"The lower the better" in hypercholesterolemia therapy: a reliable clinical guideline?

Since the publication of the second set of guidelines by the National Cholesterol Education Program, a solid body of data from landmark clinical studies has demonstrated that reduction in low-density lipoprotein (LDL) cholesterol with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor ("statin") therapy sharply diminishes the risk for coronary artery disease. These trials include the Scandinavian Simvastatin Survival Study, the West of Scotland Coronary Prevention Study, the Air Force/Texas Coronary Atherosclerosis Prevention Study, the Cholesterol and Recurrent Events investigation, and the Long-Term Intervention with Pravastatin in Ischaemic Disease trial. Coronary event rates and, in some cases, all-cause mortality decreased significantly after about 5 years of statin therapy in patients at risk for and those who had coronary artery disease at baseline. In contrast, recent subgroup analyses of these pivotal studies have in the aggregate challenged the premise that lower LDL cholesterol levels necessarily lead to further declines in risk for coronary artery disease, particularly among the patients most likely to be seen by the clinician: those with moderately elevated or normal cholesterol profiles. Indeed, when LDL cholesterol levels are in this range, further lowering with statin therapy elicits diminishing returns in terms of coronary event rates. These findings are readily accommodated by the curvilinear, or log-linear, model between serum cholesterol level and risk for coronary artery disease, which is predicated on data from large epidemiologic studies. In light of the current climate involving competing health care costs, the pursuit of progressively diminishing returns in terms of reductions in coronary artery disease risk through more aggressive lowering of LDL cholesterol levels appears to be unwarranted. Until data are published from ongoing randomized, clinical trials that can more effectively resolve the clinical utility of aggressive lipid-lowering strategies to improve coronary event rates, a prudent, evidence-based strategy seems warranted.     

Anterior pituitary hormone replacement therapy—a clinical review

This clinical review summarizes current approaches to diagnosis and treatment of anterior pituitary hormone deficiency. The diagnostic value of endocrine function tests and replacement strategies for hydrocortisone, thyroxine, sex steroids, and growth hormone replacement are reviewed. Female androgen deficiency syndrome and the current role of DHEA and testosterone replacement in women are also discussed.     

Predictive and protective autoimmunity in cardiovascular diseases: is vaccination therapy a reality?

The role of the immune system in modulating atherosclerosis has recently been well documented. Studies have revealed that cellular and humoral immunity plays crucial roles in atherogenic plaque formation. This includes macrophages, CD4+ T cells and dendritic cells as well as autoantigens such as oxidized low density lipoprotein (oxLDL), heat shock proteins and beta2-glycoprotein I. Given these recent advances, various modifications of the immune system in experimental models have been proposed as therapeutic strategies, with the potential of inhibiting atherosclerosis progression. These modifications are switching the immune system (CD4+ T cells) from Th1 towards a Th2 anti-inflammatory cytokine secretion, and the induction of protective antibodies both of which may be induced by specific vaccination. Recent identification of specific immunoreactive antigenic epitopes on modified LDL, their successful implementation for immunization and the induction of atheroprotection, supports the idea that active vaccination may emerge as a novel immuno-modulating atheroprotective strategy.