Optimal management of combined dyslipidemia: what have we behind statins monotherapy?

Abstract

Evidence of the effectiveness of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) within continuum of atherothrombotic conditions and particularly in the treatment and prevention of coronary heart disease (CHD) is well established. Large-scale, randomized, prospective trials involving patients with CHD have shown that statins reduce the clinical consequences of atherosclerosis, including cardiovascular deaths, nonfatal myocardial infarction and stroke, hospitalization for acute coronary syndrome and heart failure, as well as the need for coronary revascularization. Direct testing of varying degrees of low-density lipoprotein (LDL)- cholesterol lowering has now been carried out in 4 large outcomes trials: PROVE IT-TIMI 22, A to Z, TNT and IDEAL. However, the question whether more aggressive LDL-cholesterol lowering by high-dose statins monotherapy is an appropriate strategy is still open: higher doses of statins are more effective mainly for the prevention of the nonfatal cardiovascular events but such doses are associated with an increase in hepatotoxicity, myopathy and concerns regarding noncardiovascular death. Moreover, despite the increasing use of statins, a significant number of coronary events still occur and many such events take place in patients presenting with type 2 diabetes and metabolic syndrome. More and more attention is now being paid to combined atherogenic dyslipidemia which typically presented in patients with type 2 diabetes and metabolic syndrome. This mixed dyslipidemia (or 'lipid quartet') - hypertriglyceridemia, low high-density lipoprotein (HDL)-cholesterol levels, a preponderance of small, dense LDL particles and an accumulation of cholesterol-rich remnant particles - emerged as the greatest 'competitor' of LDL-cholesterol among lipid risk factors for cardiovascular disease. Most recent extensions of the fibrates trials (BIP, HHS, VAHIT and FIELD) give further support to the hypothesis that patients with insulin-resistant syndromes such as diabetes and/or metabolic syndrome might be the ones to derive the most benefit from therapy with fibrates. However, different fibrates may have a somewhat different spectrum of effects. Other lipid-modifying strategies included using of niacin, ezetimibe, bile acid sequestrants, CETP inhibitors and omega-3 fatty acids. Particularly, ezetimibe/statins combinations provide superior lipid-modifying benefits compared Tenenbaum/Fisman/Motro/Adler 128 with any statins monotherapy in patients with atherogenic dyslipidemia. Atherogenic dyslipidemia is associated with increased levels of chylomicrons and their remnants containing 3 main components: apolipoprotein B-48, triglycerides and cholesterol ester of intestinal origin. Reduction in accessibility for one of them (specifically cholesteryl ester lessening due to ezetimibe administration) could lead to a decrease of the entire production of chylomicrons and result in a decrease of the hepatic body triglycerides pool as confirmed in number of clinical studies. However, the ENHANCE study showed no difference in the progression of carotid atherosclerosis between ezetimibe/simvastatin vs. simvastatin alone over a 2-year period. Conclusions regarding ezetimibe/statins combinations should not be made until the three large clinical outcome trials will be completed within the next 2-3 years. In addition, bezafibrate as a pan-PPAR activator has clearly demonstrated beneficial pleiotropic effects related to glucose metabolism, insulin sensitivity and pancreatic beta cell protection. Because fibrates, niacin, ezetimibe, omega-3 fatty acids and statins each regulate serum lipids by different mechanisms, combination therapy - selected on the basis of their safety and effectiveness, could be more helpful in achieving a comprehensive lipid control as compared with statins monotherapy.