Atherosclerosis Supplements

Editorial Board

2011-11-01

Introduction

Philip Barter — 2011-11-01

Abstract: Lowering low-density lipoprotein-cholesterol (LDL-C) levels using statins can significantly reduce cardiovascular (CV) risk in patients with dyslipidemia. However, the risk of major vascular events in those attaining the maximum levels of LDL-C-reduction is only reduced by around one third, which leaves a substantial residual risk. The Emerging Risk Factors Collaboration has shown that low levels of high-density lipoprotein-C (HDL-C) are independent risk factors for CV disease. It is therefore important that treatment strategies for dyslipidemia should target HDL-C in addition to LDL-C. Raising HDL-C can be achieved by both lifestyle changes and pharmacological means. Therapeutic strategies include niacin, fibrates, thiazolidinediones, apolipoprotein Al mimetics, cholesteryl ester transfer protein inhibitors, statins and combinations thereof. In general, statins produce inconsistent increases in HDL-C. However, pitavastatin, a new member of the statin family that was launched in 2003, and rosuvastatin consistently elicit marked increases in HDL-C that are sustained over time. This supplement will discuss the contribution of HDL-C as a possible predictor and modifiable risk factor for CV disease and will examine the potential role for pitavastatin in reducing residual CV risk.

HDL-C: Role as a risk modifier

Philip Barter — 2011-11-01

Abstract: Evidence that low-density lipoprotein-cholesterol (LDL-C) causes cardiovascular disease (CVD) is overwhelming. It has also been proven beyond all doubt that lowering the level of LDL-C using statins reduces CV risk. However, many people remain at high risk even when their level of LDL-C has been reduced by aggressive treatment with statins. One reason for this residual risk can be a low level of high-density lipoprotein-cholesterol (HDL-C). The concentration of HDL-C is an independent, inverse predictor for CVD. This relationship is apparent even when treatment with statins has reduced the level of LDL-C to below 1.8 mmol/L (70 mg/dL). It has therefore been suggested that raising the level of HDL-C should be considered as a therapeutic strategy for reducing the residual CV risk that persists in some people, despite aggressive LDL-C lowering with statins. HDL particles have several functions with the potential to protect against arterial disease, the best known of which relates to their ability to promote cholesterol efflux from macrophages in the artery wall. However, HDLs have several additional protective properties that are independent of their involvement in cholesterol metabolism. For example, they have properties that reduce oxidation, vascular inflammation and thrombosis, improve endothelial function, promote endothelial repair, enhance insulin sensitivity and promote insulin secretion by pancreatic beta islet cells. There is also a large and compelling body of evidence in animal models showing that interventions that increase HDL levels are profoundly anti-atherogenic. Major causes of low HDL are abdominal obesity and type 2 diabetes, the worldwide incidences of which are increasing at alarming rates. Strategies to increase the concentration of HDL should begin with lifestyle changes such as weight reduction, increased physical activity and smoking cessation. However, compliance with such measures is frequently poor and pharmacological intervention may be required. Currently available HDL-raising medications include fibrates, niacin and statins. There is indisputable evidence that lowering LDL-C levels using statins translates into a large reduction in CV risk. There is also mounting evidence that increasing the level of HDL-C using statins contributes to an additional reduction in CV risk. For example, the increase in HDL-C levels that was associated with simvastatin treatment in the 4S study was a significant predictor for the reduction in CV events. Moreover, a meta-analysis of 1,455 patients in 4 coronary intravascular ultrasound imaging trials showed that both the achieved level of LDL-C and the increase in HDL-C concentration during statin treatment were significant independent predictors for coronary atheroma progression as assessed by coronary intravascular ultrasound. In conclusion, evidence suggests that low levels of HDL-C are associated with an increased CV risk even when LDL-C is reduced to below 1.7 mmol/L (70 mg/dL) with a statin. Moreover, there is mounting evidence that increasing the level of HDL-C has the capacity to reduce CV risk. Thus, there is a compelling case for targeting both the LDL and HDL fractions to reduce CV risk in people with dyslipidemia, high CV risk and low levels of HDL-C.

Pitavastatin: An overview

Yasushi Saito — 2011-11-01

Abstract: Compared to other statins, pitavastatin is a highly potent 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor and an efficient hepatocyte low-density lipoprotein-cholesterol (LDL-C) receptor inducer. Its characteristic structure (heptenoate as the basic structure, a core quinoline ring and side chains that include fluorophenyl and cyclopropyl moieties) provides improved pharmacokinetics and significant LDL-C-lowering efficacy at low doses. Unlike other statins, the cyclopropyl group on the pitavastatin molecule appears to divert the drug away from metabolism by cytochrome P450 (CYP) 3 A4 and allows only a small degree of clinically insignificant metabolism by CYP2C9. As a result, pitavastatin is minimally metabolized; most of the bioavailable fraction of an oral dose is excreted unchanged in the bile and is reabsorbed by the small intestine ready for enterohepatic recirculation. This process probably accounts for pitavastatin's increased bioavailability relative to most other statins and contributes to its prolonged duration of action. In addition to its potent LDL-C-lowering efficacy, a number of pleiotropic benefits that might lead to a reduction in residual risk have been suggested in vitro. These include beneficial effects on endothelial function, stabilisation of the coronary plaque, anti-inflammatory effects and anti-oxidation. With regard to the clinical safety and efficacy of pitavastatin, the Phase IV Collaborative study of Hypercholesterolemia drug Intervention and their Benefits for Atherosclerosis prevention (CHIBA study) showed similar changes in lipid profile with pitavastatin and atorvastatin in Japanese patients with hypercholesterolemia. However, a subgroup analysis of the CHIBA study showed that pitavastatin produced more significant changes from baseline in LDL-C, TG, and HDL-C in patients with hypercholesterolemia and metabolic syndrome. The clinical usefulness of pitavastatin has been further demonstrated in a number of Japanese patient groups with hypercholesterolemia, including those with insulin resistance, low levels of high-density lipoprotein-cholesterol (HDL-C), high levels of C-reactive protein, and chronic kidney disease. Finally, the Japan Assessment of Pitavastatin and AtorvastatiN in Acute Coronary Syndrome (JAPAN-ACS) study showed that pitavastatin induces plaque regression in patients with ACS, which suggests potential benefits for pitavastatin in reducing CV risk.

Pitavastatin: Novel effects on lipid parameters

M. John Chapman — 2011-11-01

Abstract: Atherogenic dyslipidemia is characterised by high levels of triglycerides, low levels of high-density lipoprotein-cholesterol (HDL-C), and moderate to marked elevations in low-density lipoprotein-cholesterol (LDL-C) concentrations; such dyslipidemia is further characterised by high apolipoprotein B (apoB): apolipoprotein A1 (apoA1) ratios. Numerous clinical trials have demonstrated that statins are effective in lowering LDL-C and reducing cardiovascular (CV) risk in people with dyslipidemia. However, the most effective treatments should target all of the key atherogenic features, rather than LDL-C alone. Pitavastatin is a new member of the statin class whose distinct pharmacological features translate into a broad spectrum of action on both apoB-containing and apoA1-containing lipoprotein components of the atherogenic lipid profile. The efficacy and safety of this statin has been demonstrated by a large clinical development programme conducted both in Japanese and Caucasian populations. Phase III and IV studies in a wide range of patients with primary hypercholesterolemia or combined dyslipidemia showed that 12 weeks' treatment with pitavastatin l–4 mg was well tolerated, significantly improved lipid profiles (including LDL-C, TG, and HDL-C levels) and increased the EAS-/NCEP ATP Ill-recommended LDL-C target attainment rate to a similar or greater degree as comparable doses of atorvastatin, simvastatin, or pravastatin. Results were similar across all patient groups and were generally sustained after 52 weeks of treatment. However, whereas the effects of atorvastatin and simvastatin on HDL-C levels remained constant over the long term, pitavastatin-treated patients experienced progressive and maintained elevations in HDL-C, ultimately increasing by up to 14.3% vs. initial baseline. In this context, it is significant that the in vitro studies of Yamashita et al. [J Atheroscler Thromb 2010;17:436–51] have shown pitavastatin to be distinguished by its potent stimulation of apoA1 production in hepatocyte-like cells. These findings suggest that pitavastatin may be highly efficacious in raising levels of lipid-poor apoA1 particles, which are known to be highly active in ABCA1-mediated cellular cholesterol efflux, an observation which is pertinent to the excessive accumulation of cholesterol in macrophage foam cells of the atherosclerotic plaque. Indeed, the intravascular remodelling and maturation of lipid-poor apoA1 particles is known to drive flux of apoA1, cholesterol and phospholipid through the HDL pathway. It is equally relevant that pitavastatin therapy has been shown to be efficacious in markedly reducing coronary atheroma volume in acute coronary syndrome patients in the JAPAN-ACS trial, a therapeutic effect which may be linked to its impact on apoA1/HDL metabolism and function. Overall, Phase III and IV studies demonstrate that pitavastatin 1–4 mg is well tolerated, attenuates the atherogenic lipid profile and increases LDL-C target attainment rates with a similar or greater efficacy to comparable doses of atorvastatin, simvastatin and pravastatin. Furthermore, pitavastatin may be particularly beneficial in high-risk patients with elevated concentrations of TG-rich lipoproteins and low levels of HDL-C, and in whom the atheroprotective function of HDL particles is typically defective; significantly, such patients typically exhibit persistent, residual cardiometabolic risk even when LDL-C is at goal. In this context, it is relevant that such patient groups cover a wide spectrum of metabolic diseases, including metabolic syndrome, type 2 diabetes, coronary disease, familial and non-familial forms of hypercholesterolemia, auto-immune diseases such as rheumatoid arthritis and lupus, renal disease and some forms of hepatic insufficiency.

Pitavastatin: Clinical effects from the LIVES Study

Tamio Teramoto — 2011-11-01

Abstract: Although clinical trials provide useful information on drug safety and efficacy, results do not always reflect those observed in the real world. The Japanese long-term prospective post-marketing surveillance LIVALO Effectiveness and Safety (LIVES) Study was designed to assess the efficacy and safety of pitavastatin in clinical practice in ∼20,000 patients. After 104 weeks, pitavastatin was associated with significant reductions in low-density lipoprotein-cholesterol (LDL-C) (29.1%) that largely occurred within 4 weeks of treatment initiation. In patients with abnormal triglyceride (TG) and high-density lipoprotein-cholesterol (HDL-C) levels at baseline, pitavastatin reduced TG and increased HDL-C by 22.7% and 19.9%, respectively. Overall, 88.2% of the primary prevention low-risk patients attained their Japan Atherosclerosis Society LDL-C target, compared with 82.7% of intermediate-risk patients, 66.5% of high-risk patients and 50.3% of secondary prevention patients. Only 10.4% of pitavastatin-treated patients experienced adverse events (AEs), of which approximately 84% were mild and around 1% was severe. Increases in blood creatine phosphokinase (2.7%), alanine aminotransferase (1.8%), myalgia (1.1%), aspartate aminotransferase (1.5%) and gamma-glutamyltransferase (1.0%) were the most common AEs and only 7.4% of patients discontinued pitavastatin due to AEs. Regression analysis demonstrated that age was not a significant factor for the incidence of any AE or myopathy-associated events. A subanalysis of initial LIVES data focussing on the effects of pitavastatin on HDL-C levels showed that HDL-C was elevated by 5.9% in all patients and by 24.6% in those with low (