Distinct effects of losartan and atenolol on vascular stiffness in Marfan syndrome

Novel Insights into the Aortic Mechanical Properties of Mice Modeling Hereditary Aortic Diseases

OBJECTIVE

 Hereditary aortic diseases (hADs) increase the risk of aortic dissections and ruptures. Recently, we have established an objective approach to measure the rupture force of the murine aorta, thereby explaining the outcomes of clinical studies and assessing the added value of approved drugs in vascular Ehlers-Danlos syndrome (vEDS). Here, we applied our approach to six additional mouse hAD models.

MATERIAL AND METHODS

 We used two mouse models (Fbn1C1041G and Fbn1mgR ) of Marfan syndrome (MFS) as well as one smooth-muscle-cell-specific knockout (SMKO) of Efemp2 and three CRISPR/Cas9-engineered knock-in models (Ltbp1, Mfap4, and Timp1). One of the two MFS models was subjected to 4-week-long losartan treatment. Per mouse, three rings of the thoracic aorta were prepared, mounted on a tissue puller, and uniaxially stretched until rupture.

RESULTS

 The aortic rupture force of the SMKO and both MFS models was significantly lower compared with wild-type mice but in both MFS models higher than in mice modeling vEDS. In contrast, the Ltbp1, Mfap4, and Timp1 knock-in models presented no impaired aortic integrity. As expected, losartan treatment reduced aneurysm formation but surprisingly had no impact on the aortic rupture force of our MFS mice.

CONCLUSION

 Our read-out system can characterize the aortic biomechanical integrity of mice modeling not only vEDS but also related hADs, allowing the aortic-rupture-force-focused comparison of mouse models. Furthermore, aneurysm progression alone may not be a sufficient read-out for aortic rupture, as antihypertensive drugs reducing aortic dilatation might not strengthen the weakened aortic wall. Our results may enable identification of improved medical therapies of hADs.

Genetic models of fibrillinopathies

The fibrillinopathies represent a group of diseases in which the 10-12 nm extracellular microfibrils are disrupted by genetic variants in one of the genes encoding fibrillin molecules, large glycoproteins of the extracellular matrix. The best-known fibrillinopathy is Marfan syndrome, an autosomal dominant condition affecting the cardiovascular, ocular, skeletal, and other systems, with a prevalence of around 1 in 3,000 across all ethnic groups. It is caused by variants of the FBN1 gene, encoding fibrillin-1, which interacts with elastin to provide strength and elasticity to connective tissues. A number of mouse models have been created in an attempt to replicate the human phenotype, although all have limitations. There are also natural bovine models and engineered models in pig and rabbit. Variants in FBN2 encoding fibrillin-2 cause congenital contractural arachnodactyly and mouse models for this condition have also been produced. In most animals, including birds, reptiles, and amphibians, there is a third fibrillin, fibrillin-3 (FBN3 gene) for which the creation of models has been difficult as the gene is degenerate and nonfunctional in mice and rats. Other eukaryotes such as the nematode C. elegans and zebrafish D. rerio have a gene with some homology to fibrillins and models have been used to discover more about the function of this family of proteins. This review looks at the phenotype, inheritance, and relevance of the various animal models for the different fibrillinopathies.

Exaggerated elastin turnover in young individuals with Marfan syndrome: new insights from the AIMS trial

Aims

The fragmentation and loss of elastic fibre in the tunica media of the aorta are pathological hallmarks of Marfan syndrome (MFS) but the dynamics of elastin degradation and its relationship to aortic size and physiological growth remain poorly understood.

Methods and results

In this post hoc analysis of the AIMS randomized controlled trial, the association of plasma desmosine (pDES)-a specific biomarker of mature elastin degradation-with age and aortic size was analysed in 113 patients with MFS and compared to 109 healthy controls. There was a strong association between age and pDES in both groups, with higher pDES levels in the lower age groups compared to adults. During childhood, pDES increased and peaked during early adolescence, and thereafter decreased to lower adult levels. This trend was exaggerated in young individuals with MFS but in those above 25 years of age, pDES levels were comparable to controls despite the presence of aortic root dilation. In MFS children, increased aortic diameter relative to controls was seen at an early age and although the increase in diameter was less after adolescence, aortic root size continued to increase steadily with age. In MFS participants, there was an indication of a positive association between baseline pDES levels and aortic root dilatation during up to 5 years of follow-up.

Conclusion

This study has shown that developmental age has a significant effect on levels of elastin turnover as measured by pDES in MFS individuals as well as healthy controls. This effect is exaggerated in those with MFS with increased levels seen during the period of physiologic development that plateaus towards adulthood. This suggests an early onset of pathophysiology that may present an important opportunity for disease-modifying intervention.

Differential Effects of Ca2+ Channel Blockers Nifedipine and Cilnidipine on Arterial Elasticity in the Aortic and Femoral Arterial Segments of Anesthetized Rabbits

Ca2+ channel blockers have potent vasodilatory effects and excellent efficacy in preserving organ blood flow. These hemodynamic actions may be partly controlled by the functional stiffness of conduit arteries. In this study, we assessed the effects of the L-type Ca2+ channel blocker nifedipine on aortic and femoral arterial stiffness (referred to as aortic β and femoral β, respectively) in anesthetized rabbits. To further clarify the involvement of the autonomic nervous system, we compared the effects of nifedipine with those of the L/N-type Ca2+ channel blocker cilnidipine. Further, the effect of the α-adrenergic receptor blocker doxazosin on the effects of nifedipine on arterial elasticity was examined. An antihypertensive dose of nifedipine (300 µg/kg, administered intravenously) was found to increase the aortic β but hardly affected the femoral β. An antihypertensive dose of cilnidipine (30 µg/kg, administered intravenously) increased the aortic β but decreased the femoral β. Interestingly, nifedipine decreased the femoral β in the presence of the α-adrenoceptor blocker doxazosin (1 mg/kg, administered intravenously). These effects suggest that L-type Ca2+ channel blockers essentially increase vascular elasticity via the decrement in arterial stiffness in the femoral artery segment, which is modified by the presence or absence of the inhibitory effect of each drug on reflex sympathetic nerve activity, while decreasing vascular elasticity via the increment in arterial stiffness in the aortic segment independently of sympathetic nerve activity.

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.

Aortic root dilation in adult patients with Marfan syndrome: Does aortic root stiffness matter?

Objective

Methods

Results

Conclusions

Comprehensive Characterization of Arterial and Cardiac Function in Marfan Syndrome-Can Biomarkers Help Improve Outcome?

Background: Marfan Syndrome (MFS) has been associated with increased aortic stiffness and left ventricular dysfunction. The latter may be due to the underlying genotype and/or secondary to aortic stiffening (vascular-ventricular interaction). The aim of this study was to characterize arterial and cardiac function in MFS using a multimodal approach.

Methods: Prospective observational study of MFS patients and healthy controls. Methods included echocardiography, ascending aortic distensibility, common carotid intima media thickness [cIMT], parameters of wave reflection, carotid-femoral pulse wave velocity [cfPWV]), reactive hyperemia index [RHI], and biomarker analysis (Olink, CVII panel).

Results: We included 20 patients with MFS and 67 controls. Ascending aortic distensibility, cIMT and RHI were decreased, while all parameters of arterial wave reflection, stiffness and BNP levels were increased in the MFS group. Both systolic and diastolic function were impaired relative to controls. Within the MFS group, no significant correlation between arterial and cardiac function was identified. However, cfPWV correlated significantly with indexed left ventricular mass and volume in MFS. Bran natriuretic peptide (BNP) was the only biomarker significantly elevated in MFS following correction for age and sex.

Conclusions: MFS patients have generally increased aortic stiffness, endothelial dysfunction and BNP levels while cIMT is decreased, supporting that the mechanism of general stiffening is different from acquired vascular disease. CfPWV is associated with cardiac size, blood pressure and BNP in MFS patients. These may be early markers of disease progression that are suitable for monitoring pharmacological treatment effects in MFS patients.

Angiotensin Receptor Blockers vs. Beta-Blocker Therapy for Marfan Syndrome: A Systematic Review and Meta-Analysis

OBJECTIVE

Several RCTs have been conducted to assess the efficacy and safety of angiotensin receptor blocker (ARB) and beta-blocker (BB) therapy for Marfan syndrome (MFS), but the existing evidence is limited and conflicting. This study aimed to compare the efficacy and safety of different therapies.

APPROACH

The PubMed, Embase, Web of Science, and Cochrane Library databases were electronically searched up to March 2021 to retrieve randomized controlled trials regarding the efficacy and safety of ARB-related (including ARB-only and ARB+BB treatment) and BB-only treatment for treating patients with MFS. The revised risk-of-bias tool was used for quality assessment. The odds ratio (OR) and standard mean difference (SMD) with 95% confidence interval (CI) were used to estimate the pooled effect size.

RESULTS

Fourteen reports of nine trials involving 1,449 patients were included in the meta-analysis. Regarding aortic root dilation, the ARB-related regimen has efficacy comparable with that of the BB-only regimen in patients with MFS (pooled SMD = -0.16, 95% CI [-0.33; 0.01]; p = 0.06), while in the ARB+BB vs. BB-only subgroup, a significant difference was observed (pooled SMD = -0.26; 95% CI [-0.40; -0.11]; p < 0.01). In addition, there were no significant differences in other aortic dilation-related measures (aortic root Z scores, ascending aorta, pulmonary artery, aortic annulus, sinotubular junction, aortic arch, thoracic aorta, and abdominal aorta diameter change) or cardiovascular events (aortic dissection, aortic surgery, and death) between the two regimens.

CONCLUSION

Our results showed that the clinical efficacy of ARB-only therapy is not inferior to that of BB-only therapy. Moreover, ARB+BB therapy showed superior therapeutic effects without significant adverse effects.

Medical Therapies for Marfan Syndrome and Other Thoracic Aortic Dilatation in Adults: A Contemporary Review

Thoracic aortic dilatation often has an asymptomatic course but may present with lethal complications such as aortic rupture or dissection, particularly when the thoracic aorta is aneurysmally enlarged; therefore, appropriate diagnosis, surveillance, and management are vital. Recommendations regarding imaging and surgical management are outlined in contemporary clinical practice guidelines. Dedicated guidelines regarding medical therapies for the management of thoracic aortic dilatation are lacking. Most of the medical treatment strategies, especially recommendations regarding pharmacological medical therapies related to β-blockade and angiotensin receptor blockers, are derived from data on patients with Marfan syndrome. The main aims of medical therapies for the management of thoracic aortic dilatation are (1) to control the progression of the disease, and (2) to prevent complications related to the disease (such as aortic dissection and mortality). This paper reviews the contemporary evidence and highlights the gaps in evidence to be investigated in further studies.

Deletion of AT1a (Angiotensin II Type 1a) Receptor or Inhibition of Angiotensinogen Synthesis Attenuates Thoracic Aortopathies in Fibrillin1C1041G/+ Mice

Objective: A cardinal feature of Marfan syndrome is thoracic aortic aneurysm. The contribution of the renin-angiotensin system via AT1aR (Ang II [angiotensin II] receptor type 1a) to thoracic aortic aneurysm progression remains controversial because the beneficial effects of angiotensin receptor blockers have been ascribed to off-target effects. This study used genetic and pharmacological modes of attenuating angiotensin receptor and ligand, respectively, to determine their roles on thoracic aortic aneurysm in mice with fibrillin-1 haploinsufficiency (Fbn1C1041G/+). Approach and Results: Thoracic aortic aneurysm in Fbn1C1041G/+ mice was found to be strikingly sexual dimorphic. Males displayed aortic dilation over 12 months while aortic dilation in Fbn1C1041G/+ females did not differ significantly from wild-type mice. To determine the role of AT1aR, Fbn1C1041G/+ mice that were either +/+ or -/- for AT1aR were generated. AT1aR deletion reduced expansion of ascending aorta and aortic root diameter from 1 to 12 months of age in males. Medial thickening and elastin fragmentation were attenuated. An antisense oligonucleotide against angiotensinogen was administered to male Fbn1C1041G/+ mice to determine the effects of Ang II depletion. Antisense oligonucleotide against angiotensinogen administration attenuated dilation of the ascending aorta and aortic root and reduced extracellular remodeling. Aortic transcriptome analyses identified potential targets by which inhibition of the renin-angiotensin system reduced aortic dilation in Fbn1C1041G/+ mice. Conclusions: Deletion of AT1aR or inhibition of Ang II production exerted similar effects in attenuating pathologies in the proximal thoracic aorta of male Fbn1C1041G/+ mice. Inhibition of the renin-angiotensin system attenuated dysregulation of genes within the aorta related to pathology of Fbn1C1041G/+ mice.

Meta-analysis Examining the Usefulness of Angiotensin Receptor blockers for the Prevention of Aortic Root Dilation in Patients With the Marfan Syndrome

The Marfan syndrome (MFS) patients are highly predisposed to thoracic aortic aneurysm and/or dissection, with virtually every patient having evidence of aortic disease at some point during their lifetime. We conducted a meta-analysis to investigate the efficacy of angiotensin receptor blockers (ARBs) in slowing down the progression of aortic dilatation in MFS patients. PUBMED, EMBASE, and COCHRANE databases were searched for relevant articles published from inception to February 1, 2020. We included randomized clinical trials evaluating the effect of ARBs on aortic root size in patients with MFS with a follow-up period of at least 2.5 years. Seven studies were included with a total of 1,510 patients. Our analysis demonstrated a significantly smaller change in aortic root and ascending aorta dilation in the ARBs treated group when compared with placebo (mean difference 0.68; 95% confidence interval [CI] -1.31 to -0.04; p = 0.04, I² = 94%, and mean difference -0.13, 95% CI -0.17 to -0.09; p < 0.00001, I² = 0%, respectively). ARBs as an add-on therapy to beta-blockers resulted in a significantly smaller change in aortic root dilation when compared with the arm without ARBs (mean difference -2.06, 95% CI -2.54 to -1.58; p < 0.00001, I² = 91%). However, there was no statistically significant difference in the number of clinical events (aortic complications/surgery) observed in the ARBs arm when compared with placebo (Risk ratio of 1.01, 95% CI 0.74 to 1.38; p = 0.94, I² = 0%). In conclusion, ARBs therapy is associated with a slower progression of aortic root dilation when compared with placebo and as an addition to beta-blocker therapy.

Relationship between prenatal and postnatal conditions and accelerated postnatal growth. Impact on the rigidity of the arterial wall and obesity in childhood

Restricted growth in utero and accelerated postnatal growth (APG) in the postnatal period have been associated with the development of overweight, obesity and an increased cardiovascular risk in childhood. The objectives of this study were to evaluate the influence of prenatal and perinatal conditions on APG and to evaluate the influence of this APG on different cardiovascular risk factors such as body mass index (BMI), body fat mass index (FMI), blood pressure (BP) and arterial wall stiffness [carotid to femoral pulse wave velocity (cf-PWV)]. All measurements were performed in 355 children (185 boys and 170 girls; 8-11 years). Data on mother weight before and during pregnancy, gestational age (weeks), birth weight (g) and breastfeeding of children were obtained through interviews with families. Children who presented APG were born of mothers with lower BMIs before pregnancy and who gained less weight during the second trimester of pregnancy. They also have a lower gestational age and birth weight, a shorter duration of breastfeeding and a longer duration of artificial feeding (AF). Later in childhood, they had higher values of cf-PWV, BMI, FMI and higher prevalence of hypertension. Low maternal gestational weight gain, inadequate fetal development (low birth weight, shorter gestational age) and reduced breastfeeding duration favor APG. Infants with such APG had higher values of cf-PWV, BP, BMI and FMI later in childhood, along with a higher risk of hypertension and obesity. The interaction between APG and a longer duration of AF had a negative effect on cf-PWV (arterial stiffness) and FMI.

Localized Antileptin Therapy Prevents Aortic Root Dilatation and Preserves Left Ventricular Systolic Function in a Murine Model of Marfan Syndrome

Background Marfan syndrome (MFS) is a genetically transmitted connective tissue disorder characterized by aortic root dilatation, dissection, and rupture. Molecularly, MFS pathological features have been shown to be driven by increased angiotensin II in the aortic wall. Using an angiotensin II-driven aneurysm mouse model, we have recently demonstrated that local inhibition of leptin activity restricts aneurysm formation in the ascending and abdominal aorta. As we observed de novo leptin synthesis in the ascending aortic aneurysm wall of patients with MFS, we hypothesized that local counteracting of leptin activity in MFS may also prevent aortic cardiovascular complications in this context. Methods and Results Fbn1^C1039G/+ mice underwent periaortic application of low-dose leptin antagonist at the aortic root. Treatment abolished medial degeneration and prevented increase in aortic root diameter (P<0.001). High levels of leptin, transforming growth factor β1, Phosphorylated Small mothers against decapentaplegic 2, and angiotensin-converting enzyme 1 observed in saline-treated MFS mice were downregulated in leptin antagonist-treated animals (P<0.01, P<0.05, P<0.001, and P<0.001, respectively). Leptin and angiotensin-converting enzyme 1 expression levels in left ventricular cardiomyocytes were also decreased (P<0.001) and coincided with prevention of left ventricular hypertrophy and aortic and mitral valve leaflet thickening (P<0.01 and P<0.05, respectively) and systolic function preservation. Conclusions Local, periaortic application of leptin antagonist prevented aortic root dilatation and left ventricular valve remodeling, preserving left ventricular systolic function in an MFS mouse model. Our results suggest that local inhibition of leptin may constitute a novel, stand-alone approach to prevent MFS aortic root aneurysms and potentially other similar angiotensin II-driven aortic pathological features.

Repurposing of drugs approved for cardiovascular diseases: Opportunity or mirage?

Drug repurposing is a promising way in drug discovery to identify new therapeutic uses -different from the original medical indication- for existing drugs. It has many advantages over traditional approaches to de novo drug discovery, since it can significantly reduce healthcare costs and development timeline. In this review, we discuss the possible repurposing of drugs approved for cardiovascular diseases, such as β-blockers, angiotensin converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), statins, aspirin, cardiac glycosides and low-molecular-weight heparins (LMWHs). Indeed, numerous experimental and epidemiological studies have reported promising anti-cancer activities for these drugs. It is worth mentioning, however, that the results of these studies are often controversial and very few data were obtained by controlled prospective clinical trials. Therefore, no final conclusion has yet been reached in this area and no final recommendations can be made. Moreover, β-blockers, ARBs and statins showed promising results in randomised controlled trials (RCTs) where pathological conditions other than cancer were considered. The results obtained have led or may lead to new indications for these drugs. For each drug or class of drugs, the potential molecular mechanisms of action justifying repurposing, results obtained in vitro and in animal models and data from epidemiological and randomized studies are described.

Losartan for Preventing Aortic Root Dilatation in Patients with Marfan Syndrome: A Meta-Analysis of Randomized Trials

INTRODUCTION

The role of losartan in preventing aortic root dilatation in Marfan syndrome has been evaluated in many clinical trials; however, the results are conflicting.

METHODS

We performed a computerized search of MEDLINE, EMBASE and COCHRANE databases through February 2019 for randomized clinical trials evaluating the effect of losartan in patients with Marfan syndrome. The main outcome was the change in the aortic root diameter in the losartan versus control groups.

RESULTS

Our final analysis included seven randomized trials with a total of 1352 patients and average weighted follow-up of 37.8 months. Change in aortic root diameter was significantly smaller with losartan compared with control [weighted means: 0.44 vs. 0.58 mm, mean difference (MD) = -0.13; 95% CI -0.24 to -0.02; p = 0.02]. Subgroup analysis according to the control group showed no significant subgroup interaction when comparing losartan with beta-blockers versus with standard therapy (pinteraction= 0.27). The composite outcome of aortic surgery, dissection or mortality did not differ between the losartan and control groups (risk ratio = 1.03; 95% CI 0.72-1.49, p = 0.86).

CONCLUSION

In this meta-analysis including seven randomized trials, the use of losartan was associated with a significantly smaller change in aortic root diameter in patients with Marfan syndrome.

Anatomically specific reactive oxygen species production participates in Marfan syndrome aneurysm formation

Marfan syndrome (MFS) is a connective tissue disorder that results in aortic root aneurysm formation. Reactive oxygen species (ROS) seem to play a role in aortic wall remodelling in MFS, although the mechanism remains unknown. MFS Fbn1^C1039G/+ mouse root/ascending (AS) and descending (DES) aortic samples were examined using DHE staining, lucigenin‐enhanced chemiluminescence (LGCL), Verhoeff's elastin‐Van Gieson staining (elastin breakdown) and in situ zymography for protease activity. Fbn1^C1039G/+ AS‐ or DES‐derived smooth muscle cells (SMC) were treated with anti‐TGF‐β antibody, angiotensin II (AngII), anti‐TGF‐β antibody + AngII, or isotype control. ROS were detected during early aneurysm formation in the Fbn1^C1039G/+ AS aorta, but absent in normal‐sized DES aorta. Fbn1^C1039G/+ mice treated with the unspecific NADPH oxidase inhibitor, apocynin reduced AS aneurysm formation, with attenuated elastin fragmentation. In situ zymography revealed apocynin treatment decreased protease activity. In vitro SMC studies showed Fbn1^C1039G/+‐derived AS SMC had increased NADPH activity compared to DES‐derived SMC. AS SMC NADPH activity increased with AngII treatment and appeared TGF‐β dependent. In conclusion, ROS play a role in MFS aneurysm development and correspond anatomically with aneurysmal aortic segments. ROS inhibition via apocynin treatment attenuates MFS aneurysm progression. AngII enhances ROS production in MFS AS SMCs and is likely TGF‐β dependent.

The effects of losartan versus beta-blockers on cardiovascular protection in marfan syndrome: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Variable effects of beta-blockers (BB) and/or angiotensin receptor blockers (ARB) were reported to retard aortic root growth in Marfan syndrome (MFS). This study aimed to compare the effects of BB therapy and ARB-related therapies on cardiovascular protection in MFS.

METHODS

Studies of randomized control trials comparing the efficacy of only-BB and ARB-related (only-ARB or ARB-plus-BB) therapies for MFS published before July 31, 2018 in PubMed, Embase, and the Cochrane Library were selected. The outcomes included changes in aortic growth and cardiovascular events.

RESULTS

Eight trials involving 1381 patients were included. Patients received only-BB and ARB-related therapies did not differ significantly in changes in aortic growth (aortic root diameter: standardized mean difference [SMD] = 0.04, 95% confidence interval [CI]: -0.11-0.19, p = 0.63) or cardiovascular events (aortic dissection: Peto odds ratio [OR] = 1.67, 95% CI: 0.42-6.72, p = 0.47; aortic surgery: risk ratio = 0.97, 95% CI: 0.66-1.41, p = 0.86; death: Peto OR = 2.78, 95% CI: 0.39-19.82, p = 0.31). Subgroup analysis revealed that ARB-plus-BB therapy exhibited nonsignificantly better outcomes than only-BB therapy (aortic root diameter: SMD = 0.11, 95% CI: -0.22-0.45, p = 0.52; ascending aorta diameter: SMD = 0.10, 95% CI: -0.07-0.27, p = 0.26; aortic surgery: Peto OR = 1.10, 95% CI: 0.75-1.61, p = 0.62).

CONCLUSION

For cardiovascular protection in MFS, only-ARB therapy is not inferior to only-BB therapy. Moreover, the outcomes of ARB-plus-BB therapy seemed to be favourable to those of only-BB therapy.

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.

Influence of Aortic Stiffness on Aortic-Root Growth Rate and Outcome in Patients With the Marfan Syndrome

The Pediatric Heart Network randomized trial of atenolol versus losartan in the Marfan syndrome showed no treatment differences in the rates of aortic-root growth or clinical outcomes. In this report we present treatment effects on aortic stiffness and determine whether baseline aortic stiffness predicts aortic-root growth and clinical outcomes. Echocardiograms at 0, 6, 12, 24, and 36 months from 608 subjects (6 months to 25 years) who met original Ghent criteria and had a maximum aortic-root z-score (ARz) >3 were centrally reviewed. Stiffness index (SI) and elastic modulus (EM) were calculated for aortic root and ascending aorta. Data were analyzed using multivariable mixed effects modeling and Cox regression. Heart rate-corrected aortic-root SI over 3 years decreased with atenolol but did not change with losartan (-0.298 ± 0.139 vs 0.141 ± 0.139/year, p = 0.01). In the entire cohort, above-median aortic-root SI (>9.1) and EM (>618 mm Hg) predicted a smaller annual decrease in ARz (p ≤0.001). Upper-quartile aortic-root EM (>914 mm Hg) predicted the composite outcome of aortic-root surgery, dissection, or death (hazard ratio 2.17, 95% confidence interval 1.02 to 4.63, p = 0.04). Crude 3-year event rates were 10.4% versus 3.2% for higher versus lower EM groups. In conclusion, atenolol was associated with a decrease in aortic-root SI, whereas losartan was not. Higher baseline aortic-root SI and EM were associated with a smaller decrease in ARz and increased risk for clinical outcomes. These data suggest that noninvasive aortic stiffness measures may identify patients at higher risk of progressive aortic enlargement and adverse clinical outcomes, potentially allowing for closer monitoring and more aggressive therapy.

Angiotensin, transforming growth factor β and aortic dilatation in Marfan syndrome: Of mice and humans

Marfan syndrome is consequent upon mutations in FBN1, which encodes the extracellular matrix microfibrillar protein fibrillin-1. The phenotype is characterised by development of thoracic aortic aneurysm. Current understanding of the pathogenesis of aneurysms in Marfan syndrome focuses upon abnormal vascular smooth muscle cell signalling through the transforming growth factor beta (TGFβ) pathway. Angiotensin II (Ang II) can directly induce aortic dilatation and also influence TGFβ synthesis and signalling. It has been hypothesised that antagonism of Ang II signalling may protect against aortic dilatation in Marfan syndrome. Experimental studies have been supportive of this hypothesis, however results from multiple clinical trials are conflicting. This paper examines current knowledge about the interactions of Ang II and TGFβ signalling in the vasculature, and critically interprets the experimental and clinical findings against these signalling interactions.

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.

A meta-analytical comparison of atenolol with angiotensin-converting enzyme inhibitors on arterial stiffness, peripheral blood pressure and heart rate in hypertensive patients

OBJECTIVES

This meta-analysis of randomized parallel controlled trials was designed to compare the efficacy of atenolol with angiotensin-converting enzyme inhibitors (ACEIs) in changing pulse wave velocity (PWV), peripheral blood pressure and heart rate (HR) among patients with essential hypertension.

METHODS

This study was conducted according to the PRISMA guideline. Data collection was independently completed by two investigators. Statistical analyses were completed by Stata software (v12.0).

RESULTS

Eight clinical trials were meta-analyzed in this study. Overall changes in PWV (weighted mean difference or WMD = 0.068, 95% confidence interval or CI: -0.487 to -0.623, P = 0.811) and peripheral systolic blood pressure (PSBP) (WMD = -1.281 mmHg, 95% CI: -6.936 to 4.375, P = 0.657) did not differ significantly between atenolol and ACEIs treatment. Relative to ACEIs, atenolol had a more favorable impact on peripheral diastolic blood pressure (PDBP) (WMD = -1.912 mmHg, 95% CI: -3.732 to -0.091, P = 0.040) and HR (WMD = -9.23 bpm, 95% CI: -12.53 to -5.93, P < 0.001). In stratified analyses, particularly by follow-up period, atenolol was observed to be superior over ACEIs within early 3-month treatment in PSBP (WMD = -4.097 mmHg, 95% CI: -6.589 to -1.605, P = 0.001), PDBP (WMD = -6.802 mmHg, 95% CI: -8.517 to -5.087, P < 0.001) and HR (WMD = -14.242 bpm, 95% CI: -16.427 to -12.058, P = 0.028), without heterogeneity (I² = 0.0%). There were low probabilities of publication bias for all comparisons.

CONCLUSIONS

Our findings demonstrate that atenolol and ACEIs were equally effective in reducing PWV and PSBP, while atenolol was superior over ACEIs in improving PDBP and HR, especially within short-term treatment.

Cine-CMR partial voxel segmentation demonstrates increased aortic stiffness among patients with Marfan syndrome

BACKGROUND

Standard cine-cardiac magnetic resonance (CMR) imaging is commonly used to evaluate cardiac structure, geometry and function. Prior studies have shown that automated segmentation via partial voxel interpolation (PVI) accurately quantifies phantom-based cardiac chamber volumes and necropsy left ventricular myocardial mass. Despite this, the applicability and usefulness of PVI in the determination of physiologic parameters of the aorta such as aortic stiffness has yet to be investigated.

METHODS

Routine CMR was conducted with a 1.5T (GE) scanner with pulse sequences similar to that of standard CMR (parameters: TR 3.4 msec, TE 1.14 msec, flip angle 60°, temporal resolution ~30-40 msec). Views were obtained in standard cardiac-oriented longitudinal or axial views (2, 3 and 4 chambers). Within non-dilated regions of the descending thoracic aorta, aortic area was quantified via a novel PVI automated process (LV-METRIC), which discerns relative amounts of blood pool in each voxel. Aortic stiffness, as calculated from brachial artery pulse pressure and aortic area at maximal and minimal dimensions, was evaluated in 60 total segments (one segment per patient). All segments were in the descending aorta and were not aneurysmal.

RESULTS

Sixty patients in total were studied, including 50 that had genetically-related aortic disorder [35 bicuspid aortic valve (BAV), 15 Marfan syndrome (MFS)]. Ten normal controls without aortic disease were included for comparison purposes. All patients (n=60) had evaluable CMR images for assessment of the descending aorta with use of automated segmentation. Patients with BAV and MFS were similar to controls in age, systolic blood pressure, brachial artery pulse pressure, smoking status or hypercholesterolemia (all P=NS). There were more women (P<0.001), lower body mass index (P=0.008), and greater height (P<0.001) in the MFS cohort compared to BAV and controls. Descending aortic area in either systole (maximal) or diastole (minimal) was similar among all three cohorts. However, change in aortic area (ΔArea) throughout the cardiac cycle was substantially lower in MFS than control subjects (P<0.001). In contrast, change in aortic area throughout the cardiac cycle was not significantly different between BAV vs. controls (P=0.62). Aortic stiffness was increased among MFS patients versus control subjects (P=0.014). When comparing MFS to BAV subjects, a comparable trend was observed (P=0.09). No statistical difference was evident in aortic stiffness in patients with BAV versus control subjects (P=0.29).

CONCLUSIONS

The application of PVI to standard CMR imaging can assess abnormal descending aorta functional indices in normal caliber segments in MFS subjects. Future prospective studies with larger subject populations are warranted to further determine the overall utility of automated aortic segmentation as a possible early biomarker of aortic dysfunction before overt dilatation.

Aetiology and management of hereditary aortopathy

Aortic aneurysms are a major health problem because they account for 1-2% of all deaths in the Western population. Although abdominal aortic aneurysms (AAAs) are more prevalent than thoracic aortic aneurysms (TAAs), TAAs have been more exhaustively studied over the past 2 decades because they have a higher heritability and affect younger individuals. Gene identification in both syndromic and nonsyndromic TAA is proceeding at a rapid pace and has already pinpointed >20 genes associated with familial TAA risk. Whereas these genes explain <30% of all cases of familial TAA, their functional characterization has substantially improved our knowledge of the underlying pathological mechanisms. As such, perturbed extracellular matrix homeostasis, transforming growth factor-β signalling, and vascular smooth muscle cell contractility have been proposed as important processes in TAA pathogenesis. These new insights enable novel treatment options that are currently being investigated in large clinical trials. Moreover, together with the advent of next-generation sequencing approaches, these genetic findings are promoting a shift in the management of patients with TAA by enabling gene-tailored interventions. In this Review, we comprehensively describe the molecular landscape of familial TAA, and we discuss whether familial TAA, from a biological point of view, can serve as a paradigm for the genetically more complex forms of the condition, such as sporadic TAA or AAA.

Decreased Aortic Elasticity in Children With Marfan Syndrome or Loeys-Dietz Syndrome

BACKGROUND

The characteristics of aortic elasticity are unclear in children with connective tissue disorders (CTDs) such as Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS), especially in those with a non-dilated aortic root (AoR). This study evaluated the aortic elasticity properties of pediatric MFS and LDS patients with either dilated or non-dilated AoR.

METHODS AND RESULTS

The 31 children with MFS or LDS were classified into dilated (Z score of AoR diameter ≥2.5; n=17) or non-dilated (Z score of AoR diameter <2.5; n=14) AoR groups and compared with controls. Using transthoracic echocardiography, we analyzed the aortic elasticity parameters of distensibility, strain, and stiffness index at the levels of the AoR, sinotubular junction, ascending aorta, and descending aorta. Aortic distensibility and strain were significantly lower in both test groups than in controls at the AoR level. The Z score of AoR diameter significantly correlated with aortic distensibility (R=-0.63, P<0.001), strain (R=-0.54, P=0.002), and stiffness index (R=0.52, P=0.002) in the patients' groups. Multivariate analysis revealed that aortic distensibility and the type of CTD were independently associated with AoR dilatation.

CONCLUSIONS

Aortic elasticity at the level of the AoR may be decreased in children with MFS or LDS even before AoR dilatation progresses. Less aortic distensibility and CTD type are considered important parameters in estimating AoR dilatation in these patients. (Circ J 2016; 80: 2369-2375).

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.