Apolipoproteins AI, B, and E polymorphisms in severe aortic valve stenosis

A Twenty-Year Analysis of Demographics, Surgical Management, and Outcomes of Aortic Stenosis in New Jersey

We investigated the incidence and characteristics of 14,996 patients with aortic stenosis (AS) who were hospitalized in New Jersey between the years 1995 to 2015. The average age was 72, the majority were Caucasian males and common co-morbidities were hypertension, coronary artery disease and hypercholesterolemia. Hospital admission for AS declined between 1995 to 2007, to 10/100,000 patients, and increased to 15/100,000 patients in 2015 (p for trend <0.001). During the study period, the percentage of patients who received aortic valve replacement (AVR) increased (p <0.001). All-cause and cardiovascular mortality were higher among patients who did not undergo AVR at 1-year (HR 1.98 CI 1.75 to 2.23, p <0.001 and HR 1.82 CI 1.57 to 2.11, p <0.001, respectively) and 3-years (HR 2.16 CI 1.96 to 2.38, p <0.001 and HR 2.16 CI 1.90 to 2.45, p <0.001, respectively). The probability for readmission for AS was higher in patients who did not receive AVR compared to patients who had AVR at 1 year (HR 92.95 CI 57.85 to 149.35, p <0.001) and 3 years (HR 70.36 CI 47.18 to 104.95, p <0.001). These data imply that earlier diagnosis of AS and AVR when indicated will improve outcomes.

Association between apolipoprotein B genetic polymorphism and the risk of calcific aortic stenosis in Chinese subjects, in Xinjiang, China

Background

Limited information is available when it comes to the impact of genetic on Calcific Aortic Stenosis (CAS). Apolipoprotein B (apoB) is a key component in lipid metabolism and plays an important role in the dynamic equilibrium of cholesterol. We performed a case–control study to explore the association of apoB genetic polymorphisms with CAS in Chinese subjects, in Xinjiang, China.

Methods

We designed a case-control study including 314 CAS patients and 652 age- and sex-matched control subjects. Using the polymerase chain reaction-restriction fragment length (PCR-RFLP) method, we genotyped two SNPs (rs6725189 and rs693) of apoB gene in all subjects.

Results

We found that the rs693 T allele was associated with a significantly elevated CAS risk [TT/CT vs. CC: adjusted odds ratio (AOR) = 1.58, 95% confidence interval (CI) = 1.82–2.10, P = 0.002] and the rs6725189 T allele was also associated with a significantly elevated CAS risk (GT vs. GG: AOR = 1.82, 95% CI = 1.14–2.92, P = 0.013). Furthermore, we also found that the TC levels were significantly higher in rs693 TT/CT genotypes than that in CC genotypes (P < 0.05).

Conclusions

Both rs693 and rs6725189 of the apoB gene are associated with CAS in Chinese subjects, in Xinjiang, China.

Associations of the APOB rs693 and rs17240441 polymorphisms with plasma APOB and lipid levels: a meta-analysis

BACKGROUND

The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. This meta-analysis aimed to clarify the associations of the rs693 and rs17240441 polymorphisms with fasting APOB and lipid levels.

METHODS

Sixty-one studies (50,018 subjects) and 23 studies (8425 subjects) were respectively identified for the rs693 and rs17240441 polymorphisms by searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases. The following information was collected for each study: first author, age, gender, ethnicity, health condition, sample size, genotyping, lipid assay method, mean and standard deviation or standard error of APOB and lipid variables by genotypes. A dominant model was used for this meta-analysis.

RESULTS

The carriers of the rs693 variant allele (T) had higher levels of APOB [standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) = 0.16-0.36, P < 0.01], triglycerides (TG) (SMD = 0.12, 95% CI = 0.05-0.20, P < 0.01), total cholesterol (TC) (SMD = 0.24, 95% CI = 0.17-0.30, P < 0.01) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.22, 95% CI = 0.14-0.30, P < 0.01), and lower levels of high-density lipoprotein cholesterol (HDL-C) (SMD = -0.06, 95% CI = -0.11-0.01, P = 0.01) than the non-carriers. The carriers of the rs17240441 deletion allele had higher levels of APOB (SMD = 0.13, 95% CI = 0.06-0.20, P < 0.01), TC (SMD = 0.17, 95% CI = 0.07-0.26, P < 0.01) and LDL-C (SMD = 0.15, 95% CI = 0.07-0.23, P < 0.01) than the non-carriers.

CONCLUSIONS

The rs693 polymorphism is significantly associated with higher levels of APOB, TG, TC and LDL-C, and lower levels of HDL-C. The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and LDL-C. Further studies are needed to elucidate the underlying mechanisms.

Analysis of Serum Metabolites to Diagnose Bicuspid Aortic Valve

Bicuspid aortic valve (BAV) is the most common congenital heart disease. The current study aims to construct a diagnostic model based on metabolic profiling as a non-invasive tool for BAV screening. Blood serum samples were prepared from an estimation group and a validation group, each consisting of 30 BAV patients and 20 healthy individuals, and analyzed by liquid chromatography-mass spectrometry (LC-MS). In total, 2213 metabolites were detected and 41 were considered different. A model for predicting BAV in the estimation group was constructed using the concentration levels of monoglyceride (MG) (18:2) and glycerophospho-N-oleoyl ethanolamine (GNOE). A novel model named Zhongshan (ZS) was developed to amplify the association between BAV and the two metabolites. The area under curve (AUC) of ZS for BAV prediction was 0.900 (0.782–0.967) and was superior to all single-metabolite models when applied to the estimation group. Using optimized cutoff (−0.1634), ZS model had a sensitivity score of 76.7%, specificity score of 90.0%, positive predictive value of 80% and negative predictive value of 85.0% for the validation group. These results support the use of serum-based metabolomics profiling method as a complementary tool for BAV screening in large populations.

Pilot candidate gene analysis of patients ≥ 60 years old with aortic stenosis involving a tricuspid aortic valve

The potential genetic basis of aortic stenosis in older people is poorly understood. A total of 265 patients with aortic stenosis involving tricuspid aortic valves and 961 controls were genotyped for ≤660 candidate single nucleotide polymorphisms (SNPs). After dividing the patients and controls into training and validation sets, we tested the correlation of the SNPs with the age-adjusted aortic valve area, determined by echocardiography or cardiac catheterization. A bootstrapped global p value of ≤0.005 was considered evidence of a possible significant correlation. The cases were aged 73 ± 7 years, and 72.7% were men. The median aortic valve area was 1.0 cm(2) (interquartile range 0.7 to 1.5). The controls were aged 69 ± 6 years, and 69.8% were men. The minor allele frequency was 21% ± 15% (37% <0.20). Three SNPs met the criteria for significant correlation (rs2276288 [MYO7A], p = 0.001; rs5194 [AGTR1], p = 0.004; rs207 307 [ELN], p = 0.005). Another 2 SNPs reached borderline significance (p ≤0.008). In conclusion, we report 3 SNPs to be associated with aortic stenosis involving tricuspid aortic valves in older subjects. Given the concerns regarding the problem of multiple statistical testing, validation studies are required to further assess these correlations.

Replication of genetic association studies in aortic stenosis in adults

Only a handful of studies have attempted to unravel the genetic architecture of calcific aortic valve stenosis (AS). The goal of this study was to validate genes previously associated with AS. Seven genes were assessed: APOB, APOE, CTGF, IL10, PTH, TGFB1, and VDR. Each gene was tested for a comprehensive set of single-nucleotide polymorphisms (SNPs). SNPs were genotyped in 457 patients who underwent surgical aortic valve replacement, and allele frequencies were compared to 3,294 controls. A missense mutation in the APOB gene was significantly associated with AS (rs1042031, E4181K, p = 0.00001). A second SNP located 5.6 kilobases downstream of the APOB stop codon was also associated with the disease (rs6725189, p = 0.000013). Six SNPs surrounding the IL10 locus were strongly associated with AS (0.02 > p > 6.2 × 10⁻¹¹). The most compelling association for IL10 was found with a promoter polymorphism (rs1800872) well known to regulate the production of the encoded anti-inflammatory cytokine. The frequency of the low-producing allele was greater in cases compared to controls (30% vs 20%, p = 6.2 × 10⁻¹¹). SNPs in PTH, TGFB1, and VDR had nominal p values <0.05 but did not resist Bonferroni correction. In conclusion, this study suggests that subjects carrying specific polymorphisms in the IL10 and APOB genes are at higher risk for developing AS.

Statins for calcific aortic valve stenosis: into oblivion after SALTIRE and SEAS? An extensive review from bench to bedside

Calcific aortic stenosis is the most frequent heart valve disease and the main indication for valve replacement in western countries. For centuries attributed to a passive wear and tear process, it is now recognized that aortic stenosis is an active inflammatory and potentially modifiable pathology, with similarities to atherosclerosis. Statins were first-line candidates for slowing down progression of the disease, as established drugs in primary and secondary cardiovascular prevention. Despite promising animal experiments and nonrandomized human trials, the prospective randomized trials SEAS and SALTIRE did not confirm the expected benefit. We review SEAS and SALTIRE starting with the preceding studies and discuss basic science experiments covering the major known contributors to the pathophysiology of calcific aortic valve disease, to conclude with a hypothesis on the absent effect of statins, and suggestions for further research paths.

Mechanisms of aortic valve calcification: the LDL-density-radius theory: a translation from cell signaling to physiology

Recent epidemiologic studies have revealed the risk factors associated for vascular atherosclerosis, including the male sex, smoking, hypertension, and elevated serum cholesterol, similar to the risk factors associated with the development of AV stenosis. An increasing number of models of experimental hypercholesterolemia demonstrate features of atherosclerosis in the AV, which are similar to the early stages of vascular atherosclerotic lesions. Experimental and clinical studies demonstrate that the hypercholesterolemic AV develops an atherosclerotic lesion which is proliferative and expresses high levels of osteoblast bone markers which mineralize over time to form bone. Calcification, the end-stage process of the disease, is necessary to understand as a prognostic indicator in the modification of this cellular process before it is too late. In summary, these findings suggest that medical therapies may have a potential role in patients in the early stages of this disease process to slow the progression to severe aortic stenosis and to delay the timing of the need for surgery. The translation of these experimental studies to clinical practice will be important to understand the potential for medical therapy for this disease process.

Calcific aortic stenosis: lessons learned from experimental and clinical studies

Calcific aortic stenosis is the most common indication for surgical valve replacement in the United States. For years this disease has been described as a passive degenerative process during which serum calcium attaches to the valve surface and binds to the leaflet to form nodules. Therefore, surgical treatment of this disease has been the approach toward relieving outflow obstruction in these patients. Recent studies demonstrate an association between atherosclerosis and its risk factors for aortic valve disease. In 2008, there are increasing number of epidemiology and experimental studies to provide evidence that this disease process is not a passive phenomena. There is an active cellular process that develops within the valve leaflet and causes a regulated bone formation to develop. If the atherosclerotic hypothesis is important in the initiation of aortic stenosis, then treatments used in slowing the progression of atherosclerosis may be effective in patients with aortic valve disease. This review will discuss the pathogenesis and the potential for medical therapy in the management of patients with calcific aortic stenosis by examining the lessons provided from the experimental research.

Genomics: the next step to elucidate the etiology of calcific aortic valve stenosis

With the current shift toward an older population, calcific aortic valve stenosis (AVS) is likely to become a major societal and economic burden. For many years, AVS was regarded as a degenerative and nonmodifiable process. However, molecular studies unanimously demonstrated that AVS is an actively regulated disorder with several potential therapeutic targets. Many factors are predicted to cause AVS, and an important genetic predisposition is anticipated. In this review, we describe candidate genes and signaling pathways identified by genetic research and incorporate this new knowledge into a more comprehensive picture of factors involved in the pathogenesis of AVS. We also emphasize the need for additional studies to elucidate its complete genetic architecture. Recent advances in genomic research offer a remarkable opportunity to investigate AVS at the most fundamental level. The benefits of these new approaches can be observed in many complex diseases, but the field of AVS is trailing behind. We discuss the future utility of these new genomic approaches to improve our understanding of AVS and to refine the management of patients in terms of diagnosis, prevention, and treatment.

Epidemiology and genetics of calcific aortic valve disease

Calcific aortic valve disease is a common condition in the elderly and is associated with significant morbidity and mortality. Although biologically plausible roles in disease pathogenesis have been proposed for both lipoproteins and the renin-angiotensin system, no properly controlled, randomized trials have demonstrated that any pharmacologic therapy slows development of the disease. This review defines the stages of calcific aortic valve disease; discusses the role of nonechocardiographic techniques, such as cardiac computed tomography, that may allow identification and study of earlier-stage disease; reviews associated epidemiologic factors; and summarizes recent studies of "novel" risk factors, such as metabolic syndrome and inflammatory biomarkers. Finally, the role of genetics in this disease is receiving greater attention, and recent studies are reviewed that examine genetic polymorphisms and identify single-gene defects associated with this disease. Together these latter sets of studies emphasize that unique "nonatherosclerotic" factors can influence calcific aortic valve disease development, suggesting the possibility of novel therapeutic strategies for this condition.

Reassessment of statins to retard the progression of aortic stenosis

Aortic valve stenosis is the most common indication for surgical valve replacement in the United States and Europe. For years, this valve lesion was thought to be a passive degenerative disease. In the past decade there have been a number of studies indicating that the risk factors for valvular heart disease are the same as those for vascular atherosclerosis. This correlation with atherosclerosis and valvular heart disease indicates that medical therapy may have a role in slowing the progression of this disease process. Currently, the retrospective studies indicate that medical therapy slows the progression of this disease. The prospective data are currently conflicting in terms of the final outcomes for treating the disease process with medical therapy. This review outlines the growing number of clinical studies implicating the potential for medical therapy in this patient population.

Calcific aortic stenosis: an update

Calcific aortic stenosis in the elderly is the number one cause of surgical valve replacement in the US and Europe. The incidence of calcific aortic stenosis is increasing as the general age of the population increases. For many years, rheumatic heart disease was the main cause of aortic valve disease. Over the last half century, however, there has been a change from a rheumatic etiology to a 'degenerative' mechanism because of the increase in access to health care in developed countries and the increasing age of the population in the US and Europe. For many years 'degenerative' aortic stenosis was thought to be caused by the passive accumulation of calcium on the surface of the aortic valve leaflet. Recent studies have demonstrated, however, that the etiology of aortic valve disease has a similar pathophysiology to that of vascular atherosclerosis, and that the treatment of this disease could be similar to that of chronic vascular atherosclerosis. This Review will discuss our current understanding of the pathophysiology, risk factors, cellular mechanisms, diagnosis and finally, future medical therapies for calcific aortic stenosis.

A medical therapy for aortic valve sclerosis and aortic valve stenosis? Rationale of the ASSIST study (Asymptomatic aortic Sclerosis/Stenosis: Influence of STatins): a large, observational, prospective, multicenter study of the Italian Society of Cardiovascular Echography

Progression of sclerosis and stenosis is substantially unpredictable in the individual patient: in some cases it is very slow, in others it is accelerated. In addition, different patterns of progression (linear and non-linear) are possible. It has been suggested that the aortic valve lesion can be considered a form within the spectrum of the same atherosclerotic disease. In this context it seemed reasonable to hypothesize that targeted medical therapy could retard the progression of the disease. In particular HMG-CoA reductase inhibitors (statins) and angiotensin-converting enzyme inhibitors have been tested. The first experimental and clinical studies are now available, even though they are not conclusive to date. Large, prospective, randomized trials are ideally needed, but they are quite difficult, if not even impossible, to realize in practice. The ASSIST study (Asymptomatic aortic Sclerosis/Stenosis: Influence of STatins) of the Italian Society of Cardiovascular Echography aims to create a large, prospective, observational investigation, involving many centers of echocardiography and thousands of patients, in order to provide from the real clinical world at least some of the answers to this unsolved question.

APOE alleles are not associated with calcific aortic stenosis

OBJECTIVES

To analyse the association of APOE alleles with aortic stenosis (AS) in a large study population.

METHODS

Patients with AS (n = 538) and a control group of the same age without heart disease (n = 536) were recruited. Left heart catheterisation was performed and mean gradient, aortic valve area, presence of stenotic coronary artery disease (CAD) and cardiovascular risk factors (hypercholesterolaemia, hypertension, smoking, diabetes mellitus and family history of CAD) were assessed. The frequency of the APOE major alleles e2, e3 and e4 was assessed by genotyping the polymorphisms APOE334 and APOE472 with a 5' exonuclease assay (TaqMan).

RESULTS

Mean gradient across the aortic valve in cases was 50 (SD 20) mm Hg corresponding to a mean aortic valve area of 0.84 (SD 0.34) cm(2). 270 patients with AS had stenotic CAD. Among patients with AS, the prevalence of hypercholesterolaemia (64% v 40%, p < 0.001), smoking (43% v 27%, p < 0.001), diabetes (27% v 17%, p < 0.01), family history of CAD (30% v 21%, p </= 0.05), and male sex (65% v 44%, p < 0.001) was higher in those with than in those without CAD. The frequency of the major alleles was not different between cases and controls (APOE e2: 104 (19.3%) v 94 (17.5%); APOE e3: 319 (59.3%) v 332 (61.9%); APOE e4: 115 (21.3%) v 110 (20.5%); all p > 0.10).

CONCLUSION

APOE e4 is not associated with AS, reflecting the different genetic backgrounds of CAD and AS.

Aortic valve sclerosis is associated with preclinical cardiovascular disease in hypertensive adults: the Hypertension Genetic Epidemiology Network study

RATIONALE

Aortic valve sclerosis (AVS) has been associated with atherosclerosis and increased all-cause and cardiovascular death. However, whether AVS is associated with preclinical cardiovascular disease among adults at high risk because of hypertension has not been determined in a population-based sample.

METHODS AND RESULTS

Clinical and echocardiographic parameters were measured in 1624 hypertensive participants (54 +/- 11 years, 65% women, 63% black, 17% diabetic, 19% smokers) without significant valvular or cardiovascular diseases in the population-based Hypertension Genetic Epidemiology Network study. The 152 participants with AVS (9.4%), compared with participants without AVS, were older, more often white, male, treated for hypertension or hypercholesteromia (all P < 0.05) and had longer duration and worse hypertension, but did not differ in diabetes status, smoking or fenfluramine use. Adjusting for age, gender and race, the AVS group had higher total cholesterol/high-density lipoprotein-cholesterol (P < 0.05). Controlling for age, gender, race and other clinical covariates, AVS was independently associated with higher septal, posterior and relative wall thicknesses, isovolumic relaxation time and left atrial diameter, and with mild aortic regurgitation and mitral annular calcification (all P < 0.05).

CONCLUSIONS

In a population-based sample of hypertensive adults, AVS was prevalent (9.4%) and associated with a proatherogenic clinical profile and abnormal left ventricular geometry and filling, increased left atrial size and mitral annular calcification, which may contribute to the adverse prognosis associated with AVS.

Association Between Apolipoprotein E Alleles and Calcific Valvular Heart Disease

Background— Studies on apolipoprotein E (apoE) alleles have reported an increased risk of coronary heart disease in patients with the apoE4 allele. Given the risk factor and histological similarities between coronary and calcific valvular heart disease (aortic stenosis [AS] and mitral annular calcification [MAC]), we postulated that apoE alleles might be associated with the development of these valvular lesions.

Methods and Results— We evaluated the association between apoE alleles and calcific valvular lesions in 802 patients undergoing transthoracic echocardiography using logistic regression analyses. No difference was noted in genotype distribution ( P =0.59) or prevalence of apoE4 between those with or without MAC (30% versus 27%, respectively; P =0.57). Compared with patients without AS, the genotype distribution of patients with AS differed significantly ( P =0.03), with increasing prevalences of the apoE 4 allele (27% in those without versus 40% in those with AS; P =0.01). In multivariate analyses adjusting for age, gender, low-density lipoprotein cholesterol levels, and coronary artery disease, increasing age and the apoE4 allele were significant independent predictors of AS (odds ratio, 1.94; 95% confidence interval, 1.01 to 3.71; P =0.046), whereas the apoE4 allele was not predictive of MAC.

Conclusions— These findings support extension of the importance of the apoE4 allele beyond atherosclerosis and Alzheimer’s disease to calcific AS.