HDL-C: role as a risk modifier.

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.

Barter P 《-》

Targeting low HDL-cholesterol to decrease residual cardiovascular risk in the managed care setting.

Cziraky MJ ，Watson KE ，Talbert RL 《JOURNAL OF MANAGED CARE PHARMACY》

Targeting residual cardiovascular risk: raising high-density lipoprotein cholesterol levels.

Hausenloy DJ ，Yellon DM 《-》

Pitavastatin: novel effects on lipid parameters.

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.

Chapman MJ 《-》

Targeting residual cardiovascular risk: raising high-density lipoprotein cholesterol levels.

Hausenloy DJ ，Yellon DM 《-》