Early impairment of left ventricular long-axis systolic function demonstrated by reduced atrioventricular plane displacement in patients with Marfan syndrome

Cardiomyopathy in Genetic Aortic Diseases

Genetic aortic diseases are a group of illnesses characterized by aortic aneurysms or dissection in the presence of an underlying genetic defect. They are part of the broader spectrum of heritable thoracic aortic disease, which also includes those cases of aortic aneurysm or dissection with a positive family history but in whom no genetic cause is identified. Aortic disease in these conditions is a major cause of mortality, justifying clinical and scientific emphasis on the aorta. Aortic valve disease and atrioventricular valve abnormalities are known as important additional manifestations that require careful follow-up and management. The archetype of genetic aortic disease is Marfan syndrome, caused by pathogenic variants in the Fibrillin-1 gene. Given the presence of fibrillin-1 microfibers in the myocardium, myocardial dysfunction and associated arrhythmia are conceivable and have been shown to contribute to morbidity and mortality in patients with Marfan syndrome. In this review, we will discuss data on myocardial disease from human studies as well as insights obtained from the study of mouse models of Marfan syndrome. We will elaborate on the various phenotypic presentations in childhood and in adults and on the topic of arrhythmia. We will also briefly discuss the limited data available on other genetic forms of aortic disease.

Myocardial Function, Heart Failure and Arrhythmia in Marfan Syndrome: A Systematic Literature Review

Marfan syndrome (MFS) is a heritable systemic connective tissue disease with important cardiovascular involvement, including aortic root dilatation and mitral valve prolapse. Life expectancy in patients with MFS is mainly determined by cardiovascular complications, among which aortic dissection or rupture are most dreaded. In recent years, heart failure and ventricular arrhythmia have drawn attention as extra-aortic cardiovascular manifestations and as additional reported causes of death. Imaging studies have provided data supporting a primary myocardial impairment in the absence of valvular disease or cardiovascular surgery, while studies using ambulatory ECG have demonstrated an increased susceptibility to ventricular arrhythmia. In this paper, current literature was reviewed in order to provide insights in characteristics, pathophysiology and evolution of myocardial function, heart failure and ventricular arrhythmia in MFS.

Cardiovascular Magnetic Resonance Provides Evidence of Abnormal Myocardial Strain and Primary Cardiomyopathy in Marfan syndrome

OBJECTIVE

Marfan syndrome is an autosomal-dominant genetic disorder caused by mutations in the fibrillin-1 gene. The condition is a connective tissue disease that frequently involves the cardiovascular system. The existence of a primary cardiomyopathy in Marfan syndrome, however, is controversial. The aims of this study were to investigate the prevalence of left ventricular dysfunction with both transthoracic echocardiography and cardiovascular magnetic resonance (CMR) in a cohort of Marfan syndrome patients and to investigate patterns of myocardial strain across the cohort.

METHODS

We used an institutional database to identify all patients with a firm diagnosis of Marfan syndrome based on Ghent criteria. Inclusion required left ventricular ejection fraction (LVEF) to have been measured by both CMR and transthoracic echocardiography within 12 months of each other. Normal LVEF was defined as a value of >55% when measured by CMR. Velocity vector imaging was used to measure left ventricular longitudinal strain patterns by application of feature tracking to cine magnetic resonance images. Results were compared with data from 20 age-matched control subjects.

RESULTS

Sixty-nine Marfan syndrome patients met the inclusion criteria. The mean age was 35.4 ± 15.0 years, and 56.5% were male. The mean LVEF was 59.0% ± 7.0% by CMR and 59.1% ± 5.8% by echo. One-fifth of Marfan syndrome patients (15/69; 21.7%) had reduced function with LVEF ≤55% by CMR, but only 5 of these were identified by echo. Furthermore, echo identified 5 Marfan syndrome patients as having reduced LVEF in the presence of a normal LVEF by CMR. Some Marfan syndrome patients had abnormal longitudinal strain patterns even with LVEF within the reference range.

CONCLUSIONS

These data provide support for a primary cardiomyopathy in some Marfan syndrome patients. Cardiovascular magnetic resonance is more sensitive than echo for identifying cases with mild systolic dysfunction. Strain analysis may be more sensitive than simple LVEF assessment for identifying at-risk individuals.

Heart failure and sudden cardiac death in heritable thoracic aortic disease caused by pathogenic variants in the SMAD3 gene

BACKGROUND

Predominant cardiovascular manifestations in the spectrum of Heritable Thoracic Aortic Disease include by default aortic root aneurysms- and dissections, which may be associated with aortic valve disease. Mitral- and tricuspid valve prolapse are other commonly recognized features. Myocardial disease, characterized by heart failure and/or malignant arrhythmias has been reported in humans and in animal models harboring pathogenic variants in the Fibrillin1 gene.

METHODS

Description of clinical history of three cases from one family in Ghent (Belgium) and one family in St. Louis (US).

RESULTS

We report on three cases from two families presenting end-stage heart failure (in two) and lethal arrhythmias associated with moderate left ventricular dilatation (in one). All three cases harbor a pathogenic variant in the SMAD3 gene, known to cause aneurysm osteoarthritis syndrome, Loeys-Dietz syndrome type 3 or isolated Heritable Thoracic Aortic Disease.

CONCLUSIONS

These unusual presentations warrant awareness for myocardial disease in patients harboring pathogenic variants in genes causing Heritable Thoracic Aortic Disease and indicate the need for prospective studies in larger cohorts.

Developmental Changes in Aortic Mechanical Properties in Normal Fetuses and Fetuses with Cardiovascular Disease

BACKGROUND

We hypothesized that fetal aortic mechanical properties assessed by aortic diameter (AoD) and flow show maturational changes during the gestational period, and that these properties are different in fetuses with congenital heart diseases and fetuses with normal development.

METHODS

Phasic changes in ascending AoD along with Doppler flow profile were measured in 84 consecutive normal fetuses (gestational age, 18-36 weeks) and in 30 consecutive fetuses with cardiovascular diseases (gestational age, 22-39 weeks).

RESULTS

AoD and cardiac output significantly increased with gestational age. Fetal aortic compliance (AC), assessed as (maximum AoD - minimum AoD)/stroke volume, significantly decreased with gestational age in normal fetuses, indicating maturational changes in aortic wall properties. Importantly, fetuses with Marfan syndrome and tetralogy of Fallot that exhibit "aortopathy" showed significantly lower AC than normal fetuses of the same gestational age, suggesting intrinsic abnormalities in aortic wall properties in these diseases. Fetuses with trisomy 18 and Noonan syndrome also had AC values below the normal ranges.

CONCLUSION

Measurements of phasic changes in fetal AoD and flow measurements can provide useful information about aortic mechanical properties and may help clarify abnormal arterial hemodynamics in pathologic conditions.

Aortic and Cardiac Structure and Function Using High-Resolution Echocardiography and Optical Coherence Tomography in a Mouse Model of Marfan Syndrome

Marfan syndrome (MFS) is an autosomal-dominant disorder of connective tissue caused by mutations in the fibrillin-1 (FBN1) gene. Mortality is often due to aortic dissection and rupture. We investigated the structural and functional properties of the heart and aorta in a [Fbn1^C1039G/+] MFS mouse using high-resolution ultrasound (echo) and optical coherence tomography (OCT). Echo was performed on 6- and 12-month old wild type (WT) and MFS mice (n = 8). In vivo pulse wave velocity (PWV), aortic root diameter, ejection fraction, stroke volume, left ventricular (LV) wall thickness, LV mass and mitral valve early and atrial velocities (E/A) ratio were measured by high resolution echocardiography. OCT was performed on 12-month old WT and MFS fixed mouse hearts to measure ventricular volume and mass. The PWV was significantly increased in 6-mo MFS vs. WT (366.6 ± 19.9 vs. 205.2 ± 18.1 cm/s; p = 0.003) and 12-mo MFS vs. WT (459.5 ± 42.3 vs. 205.3 ± 30.3 cm/s; p< 0.0001). PWV increased with age in MFS mice only. We also found a significantly enlarged aortic root and decreased E/A ratio in MFS mice compared with WT for both age groups. The [Fbn1^C1039G/+] mouse model of MFS replicates many of the anomalies of Marfan patients including significant aortic dilation, central aortic stiffness, LV systolic and diastolic dysfunction. This is the first demonstration of the direct measurement in vivo of pulse wave velocity non-invasively in the aortic arch of MFS mice, a robust measure of aortic stiffness and a critical clinical parameter for the assessment of pathology in the Marfan syndrome.

The Expanding Clinical Spectrum of Extracardiovascular and Cardiovascular Manifestations of Heritable Thoracic Aortic Aneurysm and Dissection

More than 30 heritable conditions are associated with thoracic aortic aneurysm and dissection (TAAD). Heritable syndromic conditions, such as Marfan syndrome, Loeys-Dietz syndrome, and vascular Ehlers-Danlos syndrome, have somewhat overlapping systemic features, but careful clinical assessment usually enables a diagnosis that can be validated with genetic testing. Nonsyndromic FTAAD can also occur and in 20%-25% of these probands mutations exist in genes that encode elements of the extracellular matrix, signalling pathways (especially involving transforming growth factor-β), and vascular smooth muscle cytoskeletal and contractile processes. Affected individuals with either a syndromic presentation or isolated TAAD can have mutations in the same gene. In this review we focus on the genes currently known to have causal mutations for syndromic and isolated FTAAD and outline the range of associated extracardiovascular and cardiovascular manifestations with each.

Cardiac remodeling in the mouse model of Marfan syndrome develops into two distinctive phenotypes

Marfan syndrome (MFS) is a systemic disorder of connective tissue caused by mutations in fibrillin-1. Cardiac dysfunction in MFS has not been characterized halting the development of therapies of cardiac complication in MFS. We aimed to study the age-dependent cardiac remodeling in the mouse model of MFS FbnC1039G+/- mouse [Marfan heterozygous (HT) mouse] and its association with valvular regurgitation. Marfan HT mice of 2-4 mo demonstrated a mild hypertrophic cardiac remodeling with predominant decline of diastolic function and increased transforming growth factor-β canonical (p-SMAD2/3) and noncanonical (p-ERK1/2 and p-p38 MAPK) signaling and upregulation of hypertrophic markers natriuretic peptides atrium natriuretic peptide and brain natriuretic peptide. Among older HT mice (6-14 mo), cardiac remodeling was associated with two distinct phenotypes, manifesting either dilated or constricted left ventricular chamber. Dilatation of left ventricular chamber was accompanied by biochemical evidence of greater mechanical stress, including elevated ERK1/2 and p38 MAPK phosphorylation and higher brain natriuretic peptide expression. The aortic valve regurgitation was registered in 20% of the constricted group and 60% of the dilated group, whereas mitral insufficiency was observed in 40% of the constricted group and 100% of the dilated group. Cardiac dysfunction was not associated with the increase of interstitial fibrosis and nonmyocyte proliferation. In the mouse model fibrillin-1, haploinsufficiency results in the early onset of nonfibrotic hypertrophic cardiac remodeling and dysfunction, independently from valvular abnormalities. MFS heart is vulnerable to stress-induced cardiac dilatation in the face of valvular regurgitation, and stress-activated MAPK signals represent a potential target for cardiac management in MFS.

Cardiovascular manifestations in Marfan syndrome and related diseases; multiple genes causing similar phenotypes

Cardiovascular abnormalities are the major cause of morbidity and mortality in Marfan syndrome (MFS) and a few clinically related diseases that share, with MFS, the pathogenic contribution of dysregulated transforming growth factor β (TGFβ) signaling. They include Loeys-Dietz syndrome, Shprintzen-Goldberg syndrome, aneurysm-osteoarthritis syndrome and syndromic thoracic aortic aneurysms. Unlike the causal association of MFS with mutations in an extracellular matrix protein (ECM), the aforementioned conditions are due to defects in components of the TGFβ pathway. While TGFβ antagonism is being considered as a potential new therapy for these heritable syndromes, several points still need to be clarified in relevant animal models before this strategy could be safely applied to patients. Among others, unresolved issues include whether elevated TGFβ signaling is responsible for all MFS manifestations and is the common trigger of disease in MFS and related conditions. The scope of our review is to highlight the clinical and experimental findings that have forged our understanding of the natural history and molecular pathogenesis of cardiovascular manifestations in this group of syndromic conditions.

Abnormal muscle mechanosignaling triggers cardiomyopathy in mice with Marfan syndrome

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

Relation between genotype and left-ventricular dilatation in patients with Marfan syndrome

Cardiovascular manifestations in patients with Marfan syndrome (MFS) are related to aortic and valvular abnormalities. However, dilatation of the left ventricle (LV) can occur, even in the absence of aortic surgery or valvular abnormalities. We evaluated genetic characteristics of patients with MFS with LV dilatation. One hundred eighty-two patients fulfilling the MFS criteria, without valvular abnormalities or previous aortic surgery, with a complete FBN1 analysis, were studied. FBN1 mutations were identified in over 81% of patients. Twenty-nine patients (16%) demonstrated LV dilatation (LV end diastolic diameter corrected for age and body surface area >112%). FBN1-positive patients carrying a non-missense mutation more often had LV dilatation than missense mutation carriers (14/74 versus 5/75; p<0.05). Finally, FBN1-negative MFS patients significantly more often demonstrated LV dilatation than FBN1-positive patients (10/33 versus 19/149; p<0.05). It is concluded that LV dilatation in MFS patients is more often seen in patients with a non-missense mutation and in those patients without an FBN1 mutation. Therefore physicians should be aware of the possibility of LV dilatation in these patients even in the absence of valvular pathology.

The prognostic value of high sensitivity troponin T 7 weeks after an acute coronary syndrome

Objective

The role of high sensitivity troponin T (hs-TnT) in the convalescence phase after an acute coronary syndrome (ACS) is unknown. The authors aim to assess the prognostic utility of a single hs-TnT level at 7-week post-ACS. Second, the authors evaluated whether any serial changes in hs-TnT between the index admission and 7 weeks post-ACS had any link with the prognosis. Third, the authors assessed whether the prognostic utility of hs-TnT is independent of various echocardiographic abnormalities.

Methods

The authors measured hs-TnT levels in 326 consecutive patients at 7 weeks after an ACS event. The composite end point of death from any cause or acute myocardial infarction was evaluated over a median duration of 30 months.

Results

A high 7-week hs-TnT (>14 ng/l) predicted adverse clinical outcomes independent of conventional risk factors, left ventricular dysfunction and left ventricular hypertrophy on echocardiography (adjusted RR: 2.69 (95% CI 1.45 to 5.00)). Patients with persistent hs-TnT elevation at 7 weeks were also at an increased risk of cardiovascular events compared with those with an initial high hs-TnT which then normalised (unadjusted RR 3.39 (95% CI 2.02 to 5.68)).

Conclusion

The authors have demonstrated the prognostic utility of a single 7-week hs-TnT measurement in routine ACS patients and that it could be used to assist medium term risk stratification in this patient cohort. In addition, the authors also showed that hs-TnT predicted long-term adverse prognosis independent of various echo parameters. Future studies should evaluate whether tailoring specific treatment interventions to higher risk individuals as identified by an elevated hs-TnT during the convalescence phase of ACS would improve clinical outcomes.

Biventricular performance in patients with marfan syndrome without significant valvular disease: comparison to normal subjects and longitudinal follow-up

BACKGROUND

The presence and progressive nature of primary myocardial involvement in Marfan syndrome are debated. The aim of this study was to evaluate the clinical relevance of left ventricular (LV) and right ventricular (RV) strain in adult patients with Marfan syndrome without significant valvular disease.

METHODS

Adult patients with Marfan syndrome (n = 50; mean age, 35.2 ± 12.9 years) were followed prospectively. Echocardiography was performed annually and consisted of comprehensive assessment of ventricular and valvular function. Using speckle-tracking imaging, the baseline strain values of the Marfan population were calculated and compared with the values of normal controls. The follow-up evaluations were used to assess changes in ventricular strain. The association between the incidence of adverse events (heart failure, [supra]ventricular arrhythmias, and proximal aorta surgery) and baseline strain values was investigated.

RESULTS

Compared with controls, patients with Marfan syndrome had significantly lower peak longitudinal LV strain (-18.9 ± 2.3% vs -20.1 ± 1.9%, P < .01) and RV strain (±26.9 ± 5.2% vs ±29.3 ± 4.25%, P < .01). The absolute changes in LV longitudinal, radial, and circumferential strain and RV longitudinal strain during a median 4 years of follow-up were 0.1 ± 2.8%, 1.12 ± 7.6%, 0.3 ± 3.7%, and 0.9 ± 5.5%, respectively, which was not statistically significant. Cox regression demonstrated that reduced LV or RV strain was not associated with adverse outcome (supraventricular arrhythmias, n = 3; proximal aorta surgery, n = 4).

CONCLUSIONS

This study suggests that patients with Marfan syndrome show lower ventricular strain and strain rate values compared with healthy controls. However, no relevant changes in LV and RV function occurred during midterm follow-up in patients with Marfan syndrome without valvular disease at baseline. Although ventricular strain and strain rate were mildly reduced in patients with Marfan syndrome, this did not affect outcomes negatively in the present study.

Evidence for Marfan cardiomyopathy

AIM

Marfan syndrome (MFS) is an inherited connective tissue disease which frequently involves the cardiovascular system. The heart can be affected since valvular regurgitation is a common complication. However, there is still debate whether a primary cardiomyopathy exists. Our aim was to evaluate the existence of a Marfan-related cardiomyopathy using cardiovascular magnetic resonance.

METHODS AND RESULTS

We retrospectively evaluated 68 consecutive adult patients with no cardiovascular surgery or significant valvular regurgitation. Left ventricular and right ventricular volumes, ejection fraction, and mass were estimated and compared with published data on a healthy control population. Patients were also assessed for heart failure, aortic dimensions, and valve disease. One quarter (25.0%) of Marfan patients had reduced left ventricular ejection fraction (LVEF), with 25.0% having increased left ventricular end-diastolic and 30.8% having increased end-systolic volumes. The right ventricular ejection fraction was reduced in 10.3%, with increased right ventricular end-diastolic volumes in 11.8% and increased end-systolic volumes in 13.2%. On univariate analysis, no association was found between reduced LVEF and age, gender, indexed aortic dimensions, presence of mitral valve prolapse, or valve regurgitation.

CONCLUSION

This study supports the existence of a primary cardiomyopathy in a subgroup of Marfan patients. The biventricular enlargement and dysfunction is usually mild, asymptomatic, and independent from other cardiovascular manifestations. Further studies are needed to assess underlying causes and natural history of this condition. Routine monitoring and treatment in MFS may need to be tailored not only to prevent aortic root expansion but also to support myocardial function.

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

BACKGROUND

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

METHODS

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

CONCLUSION

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