Some coronary risk factors related to the insulin resistance syndrome and treatment with gemfibrozil. Experience from the Helsinki Heart Study

Cholesterol reduction yields clinical benefits: meta-analysis including recent trials

BACKGROUND

Previous meta-analyses reported by Gould et al found significant decreases of 15% in the risk for coronary heart disease (CHD)-related mortality and 11 % in risk for all-cause mortality per decrease of 10% in total cholesterol (TC) level.

OBJECTIVE

To evaluate the effects of reducing cholesterol on clinical events after including data from recent clinical trials.

METHODS

Using a literature search (MeSH key terms, including: bezafibrate, coronary disease, efficacy, gemfibrozil, hydroxymethylglutaryl-CoA reductase inhibitors, hypercholesterolemia, niacin [nicotinic acids], randomized controlled trials, and treatment outcome; years: 1999-2005), we identified trials published in English that assessed the effects of lipid-modifying therapies on CHD end points, including CHD-related death, myocardial infarction, and angina pectoris. We also included all studies from the previously published meta-analysis. Using the same analytic approach as previously, we determined the effects of net absolute reductions (1 mmol/L [38.7 mg/dL]) in TC and low-density lipoprotein cholesterol (LDL-C) on the relative risks (RRs) for all-cause mortality, CHD-related mortality, any CHD event (mortality or nonfatal myocardial infarction), and non-CHD-related mortality.

RESULTS

We included 62 studies involving 216,616 patients, including 126,474 from 24 randomized controlled trials the findings of which were published since the previous meta-analysis (1998). Among all patients, for every 1-mmol/L decrease in TC, there was a 17.5 reduction in RR for all-cause mortality; 24.5 %, for CHD-related mortality; and 29.5% for any CHD event. Corresponding reductions for every 1-mmol/L decrease in LDL-C were 15.6%, 28.0%, and 26.6%, respectively. Similar relationships were observed in patients without CHD. No significant relationship was found between lipid reduction and non-CHD-related mortality risk.

CONCLUSIONS

The results from the present analysis support conclusions from previous meta-analyses that cholesterol lowering is clinically beneficial in patients with CHD or at elevated CHD risk. These results also support the previous finding that non-CHD-related mortality is unrelated to lipid reductions.

Body weight, plasma insulin, and coronary events with gemfibrozil in the Veterans Affairs High-Density Lipoprotein Intervention Trial (VA-HIT)

BACKGROUND

The Veterans Affairs High-Density Lipoprotein Intervention Trial (VA-HIT) showed that gemfibrozil significantly reduced major coronary events in men with known coronary heart disease (CHD). To better understand why therapy was especially effective with obesity, diabetes, and hyperinsulinemia, changes in body weight and plasma insulin were determined after 1 year of gemfibrozil or placebo therapy and related to changes in lipids and CHD events.

RESULTS

With gemfibrozil significantly more subjects lost weight (51.7% versus 38.6%, P<0.0001) and significantly fewer subjects gained weight (42.5% versus 54.0%, P<0.0001) than with placebo. Both a greater loss and smaller gain in weight with gemfibrozil were age-related and significant in subjects > or =66 years (median age), but not in younger subjects. Weight change was paralleled by changes in insulin. With gemfibrozil, CHD events were significantly reduced with weight loss (hazard ratio [HR], 0.61; 95% CI, 0.44-0.84; P=0.002) and, particularly, with diabetes or hyperinsulinemia (HR, 0.53; 95% CI, 0.34-0.83; P=0.006). In contrast, CHD events were not significantly reduced without weight loss (HR, 0.83; 95% CI, 0.62-1.12; P=0.22).

CONCLUSIONS

In VA-HIT, gemfibrozil resulted in weight loss associated with reductions in insulin. With weight loss gemfibrozil produced a significant reduction in CHD events that did not occur in the absence of weight loss.

Inflammation in diabetes mellitus: role of peroxisome proliferator-activated receptor-alpha and peroxisome proliferator-activated receptor-gamma agonists

Patients with type 2 diabetes mellitus and/or the metabolic syndrome have considerable cardiovascular risk. Treatment with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and with antihypertensive and some antihyperglycemic agents reduces this risk, but residual macrovascular morbidity and mortality persist, even in patients assigned to intensive multifactorial intervention programs. Therapeutic strategies that target inflammation and lipid abnormalities not well addressed by statins may offer additional opportunities for improving the prognosis of these patients. Inflammation, a key mechanism of atherogenesis, appears to have particular relevance to diabetic vascular complications, as well as in the development of diabetes itself. Oxidative stress and hyperglycemia also figure among the pathogenic factors that promote cardiovascular complications in patients with the metabolic syndrome and/or diabetes and may augment the ongoing inflammation. Peroxisome proliferator-activated receptor (PPAR)-alpha and PPAR-gamma, members of the nuclear receptor family, form ligand-activated transcription factors that regulate key important metabolic pathways. PPARs have become therapeutic targets through the use of the fibrate class of antidyslipidemic drugs (PPAR-alpha) and the insulin-sensitizing thiazolidinediones (PPAR-gamma). The activation of these PPARs may also suppress inflammation and atherosclerosis. Recent clinical trials (Fenofibrate Intervention and Event Lowering in Diabetes [FIELD], Prospective Pioglitazone Clinical Trial in Macrovascular Events [PROactive]) have considered the impact of these PPAR agonists on cardiovascular disease, with mixed effects that require careful analysis, especially given ongoing trials and additional PPAR agonists in development.

Fibrates after the FIELD study: Some answers, more questions

Fibrates have a long history in cardiovascular disease. These drugs raise high-density lipoprotein (HDL)-cholesterol, reduce triglycerides and improve small dense low-density lipoprotein (LDL) so would be expected to have large effects in type 2 diabetes, where this is the typical lipid profile. The general trial results with these agents have been confusing, with varying cardiovascular benefits. The Fenofibrate Intervention and Endpoint Lowering in Diabetes (FIELD) study recruited a low-risk population with a lipid profile that would be more usually treated with a statin. FIELD showed a non-significant 11% reduction (p = 0.16) in the primary end point of coronary events and a significant 11% benefit on the secondary end point of cardiovascular events and procedures (p = 0.04). Most of the benefits were seen in primary prevention and non-fatal myocardial events. Fenofibrate had little effect on HDL-C; the effects of the trial are consistent with the LDL-C reducing potential of this drug. FIELD, because of unequal statin drop-in, gives little evidence on statin-fibrate combination therapy but does reinforce the available data on the safety of fenofibrate-statin combination therapy. In addition, fenofibrate showed possible benefits on microvascular disease end points, including albuminuria and retinopathy. On current data fenofibrate and gemfibrozil seem to be reasonable second-line agents in type 2 diabetes or secondary prevention with low HDL-C, respectively, based on outcome evidence. In combination therapy, drug-specific safety considerations will affect the exact choice of agent, especially in combination with statins, but the efficacy of combination therapy still requires validation in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study.

Role of the fibrinolytic and matrix metalloproteinase systems in development of adipose tissue

Obesity is a common disorder and related diseases such as diabetes, atherosclerosis, hypertension, cardiovascular disease and cancer are a major cause of mortality and morbidity in Western-type societies. Development of obesity is associated with extensive modifications in adipose tissue involving adipogenesis, angiogenesis and extracellular matrix proteolysis. The fibrinolytic (plasminogen/plasmin) and matrix metalloproteinase (MMP) systems cooperate in these processes. A nutritionally induced obesity model in transgenic mice has been used extensively to study the role of the fibrinolytic and MMP systems in the development of obesity. These studies support a role of both systems in adipogenesis and obesity; the role of specific members of these families, however, remains to be determined.

Fibric acid derivatives in cardiovascular disease prevention: results from the large clinical trials

PURPOSE OF REVIEW

Results from five large placebo-controlled trials with second-generation fibrates have shown varying success in reducing cardiovascular events. This review focuses on a number of extended analyses from these trials that may relate to the success or failure of fibrate therapy and indicate who might likely benefit from this therapy.

RECENT FINDINGS

Results have been far from uniform and several trials have been adversely impacted by high off-trial statin use. Collective evidence suggests, however, that fibrates have optimum cardiovascular benefit in diabetes or other manifestations of insulin resistance. Much of this evidence comes from posttrial analysis in subgroups with more sharply defined clinical characteristics than in the overall trial population. Analyses also suggest that different fibrates have a different range of favorable clinical properties, that the cardiovascular benefit of fibrates may not be readily measured or mostly predicted by changes in traditional lipid measurements, and that other nonlipid properties of fibrates as peroxisome proliferator-activated receptor agents might explain some of the benefit of these drugs.

SUMMARY

Results of major clinical endpoint trials with fibrates, although not uniformly positive, provide substantial evidence for a selective therapeutic role of these drugs in cardiovascular event reduction in diabetes or insulin resistance.

Managing diabetic dyslipidaemia--beyond LDL-C:HDL-C and triglycerides

Treatment with statins reduces coronary risk In all people but do not remove the risk associated with a low HDL-C or with other features of the metabolic syndrome such as an elevated level of plasma triglyceride or with a high BMI. Treatment with a fibrate such as gemfibrozil (a PPAR alpha agonist) has been shown to be especially effective in people with low HDL-C and other features of the metabolic syndrome. Potential beneficial effects of the combination of a statin and an agent with PPAR alpha activity in patients with type 2 diabetes is currently being addressed in the ongoing Action to Control Cardiovascular Risk in Diabetes (ACCORD) study.

The L162V polymorphism at the peroxisome proliferator activated receptor alpha locus modulates the risk of cardiovascular events associated with insulin resistance and diabetes mellitus: The Veterans Affairs HDL Intervention Trial (VA-HIT)

BACKGROUND

The Veterans Affairs HDL Intervention Trial (VA-HIT) showed that gemfibrozil, which activates peroxisome proliferator-activator receptor alpha (PPARalpha), significantly reduced the risk of cardiovascular (CV) events in men with low HDL cholesterol (< 40 mg/dl) and established coronary heart disease. Treatment was particularly beneficial in those with insulin resistance (IR) or diabetes mellitus (DM). We hypothesized that the association between a functional polymorphism at the PPARA locus (L162V) and the risk of a CV event, as well as response to fibrate therapy, might be greatest in those with either IR or DM (DM/IR) in VA-HIT.

METHODS AND RESULTS

A total of 827 men (placebo, n = 413; gemfibrozil, n = 414) from the VA-HIT were genotyped. This population included a high proportion of subjects with DM/IR. In VA-HIT, the PPARA V162 allele was associated with reduced levels of HDL cholesterol and the presence of DM/IR at baseline. It was also associated with reduced risk of CV events in those with DM/IR but not in those with neither (DM/IR *PPARA genotype, P = 0.005). Among subjects with DM/IR, treatment with gemfibrozil reduced CV events in non-carriers from 29.9 to 17.8% and carriers of the V162 allele from 14.7 to 4.8%. In contrast, carriers of the V162 allele with no DM/IR who were treated with gemfibrozil experienced significantly more CV events than did those who received placebo (20.6% versus 13.6%; P = 0.01).

CONCLUSIONS

The effect of the L162V polymorphism at the PPARA locus on CV risk depends on the presence of DM/IR. Among subjects treated with gemfibrozil, the V162 allele was associated not only with reduced CV risk in subjects with DM/IR, but also with significantly increased CV risk in the absence of these traits, identifying this genetic variant as a potential marker for predicting which subjects may have a favorable response to fibrate therapy.

The PPAR genes, cardiovascular disease and the emergence of PPAR pharmacogenetics

The peroxisome proliferator-activated receptors (PPARs) comprise a group of related transcription factors that serve to regulate a number of cellular processes that are central to cardiovascular health and disease. Two large bodies of work strongly implicate the PPARs as key factors in normal cardiovascular physiology and in cardiovascular pathophysiology: i) studies demonstrating associations between PPAR and abnormal cardiovascular phenotypes; and ii) pharmacological studies assessing the effects of specific PPAR agonists in clinical trials. With the abundance of data available from these studies as a background, PPAR pharmacogenetics has become a promising and rapidly-advancing field. This review summarises the current state of understanding of PPAR pharmacogenetics and its profound implications for the individualisation of therapy for patients with a diverse group of cardiovascular diseases.

Hypolipidemic therapy for the metabolic syndrome

The metabolic syndrome appears to affect a significant proportion of the population and is associated with increased risk for development of cardiovascular disease as well as of type-2 diabetes. No single treatment for the metabolic syndrome as a whole yet exists. While the primary management of patients with the metabolic syndrome involves healthy lifestyle promotion, the atherogenic dyslipidemia is a primary target for cardiovascular disease risk reduction in these patients. Statin therapy provides effective reduction of LDL-cholesterol, which represents the primary therapeutic goal of lipid-lowering therapy in patients at risk for cardiovascular disease. Fibrates in turn are effective in normalizing lipid levels (mainly triglycerides and HDL-cholesterol) in patients with the metabolic syndrome and may improve insulin resistance. Whereas statins remain the drug of choice for patients who need to achieve the LDL-cholesterol goal, fibrate therapy may represent an alternative for those with low HDL-cholesterol and high triglyceride levels. The simultaneous use of fibrates could be indicated in patients whose LDL-cholesterol is controlled by statin therapy but whose HDL-cholesterol and/or triglycerides are still inappropriate. Such a combination, however, needs careful monitoring due to the potential hazard of adverse drug interactions. Nicotinic acid and ezetimibe may be useful agents for therapy, particularly when combined with statins. A number of emerging therapies offer potential as future options for the pharmacological treatment of metabolic syndrome.

Drug therapy of the metabolic syndrome: minimizing the emerging crisis in polypharmacy

The metabolic syndrome--a collection of factors associated with increased risk for cardiovascular disease and diabetes--is becoming increasingly common, largely as a result of the increase in the prevalence of obesity. Although it is generally agreed that first-line clinical intervention for the metabolic syndrome is lifestyle change, this is insufficient to normalize the risk factors in many patients, and so residual risk could be high enough to justify drug therapy. However, at present there are no approved drugs that can reliably reduce all of the metabolic risk factors over the long term, and so there is growing interest in therapeutic strategies that might target multiple risk factors more effectively, thereby minimizing problems with polypharmacy. This review summarizes current understanding of the nature of the metabolic syndrome, and discusses each of the risk factors of the metabolic syndrome as possible primary drug targets; potential secondary or tertiary targets are also considered.

Sorting out the roles of PPAR alpha in energy metabolism and vascular homeostasis

PPARalpha is a nuclear receptor that regulates liver and skeletal muscle lipid metabolism as well as glucose homeostasis. Acting as a molecular sensor of endogenous fatty acids (FAs) and their derivatives, this ligand-activated transcription factor regulates the expression of genes encoding enzymes and transport proteins controlling lipid homeostasis, thereby stimulating FA oxidation and improving lipoprotein metabolism. PPARalpha also exerts pleiotropic antiinflammatory and antiproliferative effects and prevents the proatherogenic effects of cholesterol accumulation in macrophages by stimulating cholesterol efflux. Cellular and animal models of PPARalpha help explain the clinical actions of fibrates, synthetic PPARalpha agonists used to treat dyslipidemia and reduce cardiovascular disease and its complications in patients with the metabolic syndrome. Although these preclinical studies cannot predict all of the effects of PPARalpha in humans, recent findings have revealed potential adverse effects of PPARalpha action, underlining the need for further study. This Review will focus on the mechanisms of action of PPARalpha in metabolic diseases and their associated vascular pathologies.

FIELDS of dreams, fields of tears: a perspective on the fibrate trials

Endpoint studies have been performed with fibrates in coronary heart disease since 1971. The results have been confusing - starting with initial benefits in small studies, but contradicted by either minimal benefits in the Coronary Drug Project or adverse noncardiovascular (non-CV) effects in the World Health Organization Clofibrate Study. Fibrates returned for patients with low HDL-C and low LDL-C after a 25% event reduction were seen in the Veterans Affairs HDL Intervention Trial. The greater prominence ascribed to the lipid triad of the metabolic syndrome and the increasing prevalence of diabetes increased the topicality of fibrates given their main action of converting small dense to light buoyant LDL. The Fenofibrate Intervention in Event Lowering in Diabetes (FIELD) Study has carried on the tradition. Fenofibrate therapy in 9795 patients comprising a mixed low-risk primary and a medium-risk secondary prevention cohort resulted in an 11% reduction in coronary events (p = 0.16), a similar but significant reduction in CV events (p = 0.04; number needed to treat = 70). The benefits were concentrated in primary prevention and on nonfatal myocardial events, but the study was confounded by asymmetrical statin drop-in due to the LDL-C-lowering effect of fenofibrate. Safety was generally good, including in combination with statins, but old concerns about sudden death, pancreatitis and venous thrombosis returned. Unexpected benefits were seen with fenofibrate on microvascular endpoints including microalbuminuria and retinopathy. Fenofibrate is a reasonable second-line therapy for dyslipidaemia in diabetes and safe in combination therapy. Its benefits on microvascular disease and in combination therapy require further confirmation.

Low-density lipoprotein size and cardiovascular risk assessment

A predominance of small, dense low-density lipoproteins (LDL) has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. LDL size seems to be an important predictor of cardiovascular events and progression of coronary heart disease and evidences suggests that both quality (particularly small, dense LDL) and quantity may increase cardiovascular risk. However, other authors have suggested that LDL size measurement does not add information beyond that obtained by measuring LDL concentration, triglyceride levels and HDL concentrations. Therefore, it remains debatable whether to measure LDL particle size in cardiovascular risk assessment and, if so, in which categories of patient. Therapeutic modulation of LDL particle size or number appears beneficial in reducing the risk of cardiovascular events, but no clear causal relationship has been shown, because of confounding factors, including lipid and non-lipid variables. Studies are needed to investigate the clinical significance of LDL size measurements in patients with coronary and non-coronary forms of atherosclerosis; in particular, to test whether LDL size is associated with even higher vascular risk, and whether LDL size modification may contribute to secondary prevention in such patients.

The V227A polymorphism at the PPARA locus is associated with serum lipid concentrations and modulates the association between dietary polyunsaturated fatty acid intake and serum high density lipoprotein concentrations in Chinese women

Peroxisome proliferators activated receptor alpha (PPARalpha) regulates the transcription of several proteins involved in human lipoprotein metabolism. We screened the PPARA locus for polymorphisms in 20 unrelated subjects from each of three ethnic groups (Chinese, Malays and Asian Indians). Only the V227A polymorphism was observed. We genotyped 4248 subjects (2899 Chinese, 761 Malay and 588 Asian Indians) and found allele frequencies for the A227 allele of 0.04 in Chinese, 0.006 in Malays and 0.003 in Asian Indians. We examined the associations between this polymorphism and serum lipid concentrations in Chinese. In women, but not in men, the presence of the A227 allele was associated with lower serum concentrations of total cholesterol [5.38mmol/l (95%CI: 5.22-5.54) versus 5.21mmol/l (95%CI: 4.99-5.43), p=0.047] and triglycerides [1.19mmol/l (95%CI: 1.10-1.28) versus 1.09mmol/l (95%CI: 0.98-1.21), p=0.048]. We also found that the V227A polymorphism modulates the association between dietary polyunsaturated fatty acid intake and serum high density lipoprotein concentration (p-value for interaction=0.049). Our findings implicate PPARalpha in the lipid lowering associated with diets high in PUFA and suggests that genetic variation at the PPARA locus may determine the lipid response to changes in PUFA intake.

Diagnosis and management of the metabolic syndrome in obesity

The metabolic syndrome is a constellation of interrelated abnormalities that increase the risk for cardiovascular disease and progression to type 2 diabetes. The prevalence of this syndrome is increasing because of the 'obesity epidemic'. The National Cholesterol Education Program Adult Treatment Panel III defined practical criteria for the diagnosis of the metabolic syndrome and established the basic principles for its management. Also, the International Diabetes Federation recently proposed another definition. The metabolic syndrome is a secondary target for cardiovascular risk reduction. Clinicians should identify individuals with this condition, assess their cardiovascular risk and treat them by an aggressive and multifaceted approach. The most effective therapeutic intervention in patients with the metabolic syndrome should focus on modest weight reduction and regular physical activity. Adoption of a healthier diet and smoking cessation are necessary. Drug therapy may be needed to achieve recommended goals if therapeutic lifestyle changes are not sufficient. Low-density lipoprotein cholesterol is the primary target of therapy (new aggressive goals should be achieved). Statins are probably the drugs of choice. Fibrates and nicotinic acid are also useful options. Hypertension should be managed aggressively probably starting with an inhibitor of the renin-angiotensin system or a calcium channel blocker and adding a low dose of a thiazide diuretic if necessary. Aspirin should be administered if the cardiovascular risk is high. In the future acarbose, metformin, meglitinides and thiazolidinediones may be used in patients with the metabolic syndrome to delay the onset of type 2 diabetes and reduce cardiovascular risk. Such an intense and multifactorial approach is likely to reverse the bad prognosis associated with the metabolic syndrome.

Lipid therapy for cardiovascular disease with insulin resistance, diabetes, or the metabolic syndrome

Insulin resistance with the development of diabetes or metabolic syndrome is associated with characteristic lipid abnormalities and an increased likelihood of cardiovascular events. This review examines the rationale and clinical trial evidence for the benefit of lipid drug therapy in the presence of these related high-risk conditions. In particular, the results of the more recent statin trials are discussed and contrasted with evidence from trials with fibrates, which, although fewer in number, appear to show that this particular therapy has selective benefit for the overweight individual with diabetes or features of the metabolic syndrome.

Hypertriglyceridemia—why, when and how should it be treated?

The relationship between serum triglyceride levels and cardiovascular disease has remained enigmatic despite four decades of research. The majority of the available evidence tends to support the role of hypertriglyceridemia as an independent risk factor for cardiovascular disease. However, there are no guidelines recommending a target triglyceride level for prevention of cardiovascular disease. The focus of lipid lowering therapy still remains the reduction of global cardiovascular risk by optimizing LDL cholesterol levels. Therapeutic options for triglyceride-lowering include lifestyle modification and pharmacological agents, such as fibrates, omega 3 fatty acids and niacin. Post-hoc analyses of the Helsinki Heart Study, Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial and Bezafibrate Infarction Prevention Study suggest a beneficial effect of the treatment of hypertriglyceridemia with fibrates, mainly in obese subjects with insulin resistance. However, in order to establish the actual clinical relevance of lowering triglyceride levels, prospective trials need to be conducted with the specific purpose of studying the effects of triglyceride reduction on clinical end points, i. e. coronary events and stroke.

Fibrates and coronary risk reduction

Many medications are currently available to correct lipoprotein abnormalities when lifestyle measures alone are not sufficient. No single agent or class of agents is able to correct all of the lipoprotein abnormalities. This paper reviews the role of one class, the fibrates, in the management of lipid disorders and summarizes the clinical trial information relating to their impact on coronary artery disease.

Peroxisome Proliferator-Activated Receptor-Alpha and Atherosclerosis

Atherosclerosis is an inflammatory process, triggered by the presence of lipids in the vascular wall, and encompasses a complex interaction among inflammatory cells, vascular elements, and lipoproteins through expression of several adhesion molecules and cytokines. Activation of the nuclear receptor, peroxisome proliferator-activated receptor-alpha (PPAR-alpha), has been demonstrated to modulate many aspects of lipoprotein metabolism and inflammation in vitro as well as in animal and human studies. The tissue distribution of PPAR-alpha is extensive, and it is abundantly present in the vascular wall where it may mediate many of antiinflammatory and antiatherogenic effects. Major clinical trials such as the Veterans Affairs High-Density Lipoprotein Intervention Trial (VA-HIT), the Helsinki Heart Study, and the Diabetes Atherosclerosis Intervention Study (DAIS) have demonstrated the beneficial effects of synthetic agonists of PPAR-alpha, specifically fibric acid derivatives, on cardiovascular disease outcome. Although fibric acid trials have reported cardiovascular risk reduction in patients with dyslipidemia, the favorable alterations in plasma lipids can only partially explain the reduction in cardiovascular events in these studies. One common link among these trials was a cohort with a high prevalence of insulin resistance or diabetes, conditions associated with heightened systemic inflammation and increased risk for development and progression of atherosclerosis. We review the many antiatherogenic effects of PPAR-alpha ligands and evidence from fibric acid trials that individuals with insulin resistance or diabetes benefit the most from these drugs, consistent with their antiinflammatory and antithrombotic properties.

Role of fibric acid derivatives in the management of risk factors for coronary heart disease

Although elevated low-density lipoprotein (LDL)-cholesterol is a well established coronary heart disease (CHD) risk factor, the ability to adequately discriminate high-risk individuals by this risk factor alone is limited and other metabolic risk variables are known to modulate CHD risk. For instance, it has been reported that the cluster of metabolic disturbances observed among individuals with abdominal obesity, the so-called metabolic syndrome, is associated with a substantially increased risk of CHD. Among the features of the dyslipidaemic profile observed in these individuals, the high triglyceride-low high-density lipoprotein (HDL)-cholesterol dyslipidaemia is predictive of an elevated risk of CHD. Fibric acid derivatives (fibrates) have been used in clinical practice for more than 2 decades as a class of agents known to decrease triglyceride levels while substantially increasing HDL-cholesterol levels, with a limited but significant additional lowering effect on LDL-cholesterol levels. Although the clinical benefits of HMG-CoA reductase inhibitors (statins) have been well documented by primary and secondary prevention trials that justify their widespread use, it was not until the publication of the VA-HIT (Veterans Affairs High-Density Lipoprotein Intervention Trial) that the relevance of identifying HDL-cholesterol as a therapeutic target to reduce the risk of recurrent CHD events was finally confirmed. The clinical benefits of fibrate therapy are especially important in the subpopulation of patients with low HDL-cholesterol levels with the metabolic syndrome, particularly in patients with type 2 diabetes mellitus or in abdominally obese, hyperinsulinaemic patients. Evidence also suggests that there is a 'fibrate effect' that mediates the reduction in CHD risk beyond the favourable impact of these agents on HDL-cholesterol levels. This last notion is consistent with the pleiotropic effects of fibrates which are known to be related to their mechanisms of action. Through peroxisome proliferator-activated alpha-receptors, fibrates have a significant impact on the synthesis of several apolipoproteins (apo) and enzymes of lipoprotein metabolism as well as on the expression of several genes involved in fibrinolysis and inflammation. Fibrate therapy has been reported to decrease apo CIII levels (a powerful inhibitor of lipoprotein lipase) and increase apo AI levels, as well as to increase lipoprotein lipase activity. Such changes contribute to improve the catabolism of triglyceride-rich lipoproteins, leading to a substantial increase in HDL-cholesterol levels accompanied by a shift in the size and density of LDL particles (from small, dense LDL particles to larger, more buoyant cholesteryl ester-rich LDL). It is proposed that some of these pleiotropic effects could explain some of the clinical benefits of fibrate therapy beyond its HDL-raising properties, particularly among patients with abdominal obesity, hyperinsulinaemia or type 2 diabetes with both low HDL- and low/normal LDL-cholesterol levels.

Therapeutic roles of peroxisome proliferator-activated receptor agonists

Peroxisome proliferator-activated receptors (PPARs) play key roles in the regulation of energy homeostasis and inflammation, and agonists of PPARalpha and -gamma are currently used therapeutically. Fibrates, first used in the 1970s for their lipid-modifying properties, were later shown to activate PPARalpha. These agents lower plasma triglycerides and VLDL particles and increase HDL cholesterol, effects that are associated with cardiovascular benefit. Thiazolidinediones, acting via PPARgamma, influence free fatty acid flux and thus reduce insulin resistance and blood glucose levels. PPARgamma agonists are therefore used to treat type 2 diabetes. PPARalpha and -gamma agonists also affect inflammation, vascular function, and vascular remodeling. As knowledge of the pleiotropic effects of these agents advances, further potential indications are being revealed, including roles in the management of cardiovascular disease (CVD) and the metabolic syndrome. Dual PPARalpha/gamma agonists (currently in development) look set to combine the properties of thiazolidinediones and fibrates, and they hold considerable promise for improving the management of type 2 diabetes and providing an effective therapeutic option for treating the multifactorial components of CVD and the metabolic syndrome. The functions of a third PPAR isoform, PPARdelta, and its potential as a therapeutic target are currently under investigation.

On the role of plasminogen activator inhibitor-1 in adipose tissue development and insulin resistance in mice

OBJECTIVES

To investigate the role of plasminogen activator inhibitor-1 (PAI-1) in adipose tissue development and insulin metabolism.

METHODS

Aged male wild-type (WT) or transgenic mice with adipose tissue overexpression of PAI-1 (45-55 weeks) in 50% C57Bl/6: 50% Friend Virus B-strain (FVB) genetic background, kept on normal chow, were used without or with administration of a synthetic low molecular weight PAI-1 inhibitor (PAI-039) to the food (1 mg g(-1)) for 4 weeks.

RESULTS

The PAI-1 transgenic mice showed somewhat lower body weight and adipose tissue mass than WT mice, whereas fasting insulin levels were higher. Glucose and insulin tolerance tests did not reveal significant differences between both genotypes. Addition of PAI-039 to the food did not significantly affect total body fat, weight of the isolated s.c. and gonadal fat territories or their adipocyte size and blood vessel composition in either genotype. Fasting glucose levels and glucose tolerance tests were, for both genotypes, comparable with those without inhibitor treatment. Insulin levels and insulin tolerance tests in WT, but not in PAI-1 transgenic mice, suggested a higher insulin sensitivity after inhibitor treatment (insulin level 30 min after glucose injection of 2.0 +/- 0.17 ng mL(-1) vs. 3.2 +/- 0.48 ng mL(-1) without inhibitor treatment; P = 0.028).

CONCLUSIONS

In this model, overexpression of PAI-1 moderately impaired adipose tissue formation without affecting glucose or insulin tolerance. Administration of a synthetic PAI-1 inhibitor for 4 weeks did not affect adipose tissue development in WT or PAI-1 transgenic mice, but induced a higher insulin sensitivity in WT mice.

Metabolic syndrome in relationship to type 2 diabetes and atherosclerosis

Metabolic syndrome affects approximately one quarter of population in developed countries. Its presence is a major risk for development of both type 2 diabetes (T2DM) and atherosclerosis. The prevalence of cardiovascular disease is 2-3 times higher in individuals with metabolic syndrome than in age-matched controls. Most important components of metabolic syndrome are insulin resistance with or without glucose intolerance, abdominal obesity, atherogenic dyslipidaemia, hypertension, prothrombotic state and proinflammatory state. Early identification of subjects with metabolic syndrome is very important, since they represent a target group for multiple lifestyle and pharmacological interventions. Lifestyle interventions, antiobesity drugs and drugs increasing insulin sensitivity prevented development of T2DM in subjects with impaired glucose tolerance in randomized trials. Treatment of atherogenic dyslipidaemia to the therapeutic goals defined for diabetic patients seems reasonable and both statins and fibrates could be used based on evidence from clinical trials. Treatment of hypertension should also aim for target levels similar to those in diabetic patients. Using drugs affecting renin-angiotensin II axis, as first choice seems reasonable based on evidence from clinical trials showing the ability of these drugs to prevent T2DM and decrease albuminuria.

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.

Pleiotropic functions of plasminogen activator inhibitor-1

Plasminogen activator inhibitor-1 (PAI-1), a 45-kDa serine proteinase inhibitor with reactive site peptide bond Arg345-Met346, is the main physiological plasminogen activator inhibitor. It occurs in human plasma at an antigen concentration of about 20 ng mL(-1). Besides the active inhibitory form of PAI-1 that spontaneously converts to a latent form, also a substrate form exists that is cleaved at the P1-P1' site by its target enzymes, but does not form stable complexes. Besides its role in regulating hemostasis, PAI-1 plays a role in several biological processes dependent on plasminogen activator or plasmin activity. Studies with transgenic mice have revealed a functional role for PAI-1 in wound healing, atherosclerosis, metabolic disturbances such as obesity and insulin resistance, tumor angiogenesis, chronic stress, bone remodeling, asthma, rheumatoid arthritis, fibrosis, glomerulonephritis and sepsis. It is not always clear if these functions depend on the antiproteolytic activity of PAI-1, on its binding to vitronectin or on its intereference with cellular migration or matrix binding.

Peroxisome Proliferator-Activated Receptor-Alpha and Atherosclerosis: From Basic Mechanisms to Clinical Implications

Atherosclerosis is an inflammatory process triggered by the presence of lipids in the vascular wall and encompasses a complex interaction between inflammatory cells, vascular elements and lipoproteins through the expression of several adhesion molecules and cytokines. Activation of the nuclear receptor peroxisome proliferator-activated receptor-alpha (PPAR-alpha) has been demonstrated to modulate many aspects of lipoprotein metabolism and inflammation in vitro as well as in animal and human studies. The tissue distribution of PPAR-alpha is extensive and it is abundantly present in the vascular wall where it may mediate many of anti-inflammatory and antiatherogenic effects. Major clinical trials, such as the Veterans Affairs High-Density Lipoprotein Intervention Trial, the Helsinki Heart Study and the Diabetes Atherosclerosis Intervention Study, have demonstrated the beneficial effects of synthetic agonists of PPAR-alpha, specifically fibric acid derivatives, on cardiovascular disease outcome. Although fibric acid trials have reported cardiovascular risk reduction in patients with dyslipidemia, the favorable alterations in plasma lipids can only partially explain the reduction in cardiovascular events in these studies. One common link among these trials was a cohort with a high prevalence of insulin resistance or diabetes, conditions associated with heightened systemic inflammation and increased risk for development and progression of atherosclerosis. In this paper, we will review the many antiatherogenic effects of PPAR-alpha ligands and evidence from fibric acid trials that individuals with insulin resistance or diabetes benefit the most from these drugs, consistent with their anti-inflammatory and antithrombotic properties.

Dyslipidemia in visceral obesity: mechanisms, implications, and therapy

Visceral obesity is frequently associated with high plasma triglycerides and low plasma high density lipoprotein-cholesterol (HDL-C), and with high plasma concentrations of apolipoprotein B (apoB)-containing lipoproteins. Atherogenic dyslipidemia in these patients may be caused by a combination of overproduction of very low density lipoprotein (VLDL) apoB-100, decreased catabolism of apoB-containing particles, and increased catabolism of HDL-apoA-I particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance. Weight reduction, increased physical activity, and moderate alcohol intake are first-line therapies to improve lipid abnormalities in visceral obesity. These lifestyle changes can effectively reduce plasma triglycerides and low density lipoprotein-cholesterol (LDL-C), and raise HDL-C. Kinetic studies show that in visceral obesity, weight loss reduces VLDL-apoB secretion and reciprocally upregulates LDL-apoB catabolism, probably owing to reduced visceral fat mass, enhanced insulin sensitivity and decreased hepatic lipogenesis. Adjunctive pharmacologic treatments, such as HMG-CoA reductase inhibitors, fibric acid derivatives, niacin (nicotinic acid), or fish oils, may often be required to further correct the dyslipidemia. Therapeutic improvements in lipid and lipoprotein profiles in visceral obesity can be achieved by several mechanisms of action, including decreased secretion and increased catabolism of apoB, as well as increased secretion and decreased catabolism of apoA-I. Clinical trials have provided evidence supporting the use of HMG-CoA reductase inhibitors and fibric acid derivatives to treat dyslipidemia in patients with visceral obesity, insulin resistance and type 2 diabetes mellitus. Since drug monotherapy may not adequately optimize dyslipoproteinemia, dual pharmacotherapy may be required, such as HMG-CoA reductase inhibitor/fibric acid derivative, HMG-CoA reductase inhibitor/niacin and HMG-CoA reductase inhibitor/fish oils combinations. Newer therapies, such as cholesterol absorption inhibitors, cholesteryl ester transfer protein antagonists and insulin sensitizers, could also be employed alone or in combination with other agents to optimize treatment. The basis for a multiple approach to correcting dyslipoproteinemia in visceral obesity and the metabolic syndrome relies on understanding the mechanisms of action of the individual therapeutic components.

Inflammation, dyslipidaemia, diabetes and PPARs: pharmacological interest of dual PPARα and PPARγ agonists

Cardiovascular disease (CVD) remains the leading cause of mortality in developed countries. Several risk factors are associated with CVD, including type 2 diabetes, obesity, insulin resistance, dyslipidaemia and hypertension. Different pharmacological therapies have been developed to control these risk factors. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors, which belong to the nuclear receptor superfamily that controls lipid and glucose metabolism as well as inflammatory risk factors for CVD. PPARalpha agonists, such as the fibrates, correct dyslipidaemia, thus decreasing CVD risk. PPARgamma agonists, such as the glitazones, increase insulin sensitivity and decrease plasma glucose levels in patients with diabetes. Moreover, both PPARalpha and PPARgamma agonists exert anti-inflammatory activities in liver, adipose and vascular tissues. In this review, we focus on the mode of action of PPARalpha and PPARalpha agonists, illustrating the potential of the newly developed dual PPAR agonists for the treatment of global risk in patients with the metabolic syndrome or type 2 diabetes.

Drug treatment of combined hyperlipidemia

Combined hyperlipidemia is increasing in frequency and is the most common lipid disorder associated with obesity, insulin resistance and diabetes mellitus. It is associated with other features of the metabolic syndrome including hypertension, hyperuricemia, hyperinsulinemia and highly atherogenic subfractions of lipoprotein remnant particles including small dense low density lipoprotein-cholesterol. This review examines the mechanisms by which combined hyperlipidemia arises and the various drugs including fibric acid derivatives, hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, and nicotinic acid which can be used either as monotherapy or in combination to manage it and to improve prognosis from atherosclerotic disease in diabetes mellitus, insulin resistant states and primary combined hyperlipidemia. The therapeutic approach to combined hyperlipidemia involves determination of whether the cause is hepatocyte damage or metabolic derangements. Combined hyperlipidemia due to hepatocyte damage should be treated by attention to the primary cause. In the case of metabolic dysfunction because of imbalance in glucose and fat metabolism, therapy of diabetes mellitus and obesity should be optimised prior to commencement of lipid lowering drugs. Both fibric acid derivatives and HMG-CoA reductase inhibitors can be used in the treatment of combined hyperlipidemia with fibric acid derivatives having greater effects on triglycerides and HMG-CoA reductase inhibitors on LDL-C though both have effects on the other cardiovascular risk factors. There is some evidence of benefit with both interventions in mild combined hyperlipidemias and large scale trials are underway. Fibric acid derivatives and HMG-CoA reductase inhibitor therapy can be combined with care, provided that gemfibrozil is avoided, fibric acid derivatives are given in the mornings and shorter half -life HMG-CoA reductase inhibitors are used at night. Combined hyperlipidemia emergencies occur with predominant hypertriglyceridemia in pregnancy or as a cause of pancreatitis. Therapy in the former should aim to reduce chylomicron production by a low fat diet and intervention to suppress VLDL-C secretion using omega-3 fatty acids. In the latter case, fluid therapy alone and medium chain plasma triglyceride infusions usually reduce levels satisfactorily though apheresis may be required. Blood glucose levels also need aggressive management in these conditions. Combined hyperlipidemia is likely to become an increasing problem with the increase in the prevalence of obesity and diabetes mellitus and needs aggressive management to reduce cardiovascular risk.

The metabolic syndrome: an emerging health epidemic in women

The metabolic syndrome is a compilation of factors characterized by insulin resistance and the identification of 3 of the 5 criteria of abdominal obesity, elevated triglycerides, decreased high-density lipoprotein (HDL) level, elevated blood pressure, and elevated fasting plasma glucose. According to census data from 2000, these criteria have lead to the diagnosis of approximately 47 million Americans with the metabolic syndrome, correlating with the 61% increase in the incidence of obesity between 1991 and 2000. Insulin resistance occurs when target tissues cannot respond properly to normal concentrations of insulin. The results are hypercoagulability, endothelial dysfunction, inflammation, and eventually coronary artery disease. Treatment involves lifestyle modification, including diet and exercise, to treat obesity and prevent the development of diabetes. Patients who meet the criteria for the metabolic syndrome may also be treated with insulin-sparing and insulin-sensitizing medications that help to improve endothelial function, vascular reactivity, and vascular inflammation. Ultimately, treatment goals are to prevent cardiovascular disease by both altering the risk factors that are components of the syndrome, and treating the lifestyle issues inherent to the disease process, such as caloric restriction and increased physical activity. There are 2 million more women than men in the United States categorized as being obese, with the trend of obesity and diabetes increasing. In the last decade there has been a 74% increase in obesity, mostly in women. This epidemic needs to be understood and managed to prevent further morbidity and mortality owing to diabetes and cardiovascular disease.

The role of fibrates in managing hyperlipidemia: Mechanisms of action and clinical efficacy

At a time when the lipid management guidelines give more and more emphasis to the identification and treatment of high-risk patients with the metabolic syndrome and diabetes, there is an obvious need to balance the known effects of low-density lipoprotein (LDL) lowering with the new evidence of clinical efficacy derived from the adjustment of high-density lipoprotein (HDL) and triglyceride levels. Whereas the statins remain the drug of choice for patients who need to reach the LDL goal, fibrate therapy may represent the best intervention for subjects with atherogenic dyslipidemia and an LDL already close to goal. In addition, the concomitant use of fibrates may significantly reduce cardiovascular risk in patients whose LDL is controlled by statin therapy. In this review, we evaluate the pharmacologic properties of the fibrate drugs, with particular attention to the effects of peroxisome proliferator activated receptor a activation in the control of dyslipidemia as well as in the attenuation of arterial inflammation. Clinical trials of fibrates, such as the Helsinki Heart Study, Veterans Affairs High-density lipoprotein Intervention Trial, Diabetes Atherosclerosis Intervention Study, and Bezafibrate Infarction Prevention trial, have conjured up a scenario for the clinical utility of fibrates and their possible superiority to statins in the management of obese, insulin-resistant, and diabetic patients presenting with near-goal LDL and inappropriate HDL and triglyceride levels.

Cardiovascular disease in patients who have diabetes

Although cardiovascular disease continues to be the major cause of morbidity and mortality in diabetes, the understanding that multiple risk factor intervention is the cornerstone of diabetes management is leading to significant benefits for patients. Aggressive goal setting for modifiable cardiovascular risk factors that cluster in patients with diabetes, such as dyslipidemia, hypertension, and a procoagulant state, and judicious selection of efficacious therapies have been shown to produce significant reductions in cardiovascular events, and in some cases mortality, in controlled clinical trials. Although effective control of hyperglycemia per se has at most modest impact, the choice and application of antihyperglycemic therapies add to the benefit. In addition, newer agents and early intervention in prediabetic and diabetic individuals hold promise for even greater success in the prevention of this important complication of diabetes.

Impact of adjunctive thiazolidinedione therapy on blood lipid levels and glycemic control in patients with type 2 diabetes

OBJECTIVE

This study was undertaken to assess the effect of pioglitazone hydrochloride and rosiglitazone maleate on blood lipid levels and glycemic control when these drugs are used as adjunctive therapy in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Patients with type 2 diabetes receiving metformin and/or sulfonylurea (n = 829) were evaluated in this national, multicenter, retrospective study. Medical records from 318 endocrinology practices in the USA were randomly selected and screened for study inclusion. Data related to patient demographics and laboratory data were extracted from medical records and analyzed for primary and secondary outcomes.

MAIN OUTCOME MEASURES

The primary study outcome was the mean change in plasma rosiglitazone was associated with no significant triglyceride (TG) levels. Secondary outcome measures included mean changes in total cholesterol (TChol), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) concentrations and hemoglobin A1C levels.

RESULTS

With pioglitazone, TG levels declined by a mean of 51.5 mg/dl (P < 0.001), HDL-C levels rose by 3.3mg/dl (P < 0.001), and no change was seen in LDL-C or TChol. Treatment with change in TG levels and a 1.5mg/dl mean increase in HDL-C (P < 0.001). Furthermore, rosiglitazone therapy was associated with an 8 mg/dl mean increase in TChol (P < 0.001), and a 5.8 mg/dl mean increase in LDL-C (P < 0.001). Hemoglobin A1C levels were significantly reduced by approximately 1% within thiazolidinedione (TZD) cohorts (P < 0.001), but were not significantly different between study groups (P = 0.257).

CONCLUSIONS

Results from this study suggest that pioglitazone has a more favorable effect on lipid profiles of patients with type 2 diabetes compared with rosiglitazone. In particular, differences were observed in TG and LDL-C levels. Both TZDs were equivalent at reducing hemoglobin A1C levels. These differences in lipid effects may have an impact on cardiovascular outcomes. The full clinical importance of these lipid alterations must be further assessed in prospective trials.

Role of fibrates in reducing coronary risk: a UK Consensus

This paper presents the consensus reached by a panel of experts on the role of fibrates in reducing coronary heart disease (CHD). The emphasis is on the application of these agents in clinical practice. Evidence that low levels of high-density lipoprotein cholesterol (HDL-C) play a major role in the development of CHD, plus the roles of lifestyle modification and statin treatment in raising HDL-C, are briefly reviewed. Current thinking on single agent and combination therapies with fibrates is discussed with particular relevance to patients with low baseline HDL-C- whether receiving statins or not - and those with features of the metabolic syndrome. Recommendations on the practical use of fibrates are made in the light of recently published international guidelines on HDL-C management and the relevant evidence base.

Cardiovascular disease with diabetes or the metabolic syndrome: should statins or fibrates be first line lipid therapy?

PURPOSE OF REVIEW

Subgroups with diabetes or with features of the metabolic syndrome have been increasingly highlighted in large clinical endpoint trials with lipid therapy. This review will focus on the results of trials with statins or fibrates and examine the strength of the evidence for major cardiovascular event reduction with each kind of therapy in these high-risk subgroups that typically have low-to-moderate levels of LDL cholesterol.

RECENT FINDINGS

Of six statin trials in populations with moderately increased LDL cholesterol only one, the Heart Protection Study, has shown that statin therapy will significantly reduce the major coronary heart disease events of non-fatal myocardial infarction or coronary heart disease death in diabetes. None of these trials has shown that statins have a particular predilection for reducing cardiovascular events in individuals with higher levels of body weight or other features of the metabolic syndrome. There are far fewer trial data with fibrates than with statins. However, the Veterans Affairs High Density Lipoprotein Intervention Trial has shown that a fibrate can significantly reduce major cardiovascular events, most particularly coronary heart disease death, in those with diabetes as well as those without diabetes who have insulin resistance. Indeed, all fibrate trials show that this therapy appears to selectively benefit the individual with obesity and features of the metabolic syndrome.

SUMMARY

Based principally on evidence from the Veterans Affairs High Density Lipoprotein Intervention Trial and the cumulative experience with statins, trial data would thus far suggest that the patient with a modest increase in LDL cholesterol who has diabetes or features of the metabolic syndrome might be likely to achieve more substantial cardiovascular benefit from fibrate than from statin therapy.

Pharmacologie des agonistes de PPARα et PPARγ et des activateurs PPARα/γ mixtes en développement clinique

Cardiovascular diseases (CVD) remain the leading cause of mortality in the western societies. Several risk factors predispose to CVD including diabetes, obesity, insulin resistance, dyslipidemia and hypertension. Various pharmacological therapies have been developed to control the risk factors associated to CVD. Fibrates are able to correct dyslipidemia, therefore decreasing CVD risk. Thiazolidinediones (TZD) or glitazones by increasing insulin sensitivity decrease plasma glucose levels in diabetic patients. Both fibrates and TZD activate the peroxisome proliferator-activated receptors (PPARs), a family of nuclear receptors that play a central role in the control of lipid and glucose metabolism. In this review, we will discuss the mode of action of fibrates and TZD and we will present an overview on PPAR ligands under development.

Insulin resistance and cardiovascular events with low HDL cholesterol: the Veterans Affairs HDL Intervention Trial (VA-HIT)

OBJECTIVE

To assess the effect of insulin resistance and the benefit of the fibrate, gemfibrozil, on the incidence of major cardiovascular events in subjects with low HDL cholesterol and a broad range of triglyceride values who participated in the Veterans Affairs High Density Lipoprotein Intervention Trial (VA-HIT).

RESEARCH DESIGN AND METHODS

This intention-to-treat analysis, specified as a secondary objective in VA-HIT, determined using Cox proportional hazards models the 5-year combined incidence of nonfatal myocardial infarction, coronary heart disease (CHD) death, or stroke in relation to the presence or absence of insulin resistance (defined by the highest tertile of the homeostasis model assessment of insulin resistance, HOMA-IR) in conjunction with lower and higher levels of HDL cholesterol and triglycerides. The study population consisted of 2,283 men with known coronary heart disease (CHD), treated with either placebo or gemfibrozil, who could be subdivided into groups with diabetes with or without insulin resistance, with no diabetes but insulin resistance, and with neither diabetes nor insulin resistance.

RESULTS

With insulin resistance there was a significantly higher relative risk (RR) of a cardiovascular event both with diabetes (RR of 1.62 with 95% CI of 1.28-2.06) and without diabetes (RR of 1.43 with 95% CI of 1.03-1.98) than without insulin resistance. Throughout both lower and higher ranges of HDL cholesterol and triglycerides, the rate of new cardiovascular events and the reduction of events with gemfibrozil was greater in subjects with insulin resistance than without, despite the finding that an increase in HDL cholesterol and a decrease in triglycerides with gemfibrozil was less with insulin resistance than without insulin resistance.

CONCLUSIONS

Results show that in VA-HIT the occurrence of a new cardiovascular event and the benefit of fibrate therapy was much less dependent on levels of HDL cholesterol or triglycerides than on the presence or absence of insulin resistance.

Evidence for joint action of genes on diabetes status and CVD risk factors in American Indians: the strong heart family study

OBJECTIVES

Previous research among American Indians of the strong heart family study (SHFS) has demonstrated significant heritabilities for CVD risk factors and implicated diabetes as an important predictor of several of the phenotypes. Moreover, we recently demonstrated that genetic effects on CVD risk factors differed in diabetic and nondiabetic individuals. In this paper, we investigated whether a significant genetic influence on diabetes status could be identified, and whether there is evidence for joint action of genes on diabetes status and related CVD risk factors.

METHODS AND RESULTS

Approximately 950 men and women, age 18 or older, in 32 extended families, were examined between 1997 and 1999. We estimated the effects of genes and environmental covariates on diabetes status using a threshold model and a maximum likelihood variance component approach. Diabetes status exhibited a residual heritability of 22% (h2=0.22). We also estimated the genetic and environmental correlations between diabetes susceptibility and eight risk factors for CVD. All eight CVD risk factors displayed significant genetic correlations with diabetes status (BMI (rhoG=0.55), fibrinogen (rhoG=0.40), HDL-C (rhoG=-0.37), ln triglycerides (rhoG=0.65), FAT (rhoG=0.38 ), PAI-1 (rhoG=0.67), SBP (rhoG=0.57), and WHR (rhoG=0.58)). Three of eight traits (HDL-C (rhoE=-0.32), ln triglycerides (rhoE=0.33), and fibrinogen (rhoE=0.20)) displayed significant environmental correlations with diabetes status.

CONCLUSIONS

These findings suggest that in the context of a high prevalence of diabetes, still unidentified diabetes genes may play an important role in influencing variation in CVD risk factors.

Evidence for distinct genetic effects on obesity and lipid-related CVD risk factors in diabetic compared to nondiabetic American Indians: the Strong Heart Family Study

BACKGROUND

The relationship between diabetes and increased cardiovascular disease (CVD) risk is well established. Previous data from the Strong Heart Family Study (SHFS) have demonstrated significant heritabilities for CVD risk factors and implicated diabetes as an important predictor of several of the phenotypes in three large groups of American Indians in Arizona (AZ), Oklahoma (OK), and the Dakotas (DK). However, the genetic architecture of this relationship is not well understood. The purpose of the present paper is to determine whether the genetic effects on CVD risk factors in the SHFS are different in diabetic and nondiabetic individuals.

METHODS

Approximately 950 men and women, 18 years or older, in 32 extended families, were examined between 1997 and 1999. Interaction between genotype and diabetes status was estimated for nine CVD risk factors [body fat mass (FAT), body mass index (BMI), high-density lipoprotein cholesterol (HDL-C), log-transformed fibrinogen, log-transformed triglycerides, log-transformed urinary albumin : creatinine ratio (LACR), plasminogen activator inhibitor 1 (PAI-1), systolic blood pressure (SBP), and waist-to-hip ratio (WHR)], using a maximum likelihood variance decomposition technique.

RESULTS

We found evidence that genetic factors influencing BMI, FAT, log-transformed triglycerides, HDL-C, and WHR are differentially expressed in individuals with diabetes compared to those without diabetes.

CONCLUSION

Thus, in the environmental and genetic milieu of diabetes, there may be distinct genetic determinants of various CVD risk factors.

Statin-fibrate combination: therapy for hyperlipidemia: a review

Statins and fibrates are well-established treatments for hyperlipidaemias and the prevention of vascular events. However, fibrate + statin therapy has been restricted following early reports of rhabdomyolysis that mainly involved gemfibrozil, originally with bovastatin, and recently, with cerivastatin. Despite this limitation, several reports describing combination therapy have been published. This review considers these studies and the relevant indications and contraindications. Statin + fibrate therapy should be considered if monotherapy or adding other drugs (e.g. cholesterol absorption inhibitors, omega-3 fatty acids ornicotinic acid) did not achieve lipid targets or is impractical. Combination therapy should be hospital-based and reserved for high-risk patients with a mixed hyperlipidaemia characterised by low density lipoprotein cholesterol (LDL) >2.6 mmol/l(100 mg/dl, high density lipoprotein cholesterol (HDL) <1.0 mmol/l (40 mg/dl) and/or triglycerides> 5.6 mmol/l (500 mg/dl. These three 'goals' are individually mentioned in guidelines. Patients should have normal renal, liver and thyroid function tests and should not be receiving therapy with cyclosporine, protease inhibitors or drugs metabolised through cytochrome P450 (especially 3A4). Combination therapy is probably best conducted using drugs with short plasma half-lives; fibrates should be prescribed in the morning and statins at night to minimise peak dose interactions. Both drug classes should be progressively titated from low doses. Regular (3-monthly) monitoring of liver function and creatine kinase is required. In conclusion, fibrate + statin therapy remains an option in high-risk patents. However, long-term studies involving safety monitoring and vascular endpoints are required to demonstrate the efficacy of this regimen.

Obesity and cardiovascular disease

Obesity is a major contributor to the prevalence of cardiovascular disease in the developed world, and yet has only recently been afforded the same level of attention as other risk factors of coronary artery disease. Obesity is a chronic metabolic disorder associated with cardiovascular disease and increased morbidity and mortality. It is apparent that a variety of adaptations/alterations in cardiac structure and function occur as excessive adipose tissue accumulates, even in the absence of comorbidities. Shifts toward a less physically demanding lifestyle are observed today throughout different populations, and this scourge associated with obesity implicates a corresponding increase in the number of individuals afflicted with the metabolic syndrome, which defines the obese patient as being "at risk." Adipose tissue is not simply a passive storehouse for fat, but an endocrine organ that is capable of synthesizing and releasing into the bloodstream a variety of molecules that may impact unfavorably the risk factor profile of a patient. Indeed, obesity may affect atherosclerosis through unrecognized variables and risk factors for coronary artery disease such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, and the prothrombotic state. By favorably modifying lipids, decreasing blood pressure, and decreasing levels of glycemia, proinflammatory cytokines, and adhesion molecules, weight loss may prevent the progression of atherosclerosis or the occurrence of acute coronary syndrome events in the obese high-risk population.