Rationale and design of a trial evaluating the effects of losartan vs. nebivolol vs. the association of both on the progression of aortic root dilation in Marfan syndrome with FBN1 gene mutations

Reduced Levels of Selenium and Thioredoxin Reductase in the Thoracic Aorta Could Contribute to Aneurysm Formation in Patients with Marfan Syndrome

Marfan syndrome (MFS) is an autosomal dominant disorder caused by a heterozygous mutation of the FBN1 gene. MFS patients present oxidative stress that disturbs redox homeostasis. Redox homeostasis depends in part on the enzymatic antioxidant system, which includes thioredoxin reductase (TrxR) and glutathione peroxidases (GPx), both of which require an adequate concentration of selenium (Se). Therefore, the aim of this study was to determine if Se levels are decreased in the TAA of patients with MFS since this could contribute to the formation of an aneurysm in these patients. The results show that interleukins IL-1β, IL-6 TGF-β1, and TNF-α (p ≤ 0.03), and carbonylation (p ≤ 0.03) were increased in the TAA of patients with MFS in comparison with control subjects, while Se, thiols (p = 0.02), TrxR, and GPx (p ≤ 0.001) were decreased. TLR4 and NOX1 (p ≤ 0.03), MMP9 and MMP2 (p = 0.04) and NOS2 (p < 0.001) were also increased. Therefore, Se concentrations are decreased in the TAA of MFS, which can contribute to a decrease in the activities of TrxR and GPx, and thiol groups. A decrease in the activities of these enzymes can lead to the loss of redox homeostasis, which can, in turn, lead to an increase in the pro-inflammatory interleukins associated with the overexpression of MMP9 and MMP2.

NADPH Oxidases in Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) are a progressive dilation of the infrarenal aorta and are characterized by inflammatory cell infiltration, smooth muscle cell migration and proliferation, and degradation of the extracellular matrix. Oxidative stress and the production of reactive oxygen species (ROS) have been shown to play roles in inflammatory cell infiltration, and smooth muscle cell migration and apoptosis in AAAs. In this review, we discuss the principles of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase/NOX) signaling and activation. We also discuss the effects of some of the major mediators of NOX signaling in AAAs. Separately, we also discuss the influence of genetic or pharmacologic inhibitors of NADPH oxidases on experimental pre-clinical AAAs. Experimental evidence suggests that NADPH oxidases may be a promising future therapeutic target for developing pharmacologic treatment strategies for halting AAA progression or rupture prevention in the management of clinical AAAs.

Angiotensin receptor blockers and β blockers in Marfan syndrome: an individual patient data meta-analysis of randomised trials

BACKGROUND

Angiotensin receptor blockers (ARBs) and β blockers are widely used in the treatment of Marfan syndrome to try to reduce the rate of progressive aortic root enlargement characteristic of this condition, but their separate and joint effects are uncertain. We aimed to determine these effects in a collaborative individual patient data meta-analysis of randomised trials of these treatments.

METHODS

In this meta-analysis, we identified relevant trials of patients with Marfan syndrome by systematically searching MEDLINE, Embase, and CENTRAL from database inception to Nov 2, 2021. Trials were eligible if they involved a randomised comparison of an ARB versus control or an ARB versus β blocker. We used individual patient data from patients with no prior aortic surgery to estimate the effects of: ARB versus control (placebo or open control); ARB versus β blocker; and indirectly, β blocker versus control. The primary endpoint was the annual rate of change of body surface area-adjusted aortic root dimension Z score, measured at the sinuses of Valsalva.

FINDINGS

We identified ten potentially eligible trials including 1836 patients from our search, from which seven trials and 1442 patients were eligible for inclusion in our main analyses. Four trials involving 676 eligible participants compared ARB with control. During a median follow-up of 3 years, allocation to ARB approximately halved the annual rate of change in the aortic root Z score (mean annual increase 0·07 [SE 0·02] ARB vs 0·13 [SE 0·02] control; absolute difference -0·07 [95% CI -0·12 to -0·01]; p=0·012). Prespecified secondary subgroup analyses showed that the effects of ARB were particularly large in those with pathogenic variants in fibrillin-1, compared with those without such variants (heterogeneity p=0·0050), and there was no evidence to suggest that the effect of ARB varied with β-blocker use (heterogeneity p=0·54). Three trials involving 766 eligible participants compared ARBs with β blockers. During a median follow-up of 3 years, the annual change in the aortic root Z score was similar in the two groups (annual increase -0·08 [SE 0·03] in ARB groups vs -0·11 [SE 0·02] in β-blocker groups; absolute difference 0·03 [95% CI -0·05 to 0·10]; p=0·48). Thus, indirectly, the difference in the annual change in the aortic root Z score between β blockers and control was -0·09 (95% CI -0·18 to 0·00; p=0·042).

INTERPRETATION

In people with Marfan syndrome and no previous aortic surgery, ARBs reduced the rate of increase of the aortic root Z score by about one half, including among those taking a β blocker. The effects of β blockers were similar to those of ARBs. Assuming additivity, combination therapy with both ARBs and β blockers from the time of diagnosis would provide even greater reductions in the rate of aortic enlargement than either treatment alone, which, if maintained over a number of years, would be expected to lead to a delay in the need for aortic surgery.

FUNDING

Marfan Foundation, the Oxford British Heart Foundation Centre for Research Excellence, and the UK Medical Research Council.

Loeys-Dietz Syndrome

Loeys-Dietz syndrome is an autosomal dominant aortic aneurysm syndrome characterized by multisystemic involvement. The most typical clinical triad includes hypertelorism, bifid uvula or cleft palate and aortic aneurysm with tortuosity. Natural history is significant for aortic dissection at smaller aortic diameter and arterial aneurysms throughout the arterial tree. The genetic cause is heterogeneous and includes mutations in genes encoding for components of the transforming growth factor beta (TGFβ) signalling pathway: TGFBR1, TGFBR2, SMAD2, SMAD3, TGFB2 and TGFB3. Despite the loss of function nature of these mutations, the patient-derived aortic tissues show evidence of increased (rather than decreased) TGFβ signalling. These insights offer new options for therapeutic interventions.

An Overview of Investigational and Experimental Drug Treatment Strategies for Marfan Syndrome

Marfan syndrome (MFS) is a heritable connective tissue disorder caused by pathogenic variants in the gene coding for the extracellular matrix protein fibrillin-1. While the disease affects multiple organ systems, the most life-threatening manifestations are aortic aneurysms leading to dissection and rupture. Other cardiovascular complications, including mitral valve prolapse, primary cardiomyopathy, and arrhythmia, also occur more frequently in patients with MFS. The standard medical care relies on cardiovascular imaging at regular intervals, along with pharmacological treatment with β-adrenergic receptor blockers aimed at reducing the aortic growth rate. When aortic dilatation reaches a threshold associated with increased risk of dissection, prophylactic surgical aortic replacement is performed. Although current clinical management has significantly improved the life expectancy of patients with MFS, no cure is available and fatal complications still occur, underscoring the need for new treatment options. In recent years, preclinical studies have identified a number of potentially promising therapeutic targets. Nevertheless, the translation of these results into clinical practice has remained challenging. In this review, we present an overview of the currently available knowledge regarding the underlying pathophysiological processes associated with MFS cardiovascular pathology. We then summarize the treatment options that have been developed based on this knowledge and are currently in different stages of preclinical or clinical development, provide a critical review of the limitations of current studies and highlight potential opportunities for future research.

Long-term clinical outcomes of losartan in patients with Marfan syndrome: follow-up of the multicentre randomized controlled COMPARE trial

AIMS

The COMPARE trial showed a small but significant beneficial effect of 3-year losartan treatment on aortic root dilatation rate in adults with Marfan syndrome (MFS). However, no significant effect was found on clinical endpoints, possibly due to a short follow-up period. The aim of the current study was therefore to investigate the long-term clinical outcomes after losartan treatment.

METHODS AND RESULTS

In the original COMPARE study (inclusion 2008-2009), adult patients with MFS (n = 233) were randomly allocated to either the angiotensin-II receptor blocker losartan® on top of regular treatment (β-blockers in 71% of the patients) or no additional medication. After the COMPARE trial period of 3 years, study subjects chose to continue their losartan medication or not. In a median follow-up period of 8 years, 75 patients continued losartan medication, whereas 78 patients, originally allocated to the control group, never used losartan after inclusion. No differences existed between baseline characteristics of the two groups except for age at inclusion [losartan 34 (interquartile range, IQR 26-43) years, control 41 (IQR 30-52) years; P = 0.031], and β-blocker use (losartan 81%, control 64%; P = 0.022). A pathological FBN1 mutation was present in 76% of patients and 58% of the patients were male. Clinical endpoints, defined as all-cause mortality, aortic dissection/rupture, elective aortic root replacement, reoperation, and vascular graft implantation beyond the aortic root, were compared between the two groups. A per-patient composite endpoint was also analysed. Five deaths, 14 aortic dissections, 23 aortic root replacements, 3 reoperations, and 3 vascular graft implantations beyond the aortic root occurred during follow-up. Except for aortic root replacement, all endpoints occurred in patients with an operated aortic root. Patients who used losartan during the entire follow-up period showed a reduced number of events compared to the control group (death: 0 vs. 5, P = 0.014; aortic dissection: 3 vs. 11, P = 0.013; elective aortic root replacement: 10 vs. 13, P = 0.264; reoperation: 1 vs. 2, P = 0.463; vascular graft implantations beyond the aortic root 0 vs. 3, P = 0.071; and composite endpoint: 14 vs. 26, P = 0.019). These results remained similar when corrected for age and β-blocker use in a multivariate analysis.

CONCLUSION

These results suggest a clinical benefit of combined losartan and β-blocker treatment in patients with MFS.

Management of a giant aortic root aneurysm in a young patient with Marfan syndrome: a case report

Introduction

Marfan syndrome (MFS) is a common heritable connective tissue disease involving multiple organs. Even though the clinical manifestations of MFS can be various, aortic root aneurysm is estimated as one of the most serious complications. We herein describe an individualized treatment decision-making process for a 23-year-old male with MFS, suffering from a giant but stable aortic root aneurysm which is extremely rare at his age.

Case

The patient, a 23-year-old male with a family history of MFS, presented to our cardiovascular department because of progressive exertional chest distress, fatigue and occasional precordial pain. Physical examinations revealed 190.5 cm of height, high myopia, and a diastolic murmur at the aortic valve area. Laboratory examinations for systemic vasculitis and infectious diseases were negative. Transthoracic echocardiography and enhanced thoracic computed tomography (CT) scan revealed the existence of a giant aortic root aneurysm (125.1 mm in short-axis), severe aortic valve regurgitation, cardiac dilatation (LV; 99 mm in diastolic diameter) and a poor ejection fraction (EF; 18%). Considering the risk of rupture or dissection of the dilated aortic root, we performed Bentall procedure based on the results of multidisciplinary team discussion and intraoperative exploration. Postoperative thoracic CT scan revealed a normal sized reconstructed aortic root, and the patient was discharged uneventfully 7 days later.

Conclusion

It is extremely rare to report such a giant aortic root aneurysm in a young patient. In the treatment decision-making process, the patient’s specific situation should be taken into consideration. A mechanical Bentall procedure seems to be an acceptable option for some selected cases.

Precise Therapy for Thoracic Aortic Aneurysm in Marfan Syndrome: A Puzzle Nearing Its Solution

Marfan Syndrome (MFS) is a rare connective tissue disorder, resulting from mutations in the fibrillin-1 gene, characterized by pathologic phenotypes in multiple organs, the most detrimental of which affects the thoracic aorta. Indeed, thoracic aortic aneurysms (TAA), leading to acute dissection and rupture, are today the major cause of morbidity and mortality in adult MFS patients. Therefore, there is a compelling need for novel therapeutic strategies to delay TAA progression and counteract aortic dissection occurrence. Unfortunately, the wide phenotypic variability of MFS patients, together with the lack of a complete genotype-phenotype correlation, have represented until now a barrier hampering the conduction of translational studies aimed to predict disease prognosis and drug discovery. In this review, we will illustrate available therapeutic strategies to improve the health of MFS patients. Starting from gold standard surgical overtures and the description of the main pharmacological approaches, we will comprehensively review the state-of-the-art of in vivo MFS models and discuss recent clinical pharmacogenetic results. Finally, we will focus on induced pluripotent stem cells (iPSC) as a technology that, if integrated with preclinical research and pharmacogenetics, could contribute in determining the best therapeutic approach for each MFS patient on the base of individual differences. Finally, we will suggest the integration of preclinical studies, pharmacogenetics and iPSC technology as the most likely strategy to help solve the composite puzzle of precise medicine in this condition.

Pathogenesis of aortic wall complications in Marfan syndrome

BACKGROUND

Patients with Marfan (MFS) syndrome and patients with a bicuspid aortic valve (BAV) are more prone to develop aortic dilation and dissection compared to persons with a tricuspid aortic valve (TAV). To elucidate potential common as well as distinct pathways of clinical relevance, we compared the histopathological substrates of aortic pathology.

PATIENT AND METHODS

Ascending aortic wall specimen were divided in five groups: BAV (n=36) and TAV (n=23) without and with dilation and non-dilated MFS (n=8). We performed routine histology to study aortic wall features based on the aortic consensus statement. Immunohistological markers for vascular smooth muscle cell (VSMC) maturation, and expression of fibrillin-1 were additionally investigated for the underlying pathogenesis.

RESULTS

On basis of the routine histology the aorta in MFS was similar to the aorta in dilated TAVs (overall medial degeneration, elastic fiber fragmentation, loss and disorganization, , and VSMC nuclei loss). The other markers aided in clustering the MFS and BAV patients with a significantly lower fibrillin-1 expression as compared to the TAVs (p<0.05), a lower level of differentiated VSMC markers (p<0.05) and elastic fiber thinning.

CONCLUSIONS

Pathogenesis of aortopathy in MFS overlaps with mechanisms seen in BAV and TAV, leading to a so called double hit hypothesis for aortic complications in MFS. The ascending aortic wall in MFS is immature with undifferentiated VSMCs and low levels of fibrillin-1. The immature media becomes even more vulnerable for aortopathy due to other degenerative features which develop probably as a direct consequence of the fibrillin-1 mutation.

Beta-blockers for preventing aortic dissection in Marfan syndrome

BACKGROUND

Marfan syndrome is a hereditary disorder affecting the connective tissue and is caused by a mutation of the fibrillin-1 (FBN1) gene. It affects multiple systems of the body, most notably the cardiovascular, ocular, skeletal, dural and pulmonary systems. Aortic root dilatation is the most frequent cardiovascular manifestation and its complications, including aortic regurgitation, dissection and rupture are the main cause of morbidity and mortality.

OBJECTIVES

To assess the long-term efficacy and safety of beta-blocker therapy as compared to placebo, no treatment or surveillance only in people with Marfan syndrome.

SEARCH METHODS

We searched the following databases on 28 June 2017; CENTRAL, MEDLINE, Embase, Science Citation Index Expanded and the Conference Proceeding Citation Index - Science in the Web of Science Core Collection. We also searched the Online Metabolic and Molecular Bases of Inherited Disease (OMMBID), ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) on 30 June 2017. We did not impose any restriction on language of publication.

SELECTION CRITERIA

All randomised controlled trials (RCTs) of at least one year in duration assessing the effects of beta-blocker monotherapy compared with placebo, no treatment or surveillance only, in people of all ages with a confirmed diagnosis of Marfan syndrome were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for inclusion, extracted data and assessed trial quality. Trial authors were contacted to obtain missing data. Dichotomous outcomes will be reported as relative risk and continuous outcomes as mean differences with 95% confidence intervals. We assessed the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One open-label, randomised, single-centre trial including 70 participants with Marfan syndrome (aged 12 to 50 years old) met the inclusion criteria. Participants were randomly assigned to propranolol (N = 32) or no treatment (N = 38) for an average duration of 9.3 years in the control group and 10.7 years in the treatment group. The initial dose of propranolol was 10 mg four times daily and the optimal dose was reached when the heart rate remained below 100 beats per minute during exercise or the systolic time interval increased by 30%. The mean (± standard error (SE)) optimal dose of propranolol was 212 ± 68 mg given in four divided doses daily.Beta-blocker therapy did not reduce the incidence of all-cause mortality (RR 0.24, 95% CI 0.01 to 4.75; participants = 70; low-quality evidence). Mortality attributed to Marfan syndrome was not reported. Non-fatal serious adverse events were also not reported. However, study authors report on pre-defined, non-fatal clinical endpoints, which include aortic dissection, aortic regurgitation, cardiovascular surgery and congestive heart failure. Their analysis showed no difference between the treatment and control groups in these outcomes (RR 0.79, 95% CI 0.37 to 1.69; participants = 70; low-quality evidence).Beta-blocker therapy did not reduce the incidence of aortic dissection (RR 0.59, 95% CI 0.12 to 3.03), aortic regurgitation (RR 1.19, 95% CI 0.18 to 7.96), congestive heart failure (RR 1.19, 95% CI 0.18 to 7.96) or cardiovascular surgery, (RR 0.59, 95% CI 0.12 to 3.03); participants = 70; low-quality evidence.The study reports a reduced rate of aortic dilatation measured by M-mode echocardiography in the treatment group (aortic ratio mean slope: 0.084 (control) vs 0.023 (treatment), P < 0.001). The change in systolic and diastolic blood pressure, total adverse events and withdrawal due to adverse events were not reported in the treatment or control group at study end point.We judged this study to be at high risk of selection (allocation concealment) bias, performance bias, detection bias, attrition bias and selective reporting bias. The overall quality of evidence was low. We do not know whether a statistically significant reduced rate of aortic dilatation translates into clinical benefit in terms of aortic dissection or mortality.

AUTHORS' CONCLUSIONS

Based on only one, low-quality RCT comparing long-term propranolol to no treatment in people with Marfan syndrome, we could draw no definitive conclusions for clinical practice. High-quality, randomised trials are needed to evaluate the long-term efficacy of beta-blocker treatment in people with Marfan syndrome. Future trials should report on all clinically relevant end points and adverse events to evaluate benefit versus harm of therapy.

The effect of losartan on progressive aortic dilatation in patients with Marfan's syndrome: a meta-analysis of prospective randomized clinical trials

OBJECTIVE

To assess the effect of losartan therapy on progressive aortic dilatation and on clinical outcome in patients with Marfan's syndrome (MFS).

METHODS

The meta-analysis was instituted, which included studies identified by a systematic review of MEDLINE of peer-reviewed publications. Echocardiogram or MRI measurements of the aortic root dimension and outcome measures of death, cardiovascular surgery and aortic dissection or rupture were compared between patients who were treated and untreated with losartan therapy.

RESULTS

Six randomized trials with 1398 subjects met all the inclusion criteria and were included in the meta-analysis. Compared with non-losartan treatment, losartan therapy significantly decreased the rate of aortic dilatation (SMD=-0.13 with 95% CI -0.25 to 0.00, p=0.04). The clinical outcome beneficial was not observed in the losartan treatment group when compared with no losartan treatment group (odds ratio=1.04 with 95% CI of 0.57-1.87).

CONCLUSION

Given the current results of the meta-analysis and together with the lack of associated side effects, it would be reasonable to use losartan in MFS patients with aortic root dilatation. However, no clinical outcome benefits were observed in the losartan treatment group when compared with no losartan treatment group.

Recent Clinical Drug Trials Evidence in Marfan Syndrome and Clinical Implications

Marfan syndrome is a genetic disorder of connective tissue with principal manifestations in the cardiovascular, ocular, and skeletal systems. Cardiovascular disease, mainly progressive aortic root dilation and aortic dissection, is the leading cause of morbidity and mortality. The primary aims of this report were to examine the evidence related to medical therapy for Marfan syndrome, including recently completed randomized clinical trials on the efficacy of β-blockers and angiotensin II receptor blockers for the prophylactic treatment of aortic enlargement in Marfan syndrome, and to provide recommendations for medical therapy on the basis of available evidence. Medical therapy for Marfan syndrome should be individualized according to patient tolerance and risk factors such as age, aortic size, and family history of aortic dissection. The Pediatric Heart Network trial showed that atenolol and losartan each reduced the rate of aortic dilation. All patients with known or suspected Marfan syndrome and aortic root dilation should receive medical therapy with adequate doses of either β-blocker or angiotensin receptor blocker. The Pediatric Heart Network trial also showed that atenolol and losartan are more effective at reduction of aortic root z score in younger subjects, which suggests that medical therapy should be prescribed even in the youngest children with aortic dilation. For patients with Marfan syndrome without aortic dilation, the available evidence is less clear. If aortic dilation is severe and/or progressive, therapy with a combination of β-blocker and angiotensin receptor blocker should be considered, although trial results are mixed with respect to the efficacy of combination therapy vs monotherapy.

Losartan therapy for cardiac disease in paediatricMarfan syndrome

A case of severe early-onset Marfan syndrome (MFS) led us to ask the question: 'Should an ARB, particularly losartan [intervention], compared with beta blockade alone [comparison], be commenced in all paediatric MFS patients [patient] with aortic root dilatation [outcome]?' The current literature was critically appraised to address this question.

Medical treatment of aortic aneurysms in Marfan syndrome and other heritable conditions

Thoracic aortic aneurysms can be triggered by genetic disorders such as Marfan syndrome (MFS) and related aortic diseases as well as by inflammatory disorders such as giant cell arteritis or atherosclerosis. In all these conditions, cardiovascular risk factors, such as systemic arterial hypertension, may contribute to faster rate of aneurysm progression. Optimal medical management to prevent progressive aortic dilatation and aortic dissection is unknown. β-blockers have been the mainstay of medical treatment for many years despite limited evidence of beneficial effects. Recently, losartan, an angiotensin II type I receptor antagonist (ARB), has shown promising results in a mouse model of MFS and subsequently in humans with MFS and hence is increasingly used. Several ongoing trials comparing losartan to β-blockers and/or placebo will better define the role of ARBs in the near future. In addition, other medications, such as statins and tetracyclines have demonstrated potential benefit in experimental aortic aneurysm studies. Given the advances in our understanding of molecular mechanisms triggering aortic dilatation and dissection, individualized management tailored to the underlying genetic defect may be on the horizon of individualized medicine. We anticipate that ongoing research will address the question whether such genotype/pathogenesis-driven treatments can replace current phenotype/syndrome-driven strategies and whether other forms of aortopathies should be treated similarly. In this work, we review currently used and promising medical treatment options for patients with heritable aortic aneurysmal disorders.

Histopathology of aortic complications in bicuspid aortic valve versus Marfan syndrome: relevance for therapy?

Patients with bicuspid aortic valve (BAV) and patients with Marfan syndrome (MFS) are more prone to develop aortic dilation and dissection compared to persons with a tricuspid aortic valve (TAV). To elucidate potential common and distinct pathways of clinical relevance, we compared the histopathological substrates of aortopathy. Ascending aortic wall biopsies were divided in five groups: BAV (n = 36) and TAV (n = 23) without and with dilation and non-dilated MFS (n = 8). General histologic features, apoptosis, the expression of markers for vascular smooth muscle cell (VSMC) maturation, markers predictive for ascending aortic dilation in BAV, and expression of fibrillin-1 were investigated. Both MFS and BAV showed an altered distribution and decreased fibrillin-1 expression in the aorta and a significantly lower level of differentiated VSMC markers. Interestingly, markers predictive for aortic dilation in BAV were not expressed in the MFS aorta. The aorta in MFS was similar to the aorta in dilated TAV with regard to the presence of medial degeneration and apoptosis, while other markers for degeneration and aging like inflammation and progerin expression were low in MFS, comparable to BAV. Both MFS and BAV aortas have immature VSMCs, while MFS and TAV patients have a similar increased rate of medial degeneration. However, the mechanism leading to apoptosis is expected to be different, being fibrillin-1 mutation induced increased angiotensin-receptor-pathway signaling in MFS and cardiovascular aging and increased progerin in TAV. Our findings could explain why angiotensin inhibition is successful in MFS and less effective in TAV and BAV patients.

Design and rationale of a prospective, collaborative meta-analysis of all randomized controlled trials of angiotensin receptor antagonists in Marfan syndrome, based on individual patient data: A report from the Marfan Treatment Trialists' Collaboration

Rationale

A number of randomized trials are underway, which will address the effects of angiotensin receptor blockers (ARBs) on aortic root enlargement and a range of other end points in patients with Marfan syndrome. If individual participant data from these trials were to be combined, a meta-analysis of the resulting data, totaling approximately 2,300 patients, would allow estimation across a number of trials of the treatment effects both of ARB therapy and of β-blockade.

Such an analysis would also allow estimation of treatment effects in particular subgroups of patients on a range of end points of interest and would allow a more powerful estimate of the effects of these treatments on a composite end point of several clinical outcomes than would be available from any individual trial.

Design

A prospective, collaborative meta-analysis based on individual patient data from all randomized trials in Marfan syndrome of (i) ARBs versus placebo (or open-label control) and (ii) ARBs versus β-blockers will be performed.

A prospective study design, in which the principal hypotheses, trial eligibility criteria, analyses, and methods are specified in advance of the unblinding of the component trials, will help to limit bias owing to data-dependent emphasis on the results of particular trials. The use of individual patient data will allow for analysis of the effects of ARBs in particular patient subgroups and for time-to-event analysis for clinical outcomes.

The meta-analysis protocol summarized in this report was written on behalf of the Marfan Treatment Trialists' Collaboration and finalized in late 2012, without foreknowledge of the results of any component trial, and will be made available online (http://www.ctsu.ox.ac.uk/research/meta-trials).

Molecular pathogenesis of Marfan syndrome

Marfan syndrome (MFS) is a genetic disorder that affects multiple organs. Mortality imposed by aortic aneurysm and dissections represent the most serious clinical manifestation of MFS. Progressive pathological aortic root enlargement as the result of degeneration of microfibril architecture and consequential loss of extracellular matrix integrity due to fibrillin-1 (FBN1) mutations are commonly diagnosed clinical manifestations of MFS. However, overlapping clinical manifestations with other aneurysmal disorders present a significant challenge in early and accurate diagnosis of MFS. While FBN1 mutations, abnormal transforming growth factor-β signaling and dysregulated matrix metalloproteinases have been implicated in MFS, clinically accepted risk-stratifying biomarkers have yet to be reliably identified. In this review, we summarize current consensus and recent insights in the understanding of MFS pathogenesis. Finally, we introduce the application of induced pluripotent stem cells (iPSCs) as cellular models for MFS and its potential as a novel platform into providing better appreciation of mechanisms underlying MFS diverse manifestations in the cardiovascular system.

Atenolol versus losartan in children and young adults with Marfan's syndrome

BACKGROUND

Aortic-root dissection is the leading cause of death in Marfan's syndrome. Studies suggest that with regard to slowing aortic-root enlargement, losartan may be more effective than beta-blockers, the current standard therapy in most centers.

METHODS

We conducted a randomized trial comparing losartan with atenolol in children and young adults with Marfan's syndrome. The primary outcome was the rate of aortic-root enlargement, expressed as the change in the maximum aortic-root-diameter z score indexed to body-surface area (hereafter, aortic-root z score) over a 3-year period. Secondary outcomes included the rate of change in the absolute diameter of the aortic root; the rate of change in aortic regurgitation; the time to aortic dissection, aortic-root surgery, or death; somatic growth; and the incidence of adverse events.

RESULTS

From January 2007 through February 2011, a total of 21 clinical centers enrolled 608 participants, 6 months to 25 years of age (mean [±SD] age, 11.5±6.5 years in the atenolol group and 11.0±6.2 years in the losartan group), who had an aortic-root z score greater than 3.0. The baseline-adjusted rate of change in the mean (±SE) aortic-root z score did not differ significantly between the atenolol group and the losartan group (-0.139±0.013 and -0.107±0.013 standard-deviation units per year, respectively; P=0.08). Both slopes were significantly less than zero, indicating a decrease in the aortic-root diameter relative to body-surface area with either treatment. The 3-year rates of aortic-root surgery, aortic dissection, death, and a composite of these events did not differ significantly between the two treatment groups.

CONCLUSIONS

Among children and young adults with Marfan's syndrome who were randomly assigned to losartan or atenolol, we found no significant difference in the rate of aortic-root dilatation between the two treatment groups over a 3-year period. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT00429364.).

Angiotensin receptor blockers: a panacea for Marfan syndrome and related disorders?

The study of mouse models for Marfan syndrome, an autosomal dominant connective tissue disorder caused by mutations in fibrillin-1 (FBN1), has shifted our understanding of the pathogenesis of thoracic aortic aneurysm significantly. Multiple lines of evidence support the notion that dysregulation of canonical and noncanonical transforming growth factor (TGF)β signaling is the responsible pathway in this and related thoracic aortic aneurysm conditions. This exciting knowledge has opened numerous new treatment options, including antagonism of the angiotensin II receptor blocker type 1 (AT1R). In this review, we summarize the current knowledge, the first human losartan Marfan trial results and future therapeutic perspectives for aortic disease in Marfan patients.

Abnormal muscle mechanosignaling triggers cardiomyopathy in mice with Marfan syndrome

Patients with Marfan syndrome (MFS), a multisystem disorder caused by mutations in the gene encoding the extracellular matrix (ECM) protein fibrillin 1, are unusually vulnerable to stress-induced cardiac dysfunction. The prevailing view is that MFS-associated cardiac dysfunction is the result of aortic and/or valvular disease. Here, we determined that dilated cardiomyopathy (DCM) in fibrillin 1-deficient mice is a primary manifestation resulting from ECM-induced abnormal mechanosignaling by cardiomyocytes. MFS mice displayed spontaneous emergence of an enlarged and dysfunctional heart, altered physical properties of myocardial tissue, and biochemical evidence of chronic mechanical stress, including increased angiotensin II type I receptor (AT1R) signaling and abated focal adhesion kinase (FAK) activity. Partial fibrillin 1 gene inactivation in cardiomyocytes was sufficient to precipitate DCM in otherwise phenotypically normal mice. Consistent with abnormal mechanosignaling, normal cardiac size and function were restored in MFS mice treated with an AT1R antagonist and in MFS mice lacking AT1R or β-arrestin 2, but not in MFS mice treated with an angiotensin-converting enzyme inhibitor or lacking angiotensinogen. Conversely, DCM associated with abnormal AT1R and FAK signaling was the sole abnormality in mice that were haploinsufficient for both fibrillin 1 and β1 integrin. Collectively, these findings implicate fibrillin 1 in the physiological adaptation of cardiac muscle to elevated workload.

Medical treatment for thoracic aortic aneurysm - much more work to be done

A 45 year old executive presents to your office for risk assessment after learning that his sister required an ascending aortic aneurysm repair. He is a well-informed man, concerned about his personal risk for aortic disease, and undergoes a cardiac screen which reveals a dilated ascending aortic aneurysm, measuring a maximal diameter of 4.4 cm. His aortic valve is tricuspid. He is non-Marfanoid and asymptomatic. He realizes that he does not yet meet guideline criteria for aortic surgery, but he is also cognizant of the fact that he is approaching the cut-off for surgical intervention. He wishes to minimize his future risk of aortic rupture, dissection and aortic expansion and seeks your input. Should 'medical treatment' should be employed at this stage? Is there sufficient basis to initiate any form of pharmacotherapy? Would you start a beta-adrenergic receptor blocker, an angiotensin receptor blocker, a matrix metalloproteinase inhibitor (doxycycline), or a statin to reduce his aortic risk for rupture, dissection or need for surgical repair? Does your clinical decision match evidence from existing data? Our paper will address these issues among other questions relevant to the role of medical therapy for thoracic aortic disease.

Genetic biomarkers in aortopathy

The field of aortopathy, in common with other genomic disorders, is undergoing a revolution. This is largely driven by the implementation of newer forms of genetic sequencing (massively parallel or next-generation sequencing). Advantages conferred by this technology include reduced costs, reduced sequencing time and the ability to simultaneously test multiple genes. This has a significant advantage in the identification of genes disrupted in heritable aortopathies. These advances are enabling scientists and clinicians to identify key molecular pathways; translating fundamental genetic findings into a better understanding of disease mechanisms is ultimately leading to effective treatments. In outlining contemporary knowledge of genetic biomarkers in aortopathy we seek to demonstrate that the era of genomically orientated decision-making is here.

Educational paper. Connective tissue disorders with vascular involvement: from gene to therapy

Heritable connective tissue diseases comprise a heterogeneous group of multisystemic disorders that are characterized by significant morbidity and mortality. These disorders do not merely result from defects in the amount or structure of one of the components of the extracellular matrix, as the extracellular matrix also serves other functions, including sequestration of cytokines, such as transforming growth factor beta (TGFβ). Indeed, disturbed TGFβ signaling was demonstrated in several heritable connective tissue diseases, including syndromic forms such as Marfan or Loeys-Dietz syndrome and non-syndromic presentations of thoracic aortic aneurysm/dissection. Because of these findings, new therapeutic targets have been unveiled, leading to the initiation of large clinical trials with angiotensin II type 1 receptor antagonists that also have an inhibiting effect on TGFβ signaling. Here, we present an overview of the clinical characteristics, the molecular findings, and the therapeutic strategies for the currently known syndromic and non-syndromic forms of thoracic aortic aneurysm/dissection.

A systematic review of the pharmacological management of aortic root dilation in Marfan syndrome

BACKGROUND

Marfan syndrome causes aortic dilation leading to dissection and death. This systematic review examined the use of beta-blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers in the management of aortic dilation in this disease.

METHODS

We searched four databases--Medline, EMBASE, Web of Science, and The Cochrane Central Register of Controlled Trials--two conference proceedings, references of retrieved articles, and a web-based trial registry. The primary outcome was mortality. The secondary outcomes were aortic dissection, need for elective surgical repair, change in aortic dilation, and adverse events. Two reviewers selected studies, abstracted data, and assessed study quality. Meta-analyses were not performed because of study heterogeneity.

RESULTS

A total of 18 studies were included--12 completed and six in progress. Of the completed studies, three before-and-after treatment, one prospective cohort, three retrospective cohorts, and two randomised control trials examined beta-blockers; one randomised and one non-randomised trial examined angiotensin-converting enzyme inhibitors; and one retrospective cohort study examined angiotensin II receptor blockers. Studies in progress are all randomised trials. Mortality was not impacted by drug therapy, although studies were underpowered with respect to this outcome. All drug classes were associated with a decrease in the rate of aortic dilation (angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers >beta-blockers); none had an impact on other secondary outcomes.

CONCLUSIONS

On the basis of existing evidence, beta-blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers slow the progression of aortic dilation in Marfan syndrome. Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers may have more effect than beta-blockers; however, more methodologically rigorous studies currently in progress are needed to evaluate the impact of drug therapy on clinical outcomes.

High prevalence of eosinophilic esophagitis in patients with inherited connective tissue disorders

BACKGROUND

Eosinophilic esophagitis (EoE) is an emerging chronic inflammatory disease mediated by immune hypersensitization to multiple foods and strongly associated with atopy and esophageal remodeling.

OBJECTIVE

We provide clinical and molecular evidence indicating a high prevalence of EoE in patients with inherited connective tissue disorders (CTDs).

METHODS

We examined the rate of EoE among patients with CTDs and subsequently analyzed esophageal mRNA transcript profiles in patients with EoE with or without CTD features.

RESULTS

We report a cohort of 42 patients with EoE with a CTD-like syndrome, representing 0.8% of patients with CTDs and 1.3% of patients with EoE within our hospital-wide electronic medical record database and our EoE research registry, respectively. An 8-fold risk of EoE in patients with CTDs (relative risk, 8.1; 95% confidence limit, 5.1-12.9; χ(2)1 = 112.0; P < 10(-3)) was present compared with the general population. Esophageal transcript profiling identified a distinct subset of genes, including COL8A2, in patients with EoE and CTDs.

CONCLUSION

There is a remarkable association of EoE with CTDs and evidence for a differential expression of genes involved in connective tissue repair in this cohort. Thus, we propose stratification of patients with EoE and CTDs into a subset referred to as EoE-CTD.

Association between Oro-Facial Defects and Systemic Alterations in Children Affected by Marfan Syndrome

BACKGROUND

It is important to establish an early diagnosis of the Marfan Syndrome (MFS) for providing an adequate pharmacological or surgical therapy. Nevertheless, this diagnosis may be complex, given the multi-organic involvement of this disease.

AIMS

In this work, we evaluated the oral phenotype in a group of paediatric patients with a clinical diagnosis of MFS, to quantify the association of the oro-facial defects with other systemic alterations.

SETTINGS AND DESIGN

Paediatric subjects who were aged, with a clinical diagnosis of MFS, were selected from our regional Marfan monitoring unit.

METHODS AND MATERIAL

All the patients were subjected to Paediatric Dentistry examinations and a radiological screening with Panoramic and Cephalometric X-Rays. The aortic dilation (Aortic Z-score value), the hyperlaxity of the ligaments and scoliosis were evaluated by cardio-surgical and orthopaedics specialists.

STATISTICAL ANALYSIS

The correlations between the oral and systemic alterations were analyzed by using the chi square test for the nominal variables.

RESULTS AND CONCLUSIONS

We found a significant correlation of the Aortic Z - score with multiple oral defects which included retrognathia, malar hypoplasia, cross bite, oral respiration and an ogival palate. An association of the oral defects with hyperlaxity of the ligaments and scoliosis was also found. Thus, the data suggested that dentists should be more involved in a multidisciplinary approach, to provide an early MFS diagnosis in paediatric patients.

Medical therapy of thoracic aortic aneurysms

Thoracic aortic aneurysm is a major health problem with multiple etiologies and potentially devastating consequences. Currently, no large randomized trial has shown that medical therapy can significantly slow or halt the progressive dilatation that eventually leads to dissection and rupture. A recent study that suggested that angiotensin receptor blocking agents slow the development of aneurysm dilatation in Marfan syndrome has revived interest in medical interventions to improve outcomes for patients with aortic aneurysm. In this article, we review the available data on established medical therapies and investigational medical therapies for thoracic aortic aneurysms.

Genetic dissection of marfan syndrome and related connective tissue disorders: an update 2012

Marfan syndrome (MFS) is an autosomal dominant disorder of the connective tissue characterized by early development of thoracic aortic aneurysms/dissections together with symptoms of the ocular and skeletal systems. While most patients/families with a classic phenotypic expression of MFS harbour mutations in the gene encoding fibrillin-1 (FBN1), genetic studies of the recent years revealed that the clinical features, as well as the mutated genes, show a high degree of overlap between MFS and other connective tissue diseases (e.g. Loeys-Dietz syndrome, Ehlers-Danlos syndrome, familial thoracic aneurysms and dissections and others). We summarize herein the current knowledge about the wide spectrum of differential diagnoses and their genetic background as well as novel therapeutic approaches in order to provide appropriate counselling and clinical follow-up for the patients.

Effects of atenolol, perindopril and verapamil on haemodynamic and vascular function in Marfan syndrome - a randomised, double-blind, crossover trial

BACKGROUND

Aortic dilatation is the main therapeutic target in patients with Marfan syndrome. Standard treatment with a β-blocker may not lower central pulse pressure - the major objective - because it does not do so in hypertension, unlike angiotensin-converting enzyme inhibitors and calcium-channel blockers. We therefore performed a prospective, randomised, double-blind, crossover trial to compare the effects of these three agents on large artery function and central aortic pressure in patients with Marfan syndrome.

METHODS AND RESULTS

Eighteen patients had applanation tonometry, pulse wave analysis and echocardiography, before and after atenolol 75 mg, perindopril 4 mg and verapamil 240 mg, each given for 4 weeks, in a random order, with 2 weeks between medications. Fourteen patients completed the study. Within-drug comparisons demonstrated that perindopril (-10·3 mmHg, P = 0·002), verapamil (-9·2 mmHg, P = 0·003) and atenolol (-7·1 mmHg, P = 0·01) all reduced central systolic pressure and brachial pressure; central changes were least, and peripheral changes greatest with atenolol but between-drug comparisons (analysis of covariance) were not significant. There was a trend for augmentation to be reduced by perindopril (-6·3%, P = 0·05), verapamil (-5·5%, P = 0·07) and atenolol (-3·2%, P = 0·09). Only atenolol reduced heart rate (by 16%) and delayed expansion in the arch and abdominal aorta (by 8% and 11%) (P < 0·001, P < 0·01 and P < 0·05, respectively, for between-drug comparisons).

CONCLUSIONS

Perindopril, verapamil and atenolol all reduced peripheral and central systolic pressure. As atenolol slowed heart rate and delayed aortic wave travel, β-blockade may have a continuing role in the treatment of patients with Marfan syndrome.

Marfan syndrome: from gene to therapy

PURPOSE OF REVIEW

Although historically Marfan syndrome (MFS) has always been considered as a condition caused by the deficiency of a structural extracellular matrix protein, fibrillin-1, the study of Marfan mouse models and Marfan-related conditions has shifted our current understanding to a pathogenic model that involves dysregulation of the cytokine-transforming growth factor beta (TGF-β) signaling.

RECENT FINDINGS

In this review, we focus on the impact of the revised MFS clinical diagnostic criteria. We discuss lessons that have been learned from molecular findings in relevant Marfan-related conditions, such as sporadic thoracic aortic aneurysm/dissection, stiff skin syndrome, acromelic dysplasias and Loeys-Dietz syndrome. We explore the latest insights into the role of the alternative TGF-β signaling pathways in MFS pathogenesis. Finally, we give an update on the current and future treatment strategies.

SUMMARY

The recent insights into the pathogenesis of MFS and related disorders have offered a prime example of translational medicine with immediate bridge between molecular findings and therapeutic options.

Surgical management of patients with Marfan syndrome: evolution throughout the years

AIM

To evaluate the evolution of surgical management in a large population of patients with Marfan syndrome.

METHODS

This is a retrospective study of patients fulfilling the Ghent criteria for Marfan syndrome, who visited the Centre de référence national pour le syndrome de Marfan et apparentés and underwent a surgical event before or during follow-up in the centre.

RESULTS

One thousand and ninety-seven patients with Marfan syndrome, according to international criteria, came to the clinic between 1996 and 2010. Aortic surgery was performed in 249 patients (22.7%; 20 children and 229 adults), including the Bentall procedure in 140 patients (56%) and valve-sparing surgery in 88 patients (35%); a supracoronary graft was performed in 19 patients (7.6%), usually for aortic dissection. During the past 20 years, the predominant reason for aortic surgery has switched from aortic dissection to aortic dilatation, while age at surgery has tended to increase (from 32.4 ± 11.9 years to 35.2 ± 12.4 years; P=0.075). Mitral valve surgery was performed in 61 patients (5.6%; six children and 55 adults), including 37 valvuloplasties (60.6%) and 18 mitral valve replacements (29.5%). No significant difference was observed when comparing mitral valve surgery before and after 2000.

CONCLUSION

Surgery performed in patients with Marfan syndrome has switched from emergency surgery for aortic dissection to elective surgery for aortic dilatation; this is associated with surgery performed at an older age despite the indication for surgery having decreased from 60mm to 50mm. No significant evolution was observed for mitral valve surgery.

Aortic Event Rate in the Marfan Population

Background—

Optimal management, including timing of surgery, remains debated in Marfan syndrome because of a lack of data on aortic risk associated with this disease.

Methods and Results—

We used our database to evaluate aortic risk associated with standardized care. Patients who fulfilled the international criteria, had not had previous aortic surgery or dissection, and came to our center at least twice were included. Aortic measurements were made with echocardiography (every 2 years); patients were given systematic β-blockade and advice about sports activities. Prophylactic aortic surgery was proposed when the maximal aortic diameter reached 50 mm. Seven hundred thirty-two patients with Marfan syndrome were followed up for a mean of 6.6 years. Five deaths and 2 dissections of the ascending aorta occurred during follow-up. Event rate (death/aortic dissection) was 0.17%/y. Risk rose with increasing aortic diameter measured within 2 years of the event: from 0.09%/y per year (95% confidence interval, 0.00–0.20) when the aortic diameter was <40 mm to 0.3% (95% confidence interval, 0.00–0.71) with diameters of 45 to 49 mm and 1.33% (95% confidence interval, 0.00–3.93) with diameters of 50 to 54 mm. The risk increased 4 times at diameters ≥50 mm. The annual risk dropped below 0.05% when the aortic diameter was <50 mm after exclusion of a neonatal patient, a woman who became pregnant against our recommendation, and a 72-year-old woman with previous myocardial infarction.

Conclusions—

Risk of sudden death or aortic dissection remains low in patients with Marfan syndrome and aortic diameter between 45 and 49 mm. Aortic diameter of 50 mm appears to be a reasonable threshold for prophylactic surgery.

Preventing the aortic complications of Marfan syndrome: a case-example of translational genomic medicine

The translational path from pharmacological insight to effective therapy can be a long one. We aim to describe the management of Marfan syndrome as a case-example of how pharmacological and genomic insights can contribute to improved therapy. We undertook a literature search for studies of Marfan syndrome, to identify milestones in description, understanding and therapy of the syndrome. From the studies retrieved we then weaved an evidence-based description of progress. Marfan syndrome shows considerable heterogeneity in clinical presentation. It relies on defined clinical criteria with confirmation based on FBN1 mutation testing. Surgical advances have prolonged life in Marfan syndrome. First-line prophylaxis of complications with β-adrenoceptor blockers became established on the basis that reduction of aortic pressure and heart rate would help. Over-activity of proteinases, first suggested in 1980, has since been confirmed by evidence of over-expression of matrix metalloproteinases (MMP), notably MMP-2 and MMP-9. The search for MMP inhibitors led to the evaluation of doxycycline, and both animal studies and small trials, provided early evidence that this widely used antimicrobial agent was useful. Identification of the importance of TGF-β led to evaluation of angiotensin II type I receptor (AT(1) R) blockers with highly promising results. Combination prophylactic therapy would appear rational. Pharmacological and genomic research has provided good evidence that therapy with losartan and doxycycline would prevent the aortic complications of Marfan syndrome. If on-going well designed trials confirm their efficacy, the outlook for Marfan syndrome patients would be improved considerably.

Drug-based therapies for vascular disease in Marfan syndrome: from mouse models to human patients

Marfan syndrome is a congenital disorder of the connective tissue with a long history of clinical and basic science breakthroughs that have forged our understanding of vascular-disease pathogenesis. The biomedical importance of Marfan syndrome was recently underscored by the discovery that the underlying genetic lesion impairs both tissue integrity and transforming growth factor-beta regulation of cell behavior. This discovery has led to the successful implementation of the first pharmacological intervention in a connective-tissue disorder otherwise incurable by either gene-based or stem cell-based therapeutic strategies. More generally, information gathered from the study of Marfan syndrome pathogenesis has the potential to improve the clinical management of common acquired disorders of connective-tissue degeneration.

The role of the renin-angiotensin system in thoracic aortic aneurysms: clinical implications

Thoracic aortic aneurysms (TAAs) are a potential life-threatening disease with limited pharmacological treatment options. Current treatment options are aimed at lowering aortic hemodynamic stress, predominantly with β-adrenoceptor blockers. Increasing evidence supports a role for the renin-angiotensin system (RAS) in aneurysm development. RAS blockade would not only lower blood pressure, but might also target the molecular pathways involved in aneurysm formation, in particular the transforming growth factor-β and extracellular signal-regulated kinase 1/2 pathways. Indeed, the angiotensin II type 1 (AT₁) receptor blocker losartan was effective in lowering aortic root growth in mice and patients with Marfan's syndrome. RAS inhibition (currently possible at 3 levels, i.e. renin, ACE and the AT₁ receptor) is always accompanied by a rise in renin due to interference with the negative feedback loop between renin and angiotensin II. Only during AT₁ receptor blockade will this result in stimulation of the non-blocked angiotensin II type 2 (AT₂) receptor. This review summarizes the clinical aspects of TAAs, provides an overview of the current mouse models for TAAs, and focuses on the RAS as a new target for TAA treatment, discussing in particular the possibility that AT₂ receptor stimulation might be crucial in this regard. If true, this would imply that AT₁ receptor blockers (and not ACE inhibitors or renin inhibitors) should be the preferred treatment option for TAAs.

The Ghent Marfan Trial--a randomized, double-blind placebo controlled trial with losartan in Marfan patients treated with β-blockers

BACKGROUND

Aortic root dilation, dissection and rupture are major clinical problems in Marfan syndrome (MFS). Although β-blockers remain the standard of preventive treatment, preliminary results from animal studies and a selected group of severely affected MFS children show significant benefit from treatment with losartan, an angiotensin II receptor blocker with TGF-β inhibiting potential. Large-scale human trials are now needed to confirm these results. This trial aims to evaluate the combined effect of both drugs.

METHODS

We are conducting a prospective randomized placebo controlled double blind phase III study aiming to include 174 MFS patients (age ≥ 10 years and z-score ≥ 2). Patients already taking β-blockers are randomized for weight-adjusted treatment with losartan versus placebo. The primary endpoint is decrease in aortic root growth rate. Secondary endpoints are aortic dissection/surgery, progression of aortic/mitral regurgitation, arterial stiffness, left ventricular systolic/diastolic function, quality of life and genetic modifiers. Echocardiography, vascular echo-Doppler and quality of life assessment will be performed at baseline and at 6-monthly follow-ups for 3 years. MRI evaluation will be performed at baseline and at the end of the trial.

CONCLUSION

This trial will study new therapeutic strategies for the prevention of serious cardiovascular complications in MFS. The uniqueness in our trial is that the additive effect of losartan and β-blocker will be evaluated in a large spectrum of disease severity. A combination of ultrasound and MRI will allow detailed evaluation of anatomic and functional properties of the aorta and left ventricle.

Impact of Mendelian inheritance in cardiovascular disease

Cardiovascular disease is a leading cause of mortality worldwide. While the etiology for the majority of cardiovascular disease is presumed to be a combination of genetic and environmental factors, developments in understanding the basic biology of cardiac disorders have been greatly advanced through discoveries made studying heart diseases that exhibit Mendelian forms of inheritance. Most of these diseases primarily affect children and young adults and include cardiomyopathies, arrhythmias, aortic aneurysms, and congenital heart defects. The discovery of the genetic etiologies for these diseases have had significant impact on our understanding of more complex forms of cardiovascular disease and in some cases have led to novel diagnostic and treatment modalities. In this review, we will summarize these seminal genetic discoveries, highlighting a few that have resulted in significant impact on human disease, and discuss the potential utility of studying Mendelian-inherited heart disease with the development of new genetic technologies and our increased understanding of the human genome.