High-density lipoprotein cholesterol in the cardiovascular equation: does the "good" still count?

High-density lipoprotein ameliorates palmitic acid-induced lipotoxicity and oxidative dysfunction in H9c2 cardiomyoblast cells via ROS suppression

Background

High levels circulating saturated fatty acids are associated with diabetes, obesity and hyperlipidemia. In heart, the accumulation of saturated fatty acids has been determined to play a role in the development of heart failure and diabetic cardiomyopathy. High-density lipoprotein (HDL) has been reported to possess key atheroprotective biological properties, including cellular cholesterol efflux capacity, anti-oxidative and anti-inflammatory activities. However, the underlying mechanisms are still largely unknown. Therefore, the aim of the present study is to test whether HDL could protect palmitic acid (PA)-induced cardiomyocyte injury and explore the possible mechanisms.

Results

H9c2 cells were pretreated with HDL (50–100 μg/ml) for 2 h followed by PA (0.5 mM) for indicated time period. Our results showed that HDL inhibited PA-induced cell death in a dose-dependent manner. Moreover, HDL rescued PA-induced ROS generation and the phosphorylation of JNK which in turn activated NF-κB-mediated inflammatory proteins expressions. We also found that PA impaired the balance of BCL₂ family proteins, destabilized mitochondrial membrane potential, and triggered subsequent cytochrome c release into the cytosol and activation of caspase 3. These detrimental effects were ameliorated by HDL treatment.

Conclusion

PA-induced ROS accumulation and results in cardiomyocyte apoptosis and inflammation. However, HDL attenuated PA-induced lipotoxicity and oxidative dysfunction via ROS suppression. These results may provide insight into a possible molecular mechanism underlying HDL suppression of the free fatty acid-induced cardiomyocyte apoptosis.

Prevalence of low high-density lipoprotein cholesterol (HDL-C) as a marker of residual cardiovascular risk among acute coronary syndrome patients from Oman

OBJECTIVE

To estimate the prevalence as well as predictors of low high-density lipoprotein cholesterol (HDL-C) levels among acute coronary syndrome (ACS) patients in Oman.

METHODS

Data were analyzed from the records of 1583 consecutive patients admitted with a diagnosis of ACS as part of the Gulf Registry of Acute Coronary Events (Gulf RACE). A low HDL-C was considered as <40 mg/dL for males and <50 mg/dL for females.

RESULTS

The overall mean age of the cohort was 59 ± 13 years ranging from 19 to 102 with patients being mostly male (62%) and Omani (83%). The majority were on statin therapy (84%) and 1.1% were on fenofibrate. The overall prevalence of low HDL-C for this ACS population in Oman was 53% mostly affecting females (67 vs. 43%; p < 0.001). After covariate adjustment, renal impairment (serum creatinine >2 mg/dL), triglycerides, and body mass index (BMI) were positive predictors of low HDL-C. However, male gender, total cholesterol, and heart failure (Killip class score ≥3) were negative predictors of low HDL-C.

CONCLUSIONS

Omani ACS patients have a high prevalence of low HDL-C. Renal impairment, triglycerides, and BMI were positive predictors of low HDL-C. The clinical relevance of a low HDL-C abnormality needs to be evaluated in light of the study's limitations (e.g., cross sectional study design as well as the effects of the acute phase reaction and treatment).

A very high prevalence of low HDL cholesterol in Spanish patients with acute coronary syndromes

BACKGROUND

Total and low-density lipoprotein cholesterol (LDL-C) concentrations in coronary artery disease have progressively declined, although high-density lipoprotein cholesterol (HDL-C) has not always been evaluated. The prevalence and related factors of low HDL-C in a cohort of Spanish patients with acute coronary syndromes (ACS) were assessed.

METHODS

Clinical and laboratory data registered at admission and at discharge of 648 patients admitted to coronary care units of 6 Spanish hospitals for ACS between January 2004 and September 2007 were analyzed.

RESULTS

Low HDL-C (HDL-C < 1.04 mmol/L) was observed in 367 (56.6%) patients. Male gender, smoking, hypertension, diabetes, high body mass index, and triglycerides were related to low HDL-C. Female gender was the strongest protective factor against low HDL-C (0.619; 95% confidence interval [CI]: 0.410-0.934; P = 0.022), whereas high triglycerides (1.653; 95% CI: 1.323-2.064; P < 0.001) followed by previous ischemic disease (1.504; 95% CI: 1.073-2.110; P = 0.018) were the strongest factors associated with low HDL-C. One-third of patients were taking statins at admission, but only 2% were on fibrate therapy. A large increase in statin therapy, but not in other hypolipemiant drug therapy, between admission and discharge was noted in the whole cohort and among patients with low HDL-C.

CONCLUSION

Spanish patients with ACS have a very high prevalence of low HDL-C. Male gender, high triglycerides, and previous ischemic disease are strong, independent factors associated with this disorder. As low HDL-C remains almost completely untreated in ACS, strategies to enhance the treatment of this lipoprotein abnormality are urgently required.

Impact of change in high-density lipoprotein cholesterol from baseline on risk for major cardiovascular events

INTRODUCTION

Low concentration of high-density lipoprotein cholesterol (HDL-C) has increasingly been recognized as a strong and independent predictor of cardiovascular risk. The aim of this study was to determine the association between change in HDL-C concentration from baseline and risk of a major cardiovascular event in a commercially insured population cohort with suboptimal HDL-C and low-density lipoprotein cholesterol (LDL-C) concentrations at baseline.

METHODS

A retrospective longitudinal survival analysis was conducted using claims data from a large, commercial US health plan. To be included, patients had to be > or =50 years of age on the index date (laboratory test date between January 1, 2000 and December 31, 2003 on which both their LDL-C and HDL-C were not at goal), be continuously enrolled for a minimum of 6 months prior to and 12 months after the index date, and had to have at least one other laboratory panel result within 1 year prior to the cardiovascular event or study disenrollment. Cox proportional hazards analysis was conducted to assess the association between change in HDL-C concentrations and risk of a major cardiovascular event (defined as a > or =1-day hospitalization for a cardiovascular disease [CVD] diagnosis or an invasive cardiovascular procedure) within 5 years of the index date, after adjusting for covariates.

RESULTS

A 0.026 mmol/L (1 mg/dL) increase in HDL-C from baseline was associated with a statistically significant 1.9% decreased risk of a major cardiovascular event (P<0.0001; hazard ratio: 0.981; 95% CI: 0.974, 0.989), after adjustment for covariates.

CONCLUSION

Our finding of an inverse association between change in HDL-C concentrations and risk of a major cardiovascular event confirms previously reported results. Increasing HDL-C concentrations may serve as an effective measure for preventing future cardiovascular events.

High-density lipoprotein cholesterol, C-reactive protein, and prevalence and severity of coronary artery disease in 5641 consecutive patients undergoing coronary angiography

BACKGROUND

Although high-density lipoprotein cholesterol (HDL-C) and C-reactive protein (CRP) are well-established predictors for future cardiovascular events, little information is available regarding their correlation with the prevalence and severity of angiographically evaluated coronary artery disease (CAD).

MATERIAL AND METHODS

Five thousand six hundred forty-one consecutive patients undergoing coronary angiography for the evaluation of CAD were analysed. Cardiovascular risk factors were assessed by routine blood chemistry and questionnaire. CAD severity was graded by visual estimation of lumen diameter stenosis with significant stenoses defined as lumen diameter reduction of >or= 70%. Coronary angiograms were graded as one-, two- or three-vessel disease, as nonsignificant CAD (lumen irregularities < 70%) or non-CAD.

RESULTS

HDL-C (60.3 +/- 18.5 vs. 51.9 +/- 15.3 mg dL(-1); P < 0.001) was higher and CRP was lower (0.65 +/- 1.68 vs. 1.02 +/- 2.38 mg dL(-1); P < 0.001) in non-CAD (n = 1517) compared to overall CAD patients (n = 4124). CAD patients were older (65.2 +/- 10.5 years vs. 59.9 +/- 11.4 years), more often diabetics (19.2% vs. 10.6%) and hypertensives (79.2% vs. 66.0%) and included more smokers (18.8% vs. 16.5%) (all P < 0.005). Low-density lipoprotein cholesterol (124.5 +/- 38.3 vs. 126.0 +/- 36.3 mg dL(-1); P = NS) was similar in overall CAD and non-CAD patients with more statin users (43.4% vs. 27.9%; P < 0.001) among CAD patients. Comparing non-CAD with different CAD severities using analysis of variance, results did not change substantially. In a multivariate analysis, HDL-C and CRP remained independently associated with the prevalence of CAD. In addition, HDL-C is also a potent predictor for the severity of CAD.

CONCLUSIONS

In this large consecutive patient cohort, HDL-C and CRP are independently associated with the prevalence of CAD. In this analysis, HDL-C is an even stronger predictor for CAD than some other major classical risk factors.

The safety of niacin in the US Food and Drug Administration adverse event reporting database

Of currently approved drugs, niacin is the most effective in raising high-density lipoprotein cholesterol levels, either as monotherapy or in combination with other agents. The US Food and Drug Administration's (FDA) Adverse Event Reporting System provides 1 mechanism to evaluate the safety of niacin as it is used in common clinical practice. In this report, the authors review recent analyses of adverse events reported to the FDA demonstrating that the extended-release formulation of niacin (niacin-ER) has a significantly better safety profile compared with other niacin formulations and compares favorably with other commonly used lipid-altering drugs, including 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and fibrates. In addition, analyses of FDA adverse event reports of the pill combining lovastatin and niacin-ER suggest that the safety of combination therapy with niacin-ER and a statin is comparable with the safety of each of the drugs alone. These analyses should encourage the use of niacin-ER in patients at high risk for cardiovascular disease, as recommended by current national guidelines for cardiovascular prevention.

Abdominal obesity, blood glucose and apolipoprotein B levels are the best predictors of the incidence of hypercholesterolemia (2001-2006) among healthy adults: the ATTICA study

OBJECTIVE

In this work we evaluated the 5-year incidence of hypercholesterolemia, in a sample of cardiovascular disease free adult men and women from Greece. We also evaluated the association of several socio-demographic, dietary and lifestyle habits on the incidence of this disorder.

METHODS

1514 men and 1528 women (>18 y) without any clinical evidence of cardiovascular disease, living in Attica area, Greece, were enrolled in the ATTICA study from May 2001 to December 2002. The sampling was random, multi-stage, and included information about various socio-demographic, lifestyle (diet, exercise, smoking etc), biological (lipids, and inflammatory markers), and clinical characteristics of the participants. In 2006, a group of experts performed the 5-year follow-up through telephone calls or personal visits (941 of the 3042 (31%) participants were lost to follow-up). Hypercholesterolemia, among people who had normal blood lipids at initial examination, was defined as fasting total cholesterol levels > 200 mg/dl or use of lipids lowering agents (NCEP ATPIII).

RESULTS

The 5-year incidence of hypercholesterolemia was 23.7% (n = 127) in men and 17.7% (n = 110) in women (p for gender differences < 0.001). Multi-adjusted logistic regression analysis which revealed that increased age (odds ratio = 1.05, p < 0.001), waist circumference (odds ratio = 1.02, p = 0.03), fasting blood glucose (odds ratio = 1.01, p = 0.08) and apolipoprotein B (odds ratio = 1.02, p = 0.001) levels, were the most significant baseline predictors of developing hypercholesterolemia within a 5-year period.

CONCLUSION

Incidence of hypercholesterolemia was high in both genders, emphasizing the burden of this disorder at population level. Aging, increased waist circumference, fasting blood glucose and apolipoprotein B levels were the most significant baseline predictors of hypercholesterolemia.

Prevalence of low high-density lipoprotein cholesterol in patients with documented coronary heart disease or risk equivalent and controlled low-density lipoprotein cholesterol

Current guidelines identify low-density lipoprotein (LDL) cholesterol as the primary target for cardiovascular prevention but also recognize low high-density lipoprotein (HDL) cholesterol as an important secondary target. This study was conducted to determine the prevalence of low HDL cholesterol in a contemporary ambulatory high-risk population across various LDL cholesterol levels, including patients taking statins. Screening of 44,052 electronic medical records from a primary care practice identified 1,512 high-risk patients with documented coronary heart disease (CHD) or CHD risk equivalents. Low HDL cholesterol (< or =40 mg/dl in men, < or =50 mg/dl in women) was present in 66% of the 1,512 patients. Low HDL cholesterol was prevalent across all LDL cholesterol levels but most prevalent in patients with LDL cholesterol < or =70 mg/dl (79% vs 66% in those with LDL cholesterol 71 to 100 mg/dl and 64% in patients with LDL cholesterol >100 mg/dl, p <0.01). Low HDL cholesterol was equally and highly prevalent in patients taking statins (67%) and those not taking statins (64%) (p = NS). HDL cholesterol and LDL cholesterol levels correlated poorly (R(2) = 0.01), and this was unaffected by gender or statin treatment. In conclusion, in high-risk patients with CHD or CHD risk equivalents, low HDL cholesterol levels remain prevalent despite statin treatment and the achievement of aggressive LDL cholesterol goals.

Prevention challenges: the era of atherosclerosis regression

Statins slow atherosclerosis progression and can even induce atherosclerosis regression. The reduction of cardiovascular events with statins by approximately one-third demonstrates not only their clinical efficacy but also the unmet clinical need. The aging of the population and the epidemics of the metabolic syndrome and diabetes contribute to the increasing burden of atherosclerosis in society, and fuel the need for novel complementary therapies to further improve clinical outcomes. Some targets, such as acyl-coenzyme A:cholesterol acyltransferase inhibition, have yielded disappointing clinical results. In contrast, there is strong evidence linking lower high density lipoprotein (HDL) cholesterol levels and greater cardiovascular risk, thus providing the rationale for targeting HDL in the prevention and treatment of cardiovascular diseases. Therapeutic approaches include direct infusions of HDL cholesterol or HDL-mimetic agents, as well as the inhibition of cholesteryl ester transfer protein (CETP). CETP inhibition appears to be one particularly promising strategy. The CETP inhibitor torcetrapib increases plasma HDL cholesterol levels by 40% to 60%, while modestly decreasing low density lipoprotein (LDL) cholesterol. Combining the HDL cholesterol-elevating properties of a CETP inhibitor with the LDL cholesterol-lowering properties of a statin may offer improved outcomes over targeting LDL cholesterol alone. This hypothesis is being extensively evaluated in a comprehensive program that involves several imaging studies and a large-scale clinical end point trial. The additional cardiovascular protection required for patients with atherosclerosis or risk equivalents will likely be provided by therapies that go beyond LDL reduction.

The Importance of Managing Hypertension and Dyslipidemia to Decrease Cardiovascular Disease

BACKGROUND

Clinical management of two key modifiable risk factors for cardiovascular disease (CVD), hypertension and dyslipidemia, has evolved considerably over the past 40 years, in terms of the focus of therapy, available pharmacologic agents, and therapeutic targets.

MATERIALS AND METHODS

A brief review of the epidemiology of hypertension and hyperlipidemia and of controlled clinical trials of pharmacologic therapy of these conditions in decreasing cardiovascular events is presented.

RESULTS

Risk factors for CVD generally do not occur in isolation, and the co-occurrence of hypertension and dyslipidemia, with or without other additional risk factors, greatly increases the risk of CVD. Clinical trials performed in the last 40 years have demonstrated the clinical benefit of treating hypertension and dyslipidemia. Recent trials have shown that intensive, early management of these risk factors provide the greatest clinical benefits. Emerging evidence suggests that lipid management provides clinical benefit in patients at high risk of CVD, regardless of their baseline cholesterol levels, and that lipid-lowering with statin therapy provides additional benefits over antihypertensive therapy alone in high-risk patients with hypertension. It has become evident that the most effective means of reducing CVD risk is the simultaneous management of all modifiable risk factors. Treatment of an individual risk factor can reduce CVD events by approximately 30%, whereas treatment of multiple risk factors can reduce the risk of CVD by more than 50%. However, a large number of patients are not treated or receive suboptimal treatment.

CONCLUSIONS

Overwhelming controlled clinical trial evidence supports the clinical benefit of treating hypertension and hypercholesterolemia. Fixed-dose combination medications for hypertension, and integrative combination therapies containing antihypertensive and lipid-lowering medications in a single pill contribute to better risk factor management with the potential for greater adherence and improved clinical outcomes.

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.

Reducing cardiovascular risk by targeting high-density lipoprotein cholesterol

Although lowering low-density lipoprotein (LDL) cholesterol with statins can substantially reduce cardiovascular morbidity and mortality, many treated patients retain a residual risk for cardiovascular events. Low levels of high-density lipoprotein (HDL) cholesterol may underpin this residual risk and may represent an additional target for intervention. Several new therapies for substantially increasing HDL cholesterol levels are under investigation, including cholesteryl ester transfer protein (CETP) inhibitors, apolipoprotein A-I mimetics and recombinant HDL, liver X receptor (LXR) agonists, and peroxisome proliferator-activated receptor (PPAR) agonists. Combining new HDL cholesterol-elevating agents with existing LDL cholesterol-lowering agents may improve the cardiovascular risk reductions currently attainable.

Historical milestones in measurement of HDL-cholesterol: Impact on clinical and laboratory practice

High-density lipoprotein cholesterol (HDL-C) comprises a family of particles with differing physicochemical characteristics. Continuing progress in improving HDL-C analysis has originated from two separate fields-one clinical, reflecting increased attention to HDL-C in estimating risk for coronary heart disease (CHD), and the other analytical, reflecting increased emphasis on finding more reliable and cost-effective HDL-C assays. Epidemiologic and prospective studies established the inverse association of HDL-C with CHD risk, a relationship that is consistent with protective mechanisms demonstrated in basic research and animal studies. Atheroprotective and less atheroprotective HDL subpopulations have been described. Guidelines on primary and secondary CHD prevention, which increased the workload in clinical laboratories, have led to a revolution in HDL-C assay technology. Many analytical techniques including ultracentrifugation, electrophoresis, chromatography, and polyanion precipitation methods have been developed to separate and quantify HDL-C and HDL subclasses. More recently developed homogeneous assays enable direct measurement of HDL-C on an automated analyzer, without the need for manual pretreatment to separate non-HDL. Although homogeneous assays show improved accuracy and precision in normal serum, discrepant results exist in samples with atypical lipoprotein characteristics. Hypertriglyceridemia and monoclonal paraproteins are important interfering factors. A novel approach is nuclear magnetic resonance spectroscopy that allows rapid and reliable analysis of lipoprotein subclasses, which may improve the identification of individuals at increased CHD risk. Apolipoprotein A-I, the major protein of HDL, has been proposed as an alternative cardioprotective marker avoiding the analytical limitations of HDL-C.

High-Density Lipoprotein Cholesterol-Raising Strategies

There is a distinct inverse relationship between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease risk. HDL-C mediates cholesterol efflux from the vasculature and promotes anti-oxidant, anti-inflammatory, and anti-thrombotic effects. There are multiple lifestyle and therapeutic interventions that raise HDL-C, and there is increasing evidence that these interventions improve cardiovascular outcomes. Recent findings regarding the role of HDL-C in cholesterol metabolism offer new strategies designed to target atherosclerosis. This review highlights the utility of existing HDL-C-raising strategies and examines new potential therapies.

Hyperlipidemia

Over the past 20 years, a link between lipoprotein disorders and atherosclerosis, and its clinical manifestations of myocardial infarction, stroke, and sudden cardiac death, has been conclusively demonstrated. This article reviews lipoprotein metabolism, its pathophysiology, describes an approach for the management of patients with lipid disorders and discusses therapy using the ATP III guidelines.