Familial lipoprotein disorders and premature coronary artery disease

A bibliometric analysis of coronary heart disease impacted by work stress elements and lifestyle disease

PURPOSE

One psychosocial risk factor that has drawn attention is work-related stress, although it is still unclear how exactly this risk factor relates to poor health. Prospective observational studies have found a 40%-50% raise in the incidence of coronary heart disease in those who experience chronic stress at work and in their personal lives.

THEORETICAL FRAMEWORK

In the recent decade, there has been a rise in the requirement for firms to gather information on job stress on employees that leads to coronary heart disease. As a result, this study on trends in Coronary Heart Disease induced by Work Stress becomes necessary to examine all of these efforts.

DESIGN/METHODOLOGY

This research employs bibliometric analysis and charting to describe the growth and structure of the research field of work-related stress causing coronary heart disease. The field's conceptual framework and research boundaries, the connections between publications and the contributors, key phrases, the latest networks of collaboration, the most prevalent concepts, and the most cited authors are all revealed by our findings.

FINDINGS

Research found that this field has seen a significant increase in research on coronary heart disease in recent years. Because it has been demonstrated that there is a rise in deaths from cardiovascular disease, researchers, academics, and professionals should be made aware of how stress can lead to coronary heart disease.

ORIGINALITY/VALUE

The study suggests that workplace health should be a priority for both developed and developing nations, and it must be disseminated in several languages.

Prevalence of heterozygous familial hypercholesterolemia and combined hyperlipidemia phenotype in very young survivors of myocardial infarction and their association with the severity of atheromatous burden

BACKGROUND

Heterozygous familial hypercholesterolemia (HeFH) and combined hyperlipidemia (CHL) phenotype are associated with premature myocardial infarction (MI).

OBJECTIVE

To assess the prevalence of HeFH and CHL phenotype among young survivors of MI and compare patients' characteristics with these 2 lipid disorders.

METHODS

We recruited 382 young survivors of MI (≤40 years). Fasting lipids, lipoprotein(a) [Lp(a)], apolipoprotein A-1, and apolipoprotein B (apoB) levels were determined. Using the Dutch Lipid Clinic Network (DLCN) algorithm, patients having definite or probable HeFH were identified. Patients with apoB levels >120 mg/dL and triglyceride levels >170 mg/dL (1.92 mmol/L) [>90th percentile of 326 age and sex-matched healthy controls] were classified as having CHL phenotype. Common carotid artery intima-media thickness (CCA-IMT) was measured by B-mode ultrasonography.

RESULTS

Eighty-one patients (21.2%) had definite/probable HeFH and 62 (16.2%) had CHL phenotype. Twenty-three patients fulfilled the criteria for both HeFH and CHL phenotype and were removed from further comparisons. Patients with HeFH (n = 58) had higher levels of total cholesterol, low-density lipoprotein (LDL)-cholesterol, Lp(a), and apoB, whereas patients with CHL phenotype (n = 39) had higher levels of triglycerides and lower high-density lipoprotein (HDL)-cholesterol levels. The prevalence of metabolic syndrome was higher in patients with CHL phenotype compared to those with HeFH (67.0% vs 16.4%, P < .001). Patients with HeFH had more extensive coronary artery disease (3-vessel disease: 36.2% vs 12.8%, P = .011) and greater right CCA-IMT (0.67 ± 0.11 mm vs 0.56 ± 0.09 mm, P < .001) and left CCA-IMT (0.68 ± 0.10 mm vs 0.56 ± 0.08 mm, P < .001) compared to CHL phenotype patients.

CONCLUSIONS

Both HeFH and CHL phenotype are common among patients with premature MI. CHL phenotype compared to HeFH is associated with less atheromatous burden in coronary and carotid arteries at the time of first MI.

The design and rationale of SAVE BC: The Study to Avoid CardioVascular Events in British Columbia

Atherosclerotic cardiovascular disease (ASCVD) is highly heritable, particularly when it occurs at a young age. The screening of individuals with premature ASCVD, although often recommended, is not routinely performed. Strategies to address this gap in care are essential. We designed the Study to Avoid CardioVascular Events in British Columbia (SAVE BC) as a prospective, observational study of individuals with a new diagnosis of very premature ASCVD (defined as age ≤ 50 years in males and age ≤ 55 years in females) and their first-degree relatives (FDRs) and spouses. FDRs and spouses will undergo screening for cardiovascular (CV) risk factors and subclinical ASCVD using a structured screening algorithm. All subjects will be followed longitudinally for ≥10 years. The overall goal of SAVE BC is to evaluate the yield of a structured screening program for identifying individuals at risk of premature ASCVD. The primary objectives of SAVE BC are to identify and follow index cases with very premature ASCVD and their FDRs and to determine the diagnostic yield of a structured screening program for these individuals. We will collect data on CV risk factors, medication use, CV events, and healthcare costs in these individuals. SAVE BC will provide insight regarding approaches to identify individuals at risk for premature ASCVD with implications for prevention and treatment in this population.

Role of MyD88-dependent and MyD88-independent signaling in Porphyromonas gingivalis-elicited macrophage foam cell formation

Clinical studies and experimental modeling identify a potential link between periodontal disease and periodontal pathogens such as Porphyromonas gingivalis and atherosclerosis and formation of macrophage foam cells. Toll-like receptors and molecules governing their intracellular signaling pathways such as MyD88 play roles in atherosclerosis, as well as host response to P. gingivalis. The aim of this study was to define roles of MyD88 and TRIF during macrophage foam cell formation in response to P. gingivalis. In the presence of human low-density lipoprotein (LDL) mouse bone-marrow-derived macrophages (BMφ) cultured with P. gingivalis responded with significant reduction in tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). The BMφ stained strongly with oil red O, regardless of whether bacterial challenge occurred concurrent with or before LDL treatment. Heat-killed P. gingivalis stimulated foam cell formation in a similar way to live bacteria. The BMφ from MyD88-knockout and Lps2 mice revealed a significant role for MyD88, and a minor role for TRIF in P. gingivalis-elicited foam cell formation. Porphyromonas gingivalis-elicited TNF-α and IL-6 were affected by MyD88 ablation and to a lesser extent by TRIF status. These data indicate that LDL affects the TNF-α and IL-6 response of macrophages to P. gingivalis challenge and that MyD88 and TRIF play important roles in P. gingivalis-elicited foam cell formation.

Qualitative characteristics of HDL in young patients of an acute myocardial infarction

AIM

Recently, the concept that high density lipoprotein (HDL) quality is an important parameter for atheroprotection is gaining ground, though little data exists so far to support it. In an attempt to identify measurable qualitative parameters of HDL associated with increased risk for premature myocardial infarction (MI), we studied the structural characteristics of HDL from patients who survived an MI at a young age (≤35 years).

METHODS AND RESULTS

We studied 20 MI patients and 20 healthy control subjects. HDL of patients had reduced apolipoprotein A-I (apoA-I), apolipoprotein M, and paraoxonase 1 levels and significantly elevated apolipoprotein C-III (apoCIII) levels (all p<0.05). Specifically, the HDL apoA-I/apoC-III ratio was 0.24±0.01 in patients versus 4.88±0.90 in controls (p<0.001). These structural alterations correlated with increased oxidation potential of HDL of the MI group compared to controls (2.5-fold, p=0.026). Electron microscopy showed no significant difference in average HDL particle diameter between the two groups though a significant difference existed in HDL diameter distribution, suggesting the presence of different HDL subpopulations in MI and control subjects. Indeed, non-denaturing two-dimensional electrophoresis revealed that MI patients had reduced pre-β1(α), pre-β1(b) and α(2), and elevated α(1), α(3), and pre-α(4) HDL.

CONCLUSIONS

Reduction in the HDL apoA-I/apoC-III ratio, changes in the HDL subpopulation distribution and an increase in HDL oxidation potential correlated with the development of MI in young patients. The possibility that such changes may serve as markers for the early identification of young individuals at high risk for an acute coronary event should be further explored.

Fibrates in the treatment of cardiovascular risk and atherogenic dyslipidaemia

PURPOSE

New data have emerged over the last few years about the role of fibrates in treatment of microvascular and macrovascular disease.

RECENT FINDINGS

Endpoint studies have been conducted with fibrates in coronary heart disease (CHD) since 1971 and initial results were contradictory. Fibrates later showed benefits in patients with low HDL-C and low LDL-C. The prominence ascribed to the lipid triad of the metabolic syndrome and the increasing prevalence of diabetes has increased the topicality of fibrates given their main action of converting small dense to light buoyant LDL. The Fenofibrate Intervention in Endpoint Lowering in Diabetes (FIELD) study has carried on the tradition. Fenofibrate therapy in 9795 patients comprising a mixed low-risk primary and a medium-risk secondary prevention cohort resulted in an 11% reduction in coronary events (P = 0.16), a similar but significant reduction in cardiovascular events (P = 0.04; number-needed-to-treat = 70). The benefits were concentrated in primary prevention and on nonfatal myocardial events, and post-hoc greater effects were seen in patients with moderate hypertriglyceridaemia (>2.3 mmol/l) and low HDL-C, as had previously been noted in a trial with bezafibrate. Safety was generally good, including in combination with statins, but old concerns about sudden death, pancreatitis and venous thrombosis returned. Unexpected benefits were seen with fenofibrate for microvascular endpoints including microalbuminuria and retinopathy.

SUMMARY

Fenofibrate and bezafibrate are reasonable second-line therapies for dyslipidaemia and in diabetes, and well tolerated in combination therapy. The benefits of fenofibrate for microvascular disease and its potential role in combination therapy require further confirmation.

Fibrates: no ACCORD on their use in the treatment of dyslipidaemia

PURPOSE OF REVIEW

New data have emerged over the last few years about the role of fibrates in treatment of microvascular and macrovascular disease.

RECENT FINDINGS

Endpoint studies have been conducted with fibrates in coronary heart disease since 1971 and results have been contradictory. Fibrates have shown benefits in patients with low HDL-cholesterol and low LDL-cholesterol. Fibrates remain topical, given their actions on the lipid triad present in the metabolic syndrome and in diabetes. In the Fenofibrate Intervention in Endpoint Lowering in Diabetes study of mixed primary and secondary prevention cohorts, fenofibrate therapy resulted in an 11% reduction in coronary or cardiovascular events in monotherapy. Despite frequent use, there was little endpoint data on fibrate-statin combination therapy until recently. The Action to Control Cardiovascular Risk in Diabetes trial of fenofibrate added to baseline simvastatin therapy in diabetes showed a nonsignificant 8% reduction in cardiovascular events. The benefits were concentrated in men, and women did slightly worse with fibrate therapy. In post-hoc analysis, slight beneficial effects of fenofibrate were seen in patients with moderate hypertriglyceridaemia (>2.3 mmol/l) and low HDL-cholesterol (<0.88 mmol/l). The safety profile of fibrate-simvastatin combination was good.

SUMMARY

Fenofibrate and bezafibrate are reasonable second-line therapies for dyslipidaemia and in diabetes. They are safe in combination therapy with statins but add little endpoint benefit except possibly in patients with a significant degree of atherogenic dyslipidaemia (high triglycerides and low HDL-cholesterol). The benefits of fibrates on microvascular disease remain to be fully explored.

Genetic causes of high and low serum HDL-cholesterol

Plasma levels of HDL cholesterol (HDL-C) have a strong inherited basis with heritability estimates of 40-60%. The well-established inverse relationship between plasma HDL-C levels and the risk of coronary artery disease (CAD) has led to an extensive search for genetic factors influencing HDL-C concentrations. Over the past 30 years, candidate gene, genome-wide linkage, and most recently genome-wide association (GWA) studies have identified several genetic variations for plasma HDL-C levels. However, the functional role of several of these variants remains unknown, and they do not always correlate with CAD. In this review, we will first summarize what is known about HDL metabolism, monogenic disorders associated with both low and high HDL-C levels, and candidate gene studies. Then we will focus this review on recent genetic findings from the GWA studies and future strategies to elucidate the remaining substantial proportion of HDL-C heritability. Comprehensive investigation of the genetic factors conferring to low and high HDL-C levels using integrative approaches is important to unravel novel pathways and their relations to CAD, so that more effective means of diagnosis, treatment, and prevention will be identified.

Myeloperoxidase gene-463G > A polymorphism and premature coronary artery disease

We investigated the association between myeloperoxidase gene -463G > A polymorphism and premature coronary artery disease (CAD) in two Chinese population samples: 229 patients and 230 controls. Genotypes were determined by ligase detection reaction-polymerase chain reaction sequencing and the grouping technique. We found lower frequencies of both the A/A genotype and the A allele in patients (p < 0.05). Multivariate logistic regression showed that the risk of premature CAD in subjects carrying the AA genotype was reduced by 83% in relation to individuals carrying the G/G genotype (OR = 0.172, 95% CI: 0.057-0.526, p = 0.002). Our results indicate that -463G > A polymorphism of the myeloperoxidase gene is associated with premature CAD in Chinese individuals, suggesting that the AA genotype is a protective factor against premature CAD.

Angptl3 regulates lipid metabolism in mice

The KK obese mouse is moderately obese and has abnormally high levels of plasma insulin (hyperinsulinemia), glucose (hyperglycemia) and lipids (hyperlipidemia). In one strain (KK/San), we observed abnormally low plasma lipid levels (hypolipidemia). This mutant phenotype is inherited recessively as a mendelian trait. Here we report the mapping of the hypolipidemia (hypl) locus to the middle of chromosome 4 and positional cloning of the autosomal recessive mutation responsible for the hypolipidemia. The hypl locus encodes a unique angiopoietin-like lipoprotein modulator, which we named Allm1. It is identical to angiopoietin-like protein 3, encoded by Angptl3, and has a highly conserved counterpart in humans. Overexpression of Angptl3 or intravenous injection of the purified protein in KK/San mice elicited an increase in circulating plasma lipid levels. This increase was also observed in C57BL/6J normal mice. Taken together, these data suggest that Angptl3 regulates lipid metabolism in animals.

Cardiovascular disease mortality in familial forms of hypertriglyceridemia: A 20-year prospective study

BACKGROUND

Familial combined hyperlipidemia (FCHL) and familial hypertriglyceridemia (FHTG) are 2 of the most common familial forms of hyperlipidemia. There is a paucity of prospective data concerning the risk of cardiovascular disease (CVD) in such families. The purposes of this study were to estimate 20-year total and CVD mortality risk among relatives in these families and to evaluate plasma triglyceride as a predictor of death.

METHODS AND RESULTS

The study was based on lipid and medical history data from 101 families ascertained in 2 studies conducted in the early 1970s. Vital status and cause of death was determined during 1993 to 1997 for 685 family members, including first-degree relatives of the probands and spouse control subjects. Compared with spouse control subjects, 20-year CVD mortality risk was increased among siblings and offspring in FCHL (relative risk 1.7, P=0.02) after adjustment for baseline covariates. In FHTG families, the relative risk was also 1.7 but was not statistically significant (P=0.39). Baseline triglyceride was associated with increased CVD mortality risk independent of total cholesterol among relatives in FHTG families (relative risk 2.7, P=0.02) but not in FCHL families (relative risk 1.5, P=0.16) after adjustment for baseline covariates.

CONCLUSIONS

This prospective study establishes that relatives in FCHL families are at increased risk for CVD mortality and illustrates the need for effective prevention strategies in this group. Baseline triglyceride level predicted subsequent CVD mortality among relatives in FHTG families, adding to the growing evidence for the importance of hypertriglyceridemia as a risk factor for CVD.

Pleiotropic genetic effects on LDL size, plasma triglyceride, and HDL cholesterol in families

The interrelationships among low density lipoprotein (LDL) particle size, plasma triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) are well established and may involve underlying genetic influences. This study evaluated common genetic effects on LDL size, TG, and HDL-C by using data from 85 kindreds participating in the Genetic Epidemiology of Hypertriglyceridemia (GET) Study. A multivariate, maximum likelihood-based approach to quantitative genetic analysis was used to estimate the additive effects of shared genes and shared, unmeasured nongenetic factors on variation in LDL size and in plasma levels of TG and HDL-C. A significant (P<0.001) proportion of the variance in each trait was attributable to the additive effects of genes. Maximum-likelihood estimates of heritability were 0.34 for LDL size, 0.41 for TG, and 0.54 for HDL-C. Significant (P<0.001) additive genetic correlations (rho(G)), indicative of the shared additive effects of genes on pairs of traits, were estimated between all 3 trait pairs: for LDL size and TG rho(G)=-0.87, for LDL size and HDL-C rho(G)=0.65, and for HDL-C and TG rho(G)=-0.54. A similar pattern of significant environmental correlations between the 3 trait pairs was also observed. These results suggest that a large proportion of the well-documented correlations in LDL size, TG, and HDL-C are likely attributable to the influence of the same gene(s) in these families. That is, the gene(s) that may contribute to decreases in LDL size also contribute significantly to higher plasma levels of TG and lower plasma levels of HDL-C. These relationships may be useful in identifying genes responsible for the associations between these phenotypes and susceptibility to cardiovascular disease in these families.

Atheroprotective mechanisms of HDL

The aim of this review was to bring together results obtained from studies on different aspects of HDL as related to CHD and atherosclerosis. As atherosclerosis is a multistep process, the various components of HDL can intervene at different stages, such as induction of monocyte adhesion molecules, prevention of LDL modification and removal of excess cholesterol by reverse cholesterol transport. Transgenic technology has provided a model for atherosclerosis, and permitted evaluation of the contributions of different HDL components towards the global effect. The availability of apo AIV transgenic mice amplified the results obtained from apo AI overexpressors with respect to prevention of atherosclerosis. Prevention of atherosclerosis in apo E deficient mice by relatively small amounts of macrophage derived apo E may open new possibilities for therapeutic intervention. Contrary to early notions, increased plasma levels of CETP, even in the presence of low but functionally normal HDL, were atheroprotective. The extent to which paraoxonase and apo J participate in prevention of human atherosclerosis needs further evaluation. The findings that LCAT overexpression in rabbits was atheroprotective in contrast to increase in atherosclerosis in h LCAT tg mice, which was only partially corrected by CETP expression, call for some caution in the extrapolation of results from transgenic animals to humans. The important discovery of SR-BI as the receptor for selective uptake of CE from HDL revived interest in the clearance of CE from plasma. This pathway supplies also the vital precursor for steroidogenesis in adrenals and gonads and was shown to be dependent on apo AI.

Effectiveness of once-nightly dosing of extended-release niacin alone and in combination for hypercholesterolemia

We performed a multicenter, open-label study to determine the long-term safety and efficacy of a new extended-release once-a-night niacin preparation, Niaspan, in the treatment of hypercholesterolemia. Niaspan, 0.5 to 3.0 g once a night at bedtime, was used alone or in combination with a statin (inhibitor of hydroxymethylglutaryl coenzyme A reductase), a bile acid sequestrant, or both. Patients included 269 hypercholesterolemic male and female adults enrolled in a 96-week study, and 230 additional adults for whom short-term safety data were available. The dosages of Niaspan attained by 269 patients were 1,000 mg (95% of patients), 1,500 mg (86%), and 2,000 mg (65%). After 48 weeks of treatment, Niaspan alone (median dose 2,000 mg) reduced low-density lipaprotein (LDL) cholesterol (18%), apolipoprotein B (15%), total cholesterol (11%), triglycerides (24%), and lipoprotein(a) (36%), and increased high-density lipoprotein (HDL) cholesterol (29%). Niaspan plus a statin lowered LDL cholesterol (32%), apolipoprotein B (26%), total cholesterol (23%), triglycerides (30%), and lipoprotein(a) (19%), and increased HDL cholesterol (26%). Reversible elevations of aspartate aminotransferase or alanine aminotransferase more than twice the normal range occurred in 2.6% of patients. One patient discontinued Niaspan because of transaminase elevations. Intolerance to flushing, leading to discontinuation of Niaspan, occurred in 4.8% of patients. The overall rate of discontinuance due to flushing in this study combined with 2 previous randomized trials was 7.3%. In the long-term treatment of hypercholesterolemia, Niaspan produced favorable changes in LDL and HDL cholesterol, triglycerides, and lipoprotein(a). Adverse hepatic effects were minor and occurred at rates similar to those reported for statin therapy.

Elevated Lp(a) is the most frequent familial lipoprotein disorder leading to premature myocardial infarction in a country with low cholesterol levels

Disorders of the lipoprotein metabolism are an important cause of premature coronary artery disease and myocardial infarction. Of the genetic lipoprotein disorders, elevation of apoprotein (apo) B containing lipoproteins is the most frequent one in the western population. We aimed to define the prevalence of genetic lipoprotein disorders and other risk factors in a population from a country with a low average cholesterol levels. We examined 48 consecutive patients with premature myocardial infarction below age 55, their 78 siblings and age and body mass index matched controls for familial lipoprotein disorders. The patients with premature myocardial infarction had higher triglyceride, low-density lipoprotein, apo B, lipoprotein (Lp) (a) and lower apo A1 levels then controls (p < 0.05). Of the nonlipid risk factors, 67% smoked, 8% had diabetes mellitus, 17% had hypertension and 58% a family history of premature coronary artery disease. Fifty percent of these patients with premature myocardial infarction had a familial lipoprotein disorder. Familial excess of Lp(a) was the most frequent lipoprotein abnormality present in 16% of the patients followed by familial combined hyperlipidemia. We conclude that, Lp(a) increase was the most frequent familial lipoprotein abnormality in this population. The frequency of familial lipoprotein disorders in this population emphasises the need to screen siblings of patients with premature myocardial infarction.

A multicenter, double-blind, one-year study comparing safety and efficacy of atorvastatin versus simvastatin in patients with hypercholesterolemia

We directly compared the safety and efficacy of atorvastatin and simvastatin in hypercholesterolemic patients. This 1-year, randomized, double-blind study was performed at 9 community- and university-based research hospitals in Australia. One-hundred seventy-seven patients between the ages of 18 and 80 years with baseline low-density-lipoprotein (LDL) cholesterol > or = 4.14 and < or = 7.76 mmol/L (160 and 300 mg/dl, respectively) and triglycerides < or = 4.52 mmol/L (400 mg/dl) received once-daily dosing with atorvastatin (Lipitor) 10 mg or simvastatin (Zocor) 10 mg. At week 16, the dose of medication was titrated to atorvastatin 20 mg or simvastatin 20 mg if patients did not meet LDL cholesterol target of < or = 3.36 mmol/L (130 mg/dl). Efficacy was reported as percent change from baseline in LDL cholesterol, total cholesterol, very low density lipoprotein cholesterol, total triglycerides, high-density lipoprotein cholesterol, apolipoproteins AI and B, and lipoprotein(a). Atorvastatin caused significantly greater reductions from baseline than did simvastatin for LDL cholesterol, total cholesterol, very low density lipoprotein cholesterol, triglycerides, and apolipoprotein B (p <0.05). No patient in either treatment group had clinically important elevations in creatine phosphokinase, alanine aminotransaminase, or aspartate aminotransaminase. No serious adverse events were considered associated with treatment. With atorvastatin 10 mg, 46% of the patients achieved LDL cholesterol target goal by week 16, whereas only 27% of the simvastatin patients achieved the target goal at the 10-mg dose. This cholesterol-lowering profile affords utility in many patient types.