International Atherosclerosis Society guidance for implementing best practice in the care of familial hypercholesterolaemia

This contemporary, international, evidence-informed guidance aims to achieve the greatest good for the greatest number of people with familial hypercholesterolaemia (FH) across different countries. FH, a family of monogenic defects in the hepatic LDL clearance pathway, is a preventable cause of premature coronary artery disease and death. Worldwide, 35 million people have FH, but most remain undiagnosed or undertreated. Current FH care is guided by a useful and diverse group of evidence-based guidelines, with some primarily directed at cholesterol management and some that are country-specific. However, none of these guidelines provides a comprehensive overview of FH care that includes both the lifelong components of clinical practice and strategies for implementation. Therefore, a group of international experts systematically developed this guidance to compile clinical strategies from existing evidence-based guidelines for the detection (screening, diagnosis, genetic testing and counselling) and management (risk stratification, treatment of adults or children with heterozygous or homozygous FH, therapy during pregnancy and use of apheresis) of patients with FH, update evidence-informed clinical recommendations, and develop and integrate consensus-based implementation strategies at the patient, provider and health-care system levels, with the aim of maximizing the potential benefit for at-risk patients and their families worldwide.

P22 Patient-level meta-analysis of efficacy and safety from STRIVE and ReSTORE: randomized, double-blinded, multicentre Phase 2 and Phase 3 trials of rezafungin in the treatment of candidaemia and/or invasive candidiasis

Background

Rezafungin is a next-generation echinocandin in development for treatment of candidaemia and invasive candidiasis (IC) and for prevention of invasive fungal disease caused by Candida, Aspergillus and Pneumocystis spp. in blood and marrow transplantation. Rezafungin once-weekly (QWk) was compared to caspofungin once-daily (QD) in two double-blind, randomized, controlled trials in patients with candidaemia and/or IC: STRIVE (Phase 2; NCT02734862) and the recently completed ReSTORE (Phase 3; NCT03667690). STRIVE demonstrated the efficacy and safety profile of rezafungin. ReSTORE showed rezafungin noninferiority to caspofungin for 30 day all-cause mortality (ACM) and global response at Day 14 with comparable safety. Patient-level meta-analyses of efficacy and safety from both trials are presented.

Methods

Details of STRIVE and ReSTORE were previously described. In this analysis of data from both trials, patients who received rezafungin QWk (400 mg in Week 1, then 200 mg) were compared with those who received caspofungin QD (70 mg on Day 1 followed by 50 mg) for ≥14 days (up to 4 weeks). Efficacy endpoints included 30 day ACM (primary US FDA), mycological response at Day 5 (secondary), and time to first negative blood culture (TTNBC) (exploratory). Safety was evaluated by adverse events (AEs).

Results

Groups were well matched (Table 1). Figure 1 shows 30 day ACM (overall and by final diagnosis). Mycological response at Day 5 was 73.4% (102/139) and 64.5% (100/155) in rezafungin and caspofungin groups, respectively (difference=9.5, 95% CI=−0.9, 19.9). In patients with positive blood culture before randomization, median TTNBC was 22.3 h in rezafungin-treated versus 26.3 h in caspofungin-treated patients (stratified log rank p=0.0034, not adjusted for multiplicity). The summary of AEs (Table 2) demonstrates similar outcomes for rezafungin and caspofungin groups.

Conclusions

In the Phase 2/3 patient-level meta-analysis, rezafungin QWk demonstrated efficacy with a similar 30 day ACM rate and safety comparable to that of caspofungin QD. Data for mycological eradication at Day 5 and TTNBC support results from the primary efficacy endpoint and provide initial evidence for the theory that high, front-loaded drug exposure leads to faster fungal clearance. Further analysis of this integrated dataset may provide additional insights on rezafungin efficacy and safety.

Use of apheresis in the age of new therapies for familial hypercholesterolaemia

PURPOSE OF REVIEW

Lipoprotein apheresis has been first line therapy for homozygous familial hypercholesterolaemia (FH) and other severe and refractory forms of dyslpidaemia for over 40 years but the recent advent of novel and potent LDL-lowering compounds necessitates a reappraisal of its role.

RECENT FINDINGS

During the past decade a substantial amount of evidence has accumulated describing the effect of LDL-lowering with apheresis and conventional drug therapy upon the cardiovascular outcomes associated with homozygous and statin-refractory heterozygous FH. This has necessitated re-defining the target levels of LDL cholesterol needed to arrest progression of atherosclerosis in these situations. At the same time, evidence has accrued regarding the pathogenicity of raised levels of lipoprotein (a) and the promising role of apheresis in mitigating the adverse effects of the latter. The latest advance in treatment has been the introduction of three classes of novel and potent LDL-lowering compounds in the shape of inhibitors of Propertin convertase subtilisin kexin 9 (PCSK9), microsomal triglyceride transfer protein and angiopoietin-like 3.

SUMMARY

These recent developments raise the question of whether these compounds will be used as adjuvants to bolster lipoprotein apheresis in FH homozygotes or whether they will render it obsolete, as is already occurring with PCSK9 inhibitors in FH heterozygotes.

The scientific basis and future of lipoprotein apheresis

Lipoprotein apheresis plays a vital role in the management of the severe hyperlipidemias that predispose to atherosclerosis. Determinants of efficacy are the acute reduction in lipoproteins achieved by each apheresis procedure, their frequency, and the fractional catabolic rates and hence pool sizes of low-density lipoprotein (LDL) or lipoprotein (a) (Lp(a)) of the patient being treated. A useful criterion of the efficacy of apheresis plus lipid-lowering drug therapy is the decrease in the interval (time-averaged) mean of serum total or LDL cholesterol or Lp(a) between procedures, expressed as the percent decrease in the interval means below the maximal levels of these lipoproteins when off all treatment. Recent advances in lipid-lowering drug therapy may diminish the use of lipoprotein apheresis but will not abolish its unique role as a therapeutic "last chance saloon," especially for children and pregnant women with homozygous familial hypercholesterolemia.

FH through the retrospectoscope

After training as a gastroenterologist in the UK, the author became interested in lipidology while he was a research fellow in the USA and switched careers after returning home. Together with Nick Myant, he introduced the use of plasma exchange to treat familial hypercholesterolemia (FH) homozygotes and undertook non-steady state studies of LDL kinetics, which showed that the fractional catabolic rate of LDL remained constant irrespective of pool size. Subsequent steady-state turnover studies showed that FH homozygotes had an almost complete lack of receptor-mediated LDL catabolism, providing in vivo confirmation of the Nobel Prize-winning discovery by Goldstein and Brown that LDL receptor dysfunction was the cause of FH. Further investigation of metabolic defects in FH revealed that a significant proportion of LDL in homozygotes and heterozygotes was produced directly via a VLDL-independent pathway. Management of heterozygous FH has been greatly facilitated by statins and proprotein convertase subtilisin/kexin type 9 inhibitors but remains dependent upon lipoprotein apheresis in homozygotes. In a recent analysis of a large cohort treated with a combination of lipid-lowering measures, survival was markedly enhanced in homozygotes in the lowest quartile of on-treatment serum cholesterol. Emerging therapies could further improve the prognosis of homozygous FH; whereas in heterozygotes, the current need is better detection.

Ibrexafungerp: A novel oral glucan synthase inhibitor

Ibrexafungerp is a novel glucan synthase inhibitor currently undergoing phase II and phase III clinical trials. This compound has demonstrated in vitro activity against clinically important fungal pathogens including Candida spp. and Aspergillus spp. It is able to retain activity against many echinocandin-resistant strains of Candida due to differential avidity for the target site compared to echinocandins. In vivo animal models have demonstrated efficacy in murine models of invasive candidiasis, aspergillosis, and pneumocystis. Due to high bioavailability, it can be administered both orally and intravenously. A favorable drug interaction and tolerability profile is observed with this compound. This review summarizes existing data that have either been published or presented at international symposia.

Coccidioidomycosis in llamas and alpacas diagnosed at the University of California, Davis (1990-2016)

Given the predisposition of South American camelids to coccidioidomycosis, we sought to describe the disease presentation in alpacas and llamas and identify potential risk factors for these species. The records of 224 llamas and alpacas that were tested for Coccidioides infection using immunodiffusion serology at the Coccidioidomycosis Serology Laboratory of the University of California, Davis, between 1990 and 2016 were examined; of those, 46 alpacas and 42 llamas had positive test results. The remaining 99 alpacas and 37 llamas were used as control groups. We found that male llamas were at increased risk for Coccidioides infection when compared with female llamas and when compared with male alpacas. South American camelids living within California were at higher risk for infection than camelids living in other states. Alpacas were more likely than llamas to have subclinical infections. We documented five cases of abortion or neonatal mortality attributable to coccidioidomycosis in alpacas. Our study demonstrates that South American camelids are susceptible to Coccidioides infection in areas where the disease is endemic, lending support to the importance of vigilance for this disease in alpacas and llamas and suggesting a possible role for these animals as sentinel species.

LAY SUMMARY

We examined cases of Valley Fever and described the disease and risk factors for llamas and alpacas. Male llamas were at increased risk for infection as were animals living within California. Five alpacas had miscarriages or neonatal deaths as a result of Valley Fever infections.

Detection of Alcohol-Induced Fatty Liver by Computerized Tomography

Computerized tomographic (CT) scanning of the liver was undertaken in 17 occasional and 19 heavy drinkers undergoing health screening. The median attenuation value of the liver (CT number) in occasional drinkers with normal liver function tests was 54.4 compared with 25.9 in the heavy drinkers (P < 0.001). Fourteen of the heavy drinkers had a CT number below the lowest value observed in occasional drinkers with normal liver function, indicating reduced liver density due to fatty change. Serum gamma-glutamyl transpeptidase was normal in 36% of these individuals. A rise in CT number was observed in 4 out of 5 heavy drinkers who underwent a second scan after decreasing their alcohol consumption. These findings suggest that CT scanning provides a noninvasive and convenient method of screening for a fatty liver, which occurred to a variable degree in over 70% of the men who admitted to regularly taking 8 or more alcoholic drinks per day.

Normal levels of inflammatory markers in treated patients with familial hypercholesterolaemia: a cross-sectional study

Objective

To assess the relationship of levels of inflammatory risk markers to presence of clinical coronary artery disease (CAD) in patients with treated heterozygous familial hypercholesterolaemia.

Design

A cross-sectional study of patients on the Simon Broome Familial Hyperlipidaemia Register.

Setting

Six hospital outpatient clinics in the UK.

Participants

A total of 211 men and 199 women with heterozygous familial hypercholesterolaemia.

Main outcome measures

Analysis of conventional risk factors and concentrations of high-sensitivity C-reactive protein (hsCRP), lipoprotein(a), serum intercellular adhesion molecule (sICAM), interleukin-6 (IL-6) and lipoprotein-associated phospholipase A₂ (LpPLA2) mass.

Results

CAD was present in 104 men and in 55 women; the mean ages of onset were 43.1 and 46.5 years, respectively. On univariate analysis there was a positive relationship of CAD with age, male sex, smoking, IL-6 and sICAM, and an inverse relationship with low-density lipoprotein (LDL) and LpPLA2. On multivariate analysis, age, smoking, low LDL and low LpPLA2 were associated with CAD. When LpPLA2 values were adjusted for apoB and aspirin usage, there was no significant difference between those with and without CAD. Only age and smoking were independently associated with CAD in men, and IL-6 and lipoprotein(a) in women.

Conclusions

Although on univariate analysis inflammatory marker levels were associated with CAD in these patients, the majority of the associations, including that for hsCRP, disappeared when corrected for smoking and apoB. This may be because atherosclerotic plaques in these statin-treated patients were quiescent or an effect of aspirin usage. In this observational study newer risk markers were not usefully associated with the presence or absence of symptomatic CAD.

Severe hypercholesterolaemia: therapeutic goals and eligibility criteria for LDL apheresis in Europe

PURPOSE OF REVIEW

Despite the use of currently available lipid-lowering therapies, a significant proportion of patients with severe hypercholesterolaemia do not reach treatment goals and consequently remain at increased risk for cardiovascular disease (CVD). On the basis of clinical experience, these patients tend to have the most severe forms of familial hypercholesterolaemia or markedly elevated LDL cholesterol (LDL-C) levels but are unable to tolerate statin therapy.

RECENT FINDINGS

LDL apheresis is currently the best treatment option (or treatment rescue) to bring these patients closer to therapeutic LDL objectives, and has been shown to reduce the risk of CVD along with LDL-C levels. However, criteria for LDL apheresis eligibility and the percentage of patients receiving treatment vary widely from country to country across Europe. Despite the proven benefits of LDL apheresis, access to this procedure remains limited because of its high cost and low availability, reflecting inherent limitations of this treatment modality.

SUMMARY

There is a need to both better define the patient population eligible for LDL apheresis and to create unified European guidelines governing the use of apheresis. In addition to improving access to apheresis where appropriate, new therapies are needed to further decrease LDL-C and reduce the ongoing CVD risk in patients with severe hypercholesterolaemia.

Lipoprotein apheresis

PURPOSE OF REVIEW

Lipoprotein apheresis is being performed with increasing frequency, but better data collection and recording of clinical outcomes are needed. Setting up registries would facilitate this process.

RECENT FINDINGS

This review appraises recent articles that discuss the need for national registries and requirements for setting them up, the efficacy of lipoprotein apheresis in homozygous familial hypercholesterolaemia and patients with coronary disease secondary to raised levels of lipoprotein (a), and its role in the management of acute pancreatitis secondary to severe hypertriglyceridaemia.

SUMMARY

Lipoprotein apheresis seems to be going through a growth spurt, presumably reflecting better implementation of treatment guidelines or a broadening of indications for its use.

History of the cholesterol controversy in Britain

The lipid hypothesis, the concept that cholesterol plays a causal role in atherosclerosis and cardiovascular disease, has been the subject of a controversy which started in the 1950s, peaked in the 1970s and 80s and then subsided in the 1990s. It was finally resolved by the positive outcome of the Scandinavian Simvastatin Survival Study, the first of 14 prevention trials using statins which showed that lowering cholesterol reduced both cardiovascular events and total mortality. This commentary focuses primarily on the events and people involved in the cholesterol controversy in Britain. The foremost critics of the lipid hypothesis are now deceased but unfortunately for many of the patients with hypercholesterolaemia and coronary heart disease it took the best part of 50 years to disprove the sceptics. This brief account relates why it took so long.

Measurement of the reflectivity of the intima-medial layer of the common carotid artery improves the discriminatory value of intima-medial thickness measurement as a predictor of risk of atherosclerotic disease

Our aim was to assess the predictive value of a measurement of intima-medial layer (IML) reflectivity in the differentiation of pathological from physiological increases in intima-medial thickness (IMT). Both common carotid arteries (CCA) of familial hypercholesterolemia (FH) patients and age- and sex-matched controls (no cardiovascular risk factors) were imaged using a 10- to 15-MHz linear array transducer (n = 30). Images of the CCA far wall were analyzed in the IMT "plug-in" of "HDI Lab." The IML reflectivity, averaged over an 8- to 12-mm length of arterial wall, was expressed as a ratio of reflectivity at a point 0.21-mm deep to the intima-medial interface divided by the reflectivity at the intima-medial interface, termed the intima-medial reflectivity index (IMRI). The risk of atherosclerosis was assessed in terms of IMT alone and IMT coupled with IMRI. Defining high risk of atherosclerosis in FH, in terms of both IMT alone and IMT coupled with IMRI, produced an appropriate, when compared with cholesterol-years score, statistically significant stratification (p < 0.01 and p < 0.005). Analysis of the low-risk subjects revealed a tendency to define a subject as "high risk" based on a physiological increase in IMT, but when IMRI is included in the assessment, all controls are correctly identified as low risk. This method of quantifying the reflectivity of the IML improved the discriminatory performance of IMT increase as an indicator of atherosclerotic risk by enabling a smaller, therefore earlier, increase in IMT to be considered pathologic when accompanied by an increase in IMRI.

Genetic causes of familial hypercholesterolaemia in patients in the UK: relation to plasma lipid levels and coronary heart disease risk

AIMS

To determine the relative frequency of mutations in three different genes (low-density lipoprotein receptor (LDLR), APOB, PCSK9), and to examine their effect in development of coronary heart disease (CHD) in patients with clinically defined definite familial hypercholesterolaemia in UK.

PATIENTS AND METHODS

409 patients with familial hypercholesterolaemia patients (158 with CHD) were studied. The LDLR was partially screened by single-strand conformational polymorphism (SSCP) (exons 3, 4, 6-10 and 14) and by using a commercial kit for gross deletions or rearrangements. APOB (p.R3500Q) and PCSK9 (p.D374Y) were detected by specific assays. Coding exons of PCSK9 were screened by SSCP.

RESULTS

Mutations were detected in 253 (61.9%)

PATIENTS

236 (57.7%) carried LDLR, 10 (2.4%) carried APOB p.Q3500 and 7 (1.7%) PCSK9 p.Y374. No additional mutations were identified in PCSK9. After adjusting for age, sex, smoking and systolic blood pressure, compared to those with no detectable mutation, the odds ratio of having CHD in those with an LDLR mutation was 1.84 (95% CI 1.10 to 3.06), for APOB 3.40 (0.71 to 16.36), and for PCSK9 19.96 (1.88 to 211.5; p = 0.001 overall). The high risk in patients carrying LDLR and PCSK9 p.Y374 was partly explained by their higher pretreatment cholesterol levels (LDLR, PCSK9 and no mutation, 10.29 (1.85), 13.12 and 9.85 (1.90) mmol/l, respectively, p = 0.001). The post-statin treatment lipid profile in PCSK9 p.Y374 carriers was worse than in patients with no identified mutation (LDL-C, 6.77 (1.82) mmol/l v 4.19 (1.26) mmol/l, p = 0.001, HDL-C 1.09 (0.27) mmol/l v 1.36 (0.36) mmol/l, p = 0.03).

CONCLUSIONS

The higher CHD risk in patients carrying PCSK9 p.Y347 or a detected LDLR mutation supports the usefulness of DNA testing in the diagnosis and management of patients with familial hypercholesterolaemia. Mutations in PCSK9 appear uncommon in patients with familial hypercholesterolaemia in UK.

History and development of plant sterol and stanol esters for cholesterol-lowering purposes

Plant stanol esters provide a novel approach to lowering plasma low-density lipoprotein (LDL) cholesterol by dietary means. Their development was preceded by a long period of research into the cholesterol-lowering properties of plant sterols and, recently, plant stanols. Both classes of compound competitively inhibit the absorption of cholesterol and thus lower its level in plasma. Initial impressions were that stanols were more effective and safer than sterols, but the negative outcome of a study led to the recognition that the lipid solubility of free stanols was very limited. This was overcome by esterifying them with fatty acids, with the resultant stanol esters being freely soluble in fat spreads. This led to the launch of Benecol (margarine; Raisio Group, Raisio, Finland) in 1995. The coincident publication of the year-long North Karelia study conclusively demonstrated the long-term LDL-lowering efficacy of plant stanol esters. Variables that might influence the efficacy of stanol esters include dose, frequency of administration, food vehicle in which the stanol ester is incorporated, and background diet. The effective dose is 1 to 3 g/day, expressed as free stanol, which, in placebo-controlled studies, decreased LDL cholesterol by 6% to 15%. This effect is maintained, appears to be similar with once-daily or divided dosage, and is independent of the fat content of the food vehicle. Short-term studies suggest that equivalent amounts of plant sterol and stanol esters are similarly effective in lowering LDL, the main difference being that plasma plant sterol levels increase on plant sterols and decrease on plant stanols. The clinical significance of these changes remains to be determined.

Additive effects of plant sterol and stanol esters to statin therapy

Plant sterol and stanol esters each have similar additive effects in lowering low-density lipoprotein cholesterol when combined with statins. They differ in that plasma plant sterols increase when plant sterol esters are used for this purpose, especially in patients with familial hypercholesterolemia, but decrease when plant stanol esters are used.

Comparison of efficacy of plant stanol ester and sterol ester: short-term and longer-term studies

Published data suggest that the cholesterol-lowering effect of dietary plant sterol esters is less marked in longer-term than in short-term studies, whereas plant stanol esters maintain their efficacy. To investigate this further, healthy subjects and patients with familial hypercholesterolemia (FH) receiving statins were randomized to receive plant sterol ester 1.6 g/day or plant stanol ester 1.6 g/day or 2.6 g/day for 2 months. There was no difference among the 3 groups in the pooled low-density lipoprotein (LDL)-lowering response of FH patients and healthy subjects, but the effect of plant sterol diminished at 2 months and was not significantly different from baseline. This was accompanied by increases in serum plant sterols and a significant decrease in 7alpha-hydroxy-4-cholesten-3-one, a marker of bile acid synthesis, especially in FH patients not taking bile acid sequestrants. In contrast, plant stanol esters lowered significantly both LDL cholesterol and plant sterols at 2 months and had no effect on bile acid synthesis. Slight decreases in serum lipid-soluble antioxidants occurred with both plant sterol and stanol esters. Our findings suggest that absorption of dietary plant sterols downregulates bile acid synthesis, which attenuates their cholesterol-lowering efficacy. We conclude that plant stanol esters are preferable for the long-term management of hypercholesterolemia.

New prospects for lipid-lowering drugs

The advent of 3-hydroxy-methylglutaryl Co-enzyme A (HMG-CoA) reductase inhibitors has dramatically improved the treatment of dyslipidaemia and the prevention of atherosclerosis over the past 10 years. Similar but less marked benefit had previously been demonstrated for fibrates and bile acid sequestrants, which were first introduced over 30 years ago and are still in use. The discovery that fibrates are ligands for peroxisome proliferator activated receptors (PPARs) may lead to innovations in the future. However, most of the compounds now undergoing clinical trials are either HMG-CoA reductase inhibitors or bile acid sequestrants, which is indicative of the current emphasis on lowering low density lipoprotein (LDL) cholesterol. Drugs in an earlier stage of development include inhibitors of squalene synthase, which have yet to fulfil their initial promise, and of acylcholesterolacyltransferase (ACAT) and microsomal triglyceride transfer protein (MTP). Most of the earlier ACAT inhibitors were poorly absorbed, but compounds with better bioavailability hold considerable promise by virtue of their ability to inhibit ACAT in liver and arterial wall macrophages. MTP inhibitors have the potential to drastically reduce apolipoprotein B (apoB) secretion, but safety issues could negate this advantage. Thus, despite the impact of statins, the development of new lipid-modulating drugs continues to be a dynamic field of research.

Established and emerging coronary risk factors in patients with heterozygous familial hypercholesterolaemia

OBJECTIVES

To assess the clinical and biochemical factors associated with inter-individual variation in susceptibility to coronary artery disease (CAD) in treated heterozygous familial hypercholesterolaemia.

DESIGN

A cross sectional study was conducted of 410 patients recruited from six lipid clinics in the UK.

RESULTS

CAD was documented in 104 of the 211 men and in 55 of the 199 women with mean ages of onset of 43.1 and 46.5 years, respectively. CAD was significantly more common in men (49% v 28%, p < 0.001) and in patients who had smoked cigarettes versus patients who had never smoked (51% v 28%, p < 0.001). After adjusting for age, sex, and current smoking status, there were no significant differences between patients with or without CAD in lipoprotein(a), homocysteine, fibrinogen, plasminogen activator inhibitor-1, white blood cell count, body mass index, glucose, triglyceride or total cholesterol. However, high density lipoprotein (HDL) cholesterol concentrations were significantly lower in those with CAD (6%, 95% confidence interval (CI) 1% to 11%, p = 0.03) and this difference was greater in women than men (12% v 2%, p = 0.041).

CONCLUSIONS

These results indicate that emerging coronary risk factors appear not to be associated with CAD in adults with treated familial hypercholesterolaemia, but the strong association with smoking suggests that patients should be identified early in childhood and discouraged from ever starting to smoke.

Management of hyperlipidemia in the pediatric population

Heterozygous familial hypercholesterolemia (FH) affects one in every 500 persons and is the most common cause of markedly elevated cholesterol levels in children. Other causes of primary hyperlipidemia include familial combined hyperlipidemia, which is also common (approximately 1%) but not usually manifest until after puberty, and very rare genetic disorders that may lead to severe hypertriglyceridemia and chylomicronemia syndrome. In children with heterozygous FH, the short-term risk of clinical events is low; therefore, management starts with stratification of risk, followed by dietary modification, and in high-risk cases, pharmacologic treatment initiated after puberty. Male gender, a family history of premature coronary heart disease, and level of low-density lipoprotein (LDL) cholesterol above 4.9 mmol/L are important determinants of risk. Trials have shown that statins effectively lower LDL cholesterol levels; in one study, statins restored endothelial function, with no clinically adverse effects. The effects of statins for longer than 2 years have not been studied. The use of bile acid sequestrants (resins) is limited by compliance and side effects. Children with homozygous FH require expert management with LDL apheresis, high doses of effective statins, and cardiologic follow-up. Ezetimibe, the first in a new class of cholesterol absorption inhibitors, may provide additional efficacy in homozygous FH.

Current management of severe homozygous hypercholesterolaemias

PURPOSE OF REVIEW

This review focuses on recent advances in the management of patients with homozygous familial hypercholesterolaemia, autosomal recessive hypercholesterolaemia and familial defective apolipoprotein B.

RECENT FINDINGS

Autosomal recessive hypercholesterolaemia has been described as a 'phenocopy' of homozygous familial hypercholesterolaemia. Although the clinical phenotypes are similar, autosomal recessive hypercholesterolaemia seems to be less severe, more variable within a single family, and more responsive to lipid-lowering drug therapy. The cardiovascular complications of premature atherosclerosis are delayed in some individuals and involvement of the aortic root and valve is less common than in homozygous familial hypercholesterolaemia. Apheresis is still the treatment of choice in homozygous familial hypercholesterolaemia and in autosomal recessive hypercholesterolaemia patients in whom maximal drug therapy does not achieve adequate control. In addition to the profound cholesterol-lowering effects of apheresis, other potentially beneficial phenomena have been documented: improved vascular endothelial function and haemorheology, reduction in lipoprotein (a) and procoagulatory status, and a decrease in adhesion molecules and C-reactive protein.

SUMMARY

Patients with severe homozygous hypercholesterolaemia illustrate the natural history of atherosclerosis within a condensed timeframe. Effective cholesterol-lowering treatment started in early childhood is essential to prevent onset of life-threatening atherosclerotic involvement of the aortic root and valve, and the coronary arteries. Noninvasive methods for regular monitoring of the major sites involved in the atherosclerotic process are necessary in patients with no symptoms or signs of ischaemia. Management of patients with severe homozygous hypercholesterolaemia continues to be a major challenge.

Comparison of the effects of dietary plant sterol and stanol esters on lipid metabolism

BACKGROUND AND AIM

To compare the cholesterol-lowering efficacy and other metabolic effects of plant sterol and stanol esters, both of which are commonly used in the dietary management of hypercholesterolaemia.

METHODS AND RESULTS

The cholesterol-lowering efficacy of equivalent intakes of sterol and stanol esters and of different intakes of stanol esters were compared at 1 and 2 months, both in normal subjects and treated patients with familial hypercholesterolaemia. Systemic effects were assessed by measuring serum levels of plant sterols and of lathosterol and 7alpha-hydroxy-cholestenone, indices of sterol absorption and of cholesterol and bile acid synthesis respectively. There were no significant differences during the study between 1.6g daily of sterol and stanol esters in reducing total cholesterol (by 3-7%) or low density lipoprotein cholesterol (by 4-8%), nor between 1.6 and 2.6 g daily of stanol. However, the cholesterol-lowering effect of plant sterol esters was attenuated between 1 and 2 months. This was accompanied by increased serum plant sterols and decreased levels of 7alpha-hydroxy-cholestenone, especially in statin-treated hypercholesterolaemic patients not taking bile acid sequestrants.

CONCLUSIONS

These findings suggest that absorption of dietary plant sterols suppressed bile acid synthesis, thereby diminishing their cholesterol-lowering efficacy. In contrast, plant stanols reduced plant sterol absorption and maintained their cholesterol-lowering efficacy.

Coronary calcification score: the coronary-risk impact factor

CONTEXT

Identification of asymptomatic high-risk individuals is integral to current policies for preventing coronary heart disease, but existing methods of estimating risk lack sensitivity. To overcome this limitation increasing use is being made of non-invasive methods to detect subclinical coronary artery disease--eg, computed tomography (CT) to scan for coronary artery calcification. The location and extent of calcification correlate closely with pathological and angiographic abnormalities, but whether such calcification predicts clinical events, especially in younger individuals, is equivocal. Most data on coronary calcification have been obtained with electron-beam CT, but recently multislice CT, which is more versatile, less expensive, and available in most large hospitals, has been increasingly used.

STARTING POINT

Leslee Shaw and colleagues (Radiology 2003; 228: 826-33) showed that the coronary calcification score predicted total mortality within subsets of patients classified at low, intermediate, or high risk according to Framingham criteria. In a cohort of over 10000 individuals, 5-year risk-adjusted survival was 95% when the score was over 1000 compared with 99% for scores of 10 or less. These results agree with other recent studies showing strong correlations between coronary calcification and coronary heart disease events. WHERE NEXT? The increasing use of multislice CT scanners should generate more data for comparison with those obtained from electron-beam CT. Radiation dose, which is higher with multislice than with electron-beam procedures, needs to be reduced, and calcification in scans needs to be quantified more accurately than with existing computer-based analyses. Further studies are needed to establish the predictive power of the coronary calcification score for clinical events and the effects of therapeutic intervention on both these outcomes. It would also be worth investigating the relation between coronary calcification and risk factors not quantified in Framingham-based estimates, including familial and racial predisposition to premature coronary heart disease.

Effect of a statin on hepatic apolipoprotein B-100 secretion and plasma campesterol levels in the metabolic syndrome

OBJECTIVE

We aimed to study the effect of atorvastatin, a statin, on cholesterol synthesis and absorption and VLDL-apoB metabolism in obese men with the metabolic syndrome.

METHODS

A total of 25 dyslipidaemic obese men were randomized to atorvastatin (n=13) (40 mg/day) or matching placebo (n=12) for 6 weeks. Hepatic secretion and fractional catabolic rate (FCR) of VLDL-apoB was measured using an intravenous bolus of d(3)-leucine before and after treatment. ApoB isotopic enrichment was measured using GCMS and multicompartmental modelling. Plasma lathosterol: cholesterol and campesterol:cholesterol ratios were determined to assess cholesterol synthesis and cholesterol absorption, respectively.

RESULTS

Compared with placebo, atorvastatin significantly decreased (P<0.05) total cholesterol, triglyceride, LDL-cholesterol and VLDL-apoB. Plasma lathosterol:cholesterol ratio decreased from 26.4+/-2.4 to 8.8+/-0.8, while the campesterol:cholesterol ratio increased from 26.5+/-4.4 to 38.6+/-5.8 (P<0.01). Atorvastatin also increased VLDL-apoB FCR from 3.82+/-0.33 to 6.30+/-0.75 pools/day (P<0.01), but did not significantly alter VLDL-apoB secretion (12.8+/-1.7 to 13.8+/-2.0 mg/kg/day).

CONCLUSIONS

In obesity, atorvastatin inhibits cholesterogenesis but increases intestinal cholesterol absorption. The increased cholesterol absorption may counteract the inhibitory effect on hepatic VLDL-apoB secretion, but it does not apparently influence enhanced catabolism of VLDL-apoB.

Plasma markers of cholesterol homeostasis and apolipoprotein B-100 kinetics in the metabolic syndrome

OBJECTIVE

The metabolic syndrome is characterized by defective hepatic apolipoprotein B-100 (apoB) metabolism. Hepato-intestinal cholesterol metabolism may contribute to this abnormality.

RESEARCH METHODS AND PROCEDURES

We examined the association of cholesterol absorption and synthesis with the kinetics of apoB in 35 obese subjects with the metabolic syndrome. Plasma ratios of campesterol and lathosterol to cholesterol were used to estimate cholesterol absorption and synthesis, respectively. Very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein apoB kinetics were studied using stable isotopy and mass spectrometry. Kinetic parameters were derived using multicompartmental modeling.

RESULTS

Compared with controls, the obese subjects had significantly lower plasma ratios of campesterol, but higher plasma ratios of lathosterol (p < 0.05 in both). This was associated with elevated VLDL-apoB secretion rate (p < 0.05) and delayed fractional catabolism of IDL and low-density lipoprotein-apoB (p < 0.01). In the obese group, plasma ratios of campesterol correlated inversely with VLDL-apoB secretion (r = -0.359, p < 0.05), VLDL-apoB (r = -0.513, p < 0.01) and IDL-apoB (r = -0.511, p < 0.01) pool size, and plasma lathosterol ratio (r = -0.366, p < 0.05). Subjects with low cholesterol absorption had significantly higher VLDL-apoB secretion, VLDL-apoB and IDL-apoB pool size, and plasma lathosterol ratio (p < 0.05 in both) than those with high cholesterol absorption.

DISCUSSION

Subjects with the metabolic syndrome have oversecretion of VLDL-apoB and decreased catabolism of apoB-containing particles and low absorption and high synthesis rates of cholesterol. These changes in cholesterol homeostasis may contribute to the kinetic defects in apoB metabolism in the metabolic syndrome.

Relationships between cholesterol homoeostasis and triacylglycerol-rich lipoprotein remnant metabolism in the metabolic syndrome

The dysmetabolic syndrome of insulin resistance and visceral obesity is characterized by elevated plasma concentration of triacylglycerol-rich lipoprotein (TRL) remnants that may be related to increased cardiovascular risk. Perturbed hepato-intestinal cholesterol metabolism may play a contributory role in this abnormality. We therefore investigated the association between plasma markers of cholesterol absorption and synthesis with TRL remnant metabolism in 35 men with the metabolic syndrome (MS). Plasma campesterol:cholesterol and lathosterol:cholesterol ratios were measured as estimates of cholesterol absorption and synthesis respectively. Remnant metabolism was assessed by measuring remnant-like particle-cholesterol (RLP-C), apolipoprotein (apo)B-48 and the fractional catabolic rate (FCR) of a labelled remnant-like emulsion. Compared with controls, subjects with the MS had significantly lower plasma campesterol:cholesterol ratio, but higher lathosterol:cholesterol ratio ( P <0.05). Plasma RLP-C and apoB-48 concentrations were also higher ( P <0.01) and the remnant-like emulsion FCR was lower ( P <0.05). The plasma campesterol:cholesterol ratio was inversely correlated ( P <0.05) with plasma triacylglycerols ( r =-0.346), RLP-C ( r =-0.443), apoB-48 ( r =-0.427) and plasma lathosterol:cholesterol ratio ( r =-0.366); the campesterol:cholesterol ratio was also positively correlated with the remnant-like emulsion FCR ( r =0.398, P <0.05). In multiple regression analysis, the significant correlations between plasma campesterol:cholesterol ratio and plasma triacylglycerols, RLP-C, apoB-48 and FCR of the remnant-like emulsion were independent of age, dietary energy and plasma lathosterol. Our findings suggest that in subjects with the MS alterations in cholesterol absorption and synthesis may be closely linked with the kinetic defects in TRL metabolism.

LDL apheresis

Low density lipoprotein (LDL) apheresis provides a safe and effective means of treating patients with homozygous familial hypercholesterolaemia (FH). It also has a role in preventing the progression of coronary artery disease in heterozygotes and others with severe dyslipidaemia who are refractory to or intolerant of high doses of lipid-lowering drugs. Established methods involve either adsorption of apolipoprotein B-containing lipoproteins by affinity columns containing anti-apolipoprotein B antibodies or dextran sulphate, or their precipitation at low pH by heparin, in each instance after first separating plasma from blood cells with a cell separator. The most recently developed method enables lipoproteins to be adsorbed directly from whole blood, using polyacrylate columns. All 4 methods have proved to be similarly efficient when used weekly or biweekly to lower LDL cholesterol and Lp(a) without unduly reducing HDL cholesterol. Economic constraints restrict the use of LDL apheresis to the treatment of potentially fatal disorders such as FH, where there is clear evidence of benefit compared with conventional therapy. Widening the indications to include the treatment of other dyslipidaemic disorders such as steroid-resistant nephrotic syndrome, post-transplant donor vessel disease, stroke and prevention of re-stenosis after coronary angioplasty requires evidence from controlled trials that is currently lacking.

Treatment with atorvastatin alters the ratio of interleukin-12/interleukin-10 gene expression [corrected]

BACKGROUND

Statins have been shown to have pleiotropic effects extending beyond their ability to lower cholesterol.

MATERIAL AND METHODS

Seventeen patients with heterozygous familial hypercholesterolaemia participated in a single-blind placebo controlled study. The patients underwent three treatment regimens: placebo (4 weeks), atorvastatin 10 mg day(-1) (4 weeks) and atorvastatin 40 mg day(-1) (12 weeks). Following each treatment period, serum lipids and plasma mevalonic acid were measured, mononuclear leukocytes were isolated and total RNA was prepared. The content of mRNA for IL-12p35 and IL-10 was assayed, blinded, by real-time quantitative polymerase chain reactions.

RESULTS

Treatment of the subjects with atorvastatin decreased the abundance of IL-12p35 mRNA in mononuclear cells, but did not alter that of IL-10, so that the ratio of the IL-12p35 to IL-10 mRNA content was significantly reduced (P < 0.0026). The IL-12p35/IL-10 ratio correlated significantly with plasma mevalonic acid concentrations but not with serum LDL concentrations.

CONCLUSIONS

This study provides evidence that atorvastatin exerts an immunomodulatory effect in vivo, characterized by a decrease in the ratio of IL-12 mRNA to IL-10 mRNA in leukocytes. The immunomodulatory effect of statins, in addition to their cholesterol-lowering properties, may contribute to the rapid cardiovascular benefit observed during treatment with statins and reduced the rate of rejection in patients with solid organ transplantation.

Coronary calcification and predicted risk of coronary heart disease in asymptomatic men with hypercholesterolaemia

OBJECTIVE

To document the relationship between coronary calcification and coronary risk assessed clinically in asymptomatic patients with hypercholesterolaemia.

DESIGN

Prospective observational study.

SETTING

Health screening clinic.

PATIENTS

A total of 286 asymptomatic men aged 45-64 with plasma cholesterol >or= 6.5 mmol/l.

INTERVENTIONS

Electron beam computed tomography to measure coronary calcium score.

MAIN OUTCOME MEASURES

The Framingham equation was used to separate subjects into groups with either low 10-year risk of coronary artery disease (<or= 10%) or high 10-year risk (>or= 20%). Coronary calcium score was assessed in each group.

RESULTS

The mean log calcium score was significantly higher in the 97 high-risk men than in the 189 low-risk men (1.58 +/- 0.84 versus 1.00 +/- 0.85, < 0.001). Arithmetic means (158 versus 55), and the proportion with a score > 400 (11% versus 2%, p < 0.01) were also greater. However, 27% of the high-risk group had a low calcium score (<or= 10), which is known to be associated with minimal coronary artery disease assessed by angiography.

CONCLUSIONS

Approximately one quarter of asymptomatic hypercholesterolaemic men aged 45 to 64 who have an estimated risk of coronary heart disease of >or= 20% in 10 years have minimal coronary calcification. They may therefore represent a subset at lower risk of disease. However, uncertainties about the predictive power of coronary calcification for coronary events must be resolved before electron beam computed tomography can be used to select high-risk patients for primary prevention.

Goals of statin therapy: three viewpoints

The "lipid hypothesis" is now universally recognized as a law. Few issues in medicine are as completely resolved as the question of whether reducing serum cholesterol increases longevity. However, there are a few questions that remain, and the most important uncertainty is to what extent cholesterol should be reduced. The medical community, in partnership with government and industry, has contributed many excellent trials demonstrating the effects in patients with elevated cholesterol (above the mean). Where should our goal of therapy be? Until data is available from several large, ongoing trials, we do not have a final answer. We asked three investigators, Drs. Gilbert Thompson, Christopher Packard, and Neil Stone, who have all been integrally involved in the accumulation of our present database, to argue three different possible answers.