Rationale and design of a randomized clinical trial of beta-blocker therapy (atenolol) versus angiotensin II receptor blocker therapy (losartan) in individuals with Marfan syndrome

Extracardiac Manifestations Fail to Predict the Severity of Cardiac Phenotype in Children and Young Adults with Marfan Syndrome

We performed a secondary analysis of the Pediatric Heart Network (PHN) Marfan Trial public-use database to evaluate associations between extracardiac features and cardiac and aortic phenotypes in study participants. Aortic aneurysm phenotype was defined as aortic root Z-score ≥4.5, aortic root growth rate ≥75th percentile, aortic dissection, and aortic surgery. Severe cardiac phenotype was defined as aortic dissection, aortic Z-score ≥4.5, aortic valve surgery, at least moderate mitral regurgitation, mitral valve surgery, left ventricular dysfunction, or death. Extracardiac manifestations were characterized by specific organ system involvement and by a novel aggregate extracardiac score (AES) that was created for this study based on the original Ghent nosology. Mixed effects logistic regression analysis compared AES and systems involvement to outcomes. Of 608 participants (60% male), the median age at enrollment was 10.8 years (interquartile range: 6, 15.4). Aortic aneurysm phenotype was observed in 71% of participants and 64% had severe cardiac phenotype. On univariable analysis, skeletal (OR: 1.95, 95% CI: 1.01, 3.72; p = 0.05), skin manifestation (OR: 1.62, 95% CI: 1.13, 2.34; p = 0.01) and AES (OR: 1.17, 95% CI: 1.02, 1.34; p = 0.02) were associated with aortic aneurysm phenotype but were not significant in multivariable analysis. There was no association between extracardiac manifestations and severe cardiac phenotype. Thus, the severity of cardiac manifestations in Marfan syndrome (MFS) was independent of extracardiac phenotype and AES. Severity of extracardiac involvement did not appear to be a useful clinical marker for cardiovascular risk-stratification in this cohort of children and young adults with MFS.

Extracardiac Manifestations Fail to Predict the Severity of Cardiac Phenotype in Children and Young Adults with Marfan Syndrome

We performed a secondary analysis of the Pediatric Heart Network Marfan Trial public-use database to evaluate associations between extracardiac features and cardiac and aortic phenotypes in study participants. Aortic aneurysm phenotype was defined as aortic root Z-score ≥ 4.5, aortic root growth rate ≥ 75th percentile, aortic dissection, and aortic surgery. Severe cardiac phenotype was defined as aortic dissection, aortic Z-score ≥4.5, aortic valve surgery, at least moderate mitral regurgitation, mitral valve surgery, left ventricular dysfunction, or death. Extracardiac manifestations were characterized by specific organ system involvement and by a novel aggregate extracardiac score that was created for this study based on the original Ghent nosology. Logistic regression analysis compared aggregate extracardiac score and systems involvement to outcomes. Of 608 participants (60% male), the median age at enrollment was 10.8 years (interquartile range: 6, 15.4). Aortic aneurysm phenotype was observed in 71% of participants and 64% had severe cardiac phenotype. On univariate analysis, skeletal (OR: 1.95, 95% CI: 1.01, 3.72; p = 0.05), skin manifestation (OR: 1.62, 95% CI: 1.13, 2.34; p = 0.01) and aggregate extracardiac score (OR: 1.17, 95% CI: 1.02, 1.34; p = 0.02) were associated with aortic aneurysm phenotype but were not significant in multivariate analysis. There was no association between extracardiac manifestations and severe cardiac phenotype. Thus, the severity of cardiac manifestations in Marfan syndrome was independent of extracardiac phenotype and aggregate extracardiac score. Severity of extracardiac involvement did not appear to be a useful clinical marker for cardiovascular risk-stratification in this cohort of children and young adults with Marfan syndrome.

Pediatric Heart Network Trial of Losartan vs. Atenolol in Children and Young Adults with Marfan Syndrome: Impact on Prescription Practices

The Pediatric Heart Network (PHN) trial showed similar efficacy of β-blockers (BB) and angiotensin receptor blockers (ARB) for aortic root dilation in Marfan syndrome, but the impact on prescription practices is unknown. We hypothesized BB and ARB prescriptions would increase after the trial results were published (2014). Prescription data (2007-2016) were obtained from outpatient encounters (IBM Marketscan) for Marfan syndrome patients (6 months-25 years old). Excluding 2014 as a washout period, we analyzed two intervals: 2007-2013 and 2015-2016. Medication categories included BB, ARB, angiotensin converting enzyme inhibitors (ACEI), combination (BB/ARB and/or BB/ACEI), and no drug. Interrupted time-series analysis assessed immediate level change after publication and change in slope for the trend pre- and post-publication. Odds ratios (OR) and 95% confidence intervals from logistic regressions and generalized estimating equation methods accounted for correlation of prescriptions within patients. In 1499 patients (age 14.1 ± 6.1 years, 59% female) seen 2007-2013, BB trended lower [OR 0.91 (0.89, 0.93), p < 0.001] and ARB trended higher [OR 1.12 (1.07, 1.18), p < 0.001], while combination, ACEI, and no drug remained stable. This trend persisted, but was not significant, for BB [OR 0.54 (0.27, 1.08), p = 0.37] and ARB [OR 1.91 (0.55, 6.69), p = 0.31] in 2015-2016. Combination, ACEI, and no drug remained similar. In short term follow-up, changes in prescription practices following publication of the PHN trial were not statistically significant. This may be due to a change seen prior to publication with early adoption of ARBs that was maintained after confirmation of their effectiveness.

Molecular characterization and investigation of the role of genetic variation in phenotypic variability and response to treatment in a large pediatric Marfan syndrome cohort

PURPOSE

In a large cohort of 373 pediatric patients with Marfan syndrome (MFS) with a severe cardiovascular phenotype, we explored the proportion of patients with MFS with a pathogenic FBN1 variant and analyzed whether the type/location of FBN1 variants was associated with specific clinical characteristics and response to treatment. Patients were recruited on the basis of the following criteria: aortic root z-score > 3, age 6 months to 25 years, no prior or planned surgery, and aortic root diameter < 5 cm.

METHODS

Targeted resequencing and deletion/duplication testing of FBN1 and related genes were performed.

RESULTS

We identified (likely) pathogenic FBN1 variants in 91% of patients. Ectopia lentis was more frequent in patients with dominant-negative (DN) variants (61%) than in those with haploinsufficient variants (27%). For DN FBN1 variants, the prevalence of ectopia lentis was highest in the N-terminal region (84%) and lowest in the C-terminal region (17%). The association with a more severe cardiovascular phenotype was not restricted to DN variants in the neonatal FBN1 region (exon 25-33) but was also seen in the variants in exons 26 to 49. No difference in the therapeutic response was detected between genotypes.

CONCLUSION

Important novel genotype-phenotype associations involving both cardiovascular and extra-cardiovascular manifestations were identified, and existing ones were confirmed. These findings have implications for prognostic counseling of families with MFS.

Racial and ethnic differences in response to treatment for Marfan syndrome

OBJECTIVE

To determine whether racial/ethnic differences exist for the treatment of Marfan syndrome aortopathy. The 2014 Pediatric Heart Network randomised trial of losartan versus atenolol in Marfan syndrome paediatric and young adult patients showed no treatment differences in the rate of aortic root growth over 3 years; however, they did not examine racial/ethnic differences, and recent data suggest that angiotensin receptor blockers may have different pharmacologic effects in different racial/ethnic populations.

METHODS

We performed a secondary analysis of public-use data from the Pediatric Heart Network randomised trial comparing the differences by race/ethnicity (non-Hispanic White, non-Hispanic Black, and Hispanic patients) amongst the treatment groups for the primary outcome of rate of aortic root enlargement by z score and secondary outcome of rate of change of absolute diameter of aortic root, z score and absolute diameter of ascending aorta, and blood pressure changes.

RESULTS

For aortic root enlargement by z score amongst non-Hispanic White patients, patients on losartan exhibited an annual z score change of -0.090 ± 0.016, compared to -0.146 ± 0.015 for those on atenolol (p = 0.01), favouring atenolol. For Hispanic and non-Hispanic Black patients, there was no difference in primary or secondary outcomes between treatment groups.

CONCLUSION

Non-Hispanic White patients had a small, but statistically significantly greater decrease in aortic root z score favouring atenolol over losartan. There were no significant differences amongst Hispanic or non-Hispanic Black patients, which may be due to relatively small size numbers. These findings may have important implications for medication selection by race/ethnicity in Marfan syndrome patients, which has not previously been evaluated in studies.

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.

Role of Clinical Genetic Testing in the Management of Aortopathies

PURPOSE OF REVIEW

Thoracic aortic aneurysms (TAA) have a strong heritable basis, and identification of a genetic etiology has important implications for patients with TAA and their relatives. This review provides an overview of Mendelian causes of TAA, discusses important considerations for genetic testing, and summarizes the impact a genetic diagnosis may have on a patient's medical care.

RECENT FINDINGS

Thoracic aortic disease may be non-syndromic or seen as part of a genetic syndrome, such as Marfan syndrome, Loeys-Dietz syndrome, or vascular Ehlers-Danlos syndrome. Expanded access to genetic testing has revealed the wide and overlapping phenotypic spectrum of these conditions, highlighting the need for genetic testing to establish an accurate diagnosis. Important aspects of genetic evaluation include thorough phenotyping through family history and physical examination, selection of an appropriate genetic test driven by the patient's phenotype, and careful interpretation of genetic test results. Improved understanding of the natural history of these conditions has led to tailored management recommendations, including gene-based recommendations for prophylactic surgical repair. Identification of a genetic etiology allows for careful monitoring of disease progression, informs the timing of prophylactic surgical repair, and facilitates the identification of other at-risk relatives through cascade genetic testing.

The Late Effects of Pregnancy on Aortic Dimensions in Patients with Marfan Syndrome

While the immediate effects of pregnancy on aortic dimension in patients with Marfan syndrome (MFS) have been evaluated, the late effects of subsequent pregnancies in these patients are less known. For this purpose, we evaluated 2 groups of women with MFS who were under specialized care in our institution. Group A included 23 women with MFS who experienced 55 pregnancies; group B included 12 nulliparous MFS patients. Patients in group A were similar in age (36.13 ± 5.6 years vs. 34.25 ± 6.54 years, p = 0.41) and follow-up time (group A 6.05 ± 3.56 years and group B 4.92 ± 3.37 years, p = 0.37). Baseline aortic root diameters as well as the aortic root diameters at follow-up visits were similar between groups (35.60 ± 4.42 vs. 35.08 ± 3.82 mm, p = 0.73, and 37.57 ± 4.66 vs. 37.33 ± 4.83 mm, p = 0.89, respectively). The aortic root diameter increased by 0.5 (0, 2) mm in group A and 1 (0, 4.5) mm in group B (p = 0.54). The rate of aortic dilation per year of follow-up was similar between the groups (0.34 ± 0.52 mm/year in group A vs. 0.55 ± 0.75 mm/year in group B [p = 0.52]). Chronic medical treatment was similar in both groups. Patients in both groups were treated similarly with β-blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. In summary, subsequent pregnancies in patients with MFS were not associated with an increase in the rate of aortic root dilation in these patients.

Pharmacogenetic factors affecting β-blocker metabolism and response

INTRODUCTION

β-blockers are among the most widely prescribed of all drugs, used for treatment of a large number of cardiovascular diseases. Herein we evaluate literature pertaining to pharmacogenetics of β-blocker therapy, provide insight into the robustness of the genetic associations, and determine the appropriateness for translating these genetic associations into clinical practice.

AREAS COVERED

A literature search was conducted using PubMed to collate evidence on associations between CYP2D6, ADRB1, ADRB2, and GRK5 genetic variation and drug-response outcomes in the presence of β-blocker exposure. Pharmacokinetic, pharmacodynamic, and clinical outcomes studies were included if genotype data and β-blocker exposure were documented.

EXPERT OPINION

Substantial data suggest that specific ADRB1 and GRK5 genotypes are associated with improved β-blocker efficacy and have potential for use to guide therapy decisions in the clinical setting. While the data do not justify ordering a CYP2D6 pharmacogenetic test, if CYP2D6 genotype is available in the electronic health record, there may be clinical utility for understanding dosing of β-blockers.

A scoping review presenting a wide variety of research on paediatric and adolescent patients with Marfan syndrome

Aim

The present study aimed to map and summarise the research on children, aged 0‐18 years, with Marfan syndrome, identify research gaps and point to research agendas.

Methods

A scoping review was systematically performed by searching multiple databases from January 1996 to April 2019. Primary studies presenting results on at least six individuals aged 0‐18 years with Marfan syndrome, diagnosed according to the Ghent nosology, were selected.

Results

From 2341 de‐duplicated records, 92 papers were included, mapped and described. Their topics were diagnostics (12%), cardiovascular matters (50%), skeletal matters (22%), ocular matters (9%), other medical aspects (5%) and psychosocial perspectives (2%). Most studies were from Europe and North America and published between 1999 and 2019 in subject‐specific or paediatric journals, while a few were published in genetics journals. All studies had quantitative designs, and very few were multicentre studies. Each study had six to 608 subjects for a total of approximately 5809.

Conclusion

A wide range of research topics on adolescent and paediatric Marfan syndrome was found, but qualitative studies and a focus on psychosocial matters were lacking. Future investigations addressing noncardiovascular consequences and patient experiences are needed, as well as studies reaffirming or replicating existing intervention study results.

Recruitment, retention, and adherence in a clinical trial: The Pediatric Heart Network's Marfan Trial experience

BACKGROUND/AIMS

The Pediatric Heart Network Marfan Trial was a randomized trial comparing atenolol versus losartan on aortic root dilation in 608 children and young adults with Marfan syndrome. Barriers to enrollment included a limited pool of eligible participants, restrictive entry criteria, and a diverse age range that required pediatric and adult expertise. Retention was complicated by a 3-year commitment to a complex study and medication regimen. The Network partnered with the Marfan Foundation, bridging the community with the research. The aims of this study are to report protocol and medication adherence and associated predictive factors, and to describe recruitment and retention strategies.

METHODS

Recruitment, retention, and adherence to protocol activities related to the primary outcome were measured. Retention was measured by percentage of enrolled participants with 3-year outcome data. Protocol adherence was calculated by completion rates of study visits, ambulatory electrocardiography (Holter monitoring), and quarterly calls. Medication adherence was assessed by the number of tablets or the amount of liquid in bottles returned. Centers were ranked according to adherence (high, medium, and low tertiles). Recruitment, retention, and adherence questionnaires were completed by sites. Descriptive statistics summarized recruitment, retention, and adherence, as well as questionnaire results. Regression modeling assessed predictors of adherence.

RESULTS

Completion rates for visits, Holter monitors, and quarterly calls were 99%, 94%, and 96%, respectively. Primary outcome data at 3 years were obtained for 88% of participants. The mean percentage of medication taken was estimated at 89%. Site and age were associated with all measures of adherence. Young adult and African American participants had lower levels of adherence. Higher adherence sites employed more strategies; had more staffing resources, less key staff turnover, and more collaboration with referring providers; utilized the Foundation's resources; and used a greater number of strategies to recruit, retain, and promote protocol and medication adherence.

CONCLUSION

Overall adherence was excellent for this trial conducted within a National Institutes of Health-funded clinical trial network. Strategies specifically targeted to young adults and African Americans may have been beneficial. Many strategies employed by higher adherence sites are ones that any site could easily use, such as greeting families at non-study hospital visits, asking for family feedback, providing calendars for tracking schedules, and recommending apps for medication reminders. Additional key learnings include adherence differences by age, race, and site, the value of collaborative learning, and the importance of partnerships with patient advocacy groups. These lessons could shape recruitment, retention, and adherence to improve the quality of future complex trials involving rare conditions.

Variants in ADRB1 and CYP2C9: Association with Response to Atenolol and Losartan in Marfan Syndrome

OBJECTIVE

To test whether variants in ADRB1 and CYP2C9 genes identify subgroups of individuals with differential response to treatment for Marfan syndrome through analysis of data from a large, randomized trial.

STUDY DESIGN

In a subset of 250 white, non-Hispanic participants with Marfan syndrome in a prior randomized trial of atenolol vs losartan, the common variants rs1801252 and rs1801253 in ADRB1 and rs1799853 and rs1057910 in CYP2C9 were analyzed. The primary outcome was baseline-adjusted annual rate of change in the maximum aortic root diameter z-score over 3 years, assessed using mixed effects models.

RESULTS

Among 122 atenolol-assigned participants, the 70 with rs1801253 CC genotype had greater rate of improvement in aortic root z-score compared with 52 participants with CG or GG genotypes (Time × Genotype interaction P = .005, mean annual z-score change ± SE -0.20 ± 0.03 vs -0.09 ± 0.03). Among participants with the CC genotype in both treatment arms, those assigned to atenolol had greater rate of improvement compared with the 71 of the 121 assigned to losartan (interaction P = .002; -0.20 ± 0.02 vs -0.07 ± 0.02; P < .001). There were no differences in atenolol response by rs1801252 genotype or in losartan response by CYP2C9 metabolizer status.

CONCLUSIONS

In this exploratory study, ADRB1-rs1801253 was associated with atenolol response in children and young adults with Marfan syndrome. If these findings are confirmed in future studies, ADRB1 genotyping has the potential to guide therapy by identifying those who are likely to have greater therapeutic response to atenolol than losartan.

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.

Losartan attenuates progression of osteoarthritis in the synovial temporomandibular and knee joints of a chondrodysplasia mouse model through inhibition of TGF-β1 signaling pathway

OBJECTIVE

Transforming growth factor beta 1 (TGF-β1) is implicated in osteoarthritis (OA). The purpose of this study was to explore the ability of Losartan to inhibit the inflammatory signaling pathway of TGF-β1 observed during osteoarthritic progression in the temporomandibular joint (TMJ) and knee joint using a genetic mouse model.

METHODS

A murine OA model displaying the heterozygous chondrodysplasia gene (cho/+), a col11a1 mutation, was used to test this hypothesis. Following a 7-month treatment period with Losartan, the synovial joints were analyzed for histopathological improvement comparing two experimental groups. Tissues were fixed in paraformaldehyde, processed to paraffin section, and stained with Safranin O and Fast Green to visualize proteoglycans and collagen proteins in cartilage. Using the Modified Mankin scoring system, the degree of staining and OA progression were evaluated.

RESULTS

Results show heterozygous animals receiving Losartan having diminished degeneration of TMJ condylar and knee joint articular cartilage. This was confirmed in the TMJ and knee by a statistically significant decrease in the Mankin histopathology score. Decreased expression of HtrA1, a key regulator to the TGF-β1 signaling pathway, was demonstrated in vitro as well as in vivo, via Losartan inhibition.

CONCLUSION

Using a genetic mouse model of OA, this study demonstrated the utility of Losartan to improve treatment of human OA in the TMJ and knee joint through inhibition of the TGF-β1 signaling cascade. We further demonstrated inhibition of HtrA1, the lowering of Mankin scores to wild type control levels, and the limiting of OA progressive damage with treatment of Losartan.

Health-Related Quality of Life in Children and Young Adults with Marfan Syndrome

OBJECTIVE

To assess health-related quality of life (HRQOL) in a large multicenter cohort of children and young adults with Marfan syndrome participating in the Pediatric Heart Network Marfan Trial.

STUDY DESIGN

The Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core Scales were administered to 321 subjects with Marfan syndrome (5-25 years). PedsQL scores were compared with healthy population norms. The impact of treatment arm (atenolol vs losartan), severity of clinical features, and number of patient-reported symptoms on HRQOL was assessed by general linear models.

RESULTS

Mean PedsQL scores in children (5-18 years) with Marfan syndrome were lower than healthy population norms for physical (P ≤ .003) and psychosocial (P < .001) domains; mean psychosocial scores for adults (19-25 years) were greater than healthy norms (P < .001). HRQOL across multiple domains correlated inversely with frequency of patient-reported symptoms (r = 0.30-0.38, P < .0001). Those <18 years of age with neurodevelopmental disorders (mainly learning disability, attention-deficit/hyperactivity disorder) had lower mean PedsQL scores (5.5-7.4 lower, P < .04). A multivariable model found age, sex, patient-reported symptoms, and neurodevelopmental disorder to be independent predictors of HRQOL. There were no differences in HRQOL scores by treatment arm, aortic root z score, number of skeletal features, or presence of ectopia lentis.

CONCLUSIONS

Children and adolescents with Marfan syndrome were at high risk for impaired HRQOL. Patient-reported symptoms and neurodevelopmental disorder, but not treatment arm or severity of Marfan syndrome-related physical findings, were associated with lower HRQOL.

Frequency of Ventricular Arrhythmias and Other Rhythm Abnormalities in Children and Young Adults With the Marfan Syndrome

Patients with the Marfan syndrome (MFS) are at risk for sudden death. The contribution of arrhythmias is unclear. This study examines the prevalence of arrhythmias in children with the MFS and their relation to clinical and/or echocardiographic factors. Data from the Pediatric Heart Network randomized trial of atenolol versus losartan in MFS were analyzed (6 months to 25 years old, aortic root diameter z-score > 3.0, no previous aortic surgery and/or dissection). Baseline 24-hour ambulatory electrocardiographic monitoring was performed. Significant ventricular ectopy (VE) and supraventricular ectopy (SVE) were defined as ≥10 VE or SVE/hour, or the presence of high-grade ectopy. Three-year composite clinical outcome of death, aortic dissection, or aortic root replacement was analyzed. There were 274 analyzable monitors on unique patients from 11 centers. Twenty subjects (7%) had significant VE, 13 (5%) significant SVE; of these, 2 (1%) had both. None had sustained ventricular or supraventricular tachycardia. VE was independently associated with increasing number of major Ghent criteria (odds ratio [OR] = 2.13/each additional criterion, p = 0.03) and greater left ventricular end-diastolic dimension z-score (OR = 1.47/each 1 unit increase in z-score, p = 0.01). SVE was independently associated with greater aortic sinotubular junction diameter z-score (OR = 1.56/each 1 unit increase in z-score, p = 0.03). The composite clinical outcome (14 events) was not related to VE or SVE (p ≥ 0.3), but was independently related to heart rate variability (higher triangular index). In conclusion, in this cohort, VE and SVE were rare. VE was related to larger BSA-adjusted left ventricular size. Routine ambulatory electrocardiographic monitoring may be useful for risk stratification in select MFS patients.

Predictors of Rapid Aortic Root Dilation and Referral for Aortic Surgery in Marfan Syndrome

Few data exist regarding predictors of rapid aortic root dilation and referral for aortic surgery in Marfan syndrome (MFS). To identify independent predictors of the rate of aortic root (AoR) dilation and referral for aortic surgery, we investigated the data from the Pediatric Heart Network randomized trial of atenolol versus losartan in young patients with MFS. Data were analyzed from the echocardiograms at 0, 12, 24, and 36 months read in the core laboratory of 608 trial subjects, aged 6 months to 25 years, who met original Ghent criteria and had an AoR z-score (AoRz) > 3. Repeated measures linear and logistic regressions were used to determine multivariable predictors of AoR dilation. Receiver operator characteristic curves were used to determine cut-points in AoR dilation predicting referral for aortic surgery. Multivariable analysis showed rapid AoR dilation as defined by change in AoRz/year > 90th percentile was associated with older age, higher sinotubular junction z-score, and atenolol use (R² = 0.01) or by change in AoR diameter (AoRd)/year > 90th percentile with higher sinotubular junction z-score and non-white race (R² = 0.02). Referral for aortic root surgery was associated with higher AoRd, higher ascending aorta z-score, and higher sinotubular junction diameter:ascending aorta diameter ratio (R² = 0.17). Change in AoRz of 0.72 SD units/year had 42% sensitivity and 92% specificity and change in AoRd of 0.34 cm/year had 38% sensitivity and 95% specificity for predicting referral for aortic surgery. In this cohort of young patients with MFS, no new robust predictors of rapid AoR dilation or referral for aortic root surgery were identified. Further investigation may determine whether generalized proximal aortic dilation and effacement of the sinotubular junction will allow for better risk stratification. Rate of AoR dilation cut-points had high specificity, but low sensitivity for predicting referral for aortic surgery, limiting their clinical use. Clinical Trial Number ClinicalTrials.gov number, NCT00429364.

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.

TGF-β Family Signaling in Connective Tissue and Skeletal Diseases

The transforming growth factor β (TGF-β) family of signaling molecules, which includes TGF-βs, activins, inhibins, and numerous bone morphogenetic proteins (BMPs) and growth and differentiation factors (GDFs), has important functions in all cells and tissues, including soft connective tissues and the skeleton. Specific TGF-β family members play different roles in these tissues, and their activities are often balanced with those of other TGF-β family members and by interactions with other signaling pathways. Perturbations in TGF-β family pathways are associated with numerous human diseases with prominent involvement of the skeletal and cardiovascular systems. This review focuses on the role of this family of signaling molecules in the pathologies of connective tissues that manifest in rare genetic syndromes (e.g., syndromic presentations of thoracic aortic aneurysm), as well as in more common disorders (e.g., osteoarthritis and osteoporosis). Many of these diseases are caused by or result in pathological alterations of the complex relationship between the TGF-β family of signaling mediators and the extracellular matrix in connective tissues.

Genetic diagnostics of inherited aortic diseases : Medical strategy analysis

Genetic aortic syndromes (GAS) include Marfan, Loeys-Dietz, vascular Ehlers-Danlos, and Turner syndrome as well as congenital bicuspid aortic valve. The clinical management of these diseases has certain similarities and differences. We employed medical strategy analysis to test the utility of genetic diagnostics in the management of GAS. We chose the standpoint of the cardiologist for our analysis. In the first step, the medical goals in the management of GAS are specified. In the second step, the accuracy of genetic diagnostics for GAS is examined. Finally, conclusions can be drawn about the utility of genetic diagnostics in managing GAS. We found that genetic diagnostics is necessary to exclude GAS, to diagnose GAS, and to specify disease types. Second, combining phenotype with genotype information maximizes the predictability of the course of disease. Third, with genetic diagnostics it is possible to predict the birth of children with causative mutations for GAS and to initiate drug therapy to prevent the onset of aortic dilatation or to slow down its progression to aortic aneurysm. Finally, genetic diagnostics improves prognostic predictions and thereby contributes to a better timing of elective surgery and to a better choice of procedures. The findings of our medical strategy analysis indicate the high utility of genetic diagnostics for managing GAS.

Hereditary Influence in Thoracic Aortic Aneurysm and Dissection

Thoracic aortic aneurysm is a potentially life-threatening condition in that it places patients at risk for aortic dissection or rupture. However, our modern understanding of the pathogenesis of thoracic aortic aneurysm is quite limited. A genetic predisposition to thoracic aortic aneurysm has been established, and gene discovery in affected families has identified several major categories of gene alterations. The first involves mutations in genes encoding various components of the transforming growth factor beta (TGF-β) signaling cascade (FBN1, TGFBR1, TGFBR2, TGFB2, TGFB3, SMAD2, SMAD3 and SKI), and these conditions are known collectively as the TGF-β vasculopathies. The second set of genes encode components of the smooth muscle contractile apparatus (ACTA2, MYH11, MYLK, and PRKG1), a group called the smooth muscle contraction vasculopathies. Mechanistic hypotheses based on these discoveries have shaped rational therapies, some of which are under clinical evaluation. This review discusses published data on genes involved in thoracic aortic aneurysm and attempts to explain divergent hypotheses of aneurysm origin.

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.

Postnatal Deletion of the Type II Transforming Growth Factor-β Receptor in Smooth Muscle Cells Causes Severe Aortopathy in Mice

OBJECTIVE

Prenatal deletion of the type II transforming growth factor-β (TGF-β) receptor (TBRII) prevents normal vascular morphogenesis and smooth muscle cell (SMC) differentiation, causing embryonic death. The role of TBRII in adult SMC is less well studied. Clarification of this role has important clinical implications because TBRII deletion should ablate TGF-β signaling, and blockade of TGF-β signaling is envisioned as a treatment for human aortopathies. We hypothesized that postnatal loss of SMC TBRII would cause aortopathy.

APPROACH AND RESULTS

We generated mice with either of 2 tamoxifen-inducible SMC-specific Cre (SMC-CreER(T2)) alleles and homozygous floxed Tgfbr2 alleles. Mice were injected with tamoxifen, and their aortas examined 4 and 14 weeks later. Both SMC-CreER(T2) alleles efficiently and specifically rearranged a floxed reporter gene and efficiently rearranged a floxed Tgfbr2 allele, resulting in loss of aortic medial TBRII protein. Loss of SMC TBRII caused severe aortopathy, including hemorrhage, ulceration, dissection, dilation, accumulation of macrophage markers, elastolysis, abnormal proteoglycan accumulation, and aberrant SMC gene expression. All areas of the aorta were affected, with the most severe pathology in the ascending aorta. Cre-mediated loss of SMC TBRII in vitro ablated both canonical and noncanonical TGF-β signaling and reproduced some of the gene expression abnormalities detected in vivo.

CONCLUSIONS

SMC TBRII plays a critical role in maintaining postnatal aortic homeostasis. Loss of SMC TBRII disrupts TGF-β signaling, acutely alters SMC gene expression, and rapidly results in severe and durable aortopathy. These results suggest that pharmacological blockade of TGF-β signaling in humans could cause aortic disease rather than prevent it.

Fibrillin-containing microfibrils are key signal relay stations for cell function

Fibrillins constitute the backbone of microfibrils in the extracellular matrix of elastic and non-elastic tissues. Mutations in fibrillins are associated with a wide range of connective tissue disorders, the most common is Marfan syndrome. Microfibrils are on one hand important for structural stability in some tissues. On the other hand, microfibrils are increasingly recognized as critical mediators and drivers of cellular signaling. This review focuses on the signaling mechanisms initiated by fibrillins and microfibrils, which are often dysregulated in fibrillin-associated disorders. Fibrillins regulate the storage and bioavailability of growth factors of the TGF-β superfamily. Cells sense microfibrils through integrins and other receptors. Fibrillins potently regulate pathways of the immune response, inflammation and tissue homeostasis. Emerging evidence show the involvement of microRNAs in disorders caused by fibrillin deficiency. A thorough understanding of fibrillin-mediated cell signaling pathways will provide important new leads for therapeutic approaches of the underlying disorders.

The pediatric heart network: meeting the challenges to multicenter studies in pediatric heart disease

PURPOSE OF REVIEW

Because of the relatively small numbers of pediatric patients with congenital heart disease cared for in any individual center, there is a significant need for multicenter clinical studies to validate new medical or surgical therapies. The Pediatric Heart Network (PHN), with 15 years of experience in multicenter clinical research, has tackled numerous challenges when conducting multicenter studies.

RECENT FINDINGS

This review describes the challenges encountered and the strategies employed to conduct high-quality, collaborative research in pediatric cardiovascular disease.

SUMMARY

Sharing lessons learned from the PHN can provide guidance to investigators interested in conducting pediatric multicenter studies.

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.

The pathology and pathobiology of bicuspid aortic valve: State of the art and novel research perspectives

Bicuspid aortic valve is the most prevalent cardiac valvular malformation. It is associated with a high rate of long‐term morbidity including development of calcific aortic valve disease, aortic regurgitation and concomitant thoracic aortic aneurysm and dissection. Recently, basic and translational studies have identified some key processes involved in the development of bicuspid aortic valve and its morbidity. The development of aortic valve disease and thoracic aortic aneurysm and dissection is the result of complex interactions between genotypes, environmental risk factors and specific haemodynamic conditions created by bicuspid aortic valve anatomy. Herein, we review the pathobiology of bicuspid aortic valve with a special emphasis on translational aspects of these basic findings. Important but unresolved problems in the pathology of bicuspid aortic valve and thoracic aortic aneurysm and dissection are discussed, along with the molecular processes involved.

Performant Mutation Identification Using Targeted Next-Generation Sequencing of 14 Thoracic Aortic Aneurysm Genes

At least 14 causative genes have been identified for both syndromic and nonsyndromic forms of thoracic aortic aneurysm/dissection (TAA), an important cause of death in the industrialized world. Molecular confirmation of the diagnosis is increasingly important for gene-tailored patient management but consecutive, conventional molecular TAA gene screening is expensive and labor-intensive. To circumvent these problems, we developed a TAA gene panel for next-generation sequencing of 14 TAA genes. After validation, we applied the assay to 100 Marfan patients. We identified 90 FBN1 mutations, 44 of which were novel. In addition, Multiplex ligation-dependent probe amplification identified large deletions in six of the remaining samples, whereas false-negative results were excluded by Sanger sequencing of FBN1, TGFBR1, and TGFBR2 in the last four samples. Subsequently, we screened 55 syndromic and nonsyndromic TAA patients. We identified causal mutations in 15 patients (27%), one in each of the six following genes: ACTA2, COL3A1, TGFBR1, MYLK, SMAD3, SLC2A10 (homozygous), two in NOTCH1, and seven in FBN1. We conclude that our approach for TAA genetic testing overcomes the intrinsic hurdles of consecutive Sanger sequencing of all candidate genes and provides a powerful tool for the elaboration of clinical phenotypes assigned to different genes.

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).

Thoracic aortic aneurysm and dissection

Aortic dissection is the most devastating complication of thoracic aortic disease. In the more than 250 years since thoracic aortic dissection was first described, much has been learned about diseases of the thoracic aorta. In this review, we describe normal thoracic aortic size; risk factors for dissection, including genetic and inflammatory conditions; the underpinnings of genetic diseases associated with aneurysm and dissection, including Marfan syndrome and the role of transforming growth factor beta signaling; data on the role for medical therapies in aneurysmal disease, including beta-blockers, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors; prophylactic surgery for aneurysm; surgical techniques for the aortic root; and surgical and endovascular management of aneurysm and dissection for different aortic segments.

The evolution of surgical and medical treatment of aortic root aneurysm

Since first report of aortic root replacement in 1968, the surgical risk and long term outcome of patients with aortic root aneurysm have been continuously improving. In the last 30 years, the surgical approach is also evolving towards more valve conservation with prophylactical intervention at an earlier clinical stage. Translational research has also led to emerging surgical innovation and new drug therapy. Their efficacies are currently under vigorous clinical trials and evaluations.

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.

BMP signaling modulation attenuates cerebral arteriovenous malformation formation in a vertebrate model

Cerebral arteriovenous malformations (AVMs) are vascular anomalies that carry a high risk of stroke and death. To test potential AVM therapies, a reverse genetics approach was used to model AVMs in zebrafish. Antisense morpholino oligonucleotides were used to knockdown activin receptor-like kinase I (alk1), which encodes a transforming growth factor (TGF)-beta family type I receptor implicated in a subset of human AVMs. Knockdown of alk1 caused a spectrum of morphologic, functional, and molecular defects that resemble those seen in humans with AVMs. It was found that losartan, an angiotensin II receptor antagonist, attenuated abnormal blood vessel morphology and systemic manifestations of high-output arteriovenous shunting in vivo. SMAD1 phosphorylation was significantly decreased in alk1 morphants compared with uninjected organisms (0.189±0.0201, 0.429±0.0164, P=0.0002). After treatment, morphant SMAD1 levels approached uninjected levels (0.326±0.0360, P=0.0355) and were significantly higher than those seen in the morphant-control group (P=0.0294). These data suggest that modulating the BMP signaling pathway with losartan, a drug in widespread clinical use in humans as an antihypertensive, may have the potential to be further evaluated as a therapeutic strategy for patients with AVMs.

The economic impact of Marfan syndrome: a non-experimental, retrospective, population-based matched cohort study

Background

Marfan syndrome is a rare disease of the connective tissues, affecting multiple organ systems. Elevated morbidity and mortality in these patients raises the issue of costs for sickness funds and society. To date, there has been no study analysing the costs of Marfan syndrome from a sickness fund and societal perspective.

Objective

To estimate excess health resource utilisation, direct (non-)medical and indirect costs attributable to Marfan syndrome from a healthcare payer and a societal perspective in Germany in 2008.

Methods

A retrospective matched cohort study design is applied, using claims data. For isolating the causal effect of Marfan syndrome on excess costs, a genetic matching algorithm was used to reduce differences in observable characteristics between Marfan syndrome patients and the control group. 892 patients diagnosed with Marfan syndrome (ICD-10 Q87.4) were matched from a pool of 26,645 control individuals. After matching, we compared health resource utilisation and costs.

Results

From the sickness fund perspective, an average Marfan syndrome patient generates excess annual costs of €2496 compared with a control individual. From the societal perspective, excess annual costs amount to €15,728. For the sickness fund, the strongest cost drivers are inpatient treatment and care by non-physicians. From the sickness fund perspective, the third (25–41 years) and first (0–16 years) age quartiles reveal the greatest surplus in total costs. Marfan syndrome patients have 39% more physician contacts, a 153% longer average length of hospital stay, 119% more inpatient stays, 33% more prescriptions, 236% more medical imaging and 20% higher average prescription costs than control individuals. Depending on the prevalence, the economic impact from the sickness fund perspective ranges between €24.0 million and €61.4 million, whereas the societal economic impact extends from €151.3 million to €386.9 million.

Conclusions

Relative to its low frequency, Marfan syndrome requires high healthcare expenditure. Not only the high costs of Marfan syndrome but also its burden on patients’ lives call for more awareness from policy-makers, physicians and clinical researchers. Consequently, the diagnosis and treatment of Marfan syndrome should begin as soon as possible in order to prevent disease complications, early mortality and substantial healthcare expenditure.