Gene correction and overexpression of TNNI3 improve impaired relaxation in engineered heart tissue model of pediatric restrictive cardiomyopathy.

Research on cardiomyopathy models using engineered heart tissue (EHT) created from disease-specific induced pluripotent stem cells (iPSCs) is advancing rapidly. However, the study of restrictive cardiomyopathy (RCM), a rare and intractable cardiomyopathy, remains at the experimental stage because there is currently no established method to replicate the hallmark phenotype of RCM, particularly diastolic dysfunction, in vitro. In this study, we generated iPSCs from a patient with early childhood-onset RCM harboring the TNNI3 R170W mutation (R170W-iPSCs). The properties of R170W-iPSC-derived cardiomyocytes (CMs) and EHTs were evaluated and compared with an isogenic iPSC line in which the mutation was corrected. Our results indicated altered calcium kinetics in R170W-iPSC-CMs, including prolonged tau, and an increased ratio of relaxation force to contractile force in R170W-EHTs. These properties were reversed in the isogenic line, suggesting that our model recapitulates impaired relaxation of RCM, i.e., diastolic dysfunction in clinical practice. Furthermore, overexpression of wild-type TNNI3 in R170W-iPSC-CMs and -EHTs effectively rescued impaired relaxation. These results highlight the potential efficacy of EHT, a modality that can accurately recapitulate diastolic dysfunction in vitro, to elucidate the pathophysiology of RCM, as well as the possible benefits of gene therapies for patients with RCM.

Association of Pulmonary Transit Time and Pulmonary Blood Volume From First-Pass Perfusion Cardiac MRI With Diastolic Dysfunction and Left Ventricle Deformation in Restrictive Cardiomyopathy.

BACKGROUND: Patients with restrictive cardiomyopathy (RCM) have impaired diastolic filling and hemodynamic congestion. Pulmonary transit time (PTT) and pulmonary blood volume index (PBVi) reflect the hemodynamic status, but the relationship with left ventricle (LV) dysfunction remains unclear. PURPOSE: To evaluate the PTT and PBVi in RCM patients, the association with diastolic dysfunction and LV deformation, and the effects on the occurrence of major adverse cardiac events (MACE) in RCM patients. STUDY TYPE: Retrospective. POPULATION: 137 RCM patients (88 men, age 58.80 ± 10.83 years) and 68 age- and sex-matched controls (46 men, age 57.00 ± 8.59 years). FIELD STRENGTH/SEQUENCE: 3.0T/Balanced steady-state free precession sequence, recovery prepared echo-planar imaging sequence, and phase-sensitive inversion recovery sequence. ASSESSMENT: The LV function and peak strain (PS) parameters were measured. The PTT was calculated and corrected by heart rate (PTTc). The PBVi was calculated as the product of PTTc and RV stroke volume index. STATISTICAL TESTS: Chi-squared test, student's t-test, Mann-Whitney U test, Pearson's or Spearman's correlation, multivariate linear regression, Kaplan-Meier survival analysis, and Cox regression models analysis. A P-value <0.05 was considered statistically significant. RESULTS: The PTTc showed a significant correlation with the E/A ratio (r = 0.282), and PBVi showed a significant correlation with the E/e' ratio, E/A ratio, and diastolic dysfunction stage (r = 0.222, 0.320, and 0.270). PTTc showed an independent association with LVEF, LV circumferential PS, and LV longitudinal PS (ß = 0.472, 0.299, and 0.328). In Kaplan-Meier analysis, higher PTTc and PBVi were significantly associated with MACE. In multivariable Cox regression analysis, PTTc was a significantly independent predictor of the MACE in combination with both cardiac MRI functional and tissue parameters (hazard ratio: 1.23/1.32, 95% confidence interval: 1.10-1.42/1.20-1.46). DATA CONCLUSION: PTTc and PBVi are associated with diastolic dysfunction and deteriorated LV deformation, and PTTc independently predicts MACE in patients with RCM. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Investigating TNNC1 gene inheritance and clinical outcomes through a comprehensive familial study.

Hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM) have significant phenotypic overlap and a similar genetic background, both caused mainly by variants in sarcomeric genes. HCM is the most common cardiomyopathy, while RCM is a rare and often underdiagnosed heart condition, with a poor prognosis. This study focuses on a large family with four infants diagnosed with fatal RCM associated with biventricular hypertrophy. Affected infants were found to be homozygous for NM_003280.3(TNNC1):c.23C>T(p.Ala8Val) variant. Interestingly, this variant resulted in a low penetrance and mild form of hypertrophic cardiomyopathy (HCM) in relatives carrying a single copy of the variant. Overall, this study underscores the complex nature of genetic inheritance in cardiomyopathies and the wide range of clinical presentations they can exhibit. This emphasizes the vital role of genetic testing in providing essential insights crucial for diagnosis, prognosis, early intervention, and the development of potential treatment strategies.

IgG4-Related disease with diffuse myopericardial involvement- value of CMR: a case report and literature review of cardiac involvement.

BACKGROUND: IgG4-related disease is a fibro-inflammatory disorder with an unknown etiology, which can affect multiple organ systems, including the cardiovascular system. While most reported cases of cardiovascular involvement are primarily associated with the aorta, there have been sporadic reports of isolated cardiac involvement. CASE PRESENTATION: This paper presents a documented case of IgG4-related systemic disease with symptoms indicative of restrictive cardiomyopathy. Subsequent Cardiac Magnetic Resonance imaging revealed diffuse myopericardial involvement, characterized by pericardial thickening and enhancement, accompanied by subepicardial and myocardial infiltration. Considering the rarity of cardiac involvement in our case, we conducted a thorough review of the existing literature pertaining to various patterns of cardiac involvement in IgG4-related disease, as well as the diagnostic modalities that can be employed for accurate identification and assessment. CONCLUSIONS: This case report sheds light on the importance of recognizing and evaluating cardiac manifestations in IgG4-related systemic disease to facilitate timely diagnosis and appropriate management.

Current Therapies and Future Horizons in Cardiac Amyloidosis Treatment.

PURPOSE OF REVIEW: Cardiac amyloidosis (CA) is a condition characterized by misfolding and extracellular deposition of proteins, leading to organ dysfunction. While numerous forms of CA exist, two subtypes dominate clinical prevalence: Transthyretin amyloid (ATTR) and immunoglobulin light chain amyloid. RECENT FINDINGS: The current scientific landscape reflects the urgency to advance therapeutic interventions with over 100 ongoing clinical trials. Heart failure treatment is affected by CA phenotype with poor tolerance of otherwise frequently used medications. Treating comorbidities including atrial fibrillation and valvular disease remains a challenge in CA, driven by technical difficulties and uncertain outcomes. Tafamidis is the first ATTR-stabilizer approved with a rapidly growing rate of clinical use. In parallel, various new therapeutic classes are in late-stage clinical trials including silencers, antibodies and genetic therapy. Managing CA is a critical challenge for future heart failure care. This review delineates the current standard-of-care and scientific landscape of CA therapy.

Role of the Alpha-B-Crystallin Protein in Cardiomyopathic Disease.

Alpha-B-crystallin, a member of the small heat shock family of proteins, has been implicated in a variety of cardiomyopathies and in normal cardiac homeostasis. It is known to function as a molecular chaperone, particularly for desmin, but also interacts with a wide variety of additional proteins. The molecular chaperone function is also enhanced by signal-dependent phosphorylation at specific residues under stress conditions. Naturally occurring mutations in CRYAB, the gene that encodes alpha-B-crystallin, have been suggested to alter ionic intermolecular interactions that affect dimerization and chaperone function. These mutations have been associated with myofibrillar myopathy, restrictive cardiomyopathy, and hypertrophic cardiomyopathy and promote pathological hypertrophy through different mechanisms such as desmin aggregation, increased reductive stress, or activation of calcineurin-NFAT signaling. This review will discuss the known mechanisms by which alpha-B-crystallin functions in cardiac homeostasis and the pathogenesis of cardiomyopathies and provide insight into potential future areas of exploration.

A clinical case of Takayasu disease: emphasis on cardiac manifestations.

Takayasu arteriitis (TA) is a rare systemic vasculitis, affecting large vessels, cardiac valves and myocardium. Cardiac involvement is a major cause of morbidity and mortality in such patients. This publication presents a clinical case of a patient with severe aortic regurgitation combined with restrictive cardiomyopathy. It is emphasized that surgical treatment is associated with potential difficulties in patients with TA due to its inflammatory nature, disease activity and multiorgan involvement.

Effects of diabetes mellitus on left ventricular function and deformation in patients with restrictive cardiomyopathies: a 3.0T CMR feature tracking study.

BACKGROUND: Diabetes mellitus (DM) is the most common metabolic disease worldwide and a major risk factor for adverse cardiovascular events, while the additive effects of DM on left ventricular (LV) deformation in the restrictive cardiomyopathy (RCM) cohort remain unclear. Accordingly, we aimed to investigate the additive effects of DM on LV deformation in patients with RCM. MATERIALS AND METHODS: One hundred thirty-six RCM patients without DM [RCM(DM-)], 46 with DM [RCM (DM+)], and 66 age- and sex-matched control subjects who underwent cardiac magnetic resonance (CMR) scanning were included. LV function, late gadolinium enhancement (LGE) type, and LV global peak strains (including radial, circumferential, and longitudinal directions) were measured. The determinant of reduced LV global myocardial strain for all RCM patients was assessed using multivariable linear regression analyses. The receiver operating characteristic curve (ROC) was performed to illustrate the relationship between DM and decreased LV deformation. RESULTS: Compared with the control group, RCM (DM-) and RCM(DM+) patients presented increased LV end-diastolic index and end-systolic volume index and decreased LV ejection fraction. LV GPS in all three directions and longitudinal PDSR progressively declined from the control group to the RCM(DM-) group to the RCM(DM+) group (all p < 0.05). DM was an independent determinant of impaired LV GPS in the radial, circumferential, and longitudinal directions and longitudinal PDSR (ß = - 0.217, 0.176, 0.253, and - 0.263, all p < 0.05) in RCM patients. The multiparameter combination, including DM, showed an AUC of 0.81(95% CI 0.75-0.87) to predict decreased LV GLPS and an AUC of 0.69 (95% CI 0.62-0.76) to predict decreased LV longitudinal PDSR. CONCLUSIONS: DM may have an additive deleterious effect on LV dysfunction in patients with RCM, especially diastolic dysfunction in RCM patients, indicating the importance of early identification and initiation of treatment of DM in patients with RCM.

Novel filamin C (FLNC) variant causes a severe form of familial mixed hypertrophic-restrictive cardiomyopathy.

Variants of filamin C (FLNC) have been identified as rare genetic substrate for hypertrophic cardiomyopathy (HCM). Data on the clinical course of FLNC-related HCM are conflicting with some studies suggesting mild phenotypes whereas other studies have reported more severe outcomes. In this study, we present a novel FLNC variant (Ile1937Asn) that was identified in a large family of French-Canadian descent with excellent segregation data. FLNC-Ile1937Asn is a novel missense variant characterized by full penetrance and poor clinical outcomes. End stage heart failure requiring transplantation occurred in 43% and sudden cardiac death in 29% of affected family members. Other particular features of FLNC-Ile1937Asn include an early disease onset (mean age of 19 years) and the development of a marked atrial myopathy (severe biatrial dilatation with remodeling and multiple complex atrial arrhythmias) that was present in all gene carriers. The FLNC-Ile1937Asn variant is a novel, pathogenic mutation resulting in a severe form of HCM with full disease penetrance. The variant is associated with a high proportion of end-stage heart failure, heart transplantation, and disease-related mortality. Close follow-up and appropriate risk stratification of affected individuals at specialized heart centers is recommended.

First Norwegian case of hereditary ATTR amyloidosis with a novel transthyretin variant.

An earlier healthy 64-year-old man with previous surgery for bilateral carpal tunnel syndrome (CTS) in his 50s, presented with dyspnoea on exertion. Cardiac amyloidosis was suspected due to "red flag" signs and symptoms. Further investigations with scintigraphy and genetic testing confirmed the diagnosis of hereditary ATTR variant (ATTRv) amyloidosis. This is the first case report of ATTRv amyloidosis in a patient of Norwegian origin and is caused by the mutation E54A (p.E74A) in the transthyretin (TTR) gene. This mutation is previously not reported in international databases. Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed disease with a poor prognosis. Early recognition remains essential to afford the best treatment efficacy.

Accurate Classification of Non-ischemic Cardiomyopathy.

PURPOSE OF REVIEW: This article aims to review the accurate classification of non-ischemic cardiomyopathy, including the methods, basis, subtype characteristics, and prognosis, especially the similarities and differences between different classifications. RECENT FINDINGS: Non-ischemic cardiomyopathy refers to a myocardial disease that excludes coronary artery disease or ischemic injury and has a variety of etiologies and high incidence. Recent studies suggest that traditional classification methods based on primary/mixed/acquired or genetic/non-genetic cannot meet the precise needs of contemporary clinical management. This article systematically describes the history of classifications of cardiomyopathy and presents etiological and genetic differences between cardiomyopathies. The accurate classification is described from the perspective of morphology, function, and genomics in hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, left ventricular noncompaction, and partially acquired cardiomyopathy. The different clinical characteristics and treatment needs of these cardiomyopathies are elaborated. Some single-gene mutant cardiomyopathies have unique phenotypes, and some cardiomyopathies have mixed phenotypes. These special classifications require personalized precision treatment, which is worthy of independent research. This article describes recent advances in the accurate classification of non-ischemic cardiomyopathy from clinical phenotypes and causative genes, discusses the advantages and usage scenarios of each classification, compares the differences in prognosis and patient management needs of different subtypes, and summarizes common methods and new exploration directions for accurate classification.

Restrictive cardiomyopathy: definition and diagnosis.

Restrictive cardiomyopathy (RCM) is a heterogeneous group of diseases characterized by restrictive left ventricular pathophysiology, i.e. a rapid rise in ventricular pressure with only small increases in filling volume due to increased myocardial stiffness. More precisely, the defining feature of RCM is the coexistence of persistent restrictive pathophysiology, diastolic dysfunction, non-dilated ventricles, and atrial dilatation, regardless of ventricular wall thickness and systolic function. Beyond this shared haemodynamic hallmark, the phenotypic spectrum of RCM is wide. The disorders manifesting as RCM may be classified according to four main disease mechanisms: (i) interstitial fibrosis and intrinsic myocardial dysfunction, (ii) infiltration of extracellular spaces, (iii) accumulation of storage material within cardiomyocytes, or (iv) endomyocardial fibrosis. Many disorders do not show restrictive pathophysiology throughout their natural history, but only at an initial stage (with an evolution towards a hypokinetic and dilated phenotype) or at a terminal stage (often progressing from a hypertrophic phenotype). Furthermore, elements of both hypertrophic and restrictive phenotypes may coexist in some patients, making the classification challenge. Restrictive pathophysiology can be demonstrated by cardiac catheterization or Doppler echocardiography. The specific conditions may usually be diagnosed based on clinical data, 12-lead electrocardiogram, echocardiography, nuclear medicine, or cardiovascular magnetic resonance, but further investigations may be needed, up to endomyocardial biopsy and genetic evaluation. The spectrum of therapies is also wide and heterogeneous, but disease-modifying treatments are available only for cardiac amyloidosis and, partially, for iron overload cardiomyopathy.

Left ventricular non-compaction cardiomyopathy: restrictive subtype with MYH7 gene mutation.

Left ventricular non-compaction is a very rare, still unclassified congenital cardiomyopathy. Nine distinct subtypes of functional and anatomical left ventricular non-compaction have been identified. Studies on the prognosis and mortality of subtypes are ongoing. Our study presented the first restrictive subtype left ventricular non-compaction case with family history and MYH7 gene mutation.

Towards a Diagnosis of Cardiac Amyloidosis: Single Center Experience with 99m Technetium Pyrophosphate Planar Imaging and Opportunities for Standardization of Diagnostic Workflow.

Background and Objectives: Cardiac amyloidosis is a disorder caused by amyloid fibril deposition in the extracellular space of the heart. Almost all forms of clinical cardiac amyloidosis are transthyretin amyloidosis (ATTR) or light chain amyloidosis. 99m technetium pyrophosphate (99mTc PYP scan) has changed the landscape of the non-biopsy diagnosis of ATTR cardiac amyloidosis (ATTR-CA) by providing remarkably high diagnostic accuracy. We examined our experience with PYP scans in patients undergoing workup for ATTR-CA and evaluated the diagnostic workflow in patients with intermediate PYP scan results. Materials and Methods: Retrospective chart review study in which we analyzed data of 84 patients who underwent c-99m pyrophosphate (PYP) SPECT scan for the diagnosis of ATTR-CA from 2017 till 2021 at our institution. We identified three groups: Low uptake (PYPL uptake ratio < 1.2 + visual grade 1/0), n = 30, Intermediate uptake (PYPI uptake ratio 1.2-1.49, visual grade 2/3), n = 25 and High uptake (PYPH uptake ratio ≥ 1.5 + visual grade 2/3), n = 29. We reviewed patients' demographics, medical histories, echo parameters and diagnostic testing including light chain analysis, cardiac magnetic resonance results, and biopsies. Results: Mean patients' age was 73, male-to=female ratio 3:1, 59% of patients were African American. Cardiovascular comorbidities, cardiac biomarkers (BNP and Troponin) and amyloid-related neuropathy were similar in all groups. A statistically significant difference in septal thickness/posterior wall thickness and final diagnosis were found between the groups. The distribution of overall diagnostic testing ratios for the PYPI group included serum protein electrophoresis 92%, urine protein electrophoresis 65%, free light chain 80%, CMR 32%, tissue biopsy done in 20% and BM biopsy in 16%, which are similar to the ratios of other groups. Overall, 25% (n = 5, 4 TTR-CA and 1 AL Amyloid) of patients in the PYPI group had a final diagnosis of CA established with additional testing (p = 0.001 vs. other groups). Conclusions: The 99mPYP scan is an accurate noninvasive test for cardiac ATTR-CA. Importantly, 25% of the PYPI group had a final diagnosis of ATTR-CA reiterating that diagnosis needs to be pursued in PYPI cases based on clinical suspicion. Routine evaluation and exclusion of light chain disease and establishing a consistent workflow for amyloid diagnosis and continued education for technologists and readers of PYP scans is key to a successful amyloidosis workup.

Echocardiographic assessment of cardiac amyloidosis.

Cardiac amyloidosis, a form of infiltrative cardiomyopathy, is associated with poor prognosis in untreated patients. Early diagnosis is important for timely initiation of effective therapies. Despite advances in diagnostic modalities, it remains a challenging diagnosis, requiring high index of clinical suspicion. Echocardiography represents the first-line cardiac imaging modality for evaluation of heart failure and suspected cardiac amyloidosis. In this review, we discuss echocardiographic findings in cardiac amyloidosis.

Clinical management of amyloid cardiomyopathy.

Clinical heart failure, restrictive cardiomyopathy, and arrhythmias are hallmark features of amyloid cardiomyopathy. In contrast to the advancements in targeted therapies, there is a general lack of evidence-based practice guidelines for clinical management of amyloid cardiomyopathy. In this review, we review the role of routine medical therapy in amyloid cardiomyopathy, from heart failure management to orthostatic hypotension, atrial arrhythmias, thromboembolic complications, and prevention of sudden death. We conclude by discussing approaches to patients with end-stage disease.

Restrictive cardiomyopathy: from genetics and clinical overview to animal modeling.

Restrictive cardiomyopathy (RCM), a potentially devastating heart muscle disorder, is characterized by diastolic dysfunction due to abnormal muscle relaxation and myocardial stiffness resulting in restrictive filling of the ventricles. Diastolic dysfunction is often accompanied by left atrial or bi-atrial enlargement and normal ventricular size and systolic function. RCM is the rarest form of cardiomyopathy, accounting for 2-5% of pediatric cardiomyopathy cases, however, survival rates have been reported to be 82%, 80%, and 68% at 1-, 2-, and 5-years after diagnosis, respectively. RCM can be idiopathic, familial, or secondary to a systemic disorder, such as amyloidosis, sarcoidosis, and hereditary hemochromatosis. Approximately 30% of cases are familial RCM, and the genes that have been linked to RCM are cTnT, cTnI, MyBP-C, MYH7, MYL2, MYL3, DES, MYPN, TTN, BAG3, DCBLD2, LNMA, and FLNC. Increased Ca2+ sensitivity, sarcomere disruption, and protein aggregates are some of the few mechanisms of pathogenesis that have been revealed by studies utilizing cell lines and animal models. Additional exploration into the pathogenesis of RCM is necessary to create novel therapeutic strategies to reverse restrictive cardiomyopathic phenotypes.

Genotype-Phenotype Associations with Restrictive Cardiomyopathy Induced by Pathogenic Genetic Mutations.

Restrictive cardiomyopathy (RCM) is an uncommon cardiac muscle disease characterized by impaired ventricular filling and severe diastolic dysfunction with or without systolic dysfunction. The patients with RCM present poor prognosis and high prevalence of sudden cardiac death, especially in the young. The etiology of RCM may be idiopathic, familial or acquired predispositions from various systemic diseases. The genetic background of familial RCM is often caused by mutations in genes encoding proteins of sarcomeres and a significant minority by mutations in non-sarcomeric proteins and transthyretin proteins. It is important to identify the associations between genotype and phenotype to guide clinical diagnosis and treatment. Here, we have summarized the reported index cases with RCM involving genetic etiology to date and highlighted the most significant phenotype results.

Echocardiography in the Diagnosis of Cardiomyopathies: Current Status and Future Directions.

Cardiomyopathies are a challenging pathology and echocardiography is essential for diagnosis and prognosis. The most frequent cardiomyopathies are the dilated cardiomyopathy (DCM) and the hypertrophic cardiomyopathy (HCM), followed by the less frequent restrictive (RCM) and arrhythmogenic right ventricle cardiomyopathies (ARVC). Echocardiography can identify diagnostic features, and guide further testing for a definitive diagnosis. Echographic parameters are involved in risk score computing and prognosis assessment. While the most prevalent hallmark of HCM is the asymmetric left ventricular hypertrophy and systolic anterior motion of the mitral valve with the obstructive phenotype, DCM shows dilated left ventricle with different degrees of systolic dysfunction, and RCM is usually characterized by undilated ventricles associated with atrial enlargement. The aim of this review is to display and compare the most frequent cardiomyopathies encountered in clinical practice and highlight their most characteristic features in a useful way for the practicing clinician.

Expanded cardiovascular phenotype of Myhre syndrome includes tetralogy of Fallot suggesting a role for SMAD4 in human neural crest defects.

Tetralogy of Fallot (ToF) can be associated with a wide range of extracardiac anomalies, with an underlying etiology identified in approximately 10% of cases. Individuals affected with Myhre syndrome due to recurrent SMAD4 mutations frequently have cardiovascular anomalies, including congenital heart defects. In addition to two patients in the literature with ToF, we describe five additional individuals with Myhre syndrome and classic ToF, ToF with pulmonary atresia and multiple aorto-pulmonary collaterals, and ToF with absent pulmonary valve. Aorta hypoplasia was documented in one patient and suspected in another two. In half of these individuals, postoperative cardiac dysfunction was thought to be more severe than classic postoperative ToF repair. There may be an increase in right ventricular pressure, and right ventricular dysfunction due to free pulmonic regurgitation. Noncardiac developmental abnormalities in our series and the literature, including corectopia, heterochromia iridis, and congenital miosis suggest an underlying defect of neural crest cell migration in Myhre syndrome. We advise clinicians that Myhre syndrome should be considered in the genetic evaluation of a child with ToF, short stature, unusual facial features, and developmental delay, as these children may be at risk for increased postoperative morbidity. Additional research is needed to investigate the hypothesis that postoperative hemodynamics in these patients may be consistent with restrictive myocardial physiology.