Achieving optimal lipid goals in the metabolic syndrome: a global health problem.

The metabolic syndrome is defined by a constellation of cardiometabolic risk factors that include abdominal obesity, elevated blood sugar, high blood pressure, low high-density lipoprotein (HDL) cholesterol and elevated triglycerides. The metabolic syndrome is diagnosed when 3 of these 5 risk factors are present [1]. Underlying these metabolic risk factors is adipose tissue dysfunction and insulin resistance which leads to an increase in circulating free fatty acids (FFA). Increased FFA delivery to the liver increases hepatic secretion and triglyceride enrichment of very-low density lipoprotein (VLDL) cholesterol. Incomplete lipolysis of VLDL particles leads to an accumulation of triglyceride-rich remnant lipoproteins and triglyceride enrichment of HDL cholesterol via cholesteryl ester transfer protein (CETP) results in smaller HDL particles and low levels of HDL cholesterol [2]. Although lowdensity lipoprotein (LDL) cholesterol is not specifically part of the metabolic syndrome, individuals with the metabolic syndrome have a high concentration of small dense LDL cholesterol particles. The atherogenic dyslipidemia associated with the metabolic syndrome is an important risk factor for atherosclerosis and cardiovascular (CV) disease. The presence of the metabolic syndrome is associated with a 2-fold increased risk of CV disease and a 5-fold increased risk of diabetes [3]. The prevalence of the metabolic syndrome worldwide is on the rise. This is due to an increase in the rates of obesity in both adults and children, especially in developing countries [4]. Most deaths related to the metabolic syndrome are attributable to CV disease and this is mediated in large part by the hypertension and dyslipidemia associated with the metabolic syndrome. First-line management of the metabolic syndrome is lifestyle intervention; however when lifestyle changes alone are unsuccessful, pharmacologic therapy to target the high blood pressure and dyslipidemia associated with the metabolic syndrome is recommended. Statins are the drug of choice totarget the dyslipidemia associated with the metabolic syndrome and are effective in lowering not only LDL cholesterol, but also lower triglyceride-rich remnant lipoproteins and have favorable effects on the size and concentration of LDL cholesterol particles [5]. Post-hoc analyses from several clinical outcome studies have shown that statin therapy reduces major CV event in patients with the metabolic syndrome [6,7] and subgroup analyses from other clinical trials suggest that fibrates, niacin and omega-3 fatty acids may further reduce CV risk in statin treated patients with high triglycerides and low HDL cholesterol [8e10]. Although the new ACC/AHA cholesterol lowering guidelines [11] do not specifically address the metabolic syndrome nor set cholesterol goals for treatment, most individuals who have the metabolic syndrome will have a high CV risk score or other indications that would warrant statin therapy. The National Lipid Association [12] and several international societies [13,14] also recommend lipidlowering therapy for individuals with the metabolic syndrome and in contrast to the ACC/AHA cholesterol guidelines have set both LDL and non-HDL cholesterol goals for these patients. The question then is how successful have we been as clinicians in treating the dyslipidemia associated with the metabolic syndrome? In this issue of Atherosclerois, Wang and colleagues [15] help answer this question. They evaluated the use of lipid-lowering drugs and lipid goal attainment in patients with the metabolic syndrome from the large observational Dyslipidemia International Study of China (DYSIS-China). In this large study of 25, 697 patients of varying CV risk, over one-third had the metabolic syndrome. Among these patients 37% had coronary heart disease and 57% had type 2 diabetes. Patients with the metabolic syndrome were less likely to achieve their LDL and non-HDL cholesterol goals compared to patients without the metabolic syndrome. LDL cholesterol goal attainment was achieved in 47% of patients with the metabolic syndrome compared to 69% in those without the metabolic syndrome (p < 0.001). Non-HDL cholesterol goals were achieved in 51% of patients with the metabolic syndrome compared to 72% in those without the metabolic syndrome (p < 0.001). The higher the CV risk