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Objectives The aim of our study was to investigate the benefit of antiarrhythmic drugs (AAD) - beta-blockers, sotalol or amiodarone - in a cohort of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) patients with long-term longitudinal follow up. Background AAD are prescribed in ARVC to prevent ventricular arrhythmias and control symptoms. However, there are no controlled clinical trials and knowledges regarding the efficacy of AAD in ARVC are limited. Methods The study population included 123 patients with definite diagnosis of ARVC and ≥ 2 clinical evaluations. The primary outcome was a composite of sudden cardiac death (SCD)/recurrent major ventricular arrythmias (MVA): sudden cardiac arrest, sustained ventricular tachycardia (VT) and appropriate implantable cardioverter defibrillator interventions, including recurrent events in patients with >1 MVA. Time to first event (SCD or MVA) was considered as secondary composite endpoint. Results Sixteen patients were taking AAD at baseline and 75 started at least one AAD during a median follow-up of 132 months [61–255]. A total of 37 patients experienced ≥1 MVA with a total count of 83 recurrent MVA. After adoption of a propensity score analysis, no AAD were associated with lower risk of recurrent MVA. However, if dosage of AAD was considered, beta-blockers at >50% target dose were associated with a significant reduction in the risk of MVA compared to patients not taking beta-blockers (HR 0.10, 95% CI 0.02–0.46, p = 0.004). Conclusions In a large cohort of ARVC patients with a long-term follow-up, only beta-blockers administrated at >50% target dose were associated with lower risk of SCD/recurrent MVA.

FLNC truncating mutations ( FLNCtv ) are prevalent causes of inherited dilated cardiomyopathy (DCM), with a high risk of developing arrhythmogenic cardiomyopathy. We investigated the molecular mechanisms of mutant FLNC in the pathogenesis of arrhythmogenic DCM (a-DCM) using patient-specific induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs). We demonstrated that iPSC-CMs from two patients with different FLNCtv mutations displayed arrhythmias and impaired contraction. FLNC ablation induced a similar phenotype, suggesting that FLNCtv are loss-of-function mutations. Coimmunoprecipitation and proteomic analysis identified β-catenin (CTNNB1) as a downstream target. FLNC deficiency induced nuclear translocation of CTNNB1 and subsequently activated the platelet-derived growth factor receptor alpha (PDGFRA) pathway, which were also observed in human hearts with a-DCM and FLNCtv . Treatment with the PDGFRA inhibitor, crenolanib, improved contractile function of patient iPSC-CMs. Collectively, our findings suggest that PDGFRA signaling is implicated in the pathogenesis, and inhibition of this pathway is a potential therapeutic strategy in FLNC-related cardiomyopathies.

IMPORTANCE: Dilated cardiomyopathy (DCM) is frequently caused by genetic factors. Studies identifying deleterious rare variants have predominantly focused on early-onset cases, and little is known about the genetic underpinnings of the growing numbers of patients with DCM who are diagnosed when they are older than 60 years (ie, late-onset DCM). OBJECTIVE: To investigate the prevalence, type, and prognostic impact of disease-associated rare variants in patients with late-onset DCM. DESIGN, SETTING, AND PARTICIPANTS: A population of patients with late-onset DCM who had undergone genetic testing in 7 international tertiary referral centers worldwide were enrolled from March 1990 to August 2020. A positive genotype was defined as the presence of pathogenic or likely pathogenic (P/LP) variants. MAIN OUTCOMES AND MEASURES: The study outcome was all-cause mortality. RESULTS: A total of 184 patients older than 60 years (103 female [56%]; mean [SD] age, 67 [6] years; mean [SD] left ventricular ejection fraction, 32% [10%]) were studied. Sixty-six patients (36%) were carriers of a P/LP variant. Titin-truncating variants were the most prevalent (present in 46 [25%] of the total population and accounting for 46 [69%] of all genotype-positive patients). During a median (interquartile range) follow-up of 42 (10-115) months, 23 patients (13%) died; 17 (25%) of these were carriers of P/LP variants, while 6 patients (5.1%) were genotype-negative. CONCLUSIONS AND RELEVANCE: Late-onset DCM might represent a distinct subgroup characterized by and a high genetic variation burden, largely due to titin-truncating variants. Patients with a positive genetic test had higher mortality than genotype-negative patients. These findings support the extended use of genetic testing also in older patients.

Background Genotype-phenotype correlations in dilated cardiomyopathy (DCM) and, in particular, the effects of gene variants on clinical outcomes remain poorly understood. Objectives The purpose of this study was to investigate the prognostic role of genetic variant carrier status in a large cohort of DCM patients. Methods A total of 487 DCM patients were analyzed by next-generation sequencing and categorized the disease genes into functional gene groups. The following composite outcome measures were assessed: 1) all-cause mortality; 2) heart failure–related death, heart transplantation, or destination left ventricular assist device implantation (DHF/HTx/VAD); and 3) sudden cardiac death/sustained ventricular tachycardia/ventricular fibrillation (SCD/VT/VF). Results A total of 183 pathogenic/likely pathogenic variants were found in 178 patients (37%): 54 (11%) Titin; 19 (4%) Lamin A/C (LMNA); 24 (5%) structural cytoskeleton-Z disk genes; 16 (3.5%) desmosomal genes; 46 (9.5%) sarcomeric genes; 8 (1.6%) ion channel genes; and 11 (2.5%) other genes. All-cause mortality was no different between variant carriers and noncarriers (p = 0.99). A trend toward worse SCD/VT/VF (p = 0.062) and DHF/HTx/VAD (p = 0.061) was found in carriers. Carriers of desmosomal and LMNA variants experienced the highest rate of SCD/VT/VF, which was independent of the left ventricular ejection fraction. Conclusions Desmosomal and LMNA gene variants identify the subset of DCM patients who are at greatest risk for SCD and life-threatening ventricular arrhythmias, regardless of the left ventricular ejection fraction.

Arrhythmogenic cardiomyopathy (ACM) is an inherited arrhythmia syndrome characterized by severe structural and electrical cardiac phenotypes, including myocardial fibrofatty replacement and sudden cardiac death. Clinical management of ACM is largely palliative, owing to an absence of therapies that target its underlying pathophysiology, which stems partially from our limited insight into the condition. Following identification of deceased ACM probands possessing ANK2 rare variants and evidence of ankyrin-B loss of function on cardiac tissue analysis, an ANK2 mouse model was found to develop dramatic structural abnormalities reflective of human ACM, including biventricular dilation, reduced ejection fraction, cardiac fibrosis, and premature death. Desmosomal structure and function appeared preserved in diseased human and murine specimens in the presence of markedly abnormal beta-catenin expression and patterning, leading to identification of a previously unknown interaction between ankyrin-B and beta-catenin. A pharmacological activator of the WNT/beta-catenin pathway, SB-216763, successfully prevented and partially reversed the murine ACM phenotypes. Our findings introduce what we believe to be a new pathway for ACM, a role of ankyrin-B in cardiac structure and signaling, a molecular link between ankyrin-B and beta-catenin, and evidence for targeted activation of the WNT/beta-catenin pathway as a potential treatment for this disease. Funding Agencies|Marianne Barrie Philanthropic Fund; Canadian Institutes of Health Research [RN332805]; Netherlands CardioVascular Research Initiative: the Dutch Heart Foundation; Dutch Federation of University Medical Centers; Netherlands Organisation for Health Research and Development; Royal Netherlands Academy of Sciences [CVON-PREDICT 2012-10]; Netherlands Cardiovascular Research Initiative - Dutch Heart Foundation [CVON2012-10 PREDICT CVON2018-30 PREDICT2, CVON2015-12 eDETECT]; Netherlands Organization for Scientific Research (NWO) [040.11.586]; Fondation Leducq [16 CVD 02]; Dr. Francis P. Chiramonte Private Foundation; Leyla Erkan Family Fund for ARVD Research; Robin Shah ARVD Fund at Johns Hopkins; Bogle Foundation; Healing Hearts Foundation; Campanella Family; Patrick J. Harrison Family; Peter French Memorial Foundation; Wilmerding Endowments; NIH [HL135754, HL134824, HL139348, HL135096, HL114383, HL114893, HL137331, HL137325, 2UM1HG006542, UL1 TR 001079]; Ohio State Frick Center; JB Project

The term dilated cardiomyopathy (DCM) defines a heterogeneous group of cardiac disorders, which are characterized by left ventricular or biventricular dilatation and systolic dysfunction in the absence of abnormal loading conditions or coronary artery disease sufficient to cause global systolic impairment. In approximately one third of cases, DCM is familial with a genetic pathogenesis and various patterns of inheritance. Although the electrocardiogram (ECG) has been considered traditionally non-specific in DCM, the recently acquired knowledge of the genotype-phenotype correlations provides novel opportunities to identify patterns and abnormalities that may point toward specific DCM subtypes. A learned ECG interpretation in combination with an appropriate use of other ECG-based techniques including ambulatory ECG monitoring, exercise tolerance test and imaging modalities, such as echocardiography and cardiovascular magnetic resonance, may allow the early identification of specific genetic or acquired forms of DCM. Furthermore, ECG abnormalities may reflect the severity of the disease and provide a useful tool in risk stratification and management. In the present review, we discuss the current role of the ECG in the diagnosis and management of DCM. We describe various clinical settings where the appropriate use and interpretation of the ECG can provide invaluable clues, contributing to the important role of this basic tool as cardiovascular medicine evolves.

BackgroundArrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease that affects predominantly the right ventricle and is part of the spectrum of arrythmogenic cardiomyopathies (ACMs). ARVC is a genetic condition; however, a pathogenic gene variant is found in only half of patients.ObjectiveFilamin C gene truncations (FLNCtv) have recently been identified in dilated cardiomyopathy with ventricular arrhythmia and sudden cardiac death, a phenotype partially overlapping with ARVC and part of the ACM spectrum. We hypothesised that FLNCtv could be a novel gene associated with ARVC.MethodsOne hundred fifty-six patients meeting 2010 ARVC Task Force Criteria and lacking variants in known ARVC genes were evaluated for FLNC variants. Available family members were tested for cosegregation.ResultsWe identified two unique FLNCtv variants in two families (c.6565 G>T, p.Glu2189Ter and c.8107delG, p.Asp2703ThrfsTer69), with phenotypes of dominant RV disease fulfilling ‘definite’ diagnosis of ARVC according to the 2010 Task Force Criteria. Variants in other cardiomyopathy genes were excluded in both kindreds, and segregation analysis revealed that p.Asp2703ThrfsTer69 was a de novo variant. In both families, the disease phenotype was characterised by prominent ventricular arrhythmias and sudden cardiac arrest.ConclusionThe identification of FLNCtv as a novel cause of ARVC in two unrelated families expands the spectrum of ARVC non-desmosome disease genes for this disorder. Our findings should prompt inclusion of FLNC genetic testing in ARVC to improve diagnostic yield and testing of at-risk relatives in ARVC.

Article, see p 1595 Arrhythmogenic cardiomyopathy (AC) is a genetic disorder characterized by high risk of life-threatening ventricular arrhythmias, sudden cardiac death, and progressive heart failure. Currently, there is evidence that AC includes a spectrum of cardiomyopathy phenotypes, ranging from the classical form of arrhythmogenic right ventricular cardiomyopathy (ARVC) to more recently identified forms of arrhythmogenic left ventricular cardiomyopathy.1,2 ARVC is considered a disease of the desmosome, because in the majority of cases, it is caused by mutations in genes encoding proteins of the cardiac desmosomes.3 However, mutations in nondesmosomal genes have also been found in ARVC, such as the genes encoding the cardiac ryanodine receptor 2 ( RYR2 ), the transforming growth factor β-3 ( TGFB3 ), the nuclear transmembrane protein 43 ( TMEM43 ), and desmin ( DES ). Mutations in LMNA , encoding the nuclear envelope protein lamin A/C, known to cause dilated cardiomyopathy with an arrhythmic phenotype, was reported to cause also an ARVC phenotype,3 even though the association between LMNA and ARVC is still questioned. In the left dominant form, which clinically presents as an arrhythmogenic dilated cardiomyopathy, the same desmosomal genes causing ARVC can be found,1 as well as LMNA and the more recently identified filamin C gene ( FLNC ), encoding an actin …

Utilizing polymers in cardiac tissue engineering holds promise for restoring function to the heart following myocardial infarction, which is associated with grave morbidity and mortality. To properly mimic native cardiac tissue, materials must not only support cardiac cell growth but also have inherent conductive properties. Here, we present an injectable reverse thermal gel (RTG)-based cardiac cell scaffold system that is both biocompatible and conductive. Following the synthesis of a highly functionalizable, biomimetic RTG backbone, gold nanoparticles (AuNPs) were chemically conjugated to the backbone to enhance the system´s conductivity. The resulting RTG-AuNP hydrogel supported targeted survival of neonatal rat ventricular myocytes (NRVMs) for up to 21 days when cocultured with cardiac fibroblasts, leading to an increase in connexin 43 (Cx43) relative to control cultures (NRVMs cultured on traditional gelatin-coated dishes and RTG hydrogel without AuNPs). This biomimetic and conductive RTG-AuNP hydrogel holds promise for future cardiac tissue engineering applications.

Cardiomyopathies affect individuals worldwide, without regard to age, sex and ethnicity and are associated with significant morbidity and mortality. Inherited cardiomyopathies account for a relevant part of these conditions. Although progresses have been made over the years, early diagnosis and curative therapies are still challenging. Understanding the events occurring in normal and diseased cardiac cells is crucial, as they are important determinants of overall heart function. Besides chemical and molecular events, there are also structural and mechanical phenomena that require to be investigated. Cell structure and mechanics largely depend from the cytoskeleton, which is composed by filamentous proteins that can be cross-linked via accessory proteins. Alpha-actinin 2 (ACTN2), filamin C (FLNC) and dystrophin are three major actin cross-linkers that extensively contribute to the regulation of cell structure and mechanics. Hereby, we review the current understanding of the roles played by ACTN2, FLNC and dystrophin in the onset and progress of inherited cardiomyopathies. With our work, we aim to set the stage for new approaches to study the cardiomyopathies, which might reveal new therapeutic targets and broaden the panel of genes to be screened.

PURPOSE OF REVIEW: This review aims to summarize the current knowledge on the genetic background of dilated cardiomyopathy (DCM), with particular attention to the genotype-phenotype correlations and the possible implications for clinical management. RECENT FINDINGS: Next generation sequencing (NGS) has led to the identification of an increasing number of genes and mutations responsible for DCM. This genetic variability is probably related to the extreme heterogeneity of disease manifestation. Important findings have associated mutations of Lamin A/C (LMNA) and Filamin C (FLNC) to poor prognosis and the propensity to cause an arrhythmic phenotype, respectively. However, a deeper understanding of the genotype-phenotype correlation is necessary, because it could have several implications for the clinical management of the patients. Furthermore, the correct interpretation of pathogenicity of mutations and the clinical impact of genetic testing in DCM patients still represent important fields to be implemented. A pathogenic gene mutation can be identified in almost 40% of DCM patients. The recent discoveries and future research in the field of genotype-phenotype correlation may lead to a more personalized management of the mutation carriers towards the application of precision medicine in DCM.

Pathophysiology and treatment of pediatric heart failure (HF) is poorly understood. A growing body of literature demonstrates age-related differences in mechanisms and in therapies efficacy. HF results from ventricular dysfunction due to volume or/and pressure overload. Circulatory, neurohormonal, and molecular alterations promote the progression of HF and ventricular remodeling; they include inflammation, oxidative stress, mitochondrial dysfunction, loss of cardiomyocytes, and fibrosis. Children and young affected by cardiomyopathies have the greatest risk of HF and heart transplantation. Genetic mutations of sarcomere, cytoskeleton, cell membrane proteins, and ion channels have been recognized as the main causes of many cardiomyopathy phenotypes. In particular, sarcomeric and cytoskeleton genes mutations seem to have an important role in the progression of HF. Prognostic stratification and clinical management could benefit from identification of biomarkers such as inflammatory mediators or microRNA (miRNA). miRNA and myocardial regenerative strategies are under investigations as potential novel therapeutic approaches.

In a tissue continuously challenged by mechanical stresses, such as the skin or the heart, cells perceive information about their microenvironment through several adhesive protein complexes and activate cell-signaling events to maintain tissue cohesion. Consequently, alteration of cell adhesion components leads to aberrant assembly of the associated cytoplasmic scaffolding and signaling pathways, which may reflect changes to the tissue physiology and mechanical resistance. Desmoplakin is an essential component of the cell-cell junction, anchoring the desmosomal protein complex to the intermediate filaments (IFs). Inherited mutations in desmoplakin are associated with both heart and skin disease (cardiocutaneous syndrome). In this study, we investigated the mechanical properties of human keratinocytes harboring a cardiocutaneous-associated homozygous C-terminal truncation in desmoplakin (JD-1) compared to a control keratinocyte line (K1). Using Single Cell Force Spectroscopy (SCFS) AFM-based measurements, JD-1 keratinocytes displayed an overall alteration in morphology, elasticity, adhesion capabilities and viscoelastic properties, highlighting the profound interconnection between the adhesome pathways and the IF scaffold.

Mechanical stimulation appears to be a critical modulator for many aspects of biology, both of living tissue and cells. The cell-stretcher, a novel device for the mechanical uniaxial stimulation of populations of cells, is described. The system is based on a variable stroke cam-lever-tappet mechanism which allows the delivery of cyclic stimuli with frequencies of up to 10 Hz and deformation between 1% and 20%. The kinematics is presented and a simulation of the dynamics of the system is shown, in order to compute the contact forces in the mechanism. The cells, following cultivation and preparation, are plated on an ad hoc polydimethylsiloxane membrane which is then loaded on the clamps of the cell-stretcher via force-adjustable magnetic couplings. In order to show the viability of the experimentation and biocompatibility of the cell-stretcher, a set of two in vitro tests were performed. Human epithelial carcinoma cell line A431 and Adult Mouse Ventricular Fibroblasts (AMVFs) from a dual reporter mouse were subject to 0.5 Hz, 24 h cyclic stretching at 15% strain, and to 48 h stimulation at 0.5 Hz and 15% strain, respectively. Visual analysis was performed on A431, showing definite morphological changes in the form of cellular extroflections in the direction of stimulation compared to an unstimulated control. A cytometric analysis was performed on the AMVF population. Results show a post-stimulation live-dead ratio deviance of less than 6% compared to control, which proves that the environment created by the cell-stretcher is suitable for in vitro experimentation.

Aims We sought to examine the clinical presentation and natural history and to identify long-term prognostic predictors in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) as information concerning the natural history and risk stratification of ARVC is still incomplete. Methods and results A cohort of 96 ARVC patients (68% males, 35 ± 15 years) was enrolled and underwent structured diagnostic protocol and follow-up. Primary study endpoints were death and heart transplantation (HTx). Clinical and echo-Doppler data were assessed as prognostic indicators. Sixty-five per cent of patients had right ventricular (RV) systolic dysfunction (RV fractional area change < 33%) and 24% had left ventricular (LV) systolic dysfunction (LV ejection fraction

Aims Familial screening of patients with dilated cardiomyopathy (DCM) allows an early diagnosis of the disease in family members. It is unclear if familial forms (FDC) have a different long-term outcome compared with sporadic DCM. Our aim was to compare the long-term prognosis of FDC and sporadic forms in order to assess the role of familial screening. Methods and results Between 1988 and 2007, 637 DCM patients were consecutively enrolled. Of these, 130 patients (20.4%) had FDC, including 82 (12.9%) probands and 48 (7.5%) non-proband FDC patients (NP-FDC), identified by family screening. We compared the 48 NP-FDC patients with a sample of 96 patients with sporadic DCM, who were randomly matched by year of enrolment in a 2:1 ratio. At enrolment the NP-FDC patients were younger (40 ± 16 vs. 48 ± 13 years, P = 0.002), less symptomatic [New York Heart Association, (NYHA) III–IV: 8 vs. 28%, P = 0.006], had higher left ventricular ejection fraction (35 ± 10 vs. 30 ± 9%, P = 0.005) and were less intensively treated with evidence-based drugs than the sporadic DCM patients. Survival free from heart transplant at 2, 5 and 10 years was 93, 91 and 82%, respectively, in NP-FDC patients compared with 86, 76 and 62% in sporadic forms (P = 0.04). After stratification for NYHA classes, no difference in survival was observed between sporadic and NP-FDC patients. Conclusion Our study demonstrates that family screening can effectively identify DCM patients at an earlier stage of disease and can improve survival. The possibility of changing the prognosis of DCM needs to be verified in patients intensively treated with tailored medical treatment. Family screening should be recommended for all DCM patients.

BACKGROUND: To evaluate the role of nonsustained ventricular tachycardias (NSVT) for the prediction of major ventricular arrhythmias (MVA) in patients with idiopathic dilated cardiomyopathy (DCM) after optimization of medical treatment. METHODS AND RESULTS: Three hundred nineteen consecutive DCM patients were evaluated after adequate stabilization on optimal angiotensin-converting enzyme (ACE) inhibitor (88%) and beta-blocker (82%) therapy. Frequency, length, and rate of NSVT at 24-hour Holter monitoring were analyzed to assess their values in predicting MVA (unexpected sudden death, SVT, ventricular fibrillation, and appropriate implantable cardioverter defibrillator interventions). During follow-up (median 96 months, 1(st)-3(rd) interquartile range 52-130), MVA incidence was low, and not statistically different between patients with and without NSVT (3 and 2 per 100 patient-years, respectively, P = nonsignificant [NS] at log-rank analysis). At multivariable analysis, the number of NSVT was predictive of MVA only if left ventricular ejection fraction (LVEF) was > 0.35 (two NSVT/day vs no NSVT/day: hazard ratio [HR] 5.3, 95% confidence interval [CI] 1.59-17.85 in LVEF > 0.35 vs HR 0.93, 95% CI 0.3-2.81 in LVEF < or = 0.35). Consequently, in patients with LVEF < or = 0.35, MVA incidence rates were similar regardless of NSVT (3.6 and 4.1 patient-years, respectively, in those with and without NSVT, P = NS), while in patients with LVEF > 0.35, MVA incidence (3.1 per 100 patient-years vs 0.9 per 100 patient-years, P = 0.003) was significantly higher when NSVT were present. CONCLUSIONS: After medical stabilization, NSVT did not increase the risk of MVA in patients with DCM and LVEF < or = 0.35. Conversely, the number and length of NSVT runs were significantly related to the occurrence of MVA in the patients with LVEF > 0.35.

This book describes the role of basic and advanced imaging techniques in the diagnosis of different types of cardiomyopathy, including dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy and infiltrative/storage cardiomyopathies. While the main focus is on echocardiography, the applications of cardiac magnetic resonance imaging and computed tomography are also described. Throughout, a clinically oriented approach is employed: detailed attention is paid to differential diagnosis and numerous high-quality images depict the main features of the various types of cardiomyopathy. Consideration is also given to the genetics of cardiomyopathies, with analysis of genotype-phenotype relationships. Finally, the potential value of imaging in prognostic assessment and in guiding treatment is described.

The completion of the Human Genome Project was a landmark achievement that revealed the reference DNA sequence for our own genome. Almost immediately it became clear that there was no single “reference” DNA sequence, as even the approximately half-dozen human DNA samples used by the Human Genome Project contained tens of thousands of variations [1]. As clinical genetic testing becomes more mainstream, and various projects underway perform full DNA genome sequencing in thousands of individuals, the extent of this genetic variation is increasingly being appreciated. It is widely recognized that most of this variation is probably not relevant for determining health or risk of disease and it has been collectively referred to as “genetic noise”. As in much of biology, separation of the “signal” from the “noise” can be challenging, and as molecular genetic sequencing expands in use and in the total length of DNA that can be sequenced in a single assay, problems in distinguishing a diagnostic genetic change from background genetic variation will remain a difficult task for researchers and clinicians to fulfill. Newer DNA sequencing technology can now complete the sequencing of an entire human genome several times in a matter of days, which is orders of magnitude faster than the nearly 13 years required for the initial first-pass done by the Human Genome Project consortium [2]. This technology, which will shortly be widely used in clinical genetic testing, will undoubtedly add new challenges to the difficulty of distinguishing signal from noise.

Some patients diagnosed with arrhythmogenic right ventricular cardiomyopathy (ARVC) are eventually found to have cardiac sarcoidosis (CS). Accurate differentiation between these 2 conditions has implications for immunosuppressive therapy and familial screening. We sought to determine whether cardiac magnetic resonance imaging (MRI) could be used to identify the characteristic findings to accurately differentiate between CS and ARVC. Consecutive patients with a diagnostic MRI scan indicating CS and/or ARVC constituted the cohort. All patients diagnosed with CS had histologic confirmation of sarcoidosis, and all patients with ARVC met the diagnostic task force criteria. The cardiac MRI data were retrospectively analyzed to identify possible differentiating characteristics. Of the patients, 40 had CS and 21 had ARVC. Those with CS were older and had more left ventricular scar. The presence of mediastinal lymphadenopathy or left ventricular septal involvement was seen exclusively in the patients with CS (p

Dilated cardiomyopathy and hypertrophic cardiomyopathy arise from mutations in many genes. TTN, the gene encoding the sarcomere protein titin, has been insufficiently analyzed for cardiomyopathy mutations because of its enormous size.We analyzed TTN in 312 subjects with dilated cardiomyopathy, 231 subjects with hypertrophic cardiomyopathy, and 249 controls by using next-generation or dideoxy sequencing. We evaluated deleterious variants for cosegregation in families and assessed clinical characteristics.We identified 72 unique mutations (25 nonsense, 23 frameshift, 23 splicing, and 1 large tandem insertion) that altered full-length titin. Among subjects studied by means of next-generation sequencing, the frequency of TTN mutations was significantly higher among subjects with dilated cardiomyopathy (54 of 203 [27%]) than among subjects with hypertrophic cardiomyopathy (3 of 231 [1%], P=3×10(-16)) or controls (7 of 249 [3%], P=9×10(-14)). TTN mutations cosegregated with dilated cardiomyopathy in families (combined lod score, 11.1) with high (95%) observed penetrance after the age of 40 years. Mutations associated with dilated cardiomyopathy were overrepresented in the titin A-band but were absent from the Z-disk and M-band regions of titin (P≤0.01 for all comparisons). Overall, the rates of cardiac outcomes were similar in subjects with and those without TTN mutations, but adverse events occurred earlier in male mutation carriers than in female carriers (P=4×10(-5)).TTN truncating mutations are a common cause of dilated cardiomyopathy, occurring in approximately 25% of familial cases of idiopathic dilated cardiomyopathy and in 18% of sporadic cases. Incorporation of sequencing approaches that detect TTN truncations into genetic testing for dilated cardiomyopathy should substantially increase test sensitivity, thereby allowing earlier diagnosis and therapeutic intervention for many patients with dilated cardiomyopathy. Defining the functional effects of TTN truncating mutations should improve our understanding of the pathophysiology of dilated cardiomyopathy. (Funded by the Howard Hughes Medical Institute and others.).

Nanoscale manipulations of the extracellular microenvironment are increasingly attracting attention in tissue engineering. Here, combining microscopy, biological, and single-cell electrophysiological methodologies, we demonstrate that neonatal rat ventricular myocytes cultured on substrates of multiwall carbon nanotubes interact with carbon nanotubes by forming tight contacts and show increased viability and proliferation. Furthermore, we observed changes in the electrophysiological properties of cardiomyocytes, suggesting that carbon nanotubes are able to promote cardiomyocyte maturation.

Background— Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited genetic myocardial disease characterized by fibrofatty replacement of the myocardium and a predisposition to cardiac arrhythmias and sudden death. We evaluated the cardiomyopathy gene titin ( TTN ) as a candidate ARVC gene because of its proximity to an ARVC locus at position 2q32 and the connection of the titin protein to the transitional junction at intercalated disks. Methods and Results— All 312 titin exons known to be expressed in human cardiac titin and the complete 3′ untranslated region were sequenced in 38 ARVC families. Eight unique TTN variants were detected in 7 families, including a prominent Thr2896Ile mutation that showed complete segregation with the ARVC phenotype in 1 large family. The Thr2896IIe mutation maps within a highly conserved immunoglobulin-like fold (Ig10 domain) located in the spring region of titin. Native gel electrophoresis, nuclear magnetic resonance, intrinsic fluorescence, and proteolysis assays of wild-type and mutant Ig10 domains revealed that the Thr2896IIe exchange reduces the structural stability and increases the propensity for degradation of the Ig10 domain. The phenotype of TTN variant carriers was characterized by a history of sudden death (5 of 7 families), progressive myocardial dysfunction causing death or heart transplantation (8 of 14 cases), frequent conduction disease (11 of 14), and incomplete penetrance (86%). Conclusions— Our data provide evidence that titin mutations can cause ARVC, a finding that further expands the origin of the disease beyond desmosomal proteins. Structural impairment of the titin spring is a likely cause of ARVC and constitutes a novel mechanism underlying myocardial remodeling and sudden cardiac death.

Barth syndrome is an X-linked genetic condition featuring neutropenia, skeletal myopathy, and dilated cardiomyopathy in boys due to tafazzin (TAZ) mutations. Pure dilated cardiomyopathy without other features of Barth syndrome may also result from TAZ mutations and survival into adulthood has been described. Although TAZ testing is routinely included in dilated cardiomyopathy panels in adults, the prevalence of TAZ mutations in the adult population, including women who may be at risk to develop later onset disease due to TAZ mutations, has not been measured. We screened 292 families with dilated cardiomyopathy (209 male and 83 female probands) for TAZ mutations using denaturing high-performance liquid chromatography and sequence analysis. Putative mutations were evaluated based on standard criteria including screening available relatives and healthy controls and for effects on splicing efficiency in the case of one intronic variant. Two variants suspicious for being pathogenic were found in two unrelated families (c.387T>C, Phe128Ser and c.507C>T, Leu169Leu). The Phe128Ser variant had been previously reported as a pathogenic mutation; however we determined that this variant is instead a rare polymorphism restricted to African Americans. The Leu169Leu variant was detected in a male patient and altered RNA processing in our minigene assay supporting a pathogenic role. No mutations in female subjects were detected. Tafazzin mutations were rare in our population of adults with dilated cardiomyopathy and none were found in females. Our findings indicate that genetic testing for tafazzin should not be routinely performed in dilated cardiomyopathy as suggested by current guidelines. Furthermore, the Phe128Ser variant is not pathogenic, but likely represents a benign polymorphism in persons of African American ancestry.

Hypertrophic cardiomyopathy (HCM) is the most frequent autosomal dominant genetic heart muscle disease and the most common cause of sudden cardiac death in young people (under 30 y of age), who are often unaware of their underlying condition. Genetic screening is now considered a fundamental tool for clinical management of HCM families. However, the high genetic heterogeneity of HCM makes genetic screening very expensive. Here, we propose a new high-throughput genotyping method based on a HCM 96-well sequencing plate for the analysis of 8 of the most frequent HCM-causing sarcomeric genes by automating several processes required for direct sequencing, using a commercially available robotic systems and routinely used instruments. To assess the efficiency of the robot-assisted method, we have analyzed the entire coding sequence and flanking intronic sequences of the 8 sarcomeric genes in samples from 18 patients affected by HCM and their relatives, which revealed 9 different mutations, 3 of which were novel. The automated, robot-assisted assembling of polymerase chain reaction, purification of polymerase chain reaction products, and assembly of sequencing reactions resulted in a substantial saving of time, reagent costs, and reduction of human errors, and can therefore be proposed as a primary strategy for mutation identification in HCM genetic screening in many medical genetic laboratories.

Personalized medicine is a form of medicine that uses the patient's genomic information to improve diagnosis, prevention and therapy. In this review we discuss the personalized management of heart failure, from monogenic disorders, to modifier genes and pharmacogenomics. Monogenic disorders causing heart failure are cardiomyopathies. In this disease, recent guidelines assist the clinician in molecular diagnostics, genetic counseling and therapeutic choices. Several lines of evidence suggest the existence of common polymorphic variants of genes that modify the susceptibility to heart failure (modifier genes). A candidate gene approach has shown that common genetic variants of the renin-angiotensin-adrenergic pathway can also influence heart failure and may be associated with different outcomes. However, still little is known regarding this and it is expected that more advanced high throughput technologies will allow the discovery of a number of novel modifier genes that could be used for prognostic profiling and development of novel therapeutics. Finally, pharmacogenomics of heart failure appears very promising. Common genetic variants of beta-adrenergic receptors, alpha-adrenergic receptors and endothelin receptors, among others, significantly alter the response to heart failure therapy. This knowledge could be used to personalize and optimize heart failure therapy based on the patient's genetic profile. Whereas the advances in technologies will continue to transition personalized medicine from research to the clinical setting, physicians, and in particular cardiologists, need to reshape clinical diagnostics paradigms, learn how to use new genomic information to change management decisions, and provide the patients with appropriate education and management recommendations.

The last 20 years have seen impressive progress in the study of cardiomyopathies. The improved understanding of these diseases has made clear that cardiomyopathies are extremely complex entities that defy current classification standards. The 1980 and 1995 WHO/ISFC Task Forces, and very recently an American Heart Association (AHA) Scientific Statement expert panel, have systematically approached new advances as well as emerging problems. In spite of this effort and an increasingly growing understanding of myocardial disorders, several issues remain unresolved. Without a doubt, the identification of genetic defects responsible for many forms of cardiomyopathies has changed our perspective of myocardial diseases. In fact, in the last few years, we have seen that (1) clinically defined cardiomyopathies, previously considered single entities, are actually the result of mutations in different genes, (2) different mutations in the same gene may be the cause of different clinical entities and (3) in the group of cardiomyopathies, a large phenotypic and genetic heterogeneity exists that is expected to increase in the future. Genotype knowledge is a fundamental advance in medicine and in particular in the field of cardiomyopathies and is becoming increasingly more important in clinical practice for disease diagnosis and prevention, prognostic stratification and possible future therapies. Knowledge of the phenotype, including clinical, morphological and physiological features, however, continues to provide the clinical basis for diagnosis and classification of cardiomyopathies, prognostic evaluation and symptomatic treatment, and should not be abandoned.