Diet, lipoproteins, and coronary heart disease

Niacin and fibrates in atherogenic dyslipidemia: pharmacotherapy to reduce cardiovascular risk

Although statin therapy represents a cornerstone of cardiovascular disease (CVD) prevention, a major residual CVD risk (60-70% of total relative risk) remains, attributable to both modifiable and non-modifiable risk factors. Among the former, low levels of HDL-C together with elevated triglyceride (TG)-rich lipoproteins and their remnants represent major therapeutic targets. The current pandemic of obesity, metabolic syndrome, and type 2 diabetes is intimately associated with an atherogenic dyslipidemic phenotype featuring low HDL-C combined with elevated TG-rich lipoproteins and small dense LDL. In this context, there is renewed interest in pharmacotherapeutic strategies involving niacin and fibrates in monotherapy and in association with statins. This comprehensive, critical review of available data in dyslipidemic subjects indicates that niacin is more efficacious in raising HDL-C than fibrates, whereas niacin and fibrates reduce TG-rich lipoproteins and LDL comparably. Niacin is distinguished by its unique capacity to effectively lower Lp(a) levels. Several studies have demonstrated anti-atherosclerotic action for both niacin and fibrates. In contrast with statin therapy, the clinical benefit of fibrates appears limited to reduction of nonfatal myocardial infarction, whereas niacin (frequently associated with statins and/or other agents) exerts benefit across a wider range of cardiovascular endpoints in studies involving limited patient numbers. Clearly the future treatment of atherogenic dyslipidemias involving the lipid triad, as exemplified by the occurrence of the mixed dyslipidemic phenotype in metabolic syndrome, type 2 diabetes, renal, and auto-immune diseases, requires integrated pharmacotherapy targeted not only to proatherogenic particles, notably VLDL, IDL, LDL, and Lp(a), but also to atheroprotective HDL.

Combined effects of saturated fat and cholesterol intakes on serum lipids: Tehran Lipid and Glucose Study

OBJECTIVE

This study investigated the combined effect of saturated fat and cholesterol intake on serum lipids among Tehranian adults.

METHODS

In 443 subjects >or=18 y, dietary intake was assessed. Height and weight were measured and body mass index was calculated. Serum cholesterol, triacylglycerol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol levels were calculated. Cholesterol intakes >or=300 mg/d and saturated fat intakes >or=7% of total energy were defined as high intakes. Individuals were categorized into four groups based on cholesterol and saturated fat intakes.

RESULTS

Subjects' mean age was 40.1 +/- 14.6 y; those in whom cholesterol and saturated fat intake was normal had significantly less energy and fat intake than those with high cholesterol and saturated fat intakes (P < 0.01). Saturated fat intake had a significant effect on serum total and HDL-C levels. Subjects with a normal saturated fat intake had significantly less serum total and HDL-C than those who had high saturated fat intake (P < 0.01 and P < 0.05, respectively). Adjusting for age, sex, and body mass index, the main effect of cholesterol intake on HDL-C was significant (P = 0.05). Mean serum HDL-C was lower in subjects who had normal cholesterol intake than in those with high cholesterol intake.

CONCLUSION

These results show that cholesterol and saturated fat intakes have no combined effect on serum low-density lipoprotein cholesterol level, whereas cholesterol intake per se affects serum HDL-C level.

Therapy Insight: cardiovascular disease in pediatric systemic lupus erythematosus

In 15-20% of cases, systemic lupus erythematosus (SLE) presents before the age of 18 years, and such early-onset SLE seems to be particularly severe. SLE is an independent risk factor for premature atherosclerosis and death in young, premenopausal women with SLE, even after controlling for traditional cardiovascular risk factors. Children and adolescents with SLE are particularly susceptible to this long-term threat to their cardiovascular health because they have an increased disease severity and a lengthy disease burden. Factors that contribute to premature atherosclerosis include the inflammatory and immune abnormalities that are intrinsic to SLE, primary dyslipidemias, and the secondary effects of treatments such as corticosteroids. However, few rheumatologists provide appropriate preventive or management strategies for the increased atherosclerosis risk in this age-group. Screening should be performed on a regular basis, including evaluation of, and counseling for, traditional risk factors. Studies of treatment in pediatric patients are limited, and treatment strategies are often extrapolated from adult studies. Statins hold promise because they have both lipid-lowering and anti-inflammatory effects. There have been few studies of the use of statins in adults or adolescents with SLE; however, trials are currently underway to address the safety and efficacy of statin use in pediatric SLE.

Effectiveness of altering serum cholesterol levels without drugs

Drug therapy with statins and other agents can result in dramatic lipid-lowering effects. Despite the wealth of data supporting the beneficial effects of pharmacologic therapy on cardiovascular risk, patients often express a desire to accomplish similar goals with diet alone. And, except for patients with extreme cholesterol elevations, consensus panels all promote dietary therapy as an initial step in the treatment of hyperlipidemia. This review examines a variety of dietary strategies designed to lower lipid levels, including the American Heart Association diet, the Ornish diet, the Mediterranean diet, exercise, phytosterols, fiber, soy products, and fish oil. Though the declines in low-density lipoprotein cholesterol levels with these methods range from 0% to 37%, cardiovascular risk may be more significantly impacted than would be predicted from these changes alone. Significant benefits can be reaped from nonpharmacologic measures.

Nutritional and medical therapy for dyslipidemia in patients with cardiovascular disease

Dyslipidemia is a significant risk factor for the progression of cardiovascular disease, particularly when associated with other risk factors. An understanding of the pathophysiology and risks for patients with atherosclerotic diseases of undertreated dyslipidemia is essential for the healthcare provider. In this article, a review of epidemiologic data regarding the role of lipid levels in cardiovascular disease prognosis is presented. A familiarity with current dietary and drug treatment of lipid disorders is at the core of an evidence-based approach to dyslipidemia management in the patient with established cardiovascular diseases.

Low apolipoprotein A-IV plasma concentrations in men with coronary artery disease

OBJECTIVES

The objective of this study was to evaluate the relation between apolipoprotein A-IV (apoA-IV) plasma concentrations and coronary artery disease (CAD).

BACKGROUND

Experimental in vitro and in vivo studies favor apoA-IV to be protective against the development of atherosclerosis. Mice that overexpress either human or mouse apoA-IV demonstrated a significant reduction of aortic atherosclerotic lesions compared with control mice. Data on apoA-IV plasma concentrations and CAD in humans are lacking.

METHODS

We determined in two independent case-control studies of a Caucasian and an Asian Indian population whether apoA-IV plasma concentrations are related to the presence of angiographically assessed CAD.

RESULTS

Plasma apoA-IV levels were significantly lower in 114 male Caucasian subjects with angiographically defined CAD when compared with 114 age-adjusted male controls (10.2 +/-3.8 mg/dL vs. 15.1 +/- 4.0 mg/dL, p < 0.001). Logistic regression analysis indicated that the association between apoA-IV levels and CAD was independent of the high-density lipoprotein cholesterol and triglyceride concentrations. The inverse relationship between plasma levels of apoA-IV and the presence of CAD was confirmed in an independent sample of 68 male Asian Indians with angiographically documented CAD and 68 age-matched controls.

CONCLUSIONS

The results of this cross-sectional study demonstrate for the first time an association between low apoA-IV concentrations and CAD in humans and suggest that apoA-IV may play an antiatherogenic role in humans.