Niacin treatment of the atherogenic lipid profile and Lp(a) in diabetes

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY GUIDELINES FOR MANAGEMENT OF DYSLIPIDEMIA AND PREVENTION OF CARDIOVASCULAR DISEASE

OBJECTIVE

The development of these guidelines is mandated by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPGs).

METHODS

Recommendations are based on diligent reviews of the clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols.

RESULTS

The Executive Summary of this document contains 87 recommendations of which 45 are Grade A (51.7%), 18 are Grade B (20.7%), 15 are Grade C (17.2%), and 9 (10.3%) are Grade D. These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world medical care. The evidence base presented in the subsequent Appendix provides relevant supporting information for Executive Summary Recommendations. This update contains 695 citations of which 203 (29.2 %) are EL 1 (strong), 137 (19.7%) are EL 2 (intermediate), 119 (17.1%) are EL 3 (weak), and 236 (34.0%) are EL 4 (no clinical evidence).

CONCLUSION

This CPG is a practical tool that endocrinologists, other health care professionals, health-related organizations, and regulatory bodies can use to reduce the risks and consequences of dyslipidemia. It provides guidance on screening, risk assessment, and treatment recommendations for a range of individuals with various lipid disorders. The recommendations emphasize the importance of treating low-density lipoprotein cholesterol (LDL-C) in some individuals to lower goals than previously endorsed and support the measurement of coronary artery calcium scores and inflammatory markers to help stratify risk. Special consideration is given to individuals with diabetes, familial hypercholesterolemia, women, and youth with dyslipidemia. Both clinical and cost-effectiveness data are provided to support treatment decisions.

ABBREVIATIONS

4S = Scandinavian Simvastatin Survival Study A1C = glycated hemoglobin AACE = American Association of Clinical Endocrinologists AAP = American Academy of Pediatrics ACC = American College of Cardiology ACE = American College of Endocrinology ACS = acute coronary syndrome ADMIT = Arterial Disease Multiple Intervention Trial ADVENT = Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial AFCAPS/TexCAPS = Air Force/Texas Coronary Atherosclerosis Prevention Study AHA = American Heart Association AHRQ = Agency for Healthcare Research and Quality AIM-HIGH = Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides trial ASCVD = atherosclerotic cardiovascular disease ATP = Adult Treatment Panel apo = apolipoprotein BEL = best evidence level BIP = Bezafibrate Infarction Prevention trial BMI = body mass index CABG = coronary artery bypass graft CAC = coronary artery calcification CARDS = Collaborative Atorvastatin Diabetes Study CDP = Coronary Drug Project trial CI = confidence interval CIMT = carotid intimal media thickness CKD = chronic kidney disease CPG(s) = clinical practice guideline(s) CRP = C-reactive protein CTT = Cholesterol Treatment Trialists CV = cerebrovascular CVA = cerebrovascular accident EL = evidence level FH = familial hypercholesterolemia FIELD = Secondary Endpoints from the Fenofibrate Intervention and Event Lowering in Diabetes trial FOURIER = Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects With Elevated Risk trial HATS = HDL-Atherosclerosis Treatment Study HDL-C = high-density lipoprotein cholesterol HeFH = heterozygous familial hypercholesterolemia HHS = Helsinki Heart Study HIV = human immunodeficiency virus HoFH = homozygous familial hypercholesterolemia HPS = Heart Protection Study HPS2-THRIVE = Treatment of HDL to Reduce the Incidence of Vascular Events trial HR = hazard ratio HRT = hormone replacement therapy hsCRP = high-sensitivity CRP IMPROVE-IT = Improved Reduction of Outcomes: Vytorin Efficacy International Trial IRAS = Insulin Resistance Atherosclerosis Study JUPITER = Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin LDL-C = low-density lipoprotein cholesterol Lp-PLA2 = lipoprotein-associated phospholipase A2 MACE = major cardiovascular events MESA = Multi-Ethnic Study of Atherosclerosis MetS = metabolic syndrome MI = myocardial infarction MRFIT = Multiple Risk Factor Intervention Trial NCEP = National Cholesterol Education Program NHLBI = National Heart, Lung, and Blood Institute PCOS = polycystic ovary syndrome PCSK9 = proprotein convertase subtilisin/kexin type 9 Post CABG = Post Coronary Artery Bypass Graft trial PROSPER = Prospective Study of Pravastatin in the Elderly at Risk trial QALY = quality-adjusted life-year ROC = receiver-operator characteristic SOC = standard of care SHARP = Study of Heart and Renal Protection T1DM = type 1 diabetes mellitus T2DM = type 2 diabetes mellitus TG = triglycerides TNT = Treating to New Targets trial VA-HIT = Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial VLDL-C = very low-density lipoprotein cholesterol WHI = Women's Health Initiative.

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

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

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

The Therapeutic Role of Niacin in Dyslipidemia Management

There is abundant epidemiologic evidence to support the independent, inverse relationship between low levels of high-density lipoprotein cholesterol (HDL-C) and incident cardiovascular (CV) risk, the clinical importance of which is underscored by the high prevalence of low HDL-C in populations with coronary heart disease (CHD), with or without elevated levels of low-density lipoprotein cholesterol (LDL-C). The National Cholesterol Education Program recommended that optimal treatment for high-risk patients includes both lowering LDL-C and non-HDL-C to risk stratified levels and raising HDL-C when it is <40 mg/dL, although no target level for the latter lipoprotein was suggested. Niacin is the most powerful agent currently available for raising low levels of HDL-C. It also induces significant reductions in triglycerides, lipoprotein(a), and LDL-C levels while also favorably altering LDL particle size and number. In the Coronary Drug Project, niacin treatment was associated with significant reductions in CV events and long-term mortality, similar to the reductions seen in the statin monotherapy trials. In combination trials, niacin plus a statin or bile acid sequestrant produces additive reductions in CHD morbidity and mortality and promotes regression of coronary atherosclerosis. Recently, 2 clinical outcome trials (Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides and Impact on Global Health Outcomes [AIM-HIGH] and Second Heart Protection Study [HPS-2 THRIVE]) failed to show a reduction in CV events in patients treated to optimally low levels of LDL-C. Despite favorable effects on HDL-C and triglycerides, these studies did not demonstrate incremental clinical benefit with niacin when added to simvastatin, although notable limitations were identified in each of these trials. Thus, there is insufficient evidence from clinical trials to recommend HDL-targeted therapy for additional event reduction at the present time. However, niacin should continue to be used as an adjuvant therapy for reducing atherogenic lipoprotein burden in patients who have not reached their risk stratified LDL-C and non-HDL-C targets.

The Effects of Tetrahydro-iso-alpha Acids and Niacin on Monocyte-Edothelial Cell Interactions and Flow-mediated Vasodilation

Niacin favorably modifies cardiovascular risk factors but is associated with flushing and shows limited benefit in improving endothelial function. We investigated whether combining anti-inflammatory tetrahydro-iso-alpha acids (THIAA) from hops with niacin would improve endothelial function. We hypothesized that the THIAA+niacin combination would demonstrate benefits not seen with niacin alone. In an in vitro model, a THIAA+niacin mixture inhibited several TNF-α-induced cytokines in human aortic endothelial cells and in human monocytic cells and was significantly more efficacious than niacin alone. Subsequently, the effect of 125 mg THIAA and 500 mg niacin on endothelial-regulated flow-mediated vasodilation (FMD) was explored in a pilot study of 11 dyslipidemic volunteers. The 12-week treatment (2 tablets/day) resulted in a clinically relevant FMD increase compared to a trend toward an FMD decrease with placebo; the between-arm difference was statistically significant. THIAA+niacin treatment also improved total cholesterol, low-density lipoprotein cholesterol, and uric acid. No significant improvement in these parameters was observed with placebo. High-sensitivity C-reactive protein was significantly increased only in the placebo arm. Nutritional support with a THIAA+niacin combination may provide benefits for endothelial function in those with dyslipidemia.

Metabolic syndrome in the Mediterranean region: Current status

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities including abdominal obesity, impaired fasting glucose, hypertension and dyslipidemia. It seems to affect about one-fourth to one-fifth of the Mediterranean population, and its prevalence increases with age, being similar for both sexes and depending on the region and the definition used, with the National Cholesterol Education Program-Adult Treatment Panel-III (NCEP-ATPIII) definition being the most effective in the identification of glucose intolerance and cardiovascular risk. Except for these, MetS is associated with fatty liver disease, some forms of cancer, hypogonadism, and vascular dementia. The Mediterranean diet seems to be an ideal diet in patients with MetS, being rich in fibre, monounsaturated and polyunsaturated fats, and low in animal protein; and decreases the prevalence of MetS and cardiovascular disease risk. Except for weight loss, multifactorial intervention including insulin resistance reduction and normoglycemia, management of dyslipidemia, optimizing blood pressure and administration of low-dose aspirin for patients at high or moderately high cardiovascular disease (CVD) risk are additional targets. The present review provides current understanding about MetS in the Mediterranean region, focusing on its prevalence, clinical significance, and therapeutic strategy.

Clinical applications of advanced lipoprotein testing in diabetes mellitus

Traditional lipid profiles often fail to fully explain the elevated cardiovascular risk of individuals with diabetes mellitus. Advanced lipoprotein testing offers a novel means to evaluate dyslipidemia and refine risk estimation. Numerous observational studies have demonstrated a characteristic pattern of elevated levels of small, dense LDL particles, out of proportion to traditional lipid levels, in patients with both diabetes mellitus and the metabolic syndrome. Commonly used glucose and lipid-lowering agents have varied effects in patients with diabetes on both LDL and HDL subfractions. The exact role of advanced lipoprotein testing in patients with diabetes mellitus and the metabolic syndrome remains unclear but may offer improved assessment of cardiovascular risk compared with traditional lipid measurements.

Recent advances in the treatment of atherogenic dyslipidemia in type 2 diabetes mellitus

Despite best treatment efforts reducing low-density lipoprotein cholesterol, a substantial number of type 2 diabetes mellitus patients still experience progression of cardiovascular risk. Even with intensification of statin therapy, a substantial residual cardiovascular risk remains and atherogenic dyslipidemia is an important driver of this so-called residual risk. Besides statin therapy, new strategies evaluate the role of intensive combination lipid treatment for the entire type 2 diabetic population. The results from the ACCORD (Action to Control Cardiovascular Risk in Diabetes) Lipid trial suggest that there is a lipid-related modifiable component to cardiovascular residual risk in statin-treated type 2 diabetic patients, and that further research should address patients with triglycerides above 204 mg/dl and high-density lipoprotein cholesterol below 34 mg/dl. Based on their respective lipid-modifying activity, the combination of a fibrate and statin is a logical approach to improving achievement of lipid targets in statin-treated patients with a glomerular filtration rate of >60 ml/min/1.73 m(2) and with residual atherogenic dyslipidemia. The link between dyslipidemia treatment and diabetic retinopathy, nephropathy and neuropathy is an emerging new field and microvascular complications are targets for new treatments.

Effect of combined therapy of diabinese and nicotinic acid on liver enzymes in rabbits with dithizone-induced diabetes

The effects of diabinese, a known antidiabetic drug, and the combined effects of diabinese and nicotinic acid, a vitamin and antilipidemic drug, were studied in rabbits with dithizone-induced diabetes. Side effects of diabinese include hypoglycemia and liver toxicity. Dithizone was used to induce partial experimental diabetes and to increase blood glucose significantly (P < 0.05) by 31.3%, 23.5%, 19.5, 24.7%, and 23.9% in groups A (single therapy of diabinese 10 mg/kg body weight), B (10 mg of diabinese and nicotinic acid 150 mg/kg), C (10 mg diabinese and nicotinic acid 200 mg/kg), D (10 mg diabinese and nicotinic acid 250 mg/kg) and E control (distilled water 5 mL), respectively. Dithizone administration also increased bilirubin, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels by 28.9%-35.6%, 41.2%-54.8%, 40.1%-46.1%, and 60.9%-68.4%, respectively. Diabinese monotherapy reduced bilirubin levels, while combined therapy reduced glucose, ALP, AST, and ALT levels more than single therapy. Reduction from the hyperglycemic level 48 hours after drug administration was 20.0%, 24.6%, 41.0%, and 42.0% for groups A, B, C, and D, respectively, and was concentration-dependent. Also, combined therapy produced a significant (P < 0.05) decrease in AST and ALT levels, especially at 72 hours after drug administration, but did not affect ALP levels. No significant changes in glucose, bilirubin, ALP, AST, and ALT levels were observed in Group E (control). This study shows that liver toxicity and the hypoglycemic side effects of diabinese could be managed by the concomitant administration of nicotinic acid.

The Effects of Extended Release Niacin in Combination with Omega 3 Fatty Acid Supplements in the Treatment of Elevated Lipoprotein (a)

Objective. To assess the effectiveness of niacin/fish oil combination therapy in reducing Lipoprotein (a) [Lp(a)] levels after twelve weeks of therapy. Background. Lipoprotein (a) accumulates in atherosclerotic lesions and promotes smooth muscle cell growth and is both atherogenic and thrombogenic. A clinical trials of combination therapy for the reduction of Lp(a) has not been previously reported. Methods. The study was an observational study following subjects with an elevated Lp(a) (>70 nmol/L) to assess impact of 12 weeks of combination Omega 3FA, niacin, and the Mediterranean diet on Lp(a). Results. Twenty three patients were enrolled with 7 patients lost to follow up and 2 patients stopped due to adverse events. The average Lp(a) reduction in the remaining 14 subjects after 12 weeks of combination therapy was 23%  ± 17% [P = .003] with a significant association of the reduction of Lp(a) with increasing baseline levels of Lp(a) [R² = 0.633, P = .001]. Conclusions. There was a significant reduction in Lp(a) levels with combination therapy. A more pronounced effect was noted in patients with higher baseline levels of Lp(a).

Relationship of heavy drinking, lipoprotein (a) and lipid profile to infrarenal aortic diameter

Abstract

The objective of this study was to examine the association of alcohol drinking and lipid profile with infrarenal aortic dimension. The diameter of the infrarenal aorta was measured using ultrasound in 395 individuals (mean 66.6 ± 10.3 years) with atherosclerotic diseases or risk factors. The associations between heavy drinking, serum lipoprotein (a) levels, lipid profile and infrarenal aorta diameters were examined. Heavy drinking and lipoprotein (a) were positively related with infrarenal aortic dimension, while low-density lipoprotein cholesterol (LDL-C)/high-density lipoprotein cholesterol (HDL-C), LDL-C and total cholesterol (TC)/HDL-C were negatively associated with infrarenal aortic diameter ( p < 0.05). In addition, there were negative associations of LDL-C/HDL-C, TC/HDL-C and positive associations of HDL-C and apolipoprotein AI (Apo AI) with heavy drinking ( p < 0.05). In conclusion, there was a positive association between infrarenal aortic diameters and heavy drinking, as well as lipoprotein (a) levels. Furthermore, the novel and unexpected inverse association between LDL-C/HDL-C, LDL-C, TC/HDL-C and abdominal aortic diameter may suggest a possible role for anti-atherogenic lipid profile (characterized by a higher level of HDL-C and lower level of LDL-C) in aortic dilatation processes, which need to be clarified by further studies.

Animal models of catheter-induced intimal hyperplasia in type 1 and type 2 diabetes and the effects of pharmacologic intervention

Diabetes is a complex disorder characterized by impaired insulin formation, release or action (insulin resistance), elevated blood glucose, and multiple long-term complications. It is a common endocrine disorder of humans and is associated with abnormalities of carbohydrate and lipid metabolism. There are two forms of diabetes, classified as type 1 and type 2. In type 1 diabetes, hyperglycemia is due to an absolute lack of insulin, whereas in type 2 diabetes, hyperglycemia is due to a relative lack of insulin and insulin resistance. More than 90% of people with diabetes have type 2 with varied degrees of insulin resistance. Insulin resistance is often associated with impaired insulin secretion, and hyperglycemia is a common feature in both types of diabetes, but failure to make a distinction between the types of diabetes in different animal models has led to confusion in the literature. This is particularly true in relation to cardiovascular disease in the presence of diabetes and especially the response to vascular injury, in which there are major differences between the two types of diabetes. Animal models do not completely mimic the clinical disease seen in humans. Animal models are at best analogies of the pathologic process they are designed to represent. The focus of this review is an analysis of intimal hyperplasia following catheter-induced vascular injury, including factors that may complicate comparisons between different animal models or between in vitro and in vivo studies. We examine the variables, pitfalls, and caveats that follow from the manner of induction of the injury and the diabetic state of the animal. The efficacy of selected antidiabetic drugs in inhibiting the development of the hyperplastic response is also discussed.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

The Residual Risk Reduction Initiative: a call to action to reduce residual vascular risk in dyslipidaemic patient

Despite current standards of care aimed at achieving targets for low-density lipoprotein (LDL) cholesterol, blood pressure and glycaemia, dyslipidaemic patients remain at high residual risk of vascular events. Atherogenic dyslipidaemia, specifically elevated triglycerides and low levels of high-density lipoprotein (HDL) cholesterol, often with elevated apolipoprotein B and non-HDL cholesterol, is common in patients with established cardiovascular disease, type 2 diabetes, obesity or metabolic syndrome and is associated with macrovascular and microvascular residual risk. The Residual Risk Reduction Initiative (R3I) was established to address this important issue. This position paper aims to highlight evidence that atherogenic dyslipidaemia contributes to residual macrovascular risk and microvascular complications despite current standards of care for dyslipidaemia and diabetes, and to recommend therapeutic intervention for reducing this, supported by evidence and expert consensus. Lifestyle modification is an important first step. Additionally, pharmacotherapy is often required. Adding niacin, a fibrate or omega-3 fatty acids to statin therapy improves achievement of all lipid risk factors. Outcomes studies are evaluating whether these strategies translate to greater clinical benefit than statin therapy alone. In conclusion, the R3I highlights the need to address with lifestyle and/or pharmacotherapy the high level of residual vascular risk among dyslipidaemic patients who are treated in accordance with current standards of care.

Niacin and lipoprotein(a): facts, uncertainties, and clinical considerations

Over the years, niacin has gained recognition as an atheroprotective agent, in part because of its capacity to lower the plasma levels of cholesterol, triglycerides, and very-low- and low-density lipoproteins and to substantially raise high-density lipoprotein. In high doses, niacin has also been reported to lower the plasma level of lipoprotein(a) (Lp[a]). However, the published research on the subject suffers from a lack of uniformity regarding patient selection, drug dose, length of administration, and methods for plasma Lp(a) quantification. In this report, the authors examine the most relevant niacin-related Lp(a) studies and hypothetical mechanisms of drug action, also considering the emerging notion of Lp(a) as a potential proinflammatory entity.

Cyclic relationships between diabetic nephropathy and cardiovascular risk factors

The most common cause of death in diabetes is cardiovascular. Diabetic nephropathy has an important role in cardiovascular disease among susceptible diabetic patients. What is not well appreciated is that independent cardiovascular death risk factors (e.g., hypertension, hyperglycemia, dyslipidemias and microalbuminuria) may each have a cyclic relationship with diabetic nephropathy. Thus, as discussed in this review, each risk factor may aggravate diabetic nephropathy, increasing the likelihood of end-stage renal disease. Diabetic nephropathy in turn may aggravate each of the risk factors, increasing the likelihood of a cardiovascular event. These cardiovascular risk factors, amplified by vicious cycles with diabetic nephropathy, may then lead to accelerated cardiovascular morbidity and mortality.

Atherogenic lipid phenotype in a general group of subjects

CONTEXT

The atherogenic lipid phenotype is a major cardiovascular risk factor, but normal values do not exist derived from 1 analysis in a general study group.

OBJECTIVE

To determine normal values of all of the atherogenic lipid phenotype parameters using subjects from a general study group.

DESIGN

One hundred two general subjects were used to determine their atherogenic lipid phenotype using polyacrylamide gradient gels.

RESULTS

Low-density lipoprotein (LDL) size revealed 24% of subjects express LDL phenotype B, defined as average LDL peak particle size 258 A or less; however, among the Chinese subjects, the expression of the B phenotype was higher at 44% (P = .02). For the total group, mean LDL size was 265 +/- 11 A (1 SD); however, histograms were bimodal in both men and women. After excluding subjects expressing LDL phenotype B, because they are at increased cardiovascular risk and thus are not completely healthy, LDL histograms were unimodal and the mean LDL size was 270 +/- 7 A. A small, dense LDL concentration histogram (total group) revealed skewing; thus, phenotype B subjects were excluded, for the rationale described previously, and the mean value was 13 +/- 9 mg/dL (0.33 +/- 0.23 mmol/L). High-density lipoprotein (HDL) cholesterol histograms were bimodal in both sexes. After removing subjects as described previously or if HDL cholesterol levels were less than 45 mg/dL, histograms were unimodal and revealed a mean HDL cholesterol value of 61 +/- 12 mg/dL (1.56 +/- 0.31 mmol/L). HDL 2, HDL 2a, and HDL 2b were similarly evaluated.

CONCLUSIONS

Approximate normal values for the atherogenic lipid phenotype, similar to those derived from cardiovascular endpoint trials, can be determined if those high proportions of subjects with dyslipidemic cardiovascular risk are excluded.

The Effects of Niacin on Lipoprotein Subclass Distribution

Dyslipidemia is a heterogeneous metabolic condition; high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low-density lipoprotein represent families of lipoprotein particles that differ in size and composition and vary in atherogenicity. Lipoprotein subclasses containing apolipoprotein B promote atherosclerosis, of which the most atherogenic appear to be the small, dense LDL and large very-low-density lipoprotein subclasses, while the large HDL2 subclass, which transports esterified cholesterol from the periphery to the liver, is considered the more cardioprotective. Niacin has long been known to improve concentrations of all major lipids and lipoproteins, but it also has consistently favorable effects on subclass distribution. A MEDLINE search was conducted for clinical studies reporting the effects of niacin on lipoprotein subclasses. The niacin-associated elevations in HDL cholesterol likely stem from differential drug effects on subclasses, producing favorable changes in levels of HDL2 and apolipoprotein A-I. Niacin has more moderate LDL cholesterol-lowering efficacy, but this change is associated with an increase in LDL particle size and a shift from small LDL to the less atherogenic, large LDL subclasses. In addition, it also tends to decrease concentrations of the larger very-low-density lipoprotein subclasses. Niacin confers diverse benefits with respect to both the quantity and quality of lipid and lipoprotein particles.

Polyacrylamide gradient gel electrophoresis of lipoprotein subclasses

High-density (HDL), low-density (LDL), and very-low-density (VLDL) lipoproteins are heterogeneous cholesterol-containing particles that differ in their metabolism, environmental interactions, and association with disease. Several protocols use polyacrylamide gradient gel electrophoresis (GGE) to separate these major lipoproteins into known subclasses. This article provides a brief history of the discovery of lipoprotein heterogeneity and an overview of relevant lipoprotein metabolism, highlighting the importance of the subclasses in the context of their metabolic origins, fates, and clinical implications. Various techniques using polyacrylamide GGE to assess HDL and LDL heterogeneity are described, and how the genetic and environmental determinations of HDL and LDL affect lipoprotein size heterogeneity and the implications for cardiovascular disease are outlined.

Clinical evidence for use of acetyl salicylic acid in control of flushing related to nicotinic acid treatment

Nicotinic acid (NA) is highly effective and widely used in the management of dyslipidaemia. For many patients, the side effect of flushing of the face and upper body leads to discontinuation. Flushing with NA is mediated by prostaglandins, and as acetyl salicylic acid (ASA, 'aspirin') is a highly effective inhibitor of prostaglandin synthesis, there is a rationale for its use to prevent or reduce the severity of NA-related flushing. This literature survey identified four studies specifically exploring the utility of ASA in preventing NA-related flushing in healthy volunteers. Twenty-three NA studies, where ASA was mandatory or optional within the protocol, and four studies, where background ASA therapy was reported in most participants, were also identified. Although the incidence of flushing in studies using ASA was often high, discontinuation rates due to flushing were low (mean 7.7%). This figure compares favourably with discontinuation rates with NA commonly reported in the literature (up to approximately 40%). There is good supportive evidence for the use of ASA in reducing the severity of NA-related flushing.

The metabolic syndrome: prevalence, CHD risk, and treatment

An increased risk of coronary heart disease (CHD) morbidity and mortality is associated with the metabolic syndrome, a condition characterized by the concomitant presence of several abnormalities, including abdominal obesity, dyslipidemia, hypertension, insulin resistance (with or without glucose intolerance or diabetes), microalbuminuria, prothrombotic, and proinflammatory states. Estimates of the prevalence of the metabolic syndrome indicate that this condition is now common and likely to increase dramatically over the coming decades, in parallel with greater rates of obesity and Type 2 diabetes. Risk factors for the metabolic syndrome are already present in obese children and adolescents. Thus, identifying and treating all affected individuals promptly and optimally are critical to ensure that this potentially challenging healthcare burden is minimized. Here, we review the prevalence of the metabolic syndrome, dyslipidemias, and CHD risk. Although changes in lifestyle are fundamental to reducing many of the CHD risk factors associated with the metabolic syndrome, pharmacologic interventions also play an important role. Retrospective subanalyses of the effects of statins on coronary event rates and lipid levels in patients with the metabolic syndrome included in clinical trials indicate that these agents are beneficial in correcting the extensive lipid abnormalities that are frequently present in these individuals. However, the optimal management of metabolic syndrome dyslipidemia will depend on the outcomes of future prospective clinical trials. This review examines the underlying causes and prevalence of the metabolic syndrome and its impact on CHD morbidity and mortality and discusses the role of statins in optimizing its management.

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.

Nicotinic acid in the management of dyslipidaemia associated with diabetes and metabolic syndrome: a position paper developed by a European Consensus Panel

Individuals with type 2 diabetes and metabolic syndrome are at markedly increased risk of cardiovascular morbidity and mortality. The increasing prevalence of both conditions poses a major challenge for clinicians in the 21st century. Both diabetes and metabolic syndrome are associated with a clustering of cardiovascular risk factors. In particular, dyslipidaemia characterised by low plasma levels of high-density lipoprotein cholesterol (HDL-C), elevated triglycerides and an increase in small, dense low-density lipoprotein (LDL) particles (the lipid triad), has been established as the most important modifiable risk factor for coronary heart disease (CHD). Current treatment guidelines recognise the increased CHD risk associated with diabetes and metabolic syndrome and focus on LDL-C lowering with statin treatment, in addition to dietary and lifestyle modification, as the primary lipid-modifying therapy. However, while there is no doubt that statin therapy significantly reduces CHD risk in these patients, their residual absolute risk remains higher than in individuals without diabetes or metabolic syndrome. Thus, there is a clear need to target other aspects of lipoprotein metabolism, notably low HDL-C and hypertriglyceridaemia, to further reduce CHD risk. Combining statin therapy (targeting LDL-C) with interventions that also modify low HDL-C and elevated triglycerides could be a useful strategy to optimise CHD risk reduction. Cautious combination of a fibrate or nicotinic acid with a statin is useful for the management of combined dyslipidaemia. Nicotinic acid is the more potent agent for raising HDL-C (by up to 29% at clinically recommended doses). It also substantially reduces triglycerides and LDL-C, and promotes a shift from small, dense LDL to larger, more buoyant LDL particles. Preliminary clinical data suggest that combining nicotinic acid with a statin will produce a greater reduction in cardiovascular risk in patients with diabetes and metabolic syndrome than statin monotherapy alone. Nicotinic acid is also safe for use in patients with diabetes, with no evidence of clinically relevant deterioration in glycaemic control at recommended doses (< or = 2 g/day). On review of the available evidence, this European Consensus Panel recommends the combination of nicotinic acid and a statin, together with lifestyle modification, as a useful strategy to lower CHD risk in patients with diabetes and metabolic syndrome. Prolonged-release nicotinic acid with improved tolerability compared with previous formulations may have obvious advantages for use in this setting.

The dyslipidemia of diabetes mellitus: giving triglycerides and high-density lipoprotein cholesterol a higher priority?

CVD is the primary cause of morbidity and mortality in patients who have diabetes mellitus. Most such patients have at least one lipid abnormality. Managing these complex lipid disorders is a crucial component of comprehensive diabetes mellitus care and limits the risk for cardiovascular morbidity and mortality. With the high prevalence of mixed lipid disorders, management must focus on all components of the lipid profile. Lowering LDL-C levels remains the first priority, but abnormalities in HDL-C and TG levels also should be treated aggressively. Statins, fibrates, and niacin, along with newer therapies such as ezetimibe, can improve significantly components of the lipid profile. Alone or in combination, these agents can treat the dyslipidemia of diabetes mellitus effectively and safely.

Therapeutic approaches in the prevention of cardiovascular disease in metabolic syndrome and in patients with type 2 diabetes

PURPOSE OF REVIEW

The metabolic syndrome is commonly encountered in the United States. It has been estimated from a survey conducted nearly a decade ago that one in four American adults fulfill the criteria for the metabolic syndrome. As obesity has become more common, the prevalence of type 2 diabetes has increased, and these trends can be expected to translate into more cardiovascular disease in future years. The high cardiovascular risk that accompanies the metabolic syndrome and type 2 diabetes mandates comprehensive and aggressive preventive care. This article reviews evidence that treatments directed at the individual components of the metabolic syndrome will delay the progression to type 2 diabetes and will reduce the incidence of cardiovascular disease.

RECENT FINDINGS

In overweight individuals with the metabolic syndrome, the onset of type 2 diabetes can be delayed by therapeutic lifestyle changes (weight loss and exercise), insulin sensitizers (metformin, troglitazone), angiotensin converting enzyme inhibitors (captopril, fosinopril, ramipril), and angiotensin receptor blockers (losartan, candesartan). Lipid altering therapies (statins, fibrates, and niacin) are especially efficacious for reducing cardiovascular events in metabolic syndrome and type 2 diabetes patients.

SUMMARY

An aggressive multifactorial approach to cardiovascular risk factor modification facilitates a delay in the onset of type 2 diabetes and cardiovascular events among individuals with the metabolic syndrome.

Clinical Update on the Use of Niacin for the Treatment of Dyslipidemia

PURPOSE

To provide nurse practitioners (NPs) with clinical and practical information about the use of niacin in the treatment of dyslipidemia.

DATA SOURCES

Research-based and review articles in the medical literature and National Cholesterol Education Program guidelines.

CONCLUSIONS

Niacin provides beneficial effects on all major lipid fractions, particularly high-density lipoprotein cholesterol and triglycerides. Niacin also reduces low-density lipoprotein (LDL) cholesterol; lipoprotein (a); and the number of highly atherogenic small, dense LDL particles. Niacin promotes angiographic regression when used in combination with other drugs that lower LDL cholesterol and can reduce cardiovascular risk in patients with coronary heart disease. Several niacin formulations are available, but the safety (i.e., from hepatotoxicity) and tolerability (i.e., severity of flushing) of these niacin formulations may differ.

IMPLICATIONS FOR PRACTICE

Niacin therapy is appropriate for many types of lipid abnormalities, including complex dyslipidemias. NPs can take several steps to minimize potential side effects of niacin therapy and to ensure that patients adhere to this important intervention.

Are the effects of nicotinic acid on insulin resistance precipitated by abnormal phosphorous metabolism?

Nicotinic acid is a unique cholesterol modifying agent that exerts favorable effects on all cholesterol parameters. It holds promise as one of the main pharmacological agents to treat mixed dyslipidemia in metabolic syndrome and diabetic patients. The use of nicotinic acid has always been haunted with concerns that it might worsen insulin resistance and complicate diabetes management.

We will discuss the interaction between phosphorous metabolism and carbohydrate metabolism and the possibility that worsening of insulin resistance could be related to adrug induced alteration in phosphorous metabolism, and the implications of that in medical management of diabetes and metabolic syndrome patients with mixed dyslipidemia.

Management of the metabolic syndrome-nicotinic acid

Nicotinic acid effectively treats each of the common lipid abnormalities found in the metabolic syndrome, and much progress has recently been made in understanding its mechanisms of action. Early concern that nicotinic acid can precipitate or worsen diabetes has been eased with recent trials, which demonstrated its safety and effectiveness in insulin-resistant states. Furthermore, nicotinic acid prevents cardiovascular disease and death in persons with a high prevalence of risk factors for the metabolic syndrome. When used by an experienced physician and taken by a motivated patient, nicotinic acid can be safe and effective in treating the dyslipidemia of the metabolic syndrome.

Does Lipoprotein(a) Inhibit Elastolysis in Abdominal Aortic Aneurysms?

PURPOSE

to test the hypothesis that there is a negative association between serum levels of lipoprotein(a) (Lp(a)) and elastin-derived peptides (EDP) as well as matrix metalloproteinase (MMP)-9 activation in the aneurysm wall in patients with asymptomatic abdominal aortic aneurysms (AAA).

MATERIAL AND METHODS

from 30 patients operated for asymptomatic AAAs, preoperative serum samples and AAA biopsies were collected. Lp(a) (mg/L) and EDP (ng/ml) in serum were measured by enzyme linked immunosorbent assays. MMP-9 activity (arbitrary units) in the AAA wall was measured by gelatin zymography and the ratio: active MMP-9/total MMP-9 were calculated.

RESULTS

there was a significant negative correlation (Spearman's rho) between serum levels of Lp(a) and EDP (r= -0.707, p<0.001), as well as the share of activated MMP-9 (r= -0.461, p=0.01) in the AAA wall.

CONCLUSION

this preliminary study indicate that Lp(a) inhibit elastolysis in asymptomatic AAA.