Effective lipid modification by partial ileal bypass reduced long-term coronary heart disease mortality and morbidity: five-year posttrial follow-up report from the POSCH. Program on the Surgical Control of the Hyperlipidemias

Aggressive statin therapy for acute coronary syndromes

Acute coronary syndromes (ACS) account for an enormous disease burden, especially in the Western world. Patients suffering acute coronary events are now understood to carry a very high risk of further coronary events and although improvements in conventional medical therapy over the past two decades have significantly reduced the risk, it remains high. Therapy with HMG CoA reductase inhibitors (statins) have now been well established for the primary and secondary prevention of stable coronary heart disease, but recently a substantial body of evidence has proven their efficacy in the treatment of ACS. This article examines this emerging evidence for the use of statins in ACS.

Gastric bypass reduces biochemical cardiac risk factors

BACKGROUND

Coronary artery disease (CAD) is the leading cause of death in the United States, with obesity as a leading preventable risk factor for CAD. Certain biochemical markers have demonstrated strong prediction for cardiovascular events. We hypothesized that in addition to weight reduction, gastric bypass will also induce a salutary effect on the biochemical cardiac risk factors.

METHODS

At a single academic institution, from 2003 to 2004, we measured the biochemical cardiac risk factors in gastric bypass patients preoperatively and at 3, 6, and 12 months postoperatively. These risk factors included total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, total cholesterol/HDL cholesterol ratio, triglyceride/HDL cholesterol ratio, triglycerides, lipoprotein A, high-sensitivity C-reactive protein, and homocysteine. The data were analyzed using the Wilcoxon signed rank test.

RESULTS

The mean age of the 356 patients was 43 years; 84% were women; the mean body mass index was 47 kg/m(2); 33% were diabetic; 50% were hypertensive; 23% were taking lipid-lowering medications; and 2% had known CAD. Significant improvement occurred in the biochemical cardiac factors from preoperatively to 12 months. The beneficial changes were as follows: total cholesterol, 192 mg/dL preoperatively to 166 mg/dL at 12 months; HDL cholesterol, 46 mg/dL preoperatively to 54 mg/dL at 12 months; low-density lipoprotein, 125 mg/dL preoperatively to 88 mg/dL at 12 months; total cholesterol/HDL cholesterol ratio, 4 preoperatively to 3 at 12 months; triglyceride/HDL cholesterol ratio, 3 preoperatively to 2 at 12 months; triglycerides, 133 mg/dL preoperatively to 92 mg/dL at 12 months; lipoprotein A, 14 mg/dL preoperatively to 13 mg/dL at 12 months; high-sensitivity C-reactive protein, 8 mg/L preoperatively to 1 mg/L; and homocysteine, 10 mumol/L preoperatively to 8 mumol/L at 12 months.

CONCLUSIONS

The results of our study have shown that gastric bypass significantly improves all biochemical markers of CAD risk, particularly C-reactive protein, which had an 80% reduction. As a result, gastric bypass decreases the cardiac risk by both weight loss and advantageous alterations of biochemical cardiac risk factors.

Dyslipidaemia and microvascular disease in the retina

PURPOSE

There are few data on the effect of serum lipids on microvascular disease. This study assessed the relationships between serum lipid levels and microvascular disease, as seen in the retina, among participants who attended a population-based study in Australia (n=3654, aged 49+years).

METHODS

Diameters of retinal arterioles and venules were measured from digitised photographs of each participant to obtain an estimate of generalised arteriolar narrowing. Focal arteriolar narrowing, arteriovenous nicking, and retinopathy lesions (microaneurysms, haemorrhages, hard/soft exudates) were graded using a standard protocol. Fasting blood tests were performed in 89% of subjects. Adjusted means were calculated using general linear models. Logistic regression models were used to determine the odds ratios for retinal microvascular signs.

RESULTS

After controlling for age, sex, body mass index, smoking, and mean arterial blood pressure, elevated high-density lipoprotein cholesterol was associated with narrower retinal arterioles (Ptrend=0.002) and venules (Ptrend=0.03) and with increased odds of generalised arteriolar narrowing (odds ratio 1.6, 95% confidence interval 1.1-2.2 for the highest vs the lowest quintile of high-density lipoprotein cholesterol). Serum triglyceride had a U-shaped relationship with venular diameter (Ptrend=0.003). We found no consistent pattern of association between serum total cholesterol or low-density lipoprotein cholesterol and any retinal microvascular signs.

CONCLUSIONS

These findings suggest that microvascular disease in the retina may result from processes distinct from dyslipidaemia.

Thematic review series: The Pathogenesis of Atherosclerosis. An interpretive history of the cholesterol controversy, part IV: The 1984 Coronary Primary Prevention Trial ends it—almost

As of the early 1980s, despite the wealth of evidence from experimental animal models, the extensive epidemiologic evidence, the powerful genetic evidence, and the strongly suggestive clinical intervention trial results, most clinicians still remained unpersuaded regarding the relevance of the lipid hypothesis. What was needed was a well-designed, large-scale, long-term, double-blind study demonstrating a statistically significant impact of treatment on coronary heart disease events. The National Institutes of Health (NIH) had laid the groundwork for such a study as early as 1970, but the study was not completed and the results published until 1984. This study, the Coronary Primary Prevention Trial, showed that treatment with a bile acid binding resin reduced major coronary events in hypercholesterolemic men by 19%, with a P value of 0.05. The NIH followed this up with a national Consensus Development Conference on Lowering Blood Cholesterol to Prevent Heart Disease. For the first time, the NIH now went on record advocating screening for hypercholesterolemia and urging aggressive treatment for those at high risk. The Institute initiated a national cooperative program to that end, the National Cholesterol Education Program. For the first time, preventing coronary heart disease became a national public health goal.

Nonpharmacologic Approaches for the Treatment of Hyperlipidemia

Coronary heart disease (CHD) is the leading cause of death in the United States. Dyslipidemias, like decreased high-density lipoprotein (HDL) and increased low-density lipoprotein (LDL), have been linked through epidemiologic and experimental studies with the development of atherosclerosis and an increased risk of CHD. The introduction of various classes of lipid-lowering drugs, especially the hydroxymethylglutaryl-coenzyme-A-reductase inhibitors (statins), has allowed for effective treatment of hyperlipidemia. This article reviews the following nonpharmacologic approaches to hyperlipidemia: LDL apheresis, surgery, the emergence of HDL as a therapeutic target, gene therapy, and finally, the possibility of developing a vaccine against atherosclerosis.

Old and new cardiovascular risk factors: from unresolved issues to new opportunities

With the aim of identifying areas that may deserve some further thinking the present review deliberately points out controversial issues in cardiovascular research and risk assessment. In the first part of the review general aspects are addressed regarding the evaluation of risk factors. A first point of concern is the frequent practice of combining different vascular events and effects in different vascular beds into a single endpoint. Furthermore, verification of vascular events in clinical reality may be surprisingly inaccurate. Problems in risk assessment also arise from overlapping properties (shared pathophysiological pathways) of traditional risk factors like hypertension, obesity and diabetes. In the second part of the review unresolved issues concerning selected established and emerging risk factors are discussed. The difficulty of establishing causality in cardiovascular disease is addressed, using modification of LDL cholesterol and accumulating evidence for pleiotropic effects of the LDL cholesterol-lowering statins as an example. As an alternative or supplement to the notion of LDL-related cardiovascular risk it is proposed to distinguish between statin-sensitive and statin-insensitive cardiovascular risk. Finally the future prospects of selected new and emerging risk factors like CRP, homocysteine, asymmetrical dimethylarginine (ADMA), oxLDL, and isoprostanes are evaluated. In summary, imprecise terminology and varying definitions of "cardiovascular risk" may lead to a considerable blurring of our current risk estimates, which may also explain some presently controversial issues. With several new risk factors and substantial changes in lifestyle and treatment patterns on the horizon major changes in the hierarchy of risk factors may be inevitable.

Isoprenoid metabolism and the pleiotropic effects of statins

Convincing evidence from basic research and animal studies shows that HMG CoA reductase inhibitors or statins, exert cardiovascular protective effects beyond cholesterol-lowering. Because of the central role of LDL-C in mediating vascular pathology and the efficacy of statins for lowering LDL-C, the clinical importance of these additional non-lipid effects remains to be determined. Nevertheless, there is growing evidence from recent clinical trials, which suggests that some of the beneficial effects of statins may be unrelated to changes in LDL-C. Indeed, in animal studies, many of the cholesterol-independent or “pleiotropic” effects of statins are due predominantly to inhibition of isoprenoid, but not cholesterol synthesis. Thus, with the recent findings of the HPS and ASCOT-LLA, the potential cholesterol-independent effects of statins have shifted the treatment strategy from numerical lipid parameters to the global assessment of cardiovascular risks.

The place of ezetimibe in clinical practice

Ezetimibe is the first selective cholesterol absorption inhibitor to be licensed in the UK. It interferes both with dietary cholesterol absorption and the enterohepatic circulation of cholesterol synthesized by the liver. As monotherapy it leads to modest reductions in plasma low-density lipoprotein cholesterol levels, but has synergistic effects when used with statins.

Imaging of the postsurgical small bowel

The small bowel is subject to a variety of surgical interventions for the treatment of a broad spectrum of disease processes. Most operative procedures applied to the small bowel are straightforward techniques encumbered by few complications, whereas other procedures are considerably more complex and can be associated with significant postoperative morbidity. Familiarity with the anatomic alterations related to the various operations is essential, both for evaluation of early postoperative complications and those abnormalities that manifest late in the postoperative course. The surgeon and radiologist should carefully coordinate clinical suspicion with the strengths of the various imaging modalities to optimize postsurgical assessment and provide timely and accurate diagnosis. Enteric anastomoses, the different forms of enterostomy, and the varied constructions of small bowel pouches and reservoirs are each associated with unique anatomy and therefore optimal techniques of assessment. Small bowel contrast studies such as enteroclysis--including its recent modification, CT enteroclysis--and CT imaging represent the primary modalities for imaging of the postoperative bowel and its related abnormalities. Small bowel transplantation continues to progress as a realistic treatment for intestinal failure, and the role of diagnostic imaging in these unique and challenging patients is evolving.

Overall mortality in the program on the surgical control of the hyperlipidemias

BACKGROUND

The Program on the Surgical Control of the Hyperlipidemias (POSCH), a secondary intervention trial, was the only lipid/atherosclerosis randomized clinical trial that used a surgical modality--partial ileal bypass. POSCH provided solid evidence for the clinical and arteriographic benefits of lipid profile normalization. Few longterm followup reports have been published in this field. This report concerns overall mortality, the primary endpoint of POSCH, with a mean followup of 18 years (range 15.5 to 23.0 years).

STUDY DESIGN

Overall mortality data were compiled from reports to the POSCH clinics, followup telephone calls, death certificates, and the US National Death Index.

RESULTS

There were 144 deaths in the control group (n = 417) and 120 deaths in the intervention group (n = 421), using intent-to-treat analysis. The risk reduction in the intervention group was 0.201 (20%); the risk ratio was 0.799, or 0.8 (95% confidence intervals, 0.628 to 1.018, p = 0.07). The proportion of patients alive was 65.7% in the control group and 72.0% in the intervention group, for a difference of 6.3% in the intervention group (p = 0.05). Kaplan-Meier survival analysis (p = 0.046) and disease-free intervals analysis at 70% survival (p < 0.001) were confirmatory. The gain in life expectancy in the intervention group was 2.7 years.

CONCLUSIONS

Longterm followup POSCH data demonstrate that lipid profile normalization will decrease overall mortality and will maintain a persistent and constant increase in life expectancy.

New cholesterol guidelines, new treatment challenges

Coronary heart disease (CHD) is the largest single killer of Americans. Epidemiologic trials have indicted low-density lipoprotein cholesterol (LDL) as directly correlating with CHD events, and clinical trials confirmed that lipid-lowering therapy decreases the risk of CHD events. The literature also indicates that only about 18% of these patients are treated to their goal LDL levels. New guidelines from the National Cholesterol Education Program extend the LDL-lowering recommendations, add a new non-high-density lipoprotein cholesterol (non-HDL) goal for patients with hypertriglyceridemia, and increase the number of drug-eligible patients from about 15 to 36 million. Most of those who are eligible for lipid-altering drug therapy have the highest CHD risk and require the most aggressive treatment to achieve goals. This presents a challenge to clinicians: how best to achieve LDL and non-HDL goals. Statins are the most effective agents for lowering LDL and one of the most effective for lowering non-HDL. This efficacy and the ability to reduce CHD risk were well documented in a number of randomized clinical trials. When statin monotherapy fails to achieve goals, a bile acid resin, niacin, or both may be added to lower LDL further, or a fibrate, niacin, or fish oils may be added to lower non-HDL further. Drugs are under development that may enhance our ability to reach LDL and non-HDL goals. Included are a group of so-called super statins, rosuvastatin and pitavastatin; agents that interfere with cholesterol or bile acid transport in the gut, such as ezetimibe; and dual peroxisome proliferator-activated receptor agonists that have both fibrate and thiazolidinedione-like effects.

Cholesterol absorption inhibitors in development as potential therapeutics

Drugs that lower low-density lipoprotein cholesterol through their actions in the gastrointestinal tract have been used for > 30 years. Bile acid sequestrants have very excellent safety profiles but their poor tolerability means they have limited clinical use. Recently developed new compounds are better tolerated in clinical trials and show greater benefit in reducing low-density lipoprotein cholesterol level, as compared to "older" sequestrants. Cholesterol absorption inhibitors and bile acid transporter inhibitors have recently been reported to show clinical efficacy and safety as novel gut-acting drugs for lowering cholesterol. Further advances in our understanding of the cholesterol absorption mechanism will provide novel therapeutic targets, such as the ATP-binding cassette transporter. This approach in the treatment of lowering cholesterol appears to play a more significant role in the clinical field of atherosclerotic vascular disease.

Familial Hypercholesterolemia

Heterozygous familial hypercholesterolemia is a common, severe form of elevated plasma, low-density lipoprotein (LDL) cholesterol. Familial hypercholesterolemia is under-recognized and under-treated despite well-known benefits from available lipid-lowering medications. To help address these problems, the humanitarian MEDPED (Make Early Diagnoses, Prevent Early Deaths) organization was developed as a means to find and help persons with familial hypercholesterolemia all over the world. Although some patients with familial hypercholesterolemia can be treated adequately with a statin alone, many require aggressive treatment with a combination of drugs, including a statin, bile acid sequestrant, and niacin to reach LDL goals. Such treatment has resulted in regression of angiographically monitored coronary lesions in patients with familial hypercholesterolemia.

Gut-acting drugs for lowering cholesterol

Drugs that indirectly lower blood cholesterol through their actions in the gut have been used for many years. Their utility has been limited by poor tolerability, and hence, poor compliance. New resins are better tolerated and offer an advantage to older drugs. New strategies focusing on reducing serum cholesterol by acting on the gastrointestinal tract may hold even greater promise, combining the safety of nonsystemic agents with the acceptance of statins.

Low-density lipoprotein apheresis for the treatment of refractory hyperlipidemia

The advent of treatment with 3-hydroxy-3-methylglutaryl coenzyme A inhibitors has meant that, with a combination of diet and drug therapy, adequate control of serum cholesterol concentrations can be achieved in most patients with hypercholesterolemia. However, some patients, primarily those with familial hypercholesterolemia (FH), may require additional therapy to lower their cholesterol levels. In recent years, low-density lipoprotein (LDL) apheresis has emerged as an effective method of treatment in these patients. The criteria for commencement of LDL apheresis are LDL cholesterol levels of 500 mg/dL or higher for homozygous FH patients, 300 mg/dL or higher for heterozygous FH patients in whom medical therapy has failed, and 200 mg/dL or higher for heterozygous FH patients with documented coronary disease and in whom medical therapy has failed. In addition to cholesterol lowering in patients with FH, other indications for LDL apheresis are emerging. These include its use in the treatment of graft vascular disease in patients receiving cardiac transplants as well as in the treatment of certain glomerulonephritides. This review examines the role of LDL apheresis in the management of lipid disorders and the evidence available to support its use in clinical practice.

Atorvastatin

Atorvastatin (Lipitor, Pfizer) is a safe and effective 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor (statin). It is the most potent currently available statin in terms of lowering low-density lipoprotein (LDL) and total cholesterol levels. It was the first statin shown to lower triglycerides in patients with isolated hypertriglyceridaemia. It has a good safety profile. In common with other statins, it has non-lipid-lowering effects including improving endothelial function, antiproliferative actions on smooth muscle and reducing platelet aggregation. It also has anti-inflammatory effects and may reduce plasma glucose levels. Clinical trial evidence with this statin is currently limited. It did slightly reduce events in the AVERT trial comparing patients receiving coronary angioplasty with those receiving high-dose atorvastatin therapy and in the MIRACL study reduced ischemia in patients with acute coronary syndromes. Other end point trials are in progress.

New pharmacological agents under clinical investigation for treating disorders of lipoprotein regulation leading to atherosclerosis

Coronary heart disease (CHD), whose primary aetiology is atherosclerosis, is the leading cause of mortality and a major cause of morbidity in the industrialised world [1]. Serum lipoprotein levels are aetiologically related to the risk of atherosclerosis and CHD [2]. The liver and the gastrointestinal system are the major protagonists involved in regulation of lipoprotein biochemical-physiological mechanisms and the development of hypercholesterolaemia. Furthermore, specific lipoprotein receptors are being discovered as targets for pharmacological intervention to correct lipoprotein disorders. Agents that target lipoprotein regulation in the liver, gastrointestinal-biliary and atherosclerotic tissues resulting in improved serum lipoprotein levels and/or control of primary and secondary dyslipidaemic disorders including diabetes, are currently undergoing clinical trials. The most novel promising compounds, after the greatly effective newest HMG-CoA reductase inhibitors, are drugs that affect peroxisome proliferator-activated receptors, PPARalpha and PPARgamma receptors, bile acid transport mechanisms, cholesterol absorption and cholesterol acyltransferase and other biochemical targets of lipoprotein regulation. Current knowledge and ongoing trials with these agents are described here within the boundaries of investigator confidentiality agreements.

Non-pharmacological lowering of low-density lipoprotein by apheresis and surgical techniques

In the past year, new data have appeared on the long-term benefits of low-density lipoprotein apheresis in severely hypercholesterolemic patients who are refractory to lipid-lowering drug therapy. Such data are critical for clinical decision-making, because they confirm the hypothesis that the dramatic reduction in low-density lipoprotein made possible by this technique produces clear-cut clinical benefits. Because of its efficacy and low incidence of side-effects, apheresis for severe drug-refractory hypercholesterolemia has superseded surgical approaches, such as liver transplantation or ileal bypass.

Low-density lipoproteins and risk for coronary artery disease

Based on the established relation between low-density lipoprotein (LDL) cholesterol and coronary artery disease (CAD), the treatment guidelines of the US National Cholesterol Education Program (NCEP) focus on LDL cholesterol reduction for primary and secondary prevention of CAD events. Abundant clinical trial evidence supports the importance of LDL cholesterol-lowering in decreasing CAD risk, both in angiographic trials, which measure CAD progression, and in trials with morbidity and mortality endpoints. The LDL cholesterol targets in the guidelines remain important treatment goals, and ongoing trials should answer questions of whether further reduction in LDL cholesterol will provide much additional benefit. Even in trials of statin therapy, in which substantial reductions of LDL cholesterol have been obtained, statins decrease (by 23-37%) but do not entirely eliminate events, suggesting that lipid parameters besides LDL cholesterol, such as high-density lipoprotein (HDL) cholesterol, triglyceride, lipoprotein(a), and LDL particle size and susceptibility to oxidation, as well as other risk factors, influence CAD risk. Unfortunately, at present, the majority of high-risk patients are not receiving either diet or drug therapy. Systematic screening to identify high-risk patients and methodical follow-up to implement diet, lifestyle modification, and drug therapy to lower LDL cholesterol, as provided for in the NCEP guidelines, should lead to significant benefits in the prevention of CAD events.