Left ventricular non-compaction cardiomyopathy

The developmental origin of heart size and shape differences in Astyanax mexicanus populations

Regulation of heart size and shape is one of the least understood processes in developmental biology. We have for the first time analysed the hearts of Astyanax mexicanus and identified several differences in heart morphology between the surface (epigean morph) and cave-dwelling (troglomorph) morphs. Examination of the adult revealed that the troglomorph possesses a smaller heart with a rounder ventricle in comparison to the epigean morph. The size differences identified appear to arise early in development, as early as 24 h post-fertilisation (hpf), while shape differences begin to appear at 2 days post-fertilisation. The heart of the first-generation cross between the cave-dwelling and river-dwelling morph shows uncoupling of different phenotypes observed in the parental populations and indicates that the cardiac differences have become embedded in the genome during evolution. The differences in heart morphology are accompanied by functional changes between the two morphs, with the cave-dwelling morph exhibiting a slower heart rate than the river-dwelling morph. The identification of morphological and functional differences in the A. mexicanus heart could allow us to gain more insight into how such parameters are regulated during cardiac development, with potential relevance to cardiac pathologies in humans.

•

Differences in heart size, shape and tissue structure between Astyanax populations.

•

Furthermore, differences in cardiac melanophore and adipocyte numbers.

•

Heart size and shape differences are apparent early in development.

•

Surface and Pachón show differences in heart rate during development and adulthood.

•

F1 hybrids show uncoupling of features observed in surface and Pachón populations.

Cardiac-specific developmental and epigenetic functions of Jarid2 during embryonic development

Epigenetic regulation is critical in normal cardiac development. We have demonstrated that the deletion of Jarid2 (Jumonji (Jmj) A/T-rich interaction domain 2) in mice results in cardiac malformations recapitulating human congenital cardiac disease and dysregulation of gene expression. However, the precise developmental and epigenetic functions of Jarid2 within the developing heart remain to be elucidated. Here, we determined the cardiac-specific functions of Jarid2 and the genetic networks regulated by Jarid2. Jarid2 was deleted using different cardiac-specific Cre mice. The deletion of Jarid2 by Nkx2.5-Cre mice (Jarid2^Nkx) caused cardiac malformations including ventricular septal defects, thin myocardium, hypertrabeculation, and neonatal lethality. Jarid2^Nkx mice exhibited elevated expression of neural genes, cardiac jelly, and other key factors including Isl1 and Bmp10 in the developing heart. By employing combinatorial genome-wide approaches and molecular analyses, we showed that Jarid2 in the myocardium regulates a subset of Jarid2 target gene expression and H3K27me3 enrichment during heart development. Specifically, Jarid2 was required for PRC2 occupancy and H3K27me3 at the Isl1 promoter locus, leading to the proper repression of Isl1 expression. In contrast, Jarid2 deletion in differentiated cardiomyocytes by cTnt-Cre mice caused no gross morphological defects or neonatal lethality. Thus, the early deletion of Jarid2 in cardiac progenitors, prior to the differentiation of cardiac progenitors into cardiomyocytes, results in morphogenetic defects manifested later in development. Our studies reveal that there is a critical window during early cardiac progenitor differentiation when Jarid2 is crucial to establish the epigenetic landscape at later stages of development.

Cardiac magnetic resonance evaluation of left ventricular functional, morphological, and structural features in children and adolescents vs. young adults with isolated left ventricular non-compaction

AIM

To investigate the left ventricular (LV) functional, morphological, and structural features revealed by cardiac magnetic resonance (CMR) in children/adolescents with isolated LV non-compaction (iLVNC), and to compare them with those observed in young adults with iLVNC and healthy controls.

METHODS

56 subjects were included: 12 children/adolescents (mean age 15±3years, 75% male) and 20 young adults (mean age 35±7years, 75% male) with first diagnosis of iLVNC, 12 healthy children/adolescents (mean age 15±3years, 75% male) and 12 healthy young adults (mean age 34±8years, 75% male). CMR with late gadolinium enhancement (LGE) imaging was performed to evaluate LV function, extent of LV trabeculation, and presence/extent of LV LGE, a surrogate of myocardial fibrosis. Tissue-tracking analysis was applied to assess LV global longitudinal (GLS), circumferential (GCS) and radial (GRS) strain.

RESULTS

The extent of LVNC and the presence/extent of LV LGE in children/adolescents and young adults with iLVNC were similar. Compared to healthy subjects, young adults with iLVNC had significantly lower LVEF; conversely, no significant difference in this parameter was observed between children/adolescents with iLVNC and healthy subjects. However, compared to healthy subjects, LV strain parameters were lower in both children/adolescents and young adults with iLVNC.

CONCLUSIONS

Complete phenotypic expression, subclinical impairment of myocardial deformation properties, and cardiac injury occur early in iLVNC patients, being already noticeable in the pediatric age group. The application of CMR myocardial deformation imaging permits earlier detection of LV functional impairment in children/adolescents with iLVNC, which would otherwise be missed with standard CMR imaging.

Mesenchymal stem cells attenuate doxorubicin‑induced cellular senescence through the VEGF/Notch/TGF‑β signaling pathway in H9c2 cardiomyocytes

The clinical use of doxorubicin (Dox) is limited by its cardiotoxicity. The fundamental changes it induces include interstitial myocardial fibrosis and the appearance of senescent cardiomyocytes. Mesenchymal stem cell (MSC)‑based therapies have also been reported to modulate cellular senescence, and have been used effectively to treat age‑related cardiovascular diseases. In the present study, the Transwell system was used to coculture H9c2 cells with MSCs, and their proliferation and viability were assessed. The expression of senescence‑related genes p53 and p16, and telomere length were measured using reverse transcription‑quantitative polymerase chain reaction analysis, and the Jagged‑1/Notch‑1 signaling pathway was detected using western blot analysis. The results revealed that Dox induced the senescence of H9c2 cells, characterized by a low proliferation rate, poor viability, reduced telomere length and impaired telomerase activity, and by marked increases in the expression of p53 and p16. By contrast, when cocultured with MSCs in the presence of Dox, H9c2 cell proliferation and viability increased, whereas the expression levels of p53 and p16 decreased, and telomere length and telomerase activity increased. The mechanism underlying the antisenescence function of MSCs was clarified, which involved the vascular endothelial growth factor (VEGF)/Jagged‑1/Notch‑1/transforming growth factor‑β1 (TGF‑β1) signaling pathway. It was confirmed that inhibiting VEGF, or silencing Jagged‑1 or Notch‑1 with small interfering RNA, or using recombinant TGF‑β1 eliminated the antisenescence effects of MSCs on the Dox‑treated H9c2 cells. The results revealed that MSCs rescued H9c2 cells from Dox‑induced senescence through the release of VEGF, which activated the Jagged‑1/Notch‑1 signaling pathway, leading to the inhibition of TGF‑β1 release. Therefore, treatment with MSCs may have important therapeutic implications on the attenuation of cardiotoxicity in patients with cancer treated with Dox.

Common presentation of rare cardiac diseases: Arrhythmias

Ventricular or supraventricular ectopic beats or atrial fibrillation may be the first presentation of uncommon cardiac disease, both acquired and genetically determined. In some patients, these manifestations can be the first sign of the underlying cardiac disorder. In others, however, they are also important as prognostic indicators, reflecting electrical instability and risk. Most cardiology clinics are busy environments where the implementation of complex diagnostic algorithms is not feasible. However, it is equally impossible to reach a final diagnosis, among the thousands of rare diseases that involve the heart, moving from a first line clinical and instrumental examination. Cardiac and extra-cardiac red flags, an accurate family and clinical history and ECG interpretation may be of help in identifying a rare disease. Advanced imaging and laboratory testing at experienced referral centers is then necessary to reach a final diagnosis, but the first step in the right direction, based on these simple elements, is the most important. We here review arrhythmic presentations of rare or relatively rare diseases, and suggest a simple "rule out-rule in" approach to help direct clinical suspicion and minimize risk of neglect.

Novel α-Actin Gene Mutation p.(Ala21Val) Causing Familial Hypertrophic Cardiomyopathy, Myocardial Noncompaction, and Transmural Crypts. Clinical-Pathologic Correlation

Background

Mutations of α‐actin gene (ACTC1) have been phenotypically related to various cardiac anomalies, including hypertrophic cardiomyopathy and dilated cardiomyopathy and left ventricular (LV) myocardial noncompaction. A novel ACTC mutation is reported as cosegregating for familial hypertrophic cardiomyopathy and LV myocardial noncompaction with transmural crypts.

Methods and Results

In an Italian family of 7 subjects, 4 aged 10 (II‐1), 14 (II‐2), 43 (I‐4) and 46 years (I‐5), presenting abnormal ECG changes, dyspnea and palpitation (II‐2, I‐4, and I‐5), and recurrent cerebral ischemic attack (I‐5), underwent 2‐dimensional echo, cardiac magnetic resonance, Holter monitoring, and next‐generation sequencing gene analysis. Patients II‐2 and I‐5 with ventricular tachycardia underwent a cardiac invasive study, including coronary with LV angiography and endomyocardial biopsy. In all the affected members, ECG showed right bundle branch block and left anterior hemiblock with age‐related prolongation of QRS duration. Two‐dimensional echo and cardiac magnetic resonance documented LV myocardial noncompaction in all and in I‐4, I‐5, and II‐2 a progressive LV hypertrophy up to 22‐mm maximal wall thickness. Coronary arteries were normal. LV angiography showed transmural crypts progressing to spongeous myocardial transformation with LV dilatation and dysfunction in the oldest subject. At histology and electron microscopy detachment of myocardiocytes were associated with cell and myofibrillar disarray and degradation of intercalated discs causing disanchorage of myofilaments to cell membrane. Next‐generation sequencing showed in affected members an unreported p.(Ala21Val) mutation of ACTC.

Conclusions

Novel p.(Ala21Val) mutation of ACTC1 causes myofibrillar and intercalated disc alteration leading to familial hypertrophic cardiomyopathy and LV myocardial noncompaction with transmural crypts.

Endothelial deletion of Ino80 disrupts coronary angiogenesis and causes congenital heart disease

During development, the formation of a mature, well-functioning heart requires transformation of the ventricular wall from a loose trabecular network into a dense compact myocardium at mid-gestation. Failure to compact is associated in humans with congenital diseases such as left ventricular non-compaction (LVNC). The mechanisms regulating myocardial compaction are however still poorly understood. Here, we show that deletion of the Ino80 chromatin remodeler in vascular endothelial cells prevents ventricular compaction in the developing mouse heart. This correlates with defective coronary vascularization, and specific deletion of Ino80 in the two major coronary progenitor tissues—sinus venosus and endocardium—causes intermediate phenotypes. In vitro, endothelial cells promote myocardial expansion independently of blood flow in an Ino80-dependent manner. Ino80 deletion increases the expression of E2F-activated genes and endothelial cell S-phase occupancy. Thus, Ino80 is essential for coronary angiogenesis and allows coronary vessels to support proper compaction of the heart wall.

Heart development requires compaction of the ventricular wall into a dense myocardium at mid-gestation. Here, Rhee and colleagues show that the chromatin remodeller Ino80 is critical for the formation of the coronary vasculature, and show that coronary vessels are needed for successful cardiac compaction during embryonic development.

Novel Genetic Triggers and Genotype-Phenotype Correlations in Patients With Left Ventricular Noncompaction

BACKGROUND

Left ventricular noncompaction (LVNC) is a genetically and phenotypically heterogeneous disease and, although increasingly recognized in clinical practice, there is a lack of widely accepted diagnostic criteria. We sought to identify novel genetic causes of LVNC and describe genotype-phenotype correlations.

METHODS AND RESULTS

A total of 190 patients from 174 families with left ventricular hypertrabeculation (LVHT) or LVNC were referred for cardiac magnetic resonance and whole-exome sequencing. A total of 425 control individuals were included to identify variants of interest (VOIs). We found an excess of 138 VOIs in 102 (59%) unrelated patients in 54 previously identified LVNC or other known cardiomyopathy genes. VOIs were found in 68 of 90 probands with LVNC and 34 of 84 probands with LVHT (76% and 40%, respectively; P<0.001). We identified 0, 1, and ≥2 VOIs in 72, 74, and 28 probands, respectively. We found increasing number of VOIs in a patient strongly correlated with several markers of disease severity, including ratio of noncompacted to compacted myocardium (P<0.001) and left ventricular ejection fraction (P=0.01). The presence of sarcomeric gene mutations was associated with increased occurrence of late gadolinium enhancement (P=0.004).

CONCLUSIONS

LVHT and LVNC likely represent a continuum of genotypic disease with differences in severity and variable phenotype explained, in part, by the number of VOIs and whether mutations are present in sarcomeric or nonsarcomeric genes. Presence of VOIs is common in patients with LVHT. Our findings expand the current clinical and genetic diagnostic approaches for patients with LVHT and LVNC.

Adaptation and validation of the ACMG/AMP variant classification framework for MYH7-associated inherited cardiomyopathies: recommendations by ClinGen's Inherited Cardiomyopathy Expert Panel

Purpose

Integrating genomic sequencing in clinical care requires standardization of variant interpretation practices. The Clinical Genome Resource has established expert panels to adapt the American College of Medical Genetics and Genomics/Association for Molecular Pathology classification framework for specific genes and diseases. The Cardiomyopathy Expert Panel selected MYH7, a key contributor to inherited cardiomyopathies, as a pilot gene to develop a broadly applicable approach.

Methods

Expert revisions were tested with 60 variants using a structured double review by pairs of clinical and diagnostic laboratory experts. Final consensus rules were established via iterative discussions.

Results

Adjustments represented disease-/gene-informed specifications (12) or strength adjustments of existing rules (5). Nine rules were deemed not applicable. Key specifications included quantitative frameworks for minor allele frequency thresholds, the use of segregation data, and a semiquantitative approach to counting multiple independent variant occurrences where fully controlled case-control studies are lacking. Initial inter-expert classification concordance was 93%. Internal data from participating diagnostic laboratories changed the classification of 20% of the variants (n = 12), highlighting the critical importance of data sharing.

Conclusion

These adapted rules provide increased specificity for use in MYH7-associated disorders in combination with expert review and clinical judgment and serve as a stepping stone for genes and disorders with similar genetic and clinical characteristics.

Daily 10 mg rivaroxaban as a therapy for ventricular thrombus related to left ventricular non-compaction cardiomyopathy: A case report

RATIONALE

Left ventricular non-compaction cardiomyopathy (LVNC) is a rare heart disorder related to thrombosis. Anticoagulant therapy is suggested for the treatment of this disease. The success of the novel oral anticoagulant rivaroxaban as a treatment option for this disorder is unclear.

PATIENT CONCERNS

A 43-year-old man who felt dizzy at rest was found to have an intraventricular thrombus.

DIAGNOSES

The thrombus was confirmed by echocardiography. And LVNC was diagnosed by cardiac magnetic resonance (CMR) and echocardiography.

INTERVENTIONS

He was prescribed a low dose (10 mg daily) of rivaroxaban as treatment.

OUTCOMES

After 3 months, the thrombus diminished, and the manifestation disappeared.

LESSONS

Low dose of rivaroxaban may serve as a viable option for anticoagulation therapy in LVNC patients, with large clinical trials needed to determine the best course of treatment.

High proportion of genetic cases in patients with advanced cardiomyopathy including a novel homozygous Plakophilin 2-gene mutation

Cardiomyopathies might lead to end-stage heart disease with the requirement of drastic treatments like bridging up to transplant or heart transplantation. A not precisely known proportion of these diseases are genetically determined. We genotyped 43 index-patients (30 DCM, 10 ARVC, 3 RCM) with advanced or end stage cardiomyopathy using a gene panel which covered 46 known cardiomyopathy disease genes. Fifty-three variants with possible impact on disease in 33 patients were identified. Of these 27 (51%) were classified as likely pathogenic or pathogenic in the MYH7, MYL2, MYL3, NEXN, TNNC1, TNNI3, DES, LMNA, PKP2, PLN, RBM20, TTN, and CRYAB genes. Fifty-six percent (n = 24) of index-patients carried a likely pathogenic or pathogenic mutation. Of these 75% (n = 18) were familial and 25% (n = 6) sporadic cases. However, severe cardiomyopathy seemed to be not characterized by a specific mutation profile. Remarkably, we identified a novel homozygous PKP2-missense variant in a large consanguineous family with sudden death in early childhood and several members with heart transplantation in adolescent age.

Fractal analysis of left ventricular trabeculations is associated with impaired myocardial deformation in healthy Chinese

BACKGROUND

Left ventricular (LV) non-compaction (LVNC) is defined by extreme LV trabeculation, but is measured variably. Here we examined the relationship between quantitative measurement in LV trabeculation and myocardial deformation in health and disease and determined the clinical utility of semi-automated assessment of LV trabeculations.

METHODS

Cardiovascular magnetic resonance (CMR) was performed in 180 healthy Singaporean Chinese (age 20-69 years; males, n = 91), using balanced steady state free precession cine imaging at 3T. The degree of LV trabeculation was assessed by fractal dimension (FD) as a robust measure of trabeculation complexity using a semi-automated technique. FD measures were determined in healthy men and women to derive normal reference ranges. Myocardial deformation was evaluated using feature tracking. We tested the utility of this algorithm and the normal ranges in 10 individuals with confirmed LVNC (non-compacted/compacted; NC/C ratio > 2.3 and ≥1 risk factor for LVNC) and 13 individuals with suspected disease (NC/C ratio > 2.3).

RESULTS

Fractal analysis is a reproducible means of assessing LV trabeculation extent (intra-class correlation coefficient: intra-observer, 0.924, 95% CI [0.761-0.973]; inter-observer, 0.925, 95% CI [0.821-0.970]). The overall extent of LV trabeculation (global FD: 1.205 ± 0.031) was independently associated with increased indexed LV end-diastolic volume and mass (sβ = 0.35; p < 0.001 and sβ = 0.13; p < 0.01, respectively) after adjusting for age, sex and body mass index. Increased LV trabeculation was independently associated with reduced global circumferential strain (sβ = 0.17, p = 0.013) and global diastolic circumferential and radial strain rates (sβ = 0.25, p < 0.001 and sβ = -0.15, p = 0.049, respectively). Abnormally high FD was observed in all patients with a confirmed diagnosis of LVNC. Five out of 13 individuals with suspected LVNC had normal FD, despite NC/C > 2.3.

CONCLUSION

This study defines the normal range of LV trabeculation in healthy Chinese that can be used to make or refute a diagnosis of LVNC using the fractal analysis tool, which we make freely available. We also show that increased myocardial trabeculation is associated with higher LV volumes, mass and reduced myocardial strain.

Non compaction cardiomyopathy: Review of a controversial entity

Non-compaction cardiomyopathy is a heterogeneous and complex entity concerning which there are still many doubts to be resolved. While the American Heart Association includes it among genetic cardiomyopathies, the European Society of Cardiology treats it as an unclassified cardiomyopathy. It may present in a sporadic or familial form, isolated or associated with other heart diseases, affecting only the left ventricle or both and can sometimes appear as a mixed phenotype in patients with other cardiomyopathies. Different forms of clinical presentation are also associated with its different morphological manifestations, and even non-compaction of the left ventricle may be triggered by other physiological or pathological processes. The purpose of this review is an update of this entity and its controversies.

Left ventricular non-compaction cardiomyopathy with coronary artery anomaly complicated by ventricular tachycardia

Background

Non-compaction cardiomyopathy (NCCM) is characterized by prominent trabeculations, deep intertrabecular recesses, and a thick non-compacted endocardial myocardium. Prevalence in the general population remains unclear, but echocardiography series report 0.05%. During fetal development muscle fibers and trabeculae should compact into a solid myocardium and when this fails, NCCM occurs. The condition is genetic, even though acquired forms have been described. Worsening myocardial dysfunction may lead to heart failure and/or arrhythmias.

Case presentation

A 52-year-old man presented with heart failure. The diagnosis of NCCM was confirmed after echocardiography and cardiac magnetic resonance tomography. Interestingly, the angiogram revealed a coronary anomaly, in which the circumflex artery rose aberrantly from the right coronary artery. Due to left ventricular ejection fraction being less than 35% despite optimal pharmacological therapy, an implantable cardioverter defibrillator (ICD) was implanted and four years later a ventricular tachycardia was terminated by antitachycardia pacing.

Conclusion

We describe a case of NCCM with a concomitant coronary anomaly, in which systolic myocardial dysfunction developed. The ICD subsequently terminated a life-threatening ventricular arrhythmia, which supports risk stratification based on low ejection fraction and possibly coronary anomaly.

Cardiomyopathies Due to Left Ventricular Noncompaction, Mitochondrial and Storage Diseases, and Inborn Errors of Metabolism

The normal function of the human myocardium requires the proper generation and utilization of energy and relies on a series of complex metabolic processes to achieve this normal function. When metabolic processes fail to work properly or effectively, heart muscle dysfunction can occur with or without accompanying functional abnormalities of other organ systems, particularly skeletal muscle. These metabolic derangements can result in structural, functional, and infiltrative deficiencies of the heart muscle. Mitochondrial and enzyme defects predominate as disease-related etiologies. In this review, left ventricular noncompaction cardiomyopathy, which is often caused by mutations in sarcomere and cytoskeletal proteins and is also associated with metabolic abnormalities, is discussed. In addition, cardiomyopathies resulting from mitochondrial dysfunction, metabolic abnormalities, storage diseases, and inborn errors of metabolism are described.

Notch Signaling in Development, Tissue Homeostasis, and Disease

Notch signaling is an evolutionarily highly conserved signaling mechanism, but in contrast to signaling pathways such as Wnt, Sonic Hedgehog, and BMP/TGF-β, Notch signaling occurs via cell-cell communication, where transmembrane ligands on one cell activate transmembrane receptors on a juxtaposed cell. Originally discovered through mutations in Drosophila more than 100 yr ago, and with the first Notch gene cloned more than 30 yr ago, we are still gaining new insights into the broad effects of Notch signaling in organisms across the metazoan spectrum and its requirement for normal development of most organs in the body. In this review, we provide an overview of the Notch signaling mechanism at the molecular level and discuss how the pathway, which is architecturally quite simple, is able to engage in the control of cell fates in a broad variety of cell types. We discuss the current understanding of how Notch signaling can become derailed, either by direct mutations or by aberrant regulation, and the expanding spectrum of diseases and cancers that is a consequence of Notch dysregulation. Finally, we explore the emerging field of Notch in the control of tissue homeostasis, with examples from skin, liver, lung, intestine, and the vasculature.

MIB2 variants altering NOTCH signalling result in left ventricle hypertrabeculation/non-compaction and are associated with Ménétrier-like gastropathy

We performed whole exome sequencing in individuals from a family with autosomal dominant gastropathy resembling Ménétrier disease, a premalignant gastric disorder with epithelial hyperplasia and enhanced EGFR signalling. Ménétrier disease is believed to be an acquired disorder, but its aetiology is unknown. In affected members, we found a missense p.V742G variant in MIB2, a gene regulating NOTCH signalling that has not been previously linked to human diseases. The variant segregated with the disease in the pedigree, affected a highly conserved amino acid residue, and was predicted to be deleterious although it was found with a low frequency in control individuals. The purified protein carrying the p.V742G variant showed reduced ubiquitination activity in vitro and white blood cells from affected individuals exhibited significant reductions of HES1 and NOTCH3 expression reflecting alteration of NOTCH signalling. Because mutations of MIB1, the homolog of MIB2, have been found in patients with left ventricle non-compaction (LVNC), we investigated members of our family with Ménétrier-like disease for this cardiac abnormality. Asymptomatic left ventricular hypertrabeculation, the mildest end of the LVNC spectrum, was detected in two members carrying the MIB2 variant. Finally, we identified an additional MIB2 variant (p.V984L) affecting protein stability in an unrelated isolated case with LVNC. Expression of both MIB2 variants affected NOTCH signalling, proliferation and apoptosis in primary rat cardiomyocytes.In conclusion, we report the first example of left ventricular hypertrabeculation/LVNC with germline MIB2 variants resulting in altered NOTCH signalling that might be associated with a gastropathy clinically overlapping with Ménétrier disease.

Prevalence and Prognostic Significance of Left Ventricular Noncompaction in Patients Referred for Cardiac Magnetic Resonance Imaging

BACKGROUND

Presence of prominent left ventricular trabeculation satisfying criteria for left ventricular noncompaction (LVNC) on routine cardiac magnetic resonance examination is frequently encountered; however, the clinical and prognostic significance of these findings remain elusive. This registry aimed to assess LVNC prevalence by 4 current criteria and to prospectively evaluate an association between diagnosis of LVNC by these criteria and adverse events.

METHODS AND RESULTS

There were 700 patients referred for cardiac magnetic resonance: 42% were women, median age was 70 years (range, 45-71 years), mean left ventricular ejection fraction was 51% (±17%), and 32% had late gadolinium enhancement on cardiac magnetic resonance. The cohort underwent diagnostic assessment for LVNC by 4 separate imaging criteria-referenced by their authors as Petersen, Stacey, Jacquier, and Captur, with LVNC prevalence of 39%, 23%, 25% and 3%, respectively. Primary clinical outcome was combined end point of time to death, ischemic stroke, ventricular tachycardia/ventricular fibrillation, and heart failure hospitalization. Secondary clinical outcomes were (1) all-cause mortality and (2) time to the first occurrence of any of the following events: cardiac death, ischemic stroke, ventricular tachycardia/ventricular fibrillation, or heart failure hospitalization. During a median follow-up of 7 years, there were no statistically significant differences in assessed outcomes noted between patients with and without LVNC irrespective of the applied criteria.

CONCLUSIONS

Current criteria for the diagnosis of LVNC leads to highly variable disease prevalence in patients referred for cardiac magnetic resonance. The diagnosis of LVNC, by any current criteria, was not associated with adverse clinical events on nearly 7 years of follow-up. Limited conclusions can be made for Captur criteria due to low observed prevalence.

Dilated cardiomyopathy

Dilated cardiomyopathy is defined by the presence of left ventricular dilatation and contractile dysfunction. Genetic mutations involving genes that encode cytoskeletal, sarcomere, and nuclear envelope proteins, among others, account for up to 35% of cases. Acquired causes include myocarditis and exposure to alcohol, drugs and toxins, and metabolic and endocrine disturbances. The most common presenting symptoms relate to congestive heart failure, but can also include circulatory collapse, arrhythmias, and thromboembolic events. Secondary neurohormonal changes contribute to reverse remodelling and ongoing myocyte damage. The prognosis is worst for individuals with the lowest ejection fractions or severe diastolic dysfunction. Treatment of chronic heart failure comprises medications that improve survival and reduce hospital admission-namely, angiotensin converting enzyme inhibitors and β blockers. Other interventions include enrolment in a multidisciplinary heart failure service, and device therapy for arrhythmia management and sudden death prevention. Patients who are refractory to medical therapy might benefit from mechanical circulatory support and heart transplantation. Treatment of preclinical disease and the potential role of stem-cell therapy are being investigated.

Hand factor ablation causes defective left ventricular chamber development and compromised adult cardiac function

Coordinated cardiomyocyte growth, differentiation, and morphogenesis are essential for heart formation. We demonstrate that the bHLH transcription factors Hand1 and Hand2 play critical regulatory roles for left ventricle (LV) cardiomyocyte proliferation and morphogenesis. Using an LV-specific Cre allele (Hand1^LV-Cre), we ablate Hand1-lineage cardiomyocytes, revealing that DTA-mediated cardiomyocyte death results in a hypoplastic LV by E10.5. Once Hand1-linage cells are removed from the LV, and Hand1 expression is switched off, embryonic hearts recover by E16.5. In contrast, conditional LV loss-of-function of both Hand1 and Hand2 results in aberrant trabeculation and thickened compact zone myocardium resulting from enhanced proliferation and a breakdown of compact zone/trabecular/ventricular septal identity. Surviving Hand1;Hand2 mutants display diminished cardiac function that is rescued by concurrent ablation of Hand-null cardiomyocytes. Collectively, we conclude that, within a mixed cardiomyocyte population, removal of defective myocardium and replacement with healthy endogenous cardiomyocytes may provide an effective strategy for cardiac repair.

The left ventricle of the heart drives blood flow throughout the body. Impaired left ventricle function, associated either with heart failure or with certain, severe cardiac birth defects, constitutes a significant cause of mortality. Understanding how heart muscle grows is vital to developing improved treatments for these diseases. Unfortunately, genetic tools necessary to study the left ventricle have been lacking. Here we engineer the first mouse line to enable specific genetic study of the left ventricle. We show that, unlike in the adult heart, the embryonic left ventricle is remarkably tolerant of cell death, as remaining cells have the capacity to proliferate and to restore heart function. Conversely, disruption of two related genes, Hand1 and Hand2, within the left ventricle causes cells to assume the wrong identity, and to consequently overgrow and impair cardiac function. Ablation of these mutant cells rescues heart function. We conclude that selective removal of defective heart muscle and replacement with healthy cells may provide an effective therapy to treat heart failure.

Identification of a hybrid myocardial zone in the mammalian heart after birth

Noncompaction cardiomyopathy is characterized by the presence of extensive trabeculations, which could lead to heart failure and malignant arrhythmias. How trabeculations resolve to form compact myocardium is poorly understood. Elucidation of this process is critical to understanding the pathophysiology of noncompaction disease. Here we use genetic lineage tracing to mark the Nppa⁺ or Hey2⁺ cardiomyocytes as trabecular and compact components of the ventricular wall. We find that Nppa⁺ and Hey2⁺ cardiomyocytes, respectively, from the endocardial and epicardial zones of the ventricular wall postnatally. Interposed between these two postnatal layers is a hybrid zone, which is composed of cells derived from both the Nppa⁺ and Hey2⁺ populations. Inhibition of the fetal Hey2⁺ cell contribution to the hybrid zone results in persistence of excessive trabeculations in postnatal heart. Our findings indicate that the expansion of Hey2⁺ fetal compact component, and its contribution to the hybrid myocardial zone, are essential for normal formation of the ventricular walls.

Fetal trabecular muscles in the heart undergo a poorly described morphogenetic process that results into a solidified compact myocardium after birth. Tian et al. show that cardiomyocytes in the fetal compact layer also contribute to this process, forming a hybrid myocardial zone that is composed of cells derived from both trabecular and compact layers.

Fetal left ventricular non-compaction cardiomyopathy with ascites: A case report

Here we report a case of fetal left ventricular non-compaction cardiomyopathy with ascites and cardiac dysfunction at a gestational age of 34⁺⁵  weeks. Laboratory tests did not reveal any sign of viral infection in utero. A female neonate weighing 2436 g was delivered by emergency cesarean section due to non-reassuring fetal status. Postnatal echocardiography confirmed left ventricular non-compaction cardiomyopathy with severe cardiac failure. Although she was treated effectively during the acute period by continuous flow peritoneal dialysis, surgical ligation of a patent ductus arteriosus, and inhaled nitric oxide, she died on day 41 of life. Symptoms of severe cardiac dysfunction appeared antenatally in this patient and the outcome was poor.

Genetik der angeborenen Herzfehler

Strukturelle Herzfehler sind eine der häufigsten menschlichen Fehlbildungen. Es lassen sich mehrere morphologische Gruppen unterscheiden, wobei auch Überlappungen mit verschiedenen Formen der Kardiomyopathien, unter anderem mit der Non-Compaction Kardiomyopathie, beobachtet werden. Zum jetzigen Zeitpunkt liegt nur ein sehr eingeschränktes Verständnis der zugrunde liegenden genetischen Ursachen vor. Dies liegt zum einen an einer „komplexen Genetik“, bei welcher häufig reduzierte Penetranz und variable Expressivität vorliegen, zum anderen aber auch an heterogenen Literaturangaben, bei denen nur unzureichende genetische Evidenzen bestehen. Der Fokus dieses Reviews ist es, anhand von stringenten Evidenzkriterien die bekannten Gene für strukturelle Herzfehler darzustellen. Speziell durch die Nutzung von Next Generation Sequencing (NGS) können zunehmend mehr relevante genetische Zusammenhänge geklärt werden. Dies gilt nicht nur für die Validierung von Genotyp-Phänotyp-Assoziationen, sondern auch für die Identifizierung neuer Gene für angeborene Herzfehler (AHF), was besonders wegen des seltenen Vorkommens rekurrenter AHF-assoziierter Mutationen im gleichen Gen in Zukunft notwendig sein wird. Um dieses Ziel zu erreichen, ist es notwendig, große deutschlandweite oder internationale Studien zu etablieren und bereits publizierte Datensätze öffentlich zugänglich zu machen. Dies sollte auch für diagnostische Datensätze gelten. Mit einem derartigen Ansatz könnte nicht nur eine Gen-Panel-Diagnostik, sondern auch die Eingruppierung der Herzfehler in therapeutische Subgruppen erreicht werden.

Non-compaction of left ventricular myocardium in sub-Saharan African adults

BACKGROUND

Non-compaction of the left ventricle (NCLV) is an unclassified cardiomyopathy due to intrauterine arrest of compaction of the loose interwoven meshwork. Only a few studies involving sub-Saharan Africans insmall numbers have been published. The aim of our study was to determine the diagnostic, therapeutic and prognostic aspects as well as the clinical course of NCLV in a black African population.

METHODOLOGY

A multicentre retrospective study was carried out between November 2007 and June 2012 in two cardiology departments in Dakar. Patients who met the echocardiographic criteria for NCLV were included in the study.

RESULTS

35patients with the diagnosis of NCLV were evaluated in the study. Their mean age was 47±18.4 years. Heart failure was found in 77.1% of the patients. The most frequent electrocardiographic abnormalities were left ventricular hypertrophy (LVH) (46%) and sinus tachycardia (43%). Mean non-compaction/compaction ratio was 2.84±0.68 with preferential localization in the apex of the left ventricle. The main complications observed were cardiogenic shock (23.5%), pulmonary embolism (6.3%) and ventricular tachycardia (5.9%). Diuretics and ACE inhibitors were the medications most often prescribed. Age >60 years (p=0.04), male gender (p=0.03) and the occurrence of complications during follow-up (p=0.04) were noted to be predictors of poor prognosis.

CONCLUSION

Contrary to previous beliefs, NCLV may not be less common in black Africans than in other ethnic subgroups. Clinicians in Africa should be made aware of NCLV so that it can be diagnosed at earlier stages.

Autosomal Dominant Polycystic Kidney Patients May Be Predisposed to Various Cardiomyopathies

Introduction

Mutations in PKD1 and PKD2 cause autosomal dominant polycystic kidney disease (ADPKD). Experimental evidence suggests an important role of the polycystins in cardiac development and myocardial function. To determine whether ADPKD may predispose to the development of cardiomyopathy, we have evaluated the coexistence of diagnoses of ADPKD and primary cardiomyopathy in our patients.

Methods

Clinical data were retrieved from medical records for patients with a coexisting diagnosis of ADPKD and cardiomyopathies evaluated at the Mayo Clinic (1984-2015).

Results

Among the 58 of 667 patients with available echocardiography data, 39 (5.8%) had idiopathic dilated cardiomyopathy (IDCM), 17 (2.5%) had hypertrophic obstructive cardiomyopathy, and 2 (0.3%) had left ventricular noncompaction. Genetic data were available for 19, 8, and 2 cases of IDCM, hypertrophic obstructive cardiomyopathy, and left ventricular noncompaction, respectively. PKD1 mutations were detected in 42.1%, 62.5%, and 100% of IDCM, hypertrophic obstructive cardiomyopathy, and left ventricular noncompaction cases, respectively. PKD2 mutations were detected only in IDCM cases and were overrepresented (36.8%) relative to the expected frequency in ADPKD (15%). In at least 1 patient from 3 IDMC families and 1 patient from a hypertrophic obstructive cardiomyopathy family, the cardiomyopathy did not segregate with ADPKD, suggesting that the PKD mutations may be predisposing factors rather than solely responsible for the development of cardiomyopathy.

Discussion

Coexistence of ADPKD and cardiomyopathy in our tertiary referral center cohort appears to be higher than expected by chance. We suggest that PKD1 and PKD2 mutations may predispose to primary cardiomyopathies and that genetic interactions may account for the observed coexistence of ADPKD and cardiomyopathies.

Sudden cardiac death with triple pathologies: A case report

Sudden cardiac death in young adults may be associated with rare cardiomyopathies such as left ventricular noncompaction (LVNC) and arrhythmogenic right ventricular (ARVC) cardiomyopathies. LVNC is characterised by hypertrabeculations and deep recesses of the left ventricle. ARVC presents with thin myocardium as a result of extensive fibro-fatty infiltrations. In both conditions, death may be due to arrhythmia, thromboembolic events or heart failure. We report a case of a 21-year old athletic young man who collapsed at the futsal court right after the game. He was resuscitated but expired at the hospital after a brief admission. A week earlier, he had a similar episode of syncope and revived through cardio-pulmonary resuscitation at the site. Post mortem examination showed extensive acute myocardial infarction (AMI) involving the papillary muscles and the left ventricular wall. Features of LVNC were also observed. On top of that, the right ventricle showed patchy thin myocardium as the wall was largely comprised of fat. Histology examination confirmed the presence of AMI and massive fibro-fatty infiltrations of the right ventricle. This unfortunate young man had co-existing cardiomyopathies which is rare indeed. As he succumbed to AMI, this mechanism of death is also uncommonly associated with neither LVNC nor ARVC. In conclusion, young and physically active individuals may not be spared of sudden cardiac death. Mild and non-specific symptoms should not be taken lightly as it may be the subtle signs of cardiomyopathies.

Decreased glycolytic metabolism in non-compaction cardiomyopathy by 18F-fluoro-2-deoxyglucose positron emission tomography: new insights into pathophysiological mechanisms and clinical implications

Aims

The pathophysiological mechanisms of left ventricular non-compaction cardiomyopathy (LVNC) remain controversial. This study performed combined 18F-fluoro-2-deoxyglucose dynamic positron emission tomography (FDG-PET) and 99mTc-sestamibi single-photon emission computed tomography (SPECT) studies to evaluate myocardial glucose metabolism and perfusion in patients with LVNC and their clinical implications.

Methods and results

Thirty patients (41 ± 12 years, 53% male) with LVNC, diagnosed by cardiovascular magnetic resonance (CMR) criteria, and eight age-matched healthy controls (42 ± 12 years, 50% male) were prospectively recruited to undergo FDG-PET with measurement of the myocardial glucose uptake rate (MGU) and SPECT to investigate perfusion-metabolism patterns. Patients with LVNC had lower global MGU compared with that in controls (36.9 ± 8.8 vs. 44.6 ± 5.4 μmol/min/100 g, respectively, P = 0.02). Of 17 LV segments, MGU levels were significantly reduced in 8, and also a reduction was observed when compacted segments from LVNC were compared with the segments from control subjects (P < 0.001). Perfusion defects were also found in 15 (50%) patients (45 LV segments: 64.4% match, and 35.6% mismatch perfusion-metabolism pattern). Univariate and multivariate analyses showed that beta-blocker therapy was associated with increased MGU (beta coefficient = 10.1, P = 0.008). Moreover, a gradual increase occurred in MGU across the beta-blocker dose groups (P for trend = 0.01).

Conclusion

The reduction of MGU documented by FDG-PET in LVNC supports the hypothesis that a cellular metabolic pathway may play a role in the pathophysiology of LVNC. The beneficial effect of beta-blocker mediating myocardial metabolism in the clinical course of LVNC requires further investigation.

Left Ventricular Noncompaction in Older Patients

BACKGROUND

Information on left ventricular noncompaction (LVNC) in older people is sparse. This study aimed to investigate the clinical profile of LVNC in an older cohort.

MATERIALS AND METHODS

Between August 2007 and September 2015, older patients (age ≥ 60 years) who were diagnosed with LVNC using cardiovascular magnetic resonance were prospectively enrolled at our hospital.

RESULTS

A total of 35 patients (male, 80%; mean age, 65 ± 5 years) were prospectively included in this study. LVNC was not detected in 18 patients (51%) at the initial echocardiographic evaluation. Of the 21 patients who received coronary imaging, 8 patients (38%) had coronary artery disease. Left ventricular (LV) dysfunction and dilation were detected in 31 patients (89%) and 30 patients (86%), respectively. Nine patients (26%) died during a follow-up period of 2.9 ± 2.3 years. Cox analysis showed that patients with syncope (hazard ratio [HR] = 20.51; 95% CI: 1.70-246.60; P = 0.02), increased LV end-diastolic diameter (HR = 1.12; 95% CI: 1.01-1.24; P = 0.03), decreased LV ejection fraction (HR = 0.87; 95% CI: 0.77-0.98; P = 0.02) and the presence of late gadolinium enhancement on cardiovascular magnetic resonance (HR = 8.9; 95% CI: 1.07-74.08; P = 0.04) had a higher risk for death.

CONCLUSIONS

The diagnosis of LVNC is easily missed at echocardiographic assessment in older patients. Coronary artery disease is a common concomitant disorder in these patients. Older patients with LVNC have a high risk for mortality. Syncope, LV dilation, systolic dysfunction and late gadolinium enhancement are related to adverse outcomes in older patients.

Targeting the energy guardian AMPK: another avenue for treating cardiomyopathy?

5'-AMP-activated protein kinase (AMPK) is a pivotal regulator of endogenous defensive molecules in various pathological processes. The AMPK signaling regulates a variety of intracellular intermedial molecules involved in biological reactions, including glycogen metabolism, protein synthesis, and cardiac fibrosis, in response to hypertrophic stimuli. Studies have revealed that the activation of AMPK performs a protective role in cardiovascular diseases, whereas its function in cardiac hypertrophy and cardiomyopathy remains elusive and poorly understood. In view of the current evidence of AMPK, we introduce the biological information of AMPK and cardiac hypertrophy as well as some upstream activators of AMPK. Next, we discuss two important types of cardiomyopathy involving AMPK, RKAG2 cardiomyopathy, and hypertrophic cardiomyopathy. Eventually, therapeutic research, genetic screening, conflicts, obstacles, challenges, and potential directions are also highlighted in this review, aimed at providing a comprehensive understanding of AMPK for readers.

Point mutations in murine Nkx2-5 phenocopy human congenital heart disease and induce pathogenic Wnt signaling

Mutations in the Nkx2-5 gene are a main cause of congenital heart disease. Several studies have addressed the phenotypic consequences of disrupting the Nkx2-5 gene locus, although animal models to date failed to recapitulate the full spectrum of the human disease. Here, we describe a new Nkx2-5 point mutation murine model, akin to its human counterpart disease-generating mutation. Our model fully reproduces the morphological and physiological clinical presentations of the disease and reveals an understudied aspect of Nkx2-5-driven pathology, a primary right ventricular dysfunction. We further describe the molecular consequences of disrupting the transcriptional network regulated by Nkx2-5 in the heart and show that Nkx2-5-dependent perturbation of the Wnt signaling pathway promotes heart dysfunction through alteration of cardiomyocyte metabolism. Our data provide mechanistic insights on how Nkx2-5 regulates heart function and metabolism, a link in the study of congenital heart disease, and confirms that our models are the first murine genetic models to our knowledge to present all spectra of clinically relevant adult congenital heart disease phenotypes generated by NKX2-5 mutations in patients.

The Effect of Trabeculae Carneae on Left Ventricular Diastolic Compliance: Improvement in Compliance With Trabecular Cutting

The role of trabeculae carneae in modulating left ventricular (LV) diastolic compliance remains unclear. The objective of this study was to determine the contribution of trabeculae carneae to the LV diastolic compliance. LV pressure-volume compliance curves were measured in six human heart explants from patients with LV hypertrophy at baseline and following trabecular cutting. The effect of trabecular cutting was also analyzed with finite-element model (FEM) simulations. Our results demonstrated that LV compliance improved after trabecular cutting (p < 0.001). Finite-element simulations further demonstrated that stiffer trabeculae reduce LV compliance further, and that the presence of trabeculae reduced the wall stress in the apex. In conclusion, we demonstrate that integrity of the LV and trabeculae is important to maintain LV stiffness and loss in trabeculae leads to more LV compliance.

Left Ventricular Non-Compaction: A Cardiomyopathy With Acceptable Prognosis in Children

BACKGROUND

Data on children with left ventricular non-compaction (LVNC) is sparse. The purpose of this study was to evaluate its clinical profiles in a population of Chinese children.

METHODS

From January 2010 to March 2016, consecutive Chinese children (aged <18 years) with LVNC diagnosed by cardiovascular magnetic resonance (CMR) were prospectively recruited at Fuwai Hospital.

RESULTS

A total of 41 Chinese children (male: 28%; mean age: 14±4years) were included in this study. Left ventricular non-compaction was not detected in 13 (32%) patients at initial echocardiographic evaluation. Congenital heart disease (CHD) was found in 11 (27%) patients. Four (10%) patients had Wolff-Parkinson-White (WPW) syndrome. Mean left ventricular ejection fraction (LVEF) was 41±15%. Late gadolinium enhancement (LGE) was detected in eight (20%) subjects. During a mean follow-up of 2.9 years, four (9%) patients died or received heart transplantation. These patients had lower systolic blood pressure (91±10 vs. 108±14mmHg; p=0.02), diastolic blood pressure (57±7 vs. 68±8mmHg; p=0.007) and LVEF (19±7 vs. 44±12%; p=0.002) than the survivors. In addition, advanced heart failure (100% vs. 16%; p=0.002) and LGE (50% vs. 5%; p=0.04) were detected more in these subjects.

CONCLUSIONS

Left ventricular non-compaction is easily overlooked at echocardiographic assessment. Congenital heart disease and WPW syndrome were relatively common in LVNC children. The prognosis of children with LVNC seemed to be better than previous studies reported, and its long-term prognosis needs to be further investigated.

Role of T1 Mapping in Inherited Cardiomyopathies

T1 mapping by cardiovascular magnetic resonance is a rapidly evolving method for the quantitative assessment of tissue characteristics in cardiac disease. The myocardial T1 time can be measured without contrast (native T1) or following the administration of intravenous gadolinium-based contrast agent (post-contrast T1). By combining both of these measures, the myocardial extracellular volume fraction can be approximated. This value has been validated histologically in various inherited cardiomyopathies. Due to overlapping phenotypes, the diagnosis of inherited cardiomyopathy can at times be challenging. In this article we discuss when T1 mapping may be a useful tool in the differential diagnosis of cardiomyopathy. We also present evidence of when T1 mapping provides incremental risk stratification over other biomarkers.

Barth Syndrome: Connecting Cardiolipin to Cardiomyopathy

The Barth syndrome (BTHS) is caused by an inborn error of metabolism that manifests characteristic phenotypic features including altered mitochondrial membrane phospholipids, lactic acidosis, organic acid-uria, skeletal muscle weakness and cardiomyopathy. The underlying cause of BTHS has been definitively traced to mutations in the tafazzin (TAZ) gene locus on chromosome X. TAZ encodes a phospholipid transacylase that promotes cardiolipin acyl chain remodeling. Absence of tafazzin activity results in cardiolipin molecular species heterogeneity, increased levels of monolysocardiolipin and lower cardiolipin abundance. In skeletal muscle and cardiac tissue mitochondria these alterations in cardiolipin perturb the inner membrane, compromising electron transport chain function and aerobic respiration. Decreased electron flow from fuel metabolism via NADH ubiquinone oxidoreductase activity leads to a buildup of NADH in the matrix space and product inhibition of key TCA cycle enzymes. As TCA cycle activity slows pyruvate generated by glycolysis is diverted to lactic acid. In turn, Cori cycle activity increases to supply muscle with glucose for continued ATP production. Acetyl CoA that is unable to enter the TCA cycle is diverted to organic acid waste products that are excreted in urine. Overall, reduced ATP production efficiency in BTHS is exacerbated under conditions of increased energy demand. Prolonged deficiency in ATP production capacity underlies cell and tissue pathology that ultimately is manifest as dilated cardiomyopathy.