtained in rabbits where inhibition of CETP activity is markedly antiatherogenic. Two CETP inhibitors-torcetrapib and JTT-705-are currently in the preliminary stages of clinical development. Initial studies with these drugs in humans show that they substantially increase HDL-C levels and modestly decrease LDL-C levels. Larger, long-term, randomized, clinical end point trials are required to determine whether the beneficial effects of CETP inhibitors on lipoprotein metabolism can translate into reductions in cardiovascular events.

Cardiovascular effects of secondhand smoke: nearly as large as smoking

BACKGROUND

Secondhand smoke increases the risk of coronary heart disease by approximately 30%. This effect is larger than one would expect on the basis of the risks associated with active smoking and the relative doses of tobacco smoke delivered to smokers and nonsmokers.

METHODS AND RESULTS

We conducted a literature review of the research describing the mechanistic effects of secondhand smoke on the cardiovascular system, emphasizing research published since 1995, and compared the effects of secondhand smoke with the effects of active smoking. Evidence is rapidly accumulating that the cardiovascular system--platelet and endothelial function, arterial stiffness, atherosclerosis, oxidative stress, inflammation, heart rate variability, energy metabolism, and increased infarct size--is exquisitely sensitive to the toxins in secondhand smoke. The effects of even brief (minutes to hours) passive smoking are often nearly as large (averaging 80% to 90%) as chronic active smoking.

CONCLUSIONS

The effects of secondhand smoke are substantial and rapid, explaining the relatively large risks that have been reported in epidemiological studies.

Chronische Therapie des metabolischen Syndroms bei herzoperierten Diabetikern

Patients with type 2 diabetes often also exhibit additional features of the metabolic syndrome. These include specifically central obesity triggering development and maintenance of diabetes together with arterial hypertension, hypertriglyceridemia and low levels of high-density lipoprotein cholesterol. Chronic therapy of the metabolic syndrome in diabetics after coronary bypass surgery focuses on changes in lifestyle, i.e., cessation of smoking, changes in nutrition and increase in physical activity. Nutrition aims at fat reduction and modification to reduce saturated fatty acids, to allow mono- and polyunsaturated fatty acids instead, and moderate alcohol consumption. High fiber and complex carbohydrate diet complete the recommendations. Nutrition therapy connected to increases in physical activity are aimed at reducing weight in overweight and obese subjects, which should reduce their body weight by 5 to 10% within about 6 months. Normal weight subjects benefit from increases in physical activity by lipid and glucose regulation as well as by reduction in mortality.Diabetes-specific therapy aims at normoglycemia including postprandial blood glucose levels, reduces blood pressure supported by ACE inhibitors and aims at weight reduction. Reduction of LDL-cholesterol is the first line therapy, also diminishing small-dense LDL particles. Decreasing triglycerides and increasing HDL-cholesterol are further lipid-regulating aims. Specifically diabetics after coronary bypass surgery need LDL-cholesterol levels below 70 mg/d (1.8 mmol/L) and triglycerides below 150 mg/dL (1.7 mmol/L). In addition, in males HDL-cholesterol should be at least above 40 mg/dl (1 mmol/L), in females above 50 mg/dL (1.3 mmol/L).

Patients With Low High-Density Lipoprotein-Cholesterol or Smoking are More Likely to Develop Myocardial Infarction Among Subjects With a Visible Lesion or Stenosis in Coronary Artery

BACKGROUND

Traditional contrast coronary arteriography affords only an indirect view of aspects of atheromata related to their propensity to trigger thromboses, so it is urgent to recognize the vulnerable person who is more likely to develop myocardial infarction (MI) among patients with visible lesion or stenosis in coronary artery.

METHODS AND RESULTS

Two hundred and eighty-eight patients (144 MI patients, 144 controls) who had either a visible lesion or differing extent of stenosis in 1 or more major coronary arteries were consecutively enrolled. Lipid profile, C-reactive protein (CRP), smoking, hypertension, dyslipidemia and diabetes were analyzed for their association with MI. No differences in the prevalence of dyslipidemia, hypertension or diabetes was found between the patients with MI and those without, and CRP, triglycerides, total cholesterol and low-density lipoprotein-cholesterol levels did not differ between the 2 groups (all p>0.05). However, high-density lipoprotein-cholesterol (HDL-C) was significantly lower in the patients with MI than in those without (1.06+/-0.30 vs 1.14+/-0.32 mmol/L, p=0.024). On multivariate analysis after adjustment for age and gender, adjusted odds ratio (95% confidence interval) of MI was 0.44 (0.20-0.96) for HDL-C, p=0.038; 2.6 (1.48-4.56, p=0.001) for smoking, which indicated that high HDL-C was protective for MI, and smoking was associated with an increased risk of MI.

CONCLUSIONS

The present findings indicate that among subjects with a visible lesion or stenosis in coronary arteries, those with low HDL-C or smokers are more likely to develop MI.

The complex nature of the interaction between disease activity and therapy on the lipid profile in patients with pediatric systemic lupus erythematosus

OBJECTIVE

To determine the prevalence of lipid abnormalities at different times and to determine the influence of both the disease and corticosteroid therapy on lipid abnormalities in pediatric patients with systemic lupus erythematosus (SLE).

METHODS

Lipid measurements were obtained in an inception cohort of 139 pediatric patients with SLE (114 females). Fasting levels of total cholesterol, triglycerides, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol in the SLE patients were compared with those in age- and sex-matched control subjects. Disease activity levels and medication dosages were obtained at the time of lipid measurements.

RESULTS

At the time of diagnosis, the mean levels of total cholesterol, LDL cholesterol, and triglycerides were highest, whereas the mean levels of HDL cholesterol were lowest. The percentage of patients with abnormal triglyceride values was highest at diagnosis, decreased at year 1, and then remained relatively constant thereafter. The mean total cholesterol and LDL cholesterol levels decreased at year 1 as compared with the time of diagnosis and then remained relatively constant. The lowest mean HDL cholesterol levels were found at the time of diagnosis, and these values rose with time. Comparison of lipid levels at different prednisone dosages and disease activity levels revealed that changes in triglyceride levels were mainly associated with changes in disease activity, changes in both total cholesterol and LDL cholesterol levels were associated with changes in the prednisone dosage and not disease activity, and low levels of HDL cholesterol were associated with active SLE, whereas the prednisone dosage was associated with increased levels of HDL cholesterol.

CONCLUSION

Factors intrinsic to SLE appear to alter lipid levels. Control of SLE may be the most important factor in improving abnormal lipid profiles, and paradoxically, prednisone therapy may improve abnormal lipid levels.

I405V polymorphism of the cholesteryl ester transfer protein (CETP) gene in young and very old people

This study was designed to analyse the prevalence of I405V polymorphism in the cholesteryl ester transfer protein (CETP) gene, the CETP serum concentration, the lipoprotein profile, and certain clinical end-points in two populations, one young and another of very old people. We recruited 100 healthy young people (median age 31 years) and 100 very old people (median age 89 years) and analysed their DNA for the presence of I405V polymorphism. The frequency of the VV genotype in very old people was more than double that in the young population. Subjects with this genotype had lower serum concentrations of CETP. Young people with the V/V genotype had a less atherogenic lipoprotein profile (lower total cholesterol, LDL cholesterol, Apo B, and Apo B/Apo A-I ratio) than those with the I/V or I/I genotypes. The older subjects, particularly the older women with the V/V genotype, had larger LDL than the young people. The prevalence of clinical endpoints was much lower among the very old people with the V/V genotype. In conclusion, the V/V genotype of the I405V CETP polymorphism is more frequent among very old people than young ones, and is associated with a lower incidence of vascular damage.

Differential diagnosis of familial high density lipoprotein deficiency syndromes

Monogenic high density lipoprotein (HDL) deficiency, because of defects in the genes of apolipoprotein A-I (apoA-I), adenosine triphosphate binding cassette transporter A1 (ABCA1) or lecithin:cholesterol acyltransferase (LCAT), can be assumed in patients with HDL cholesterol levels below the fifth percentile within a given population. As in a first step underlying diseases should be excluded. Patients with a virtual absence of HDL must undergo careful physical examination to unravel the clinical hallmarks of certain HDL deficiency syndromes. In addition, family studies should be initiated, to demonstrate the vertical transmission of the low HDL cholesterol phenotype. Definitive diagnosis requires specialized biochemical tests and the demonstration of a functionally-relevant mutation in one of the three discussed candidate genes. As yet no routinely used drug is able to increase HDL cholesterol levels in patients with familial low HDL cholesterol so that prevention of cardiovascular disease in these patients must be focused on the avoidance and treatment of additional risk factors.

High prevalence of low HDL-cholesterol in a pan-European survey of 8545 dyslipidaemic patients

OBJECTIVE

Low HDL-cholesterol is a strong independent cardiovascular risk factor recognized as a therapeutic target in recent guidelines. The Pan-European Survey on HDL-cholesterol collected data on plasma lipid profiles from 8545 dyslipidaemic patients in the care of 1339 specialist physicians in 11 European countries. The main objective was to obtain a reliable estimation of the prevalence of low HDL (< 1.03 mmol/L [< 40 mg/dL] in men; < 1.29 mmol/L [< 50 mg/dL] in women).

RESEARCH DESIGN AND METHODS

Eligible patients were aged >or= 18 years and had received diet and exercise plus pharmacologic lipid-modifying treatment for >or= 3 months, or had serum cholesterol >or= 5.18 mmol/L (>or= 200 mg/dL) and/or serum triglycerides >or= 2.03 mmol/L (>or= 180 mg/dL) despite >or= 3 months of diet and exercise.

RESULTS

The survey population was overweight (mean body mass index 29.0 kg/m2), with a high prevalence of sedentary lifestyle (68%), type 2 diabetes (45%), hypertension (72%) and coronary heart disease (45%). Lipid-modifying treatment, received by 85% of patients, included lifestyle modification (85%) and/or lipid-lowering drugs (85% received a statin). The prevalence of low HDL-cholesterol despite lipid-modifying treatment was 40% (women) and 33% (men). Very low HDL-cholesterol (< 0.90 mmol/L [< 35 mg/dL]) occurred in 14% of treated patients, with similar prevalence in the subgroup of patients not receiving such treatment. Hypertriglyceridaemia (> 1.69 mmol/L [> 150 mg/dL]) occurred in 57% of men not under lipid-modifying treatment and in 47% of men receiving such treatment; corresponding values in women were 48% and 43%. Both low HDL-cholesterol and hypertriglyceridaemia occurred in 26% of men and 27% of women who were not receiving lipid-modifying treatment and in 21% of men and 25% of women receiving lipid-modifying treatment.

CONCLUSIONS

Low HDL-cholesterol and hypertriglyceridaemia are, therefore, common among European patients treated for dyslipidaemia. Clearly, physicians need to focus more of their attention on this major risk factor and to consider adequate treatment when indicated.

High-density lipoprotein as a therapeutic target: clinical evidence and treatment strategies

The clinical importance of low serum levels of high-density lipoprotein (HDL) cholesterol is often under-recognized and underappreciated as a risk factor for premature atherosclerosis as well as for cardiovascular morbidity and mortality. Low serum levels of HDL are frequently encountered, especially in patients who are obese or have the metabolic syndrome. In prospective epidemiologic studies, every 1-mg/dL increase in HDL is associated with a 2% to 3% decrease in coronary artery disease risk, independent of low-density lipoprotein (LDL) cholesterol and triglyceride (TG) levels. The primary mechanism for this protective effect is believed to be reverse cholesterol transport, but several other anti-inflammatory, antithrombotic, and antiproliferative functions for HDL have also been identified. In recognition of these antiatherogenic effects, recent guidelines have increased the threshold for defining low levels of HDL for both men and women. The first step in achieving these revised targets is therapeutic lifestyle changes. When these measures are inadequate, pharmacotherapy specific to the patient's lipid profile should be instituted. Niacin therapy, currently the most effective means for raising HDL levels, should be initiated in patients with isolated low HDL (HDL <40 mg/dL, LDL and non-HDL at or below National Cholesterol Education Program (NCEP) targets based on global cardiovascular risk evaluation). Patients who have both low HDL and elevated LDL should receive a statin or statin-niacin combination therapy, and patients with concomitant low HDL and elevated TGs should receive a fibrate initially, with a statin, niacin, or ezetimibe added thereafter as needed to help attain NCEP lipoprotein targets.

Low HDL-C: a secondary target of dyslipidemia therapy

Current guidelines for the prevention of coronary heart disease (CHD) focus on lowering low-density lipoprotein cholesterol (LDL-C) as the primary target of lipid-modifying therapy. However, there is increasing interest in high-density lipoprotein cholesterol (HDL-C) as a secondary target of therapy. A wealth of epidemiologic data demonstrate that low levels of HDL-C are associated with an increased risk of CHD events, and data from large-scale clinical trials with statins and fibrates indicate that observed clinical benefits are related, at least in part, to improvements in HDL-C levels. Raising HDL-C levels with therapeutic lifestyle changes and pharmacologic intervention might afford opportunities to further reduce the risk of CHD beyond LDL-C lowering. Statins are first-line pharmacotherapy for dyslipidemia and can also improve HDL-C levels, although the extent to which they modify HDL-C varies. Combining a fibrate or niacin with statin therapy raises HDL-C more than a statin alone but might be associated with reduced tolerability and increased adverse reactions. Several new therapeutic approaches to raising HDL-C are in development, including an HDL mimetic and inhibitors of cholesteryl ester transfer protein. Although lowering LDL-C remains the primary target of lipid-modifying therapy, dyslipidemia therapies that are efficacious for both LDL-C reduction and raising HDL-C might offer further improvements in CHD risk reduction.

Nicotinic acid: the broad-spectrum lipid drug. A 50th anniversary review

Nicotinic acid has, like the Roman God Janus, two faces. One is the vitamin. The other is the broad-spectrum lipid drug. The Canadian pathologist Rudolf Altschul discovered 50 years ago that nicotinic acid in gram doses lowered plasma levels of cholesterol. From the point of view of treatment of the dyslipidaemias that are risk factors for clinical atherosclerosis nicotinic acid is a miracle drug. It lowers the levels of all atherogenic lipoproteins--VLDL and LDL with subclasses as well as Lp(a)--and in addition it raises more than any other drug the levels of the protective HDL lipoproteins. Trials have shown that treatment with nicotinic acid reduces progression of atherosclerosis, and clinical events and mortality from coronary heart disease. The new combination treatment with statin-lowering LDL and nicotinic acid-raising HDL is reviewed. A basic effect of nicotinic acid is the inhibition of fat-mobilizing lipolysis in adipose tissue leading to a lowering of plasma free fatty acids, which has many metabolic implications which are reviewed. The very recent discovery of a nicotinic acid receptor and the finding that the drug stimulates the expression of the ABCA 1 membrane cholesterol transporter have paved the way for exciting and promising new 50 years in the history of nicotinic acid.

Low high-density lipoprotein cholesterol disorders and cardiovascular risk: contribution of associated low-density lipoprotein subclass abnormalities

PURPOSE OF REVIEW

Discuss the contribution of low-density lipoprotein subclass abnormalities to cardiovascular risk among individuals with low high-density lipoprotein cholesterol levels.

RECENT FINDINGS

Low high-density lipoprotein cholesterol levels are commonly encountered among patients with early onset cardiovascular disease. Most often, a low high-density lipoprotein cholesterol level is not an isolated abnormality, but it is usually associated with a number of other lipoprotein abnormalities. Data from the Framingham Offspring Study demonstrate that among subjects with high-density lipoprotein cholesterol, 1.0 mmol/L (39 mg/dL), low-density lipoprotein particle numbers were considerably higher than indicated by the level of low-density lipoprotein cholesterol because these subjects had excess numbers of small cholesterol-depleted low-density lipoprotein particles. Elevated numbers of low-density lipoprotein particles identify individuals at highest risk for atherosclerotic vascular disease and cardiovascular events.

SUMMARY

As high levels of low-density lipoprotein particles are a robust predictor of cardiovascular events, strategies targeted at raising low levels of high-density lipoprotein cholesterol must account for low-density lipoprotein particle interactions.