Diagnostic, prognostic, and therapeutic implications of genetic testing for hypertrophic cardiomyopathy

Morphological anomalies in obstructive hypertrophic cardiomyopathy: Insights from four-dimensional computed tomography and surgical correlation

Hypertrophic cardiomyopathy (HCM) is a genetic disorder in which left ventricular outflow tract obstruction critically affects symptoms and prognosis. Traditionally, left ventricular outflow tract obstruction was primarily attributed to septal hypertrophy with systolic anterior motion of the mitral valve. However, recent evidence highlights significant contributions from the mitral valve and papillary muscle anomalies, as well as an apical-basal muscle bundle observed in HCM patients. Accurate morphological assessment is essential when considering septal reduction therapy. While transesophageal echocardiography and cardiac magnetic resonance are recommended for assessing the anomalous structures, four-dimensional computed tomography offers superior spatial resolution and multiplanar reconstruction capabilities. These features enable the evaluation of details of the morphological anomalies, such as the apical-basal muscle band, papillary muscle anomalies, subaortic stenosis, and right ventricular outflow tract obstruction. Based on the detailed assessment of these morphological features, four-dimensional computed tomography has been utilized for planning of surgical correction in a comprehensive HCM center. This approach facilitates the intervention strategies and may improve outcomes in septal reduction therapy for obstructive HCM.

Advances in Multi-Modality Imaging in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal growth of the myocardium with myofilament disarray and myocardial hyper-contractility, leading to left ventricular hypertrophy and fibrosis. Where culprit genes are identified, they typically relate to cardiomyocyte sarcomere structure and function. Multi-modality imaging plays a crucial role in the diagnosis, monitoring, and risk stratification of HCM, as well as in screening those at risk. Following the recent publication of the first European Society of Cardiology (ESC) cardiomyopathy guidelines, we build on previous reviews and explore the roles of electrocardiography, echocardiography, cardiac magnetic resonance (CMR), cardiac computed tomography (CT), and nuclear imaging. We examine each modality's strengths along with their limitations in turn, and discuss how they can be used in isolation, or in combination, to facilitate a personalized approach to patient care, as well as providing key information and robust safety and efficacy evidence within new areas of research.

ISE/ISHNE expert consensus statement on the ECG diagnosis of left ventricular hypertrophy: The change of the paradigm

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria. The classical paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces, reflected in the augmented QRS amplitude. However, the low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm. The theoretical background for voltage measured at the body surface is defined by the solid angle theorem, which relates the measured voltage to spatial and non-spatial determinants. The spatial determinants are represented by the extent of the activation front and the distance of the recording electrodes. The non-spatial determinants comprise electrical characteristics of the myocardium, which are comparatively neglected in the interpretation of the QRS patterns. Various clinical conditions are associated with LVH. These conditions produce considerable diversity of electrical properties alterations thereby modifying the resultant QRS patterns. The spectrum of QRS patterns observed in LVH patients is quite broad, including also left axis deviation, left anterior fascicular block, incomplete and complete left bundle branch blocks, Q waves, and fragmented QRS. Importantly, the QRS complex can be within normal limits. The new paradigm stresses the electrophysiological background in interpreting QRS changes, i.e., the effect of the non-spatial determinants. This postulates that the role of ECG is not to estimate LV size in LVH, but to understand and decode the underlying electrical processes, which are crucial in relation to cardiovascular risk assessment.

Apical Hypertrophic Cardiomyopathy With a Sub-aortic Membrane: A Case Report

Hypertrophic obstructive cardiomyopathy (HOCM) and subaortic membrane (SAS) are distinct cardiac conditions, but their coexistence presents complex diagnostic challenges. We report the case of a 52-year-old male with HOCM and a concurrent subaortic membrane, highlighting the intricacies of diagnosis and management. The patient's presentation included symptoms of dyspnea and chest tightness, and diagnostic evaluations revealed a unique combination of dynamic left ventricular outflow tract (LVOT) obstruction from HOCM and fixed obstruction from the subaortic membrane. This case emphasizes the importance of a comprehensive diagnostic workup to guide appropriate treatment decisions when managing multiple cardiac abnormalities.

Therapeutic Approaches Targeting Ferroptosis in Cardiomyopathy

The term cardiomyopathy refers to a group of heart diseases that cause severe heart failure over time. Cardiomyopathies have been proven to be associated with ferroptosis, a non-apoptotic form of cell death. It has been shown that some small molecule drugs and active ingredients of herbal medicine can regulate ferroptosis, thereby alleviating the development of cardiomyopathy. This article reviews recent discoveries about ferroptosis, its role in the pathogenesis of cardiomyopathy, and the therapeutic options for treating ferroptosis-associated cardiomyopathy. The article aims to provide insights into the basic mechanisms of ferroptosis and its treatment to prevent cardiomyopathy and related diseases.

ISE/ISHNE Expert Consensus Statement on ECG Diagnosis of Left Ventricular Hypertrophy: The Change of the Paradigm. The joint paper of the International Society of Electrocardiology and the International Society for Holter Monitoring and Noninvasive Electrocardiology

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria, i.e. the increased QRS complex amplitude in defined leads. The classical ECG diagnostic paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces. These increased forces are reflected in the augmented QRS amplitude in the corresponding leads. However, the clinical observations document increased QRS amplitude only in the minority of patients with LVH. The low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm.

Genetic heterogeneity of cardiomyopathy and its correlation with patient care

BACKGROUND

Cardiomyopathy, which is a genetically and phenotypically heterogeneous pathological condition, is associated with increased morbidity and mortality. Genetic diagnosis of cardiomyopathy enables accurate phenotypic classification and optimum patient management and counseling. This study investigated the genetic spectrum of cardiomyopathy and its correlation with the clinical course of the disease.

METHODS

The samples of 72 Korean patients with cardiomyopathy (43 males and 29 females) were subjected to whole-exome sequencing (WES). The familial information and clinical characteristics of the patients were reviewed and analyzed according to their genotypes.

RESULTS

Dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), left ventricular non-compaction cardiomyopathy, and restrictive cardiomyopathy was detected in 41 (56.9%), 25 (34.7%), 4 (5.6%), and 2 (2.8%) patients, respectively. WES analysis revealed positive results in 37 (51.4%) patients. Subsequent familial testing identified ten additional familial cases. Among DCM cases, 19 (46.3%) patients exhibited positive results, with TTN variants being the most common alteration, followed by LMNA and MYH7 variants. Meanwhile, among HCM cases, 15 (60%) patients exhibited positive results with MYH7 variants being the most common alteration. In six patients with positive results, extracardiac surveillance was warranted based on disease information. The incidence of worse outcomes, such as mortality and life-threatening arrhythmic events, in patients with DCM harboring LMNA variants, was higher than that in patients with DCM harboring TTN or MYH7 variants.

CONCLUSIONS

Diverse genotypes were identified in a substantial proportion of patients with cardiomyopathy. Genetic diagnosis enables personalized disease surveillance and management.

Hypertrophic Cardiomyopathy Diagnosis and Treatment in High- and Low-Income Countries: A Narrative Review

Hypertrophic cardiomyopathy (HCM) is a hereditary cardiac condition characterized by unexplained left ventricular hypertrophy without a hemodynamic cause. This condition is prevalent in the United States, resulting in various clinical manifestations, including diastolic dysfunction, left ventricular outflow obstruction, cardiac ischemia, and atrial fibrillation. HCM is associated with several genetic mutations, with sarcomeric mutations being the most common and contributing to a more complex disease course. Early diagnosis of HCM is essential for effective management, as late diagnosis often requires invasive treatments and creates a substantial financial burden. Disparities in HCM diagnosis and treatment exist between high-income and low-income countries. High-income countries have more resources to investigate and implement advanced diagnostic and treatment modalities. In contrast, low-income countries face challenges in accessing diagnostic equipment, trained personnel, and affordable medications, leading to a lower quality of life and life expectancy for affected individuals. Diagnostic tools for HCM include imaging studies such as 2D echocardiography, cardiovascular magnetic resonance (CMR), and electrocardiograms (ECGs). CMR is considered the gold standard but remains inaccessible to a significant portion of the world's population, especially in low-income countries. Genetics plays a crucial role in HCM, with numerous mutations identified in various genes. Genetic counseling is essential but often limited in low-income countries due to resource constraints. Disparities in healthcare access and adherence to treatment recommendations exist between high-income and low-income countries, leading to differences in patient outcomes. Addressing these disparities is essential to improve the overall management of HCM on a global scale. In conclusion, this review highlights the complex nature of HCM, emphasizing the importance of early diagnosis, genetic counseling, and access to appropriate diagnostic and therapeutic interventions. Addressing healthcare disparities is crucial to ensure that all individuals with HCM receive timely and effective care, regardless of their geographic location or socioeconomic status.

Multimodality imaging of hypertrophic cardiomyopathy

The diagnosis and management of hypertrophic cardiomyopathy (HCM) requires multimodality imaging. Transthoracic echocardiogram (TTE) remains the first-line imaging modality to diagnose HCM identifying morphology and obstruction, which includes left ventricular outflow obstruction, midcavitary obstruction and systolic anterior motion. Cardiac magnetic resonance imaging (CMR) can adjudicate equivocal cases, rule out alternative diagnoses and evaluate for risk factors of sudden cardiac death. Imaging with TTE or transesophageal echocardiogram can also guide alcohol septal ablation or surgical myectomy respectively. Furthermore, TTE can guide medical management of these patients by following peak gradients. Thus, multimodality imaging in HCM is crucial throughout the course of these patients' care.

Regulated cell death pathways in cardiomyopathy

Heart disease is a worldwide health menace. Both intractable primary and secondary cardiomyopathies contribute to malignant cardiac dysfunction and mortality. One of the key cellular processes associated with cardiomyopathy is cardiomyocyte death. Cardiomyocytes are terminally differentiated cells with very limited regenerative capacity. Various insults can lead to irreversible damage of cardiomyocytes, contributing to progression of cardiac dysfunction. Accumulating evidence indicates that majority of cardiomyocyte death is executed by regulating molecular pathways, including apoptosis, ferroptosis, autophagy, pyroptosis, and necroptosis. Importantly, these forms of regulated cell death (RCD) are cardinal features in the pathogenesis of various cardiomyopathies, including dilated cardiomyopathy, diabetic cardiomyopathy, sepsis-induced cardiomyopathy, and drug-induced cardiomyopathy. The relevance between abnormity of RCD with adverse outcome of cardiomyopathy has been unequivocally evident. Therefore, there is an urgent need to uncover the molecular and cellular mechanisms for RCD in order to better understand the pathogenesis of cardiomyopathies. In this review, we summarize the latest progress from studies on RCD pathways in cardiomyocytes in context of the pathogenesis of cardiomyopathies, with particular emphasis on apoptosis, necroptosis, ferroptosis, autophagy, and pyroptosis. We also elaborate the crosstalk among various forms of RCD in pathologically stressed myocardium and the prospects of therapeutic applications targeted to various cell death pathways.

An Unusual Presentation of Apical Hypertrophic Cardiomyopathy in an Orthotopic Heart Transplant Recipient

In this case study, we present the evaluation of an orthotopic heart transplant (OHT) patient who presented with persistent shortness of breath and dizziness upon standing. The investigation uncovered the presence of progressive hypertrophic cardiomyopathy (HCM) in the transplanted heart, a condition first detected 11 years after the transplantation. Utilizing echocardiography with global longitudinal strain (GLS), we determined that the HCM likely originated from genetic predominance inherited from the heart donor rather than hypertensive disease. This finding highlights the significance of genetic factors in post-transplant complications and warrants further investigation into the long-term effects of heart transplantation on recipient health.

A novel compound heterozygous variant in ALPK3 induced hypertrophic cardiomyopathy: a case report

Background

Malignant hypertrophic cardiomyopathy (HCM) phenotypes have potential risks of severe heart failure, fatal arrhythmia, and sudden cardiac death. Therefore, it is critical to predict the clinical outcomes of these patients. It was reported recently that the alpha kinase 3 (ALPK3) gene was involved in the occurrence of HCM. Herein we reported a girl with HCM, while whole-exome sequencing found novel compound heterozygous variants in ALPK3 gene, which identified a potential association.

Case presentation

We reported a 14-year-girl who suffered from clinical manifestations of cardiac failure, with sudden cardiac arrest before admission. The heartbeat recovered after cardiopulmonary resuscitation, though she remained unconscious without spontaneous breath. The patient stayed comatose when she was admitted. Physical examination indicated enlargement of the heart boundary. Laboratory results revealed a significant increment of myocardial markers, while imaging demonstrated hypertrophy of the left heart and interventricular septum. Whole-exome sequencing (WES) identified a compound heterozygous variant in ALPK3 gene consisting of c.3907_3922del and c.2200A>T, which was inherited from her parents. Both variants (p.G1303Lfs*28 and p.R734*) were disease-causing evaluated by MutationTaster (probability 1.000). The crystal structure of the complete amino acid sequence is predicted and evaluated by AlphaFold and SWISS-MODEL software (July, 2022), which revealed three domains. Moreover, both variants resulted in a wide protein-truncating variant and damaged protein function. Thus, a novel compound heterozygous variant in ALPK3 associated with HCM was diagnosed.

Conclusion

We described a young patient with ALPK3-associated HCM who experienced sudden cardiac arrest. Through WES, we identified a compound heterozygous variant in the ALPK3 gene, c.3907_3922del and c.2200A>T, which were inherited from the patient's parents and resulted in a truncated protein, indirectly causing the symptoms of HCM. In addition, WES provided clues in evaluating potential risks of gene variants on fatal clinical outcomes, and the nonsense and frameshift variants of ALPK3 were related to adverse clinical outcomes in HCM patients, which required implantable cardioverter defibrillator (ICD) timely.

Personalized Management of Sudden Death Risk in Primary Cardiomyopathies: From Clinical Evaluation and Multimodality Imaging to Ablation and Cardioverter-Defibrillator Implant

Sudden cardiac death represents the leading cause of death worldwide; although the majority of sudden deaths occur in an elderly population with coronary artery disease, some occur in young and otherwise healthy individuals, as is the case of cardiomyopathies. The aim of the present review is to provide a stepwise hierarchical approach for the global sudden death risk estimation in primary cardiomyopathies. Each individual risk factor is analyzed for its contribution to the overall risk of sudden death for each specific cardiomyopathy as well as across all primary myocardial diseases. This stepwise hierarchical and personalized approach starts from the clinical evaluation, subsequently passes through the role of electrocardiographic monitoring and multimodality imaging, and finally concludes with genetic evaluation and electro-anatomical mapping. In fact, the sudden cardiac death risk assessment in cardiomyopathies depends on a multiparametric approach. Moreover, current indications for ventricular arrhythmia ablation and defibrillator implantation are discussed.

Current and emerging pharmacotherapy for the management of hypertrophic cardiomyopathy

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic causes of heart disease. Since the initial description of HCM, there have been minimal strides in management options. Obstructive HCM constitutes a larger subset of patients with increased left ventricular outflow tract gradients causing symptoms. Septal reduction therapy (SRT) has been successful, but it is not the answer for all patients and is not disease modifying.

AREAS COVERED

Current guideline recommendations include beta-blockers, calcium channel blockers, or disopyramides for medical management, but there lacks evidence of much benefit with these drugs. In recent years, there has been the emergence of cardiac myosin inhibitors (CMI) which have demonstrated positive results in patients with both obstructive and non-obstructive HCM. In addition to CMIs, other drugs have been investigated as we have learned more about HCM's pathological mechanisms. Drugs targeting sodium channels and myocardial energetics, as well as repurposed drugs that have demonstrated positive remodeling are being investigated as potential therapeutic targets. Gene therapy is being explored with vast potential for the treatment of HCM.

EXPERT OPINION

The armamentarium of therapeutic options for HCM is continuously increasing with the emergence of CMIs as mainstays of treatment. The future of HCM treatment is promising.

Endogenous assessment of late gadolinium enhancement grey zone in patients with non-ischaemic cardiomyopathy with T1ρ and native T1 mapping

AIMS

This study aims to validate and compare the feasibility of T1ρ and native longitudinal relaxation time (T1) mapping in detection of myocardial fibrosis in patients with non-ischaemic cardiomyopathy, focusing on the performance of both methods in identifying late gadolinium enhancement (LGE) grey zone.

METHODS AND RESULTS

Twenty-seven hypertrophic cardiomyopathy (HCM) patients, 16 idiopathic dilated cardiomyopathy (DCM) patients, and 18 healthy controls were prospectively enrolled for native T1 and T1ρ mapping imaging and then all the patients underwent enhancement scan for LGE extent and extracellular volume (ECV) values. In LGE positive patients, the LGE areas were divided into LGE core (6 SDs above remote myocardium) and grey zone (2-6 SDs above remote myocardium) according to the signal intensity of LGE. Both HCM and DCM patients showed significantly higher native T1 values and T1ρ values than controls no matter the presence of LGE (all P < 0.01). There were significant differences in native T1 and T1ρ values among four different types of myocardia (LGE core, grey zone, remote area and control, P < 0.0001). However, the T1ρ values of grey zone were significantly higher than control (P < 0.01), while the native T1 values were not (P = 0.089). T1ρ values were significantly associated with both native T1 values (r = 0.54, P < 0.001) and ECV values (r = 0.54, P < 0.001).

CONCLUSION

T1ρ mapping is a feasible method to detect myocardial fibrosis in patients with non-ischaemic cardiomyopathy no matter the presence of LGE. Compared with native T1, T1ρ may serve as a better discriminator in the identification of LGE grey zone.

In Vivo Dissection of Chamber-Selective Enhancers Reveals Estrogen-Related Receptor as a Regulator of Ventricular Cardiomyocyte Identity

BACKGROUND

Cardiac chamber-selective transcriptional programs underpin the structural and functional differences between atrial and ventricular cardiomyocytes (aCMs and vCMs). The mechanisms responsible for these chamber-selective transcriptional programs remain largely undefined.

METHODS

We nominated candidate chamber-selective enhancers (CSEs) by determining the genome-wide occupancy of 7 key cardiac transcription factors (GATA4, MEF2A, MEF2C, NKX2-5, SRF, TBX5, TEAD1) and transcriptional coactivator P300 in atria and ventricles. Candidate enhancers were tested using an adeno-associated virus-mediated massively parallel reporter assay. Chromatin features of CSEs were evaluated by performing assay of transposase accessible chromatin sequencing and acetylation of histone H3 at lysine 27-HiChIP on aCMs and vCMs. CSE sequence requirements were determined by systematic tiling mutagenesis of 29 CSEs at 5 bp resolution. Estrogen-related receptor (ERR) function in cardiomyocytes was evaluated by Cre-loxP-mediated inactivation of ERRα and ERRγ in cardiomyocytes.

RESULTS

We identified 134 066 and 97 506 regions reproducibly occupied by at least 1 transcription factor or P300, in atria or ventricles, respectively. Enhancer activities of 2639 regions bound by transcription factors or P300 were tested in aCMs and vCMs by adeno-associated virus-mediated massively parallel reporter assay. This identified 1092 active enhancers in aCMs or vCMs. Several overlapped loci associated with cardiovascular disease through genome-wide association studies, and 229 exhibited chamber-selective activity in aCMs or vCMs. Many CSEs exhibited differential chromatin accessibility between aCMs and vCMs, and CSEs were enriched for aCM- or vCM-selective acetylation of histone H3 at lysine 27-anchored loops. Tiling mutagenesis of 29 CSEs identified the binding motif of ERRα/γ as important for ventricular enhancer activity. The requirement of ERRα/γ to activate ventricular CSEs and promote vCM identity was confirmed by loss of the vCM gene profile in ERRα/γ knockout vCMs.

CONCLUSIONS

We identified 229 CSEs that could be useful research tools or direct therapeutic gene expression. We showed that chamber-selective multi-transcription factor, P300 occupancy, open chromatin, and chromatin looping are predictive features of CSEs. We found that ERRα/γ are essential for maintenance of ventricular identity. Finally, our gene expression, epigenetic, 3-dimensional genome, and enhancer activity atlas provide key resources for future studies of chamber-selective gene regulation.

A Human Hereditary Cardiomyopathy Shares a Genetic Substrate With Bicuspid Aortic Valve

BACKGROUND

The complex genetics underlying human cardiac disease is evidenced by its heterogenous manifestation, multigenic basis, and sporadic occurrence. These features have hampered disease modeling and mechanistic understanding. Here, we show that 2 structural cardiac diseases, left ventricular noncompaction (LVNC) and bicuspid aortic valve, can be caused by a set of inherited heterozygous gene mutations affecting the NOTCH ligand regulator MIB1 (MINDBOMB1) and cosegregating genes.

METHODS

We used CRISPR-Cas9 gene editing to generate mice harboring a nonsense or a missense MIB1 mutation that are both found in LVNC families. We also generated mice separately carrying these MIB1 mutations plus 5 additional cosegregating variants in the ASXL3, APCDD1, TMX3, CEP192, and BCL7A genes identified in these LVNC families by whole exome sequencing. Histological, developmental, and functional analyses of these mouse models were carried out by echocardiography and cardiac magnetic resonance imaging, together with gene expression profiling by RNA sequencing of both selected engineered mouse models and human induced pluripotent stem cell-derived cardiomyocytes. Potential biochemical interactions were assayed in vitro by coimmunoprecipitation and Western blot.

RESULTS

Mice homozygous for the MIB1 nonsense mutation did not survive, and the mutation caused LVNC only in heteroallelic combination with a conditional allele inactivated in the myocardium. The heterozygous MIB1 missense allele leads to bicuspid aortic valve in a NOTCH-sensitized genetic background. These data suggest that development of LVNC is influenced by genetic modifiers present in affected families, whereas valve defects are highly sensitive to NOTCH haploinsufficiency. Whole exome sequencing of LVNC families revealed single-nucleotide gene variants of ASXL3, APCDD1, TMX3, CEP192, and BCL7A cosegregating with the MIB1 mutations and LVNC. In experiments with mice harboring the orthologous variants on the corresponding Mib1 backgrounds, triple heterozygous Mib1 Apcdd1 Asxl3 mice showed LVNC, whereas quadruple heterozygous Mib1 Cep192 Tmx3;Bcl7a mice developed bicuspid aortic valve and other valve-associated defects. Biochemical analysis suggested interactions between CEP192, BCL7A, and NOTCH. Gene expression profiling of mutant mouse hearts and human induced pluripotent stem cell-derived cardiomyocytes revealed increased cardiomyocyte proliferation and defective morphological and metabolic maturation.

CONCLUSIONS

These findings reveal a shared genetic substrate underlying LVNC and bicuspid aortic valve in which MIB1-NOTCH variants plays a crucial role in heterozygous combination with cosegregating genetic modifiers.

Cardiac Multimodality Imaging in Hypertrophic Cardiomyopathy: What to Look for and When to Image

Hypertrophic cardiomyopathy (HCM), now recognized as a common cardiomyopathy of complex genomics and pathophysiology, is defined by the presence of left ventricular hypertrophy of various morphologies and severity, significant hemodynamic consequences, and diverse phenotypic, both structural and clinical, profiles. Advancements in cardiac multimodality imaging, including echocardiography, cardiac magnetic resonance imaging, and cardiac computed tomography, with and without angiography have greatly improved the diagnosis of HCM, and enable precise measurements of cardiac mass, volume, wall thickness, function, and physiology. Multimodality imaging provides comprehensive and complementary information and hasemerged as the bedrock for the diagnosis, clinical assessment, serial monitoring, and sudden cardiac death risk stratification of patients with HCM. This review highlights the role of cardiac multimodality imaging in the modern diagnosis and management of HCM.

Cardiac Sarcomere Signaling in Health and Disease

The cardiac sarcomere is a triumph of biological evolution wherein myriad contractile and regulatory proteins assemble into a quasi-crystalline lattice to serve as the central point upon which cardiac muscle contraction occurs. This review focuses on the many signaling components and mechanisms of regulation that impact cardiac sarcomere function. We highlight the roles of the thick and thin filament, both as necessary structural and regulatory building blocks of the sarcomere as well as targets of functionally impactful modifications. Currently, a new focus emerging in the field is inter-myofilament signaling, and we discuss here the important mediators of this mechanism, including myosin-binding protein C and titin. As the understanding of sarcomere signaling advances, so do the methods with which it is studied. This is reviewed here through discussion of recent live muscle systems in which the sarcomere can be studied under intact, physiologically relevant conditions.

RNA-seq profiling reveals different pathways between remodeled vessels and myocardium in hypertrophic cardiomyopathy

OBJECTIVE

Coronary microvascular dysfunction (CMD) is a key pathophysiological feature of hypertrophic cardiomyopathy (HCM), contributing to myocardial ischemia and representing a critical determinant of patients' adverse outcome. The molecular mechanisms underlying the morphological and functional changes of CMD are still unknown. Aim of this study was to obtain insights on the molecular pathways associated with microvessel remodeling in HCM.

METHODS

Interventricular septum myectomies from patients with obstructive HCM (n = 20) and donors' hearts (CTRL, discarded for technical reasons, n = 7) were collected. Remodeled intramyocardial arterioles and cardiomyocytes were microdissected by laser capture and next-generation sequencing was used to delineate the transcriptome profile.

RESULTS

We identified 720 exclusive differentially expressed genes (DEGs) in cardiomyocytes and 1315 exclusive DEGs in remodeled arterioles of HCM. Performing gene ontology and pathway enrichment analyses, we identified selectively altered pathways between remodeled arterioles and cardiomyocytes in HCM patients and controls.

CONCLUSIONS

We demonstrate the existence of distinctive pathways between remodeled arterioles and cardiomyocytes in HCM patients and controls at the transcriptome level.

Subaortic Membrane Co-existing With Hypertrophic Cardiomyopathy: A Clinically Challenging Diagnosis

Subaortic Membrane is the most common type of subaortic stenosis. That, coexisting with hypertrophic obstructive cardiomyopathy (HOCM) is an extremely rare combination and clinically underappreciated. In this report, we will discuss an 18-year-old male patient who presented with chest pain and dyspnea due to fixed (sub-aortic membrane), as well as dynamic (HOCM), left ventricular outflow tract obstruction (LVOT) obstruction.

Protections of transcription factor BACH2 and natural product myricetin against pathological cardiac hypertrophy and dysfunction

Pathological hypertrophic myocardium under consistent adverse stimuli eventually can cause heart failure. This study aims to explore the role of BACH2, a member of the basic region leucine zipper transcription factor family, in cardiac hypertrophy and failure. Transverse aortic constriction surgery was operated to induce cardiac hypertrophy and failure in mice. BACH2 was overexpressed in mice through tail vein injection of AAV9-Bach2. Mice with systemic or cardiac-specific knockdown of Bach2 were adopted. Neonatal rat ventricular myocytes (NRVMs) were isolated and infected with lentivirus to overexpress Bach2 or transfected with siRNA to knock down Bach2. Our data showed that overexpression of BACH2 ameliorated TAC-induced cardiac hypertrophy and failure in mice and decreased isoproterenol (ISO)-triggered myocyte hypertrophy in NRVMs. Systemic or cardiac-specific knockdown of Bach2 worsened the cardiac hypertrophy and failure phenotype in mice. Further assays showed that BACH2 bound to the promotor region of Akap6 at the -600 to -587 site and repressed its expression, which functioned as a crucial scaffold for cardiac hypertrophy and failure signaling pathways. Small molecular natural product library screening suggested that myricetin could up-regulate expression of Bach2 and simultaneously suppress the transcriptional levels of hypertrophic marker genes Bnp and Myh7. Further studies showed that myricetin exerted a BACH2-dependent protective effect against cardiac hypertrophy in vivo and in vitro. Taken together, our findings demonstrated that BACH2 plays a crucial role in the regulation of cardiac hypertrophy and failure and can be a potential therapeutic target in the future.

Apical Hypertrophic Cardiomyopathy Prompting Aneurysm, Thrombus, and Cardiac Arrest in a 56-Year-Old Female

Hypertrophic cardiomyopathy (HCM) is the most prevalent genetic cardiac disease while apical hypertrophic cardiomyopathy (apHCM) is a rare subset of HCM. The significance of this case report is to present apHCM, its chronological course, and its association with left ventricular aneurysm, thrombosis, and cardiac arrest. We present the case of a 56-year-old female with a past medical history of apHCM who was admitted for substernal chest pain, developed a ventricular storm (VT), and subsequently suffered cardiac arrest; resuscitation of spontaneous circulation (ROSC) was eventually achieved after 10 minutes. It was initially thought that her arrhythmia and hemodynamic decompensation were purely secondary to cocaine use at a party six hours prior to her presentation. During hospitalization, cardiac magnetic resonance imaging demonstrated a severe apHCM apical aneurysm, thrombosis, and a re-entrant circuit as a likely cause of this patient’s decompensation and eventual cardiac arrest. After several days of hemodynamic stability and decreased dependence on intravenous antiarrhythmic medication infusions, she was extubated and transitioned to oral amiodarone and beta-blocker therapy with the implantation of a cardioverter-defibrillator (ICD). In this case, we analyze the continuum of apHCM, a rare subset of HCM once thought to be benign but with the emergence of complications, including aneurysm, thrombus formation, resistant ventricular tachycardia, and cardiac arrest. Recognition and management of apHCM with medical and/or surgical intervention are therefore critical to prevent the aforementioned sequela.

Recommendations for Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy: An Update from the American Society of Echocardiography, in Collaboration with the American Society of Nuclear Cardiology, the Society for Cardiovascular Magnetic Resonance, and the Society of Cardiovascular Computed Tomography

Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases. Symptoms can be related to a range of pathophysiologic mechanisms including left ventricular outflow tract obstruction with or without significant mitral regurgitation, diastolic dysfunction with heart failure with preserved and heart failure with reduced ejection fraction, autonomic dysfunction, ischemia, and arrhythmias. Appropriate understanding and utilization of multimodality imaging is fundamental to accurate diagnosis as well as longitudinal care of patients with HCM. Resting and stress imaging provide comprehensive and complementary information to help clarify mechanism(s) responsible for symptoms such that appropriate and timely treatment strategies may be implemented. Advanced imaging is relied upon to guide certain treatment options including septal reduction therapy and mitral valve repair. Using both clinical and imaging parameters, enhanced algorithms for sudden cardiac death risk stratification facilitate selection of HCM patients most likely to benefit from implantable cardioverter-defibrillators.

Efficacy and Safety of Hybrid Cardiac Telerehabilitation in Patients with Hypertrophic Cardiomyopathy without Left Ventricular Outflow Tract Obstruction and Preserved Ejection Fraction—A Study Design

Hypertrophic cardiomyopathy (HCM) is the most common congenital disease increasing the risk of sudden cardiac death. For many years, HCM patients were excluded from exercise training. However, there are data showing that patients with HCM undergoing supervised exercise training could improve physical performance without serious adverse events. A project was designed as a randomized clinical trial to assess the effectiveness and safety of hybrid cardiac rehabilitation (HCR)—a combination of hospital-based cardiac rehabilitation (1 month) with a new form of home-based telemonitored cardiac rehabilitation (2 months) in HCM patients without left ventricular (LV) outflow tract obstruction and preserved systolic function. Sixty patients who fulfil the inclusion criteria have been randomly assigned (1:1) to either HCR plus usual care (training group) or usual care only (control group). The primary endpoint is a functional capacity evaluated by peak oxygen uptake (pVO2). Secondary endpoints include workload time during the cardiopulmonary exercise testing, a six-minute walk test distance, NT-pro BNP level, echocardiographic parameters of the left ventricular diastolic function (E/A, E/e’, myocardial strain rate), right ventricular systolic pressure, a gradient in the LV outflow tract, and quality of life. The tertiary analysis includes safety, acceptance and adherence to the HCR program. Our research will provide innovative data on the effectiveness and safety of hybrid cardiac rehabilitation in HCM patients without LV outflow tract obstruction and preserved systolic function. Clinical trials registry: ClinicalTrials.gov Identifier NCT03178357.

A Case Series of Hypertrophic Cardiomyopathy Conducted in Vietnam Revealing a Novel Pathogenic Variant of the TNNT2 Gene

Background:

Hypertrophic Cardiomyopathy (HCM) is one of the leading causes of sudden cardiac death in adults.HCM is inherited in an autosomal dominant manner; however, the genetic etiology of the disease is not fully explained and studies on the hereditary characteristics in family trees are still underway.

Methods:

Ten HCM patients and 31 of their relatives were recruited. Targeted sequencing for 4 HCM related-genes, including MYH7, MYBPC3, TNNT2, and TNNI3, using targeted next-generation sequencing (NGS) was carried out. Demographic, clinical, electrocardiography, and echocardiography characteristics were also characterized.

Results:

Among the 10 HCM patients, 5 were identified with the HCM pathogenic variants in MYH7 (3 patients), MYBPC3 (1 patient), and TNNT2 (1 patient) genes. Eleven out of 31 relatives from these 5 genotype-positive patients carried the same pathogenic variants. We found the novel c.822-2 A>G variant in the splicing site of the TNNT2 gene responsible for HCM disease in a family with 7 subjects genotype positive and 3 others who suffered from sudden cardiac death.

Conclusion:

This case series highlighted the importance of genetic testing for clinically confirmed HCM patients and family members. The genetic information can be used as a molecular marker to complement the clinical presentation in the diagnosis of HCM, as well as a prognostic tool for the patients and their family members.

A Rare Cause of Chest Pain Identified on Point-of-care Echocardiography: A Case Report

INTRODUCTION

Cardiac masses are a rare cause of chest pain. They can often be missed on a chest radiograph performed to evaluate non-specific chest pain and are not readily evaluated with traditional laboratory testing. However, these masses can be visualized with point-of-care ultrasound.

CASE REPORT

We present a case of a 19-year-old female presenting with intermittent chest pain, palpitations, and weakness present for two months. The patient had previously been evaluated at our emergency department one week earlier and was diagnosed with anxiety before being discharged. Besides a tachycardic and labile heart rate, physical examination and laboratory testing were unremarkable. Point-of-care cardiac echocardiography subsequently demonstrated findings concerning for a cardiac mass.

CONCLUSION

Cardiac masses are a rare cause of chest pain and palpitations that are easily missed. The advent of point-of-care ultrasonography has afforded us the ability to rapidly assess for structural and functional cardiac abnormalities at bedside, and incorporation of this tool into the evaluation of patients with chest pain offers the ability to detect these rare pathologies.

Exploring the Communal Pathogenesis, Ferroptosis Mechanism, and Potential Therapeutic Targets of Dilated Cardiomyopathy and Hypertrophic Cardiomyopathy via a Microarray Data Analysis

Background

Cardiomyopathies are a heterogeneous group of heart diseases that can gradually cause severe heart failure. In particular, dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) are the two main types of cardiomyopathies, yet the independent and communal biological mechanisms of both remain far from elucidated. Meanwhile, ferroptosis is a non-apoptotic form of cell death that has been proven to be associated with cardiomyopathies, but the concrete nature of the interaction remains unclear. Hence, this study explored the pathogenesis and ferroptosis mechanism of HCM and DCM via a bioinformatics analysis.

Methods

Six datasets were downloaded from the Gene Expression Omnibus (GEO) database based on the study inclusion/exclusion criteria. After screening the differentially expressed genes (DEGs) and hub genes of HCM and DCM, subsequent analyses, including functional annotation, co-expression, validation, and transcription factors (TF)–mRNA–microRNA (miRNA) regulatory network construction, were performed. In addition, ferroptosis-related DEGs were also identified and verified in HCM and DCM.

Results

We found 171 independent DEGs of HCM mainly enriched in the regulation of ERK1 and ERK2 cascade, while 171 independent DEGs of DCM were significantly involved in cell adhesion. Meanwhile, 32 communal DEGs (26 upregulated genes and 6 downregulated genes) and 3 hub genes [periostin (POSTN), insulin-like growth factor-binding protein-5 (IGFBP5), and fibromodulin (FMOD)] were determined to be shared between HCM and DCM and the functional annotation of these genes highlighted the important position of growth hormone in HCM and DCM. Moreover, we identified activating transcription factor 3 (ATF3), lysophosphatidylcholine acyltransferase 3 (LPCAT3), and solute carrier family 1 member 5 (SLC1A5) as ferroptosis-related genes in HCM and STAT3 as a ferroptosis-related gene in DCM.

Conclusion

The identified independent and communal DEGs contribute to uncover a potentially distinct and common mechanism of HCM and DCM and ferroptosis-related genes could provide us with a novel direction for exploration. In addition, 3 hub genes could be potential biomarkers or therapeutic targets in patients with cardiomyopathy.

Echocardiographic Deformation Imaging for Early Detection of Genetic Cardiomyopathies: JACC Review Topic of the Week

Clinical screening of the relatives of patients with genetic cardiomyopathies is challenging, as they often lack detectable cardiac abnormalities at presentation. Life-threatening adverse events can already occur in these early stages of disease, so sensitive tools to reveal the earliest signs of disease are needed. The utility of echocardiographic deformation imaging for early detection has been explored for this population in multiple studies but has not been broadly implemented in clinical practice. The authors discuss contemporary evidence on the utility of deformation imaging in relatives of patients with genetic cardiomyopathies. The available body of data shows that deformation imaging reveals early disease-specific abnormalities in dilated cardiomyopathy, hypertrophic cardiomyopathy, and arrhythmogenic cardiomyopathy. Deformation imaging seems promising to enhance the screening and follow-up protocols in relatives, and the authors propose measures to accelerate its implementation in clinical care.

Clinical Characteristics for the Improvement of Cushing's Syndrome Complicated With Cardiomyopathy After Treatment With a Literature Review

Background: Endogenous Cushing's syndrome (CS), also called hypercortisolism, leads to a significant increase in mortality due to excessive cortisol production, which is mainly due to cardiovascular disease. CS complicated with cardiomyopathies, which is a rare and severe condition, has rarely been reported in the literature. Objective: To investigate the clinical characteristics of CS complicated with cardiomyopathies, we retrospectively reviewed the clinical manifestations, laboratory results, cardiac imaging results and prognosis to further understand the diagnosis, treatment, and management of these cases. Methods: The clinical data of patients diagnosed with CS complicated with cardiomyopathies obtained from discharge sheets from Peking Union Medical College Hospital from January 1986 to August 2021 were collected. Case reports of CS complicated with cardiomyopathies were retrieved from PubMed. In addition, Cushing's disease (CD) patients without cardiomyopathies were collected as controls to compare the clinical features. Results: A total of 19 cases of CS complicated with cardiomyopathies and cases of CD without cardiomyopathies (n = 242) were collected. The causes of CS included pituitary adenoma (n = 8, 42.11%), adrenal adenoma (n = 7, 36.84%), ectopic adrenocorticotropic hormone (ACTH) tumor (n = 2, 10.53%) and unclear causes (n = 2, 10.53%) in the CS complicated with cardiomyopathies group. The types of cardiomyopathies were dilated cardiomyopathies (n = 15, 78.94%) and hypertrophic cardiomyopathies (n = 4, 21.05%). The serum sodium concentration was significantly higher [145.50 (140.50-148.00) mmol/L vs. 141.00 (140.00-143.00) mmol/L], while the serum potassium concentration was significantly lower [2.70 (2.40-3.60) mmol/L] vs. 3.90 (3.50-4.20 mmol/L)] in the CS complicated with cardiomyopathies group compared to the CD patients without cardiomyopathies. There were no significant differences between the CS complicated with cardiomyopathies group and the CD patients without cardiomyopathies in the serum cortisol concentration and 24-h urine free cortisol, but a significant difference in the adrenocorticotropic hormone level [109.00 (91.78-170.30) pg/ml vs. 68.60 (47.85-110.00) pg/ml]. Twelve/16 (75.0%) patients showed significant improvement or even a complete healing of the heart structure and function after remission of hypercortisolemia after treatment with CS. Conclusions: CS complicated with cardiomyopathies is a very rare clinical entity, in which cortisol plays an important role and it can be greatly improved after remission of hypercortisolemia.

MicroRNAs: From Junk RNA to Life Regulators and Their Role in Cardiovascular Disease

MicroRNAs (miRNAs) are single-stranded small non-coding RNA (18–25 nucleotides) that until a few years ago were considered junk RNA. In the last twenty years, they have acquired more importance thanks to the understanding of their influence on gene expression and their role as negative regulators at post-transcriptional level, influencing the stability of messenger RNA (mRNA). Approximately 5% of the genome encodes miRNAs which are responsible for regulating numerous signaling pathways, cellular processes and cell-to-cell communication. In the cardiovascular system, miRNAs control the functions of various cells, such as cardiomyocytes, endothelial cells, smooth muscle cells and fibroblasts, playing a role in physiological and pathological processes and seeming also related to variations in contractility and hereditary cardiomyopathies. They provide a new perspective on the pathophysiology of disorders such as hypertrophy, fibrosis, arrhythmia, inflammation and atherosclerosis. MiRNAs are differentially expressed in diseased tissue and can be released into the circulation and then detected. MiRNAs have become interesting for the development of new diagnostic and therapeutic tools for various diseases, including heart disease. In this review, the concept of miRNAs and their role in cardiomyopathies will be introduced, focusing on their potential as therapeutic and diagnostic targets (as biomarkers).

Non-pharmaceutical Interventions for Hypertrophic Cardiomyopathy: A Mini Review

Hypertrophic cardiomyopathy is an inherited cardiovascular disease, and 70% of patients have left ventricular outflow tract obstruction. Ventricular septal myectomy has been the gold standard treatment for most patients with refractory symptoms. Due to higher mortality associated with medical facilities with less experience, alcohol septal ablation has been accepted as an alternative to conventional surgical myectomy. It offers lower all-cause in-hospital complications and mortality, which could be potentially more preferable for patients with serious comorbidities. In recent years, radiofrequency ablation, providing another option with reproducibility and a low risk of permanent atrioventricular block, has become an effective invasive treatment to relieve left ventricular outflow tract obstruction. Moreover, substantial progress has been made in gene therapy for hypertrophic cardiomyopathy. The principal objective of this review is to present recent advances in non-pharmaceutical interventions in hypertrophic cardiomyopathy.

Preintervention imaging and intraoperative management care of the hypertrophic obstructive cardiomyopathy patient

With an estimated overall mortality of less than 1 percent per year, hypertrophic cardiomyopathy, is the most common genetic cardiomyopathy. Intraoperative transesophageal echocardiography is the standard of care for assessing patients with hypertrophic obstructive cardiomyopathy undergoing surgical septal myectomy, allowing surgical planning, intraoperative hemodynamic monitoring, and postprocedural assessment of the repair, including detection of immediate complications. At various phases during surgical septal myectomy, the changing hemodynamic conditions may lead to worsening or improvement in left ventricle outflow tract obstruction by change in preload or afterload, systolic anterior motion of the mitral valve, or sympathetic stimulation. These characteristics represent unique challenges in the management of these patients, requiring a comprehensive understanding of the management of all the conditions required to decrease the left ventricle outflow tract gradient avoiding obstruction, which include the maintenance of sinus rhythm, adequate rate avoiding tachycardia and bradycardia, and avoidance of systemic hypotension preserving preload and afterload, with adequate vasoactive agents. The aim of this review is to summarize the perioperative assessment and management of patients undergoing hypertrophic obstructive myopathy surgery.

Abnormalities in sodium current and calcium homoeostasis as drivers of arrhythmogenesis in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common inherited monogenic disease with a prevalence of 1/500 in the general population, representing an important cause of arrhythmic sudden cardiac death (SCD), heart failure, and atrial fibrillation in the young. HCM is a global condition, diagnosed in >50 countries and in all continents. HCM affects people of both sexes and various ethnic and racial origins, with similar clinical course and phenotypic expression. The most unpredictable and devastating consequence of HCM is represented by arrhythmic SCD, most commonly caused by sustained ventricular tachycardia or ventricular fibrillation. Indeed, HCM represents one of the main causes of arrhythmic SCD in the young, with a marked preference for children and adults <30 years. SCD is most prevalent in patients with paediatric onset of HCM but may occur at any age. However, risk is substantially lower after 60 years, suggesting that the potential for ventricular tachyarrhythmias is mitigated by ageing. SCD had been linked originally to sports and vigorous activity in HCM patients. However, it is increasingly clear that the majority of events occurs at rest or during routine daily occupations, suggesting that triggers are far from consistent. In general, the pathophysiology of SCD in HCM remains unresolved. While the pathologic and physiologic substrates abound and have been described in detail, specific factors precipitating ventricular tachyarrhythmias are still unknown. SCD is a rare phenomenon in HCM cohorts (<1%/year) and attempts to identify patients at risk, while generating clinically useful algorithms for primary prevention, remain very inaccurate on an individual basis. One of the reasons for our limited understanding of these phenomena is that limited translational research exists in the field, while most efforts have focused on clinical markers of risk derived from pathology, instrumental patient evaluation, and imaging. Specifically, few studies conducted in animal models and human samples have focused on targeting the cellular mechanisms of arrhythmogenesis in HCM, despite potential implications for therapeutic innovation and SCD prevention. These studies found that altered intracellular Ca2+ homoeostasis and increased late Na+ current, leading to an increased likelihood of early and delayed after-depolarizations, contribute to generate arrhythmic events in diseased cardiomyocytes. As an array of novel experimental opportunities have emerged to investigate these mechanisms, including novel 'disease-in-the-dish' cellular models with patient-specific induced pluripotent stem cell-derived cardiomyocytes, important gaps in knowledge remain. Accordingly, the aim of the present review is to provide a contemporary reappraisal of the cellular basis of SCD-predisposing arrhythmias in patients with HCM and discuss the implications for risk stratification and management.

Interpretation of Incidental Genetic Findings Localizing to Genes Associated With Cardiac Channelopathies and Cardiomyopathies

Recent advances in next-genetic sequencing technology have facilitated an expansion in the use of exome and genome sequencing in the research and clinical settings. While this has aided in the genetic diagnosis of individuals with atypical clinical presentations, there has been a marked increase in the number of incidentally identified variants of uncertain diagnostic significance in genes identified as clinically actionable by the American College of Medical Genetics guidelines. Approximately 20 of these genes are associated with cardiac diseases, which carry a significant risk of sudden cardiac death. While identification of at-risk individuals is paramount, increased discovery of incidental variants of uncertain diagnostic significance has placed a burden on the clinician tasked with determining the diagnostic significance of these findings. Herein, we describe the scope of this emerging problem using cardiovascular genetics to illustrate the challenges associated with variants of uncertain diagnostic significance interpretation. We review the evidence for diagnostic weight of these variants, discuss the role of clinical genetics providers in patient care, and put forward general recommendations about the interpretation of incidentally identified variants found with clinical genetic testing.

Clinical prediction of genotypes in hypertrophic cardiomyopathy: A systematic review

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac condition and the most common cause of sudden cardiac death (SCD) in patients below the age of 35. Genetic testing is a vital part of HCM diagnostics, yet correlation with clinical phenotypes remains complex. Identifying clinical predictors of informative genetic testing may prevent unnecessary investigations and improve cost-effectiveness of services. This article reviews the current literature pertinent to identifying such predictors.

METHODS

Five literature databases were screened using a suitably designed search strategy. Studies investigating the correlation between having a positive genetic test for HCM and a range of clinical and radiological parameters were included in the systematic review.

RESULTS

Twenty-nine observational studies of a total of 9,486 patients were included. The main predictors of informative genetic testing were younger age, higher septal thickness, reverse septal curvature, family history of HCM and SCD and the absence of hypertension. Two externally validated scoring systems have also been developed: the Mayo and Toronto scores. Novel imaging markers and complex algorithmic models are emerging predictors.

CONCLUSION

Using clinical predictors to decide whom to test is a feasible alternative to investigating all comers. Nonetheless, currently there is not enough evidence to unequivocally recommend for or against this strategy. Further validation of current predictors and identification of new ones remain open research avenues.

Genotype-phenotype association by echocardiography offers incremental value in patients with Noonan Syndrome with Multiple Lentigines

BACKGROUND

Noonan Syndrome with Multiple Lentigines (NSML) and Noonan Syndrome (NS) can be difficult to differentiate clinically in early childhood. This study aims to describe characteristics of the ventricular septum that may differentiate NSML from NS. We hypothesize that the shape of the ventricular septum determined by echocardiography correlates with genotype and may distinguish patients with NSML from those with NS.

METHODS

We analyzed data from 17 NSML and 67 NS patients. Forty normal and 30 sarcomeric hypertrophic cardiomyopathy (HCM) patients were included as controls. Septal morphology was qualitatively evaluated, and septal angle was measured quantitatively at end diastole. We recorded the presence of a ventricular septal bulge (VSB) and reviewed genetic testing results for each patient.

RESULTS

The most important findings were a sigmoid septum (71%) and VSB (71%) in NSML. NSML septal angle was decreased compared to the normal and sarcomeric HCM control groups, respectively (149 ± 13 vs. 177 ± 3, p < 0.001; 149 ± 13 vs. 172 ± 7, p < 0.001). NS septal angle was similar to the controls (176 ± 6 vs. 177 ± 3, p > 0.5; 176 ± 6 vs. 172 ± 7, p > 0.5). NSML-linked pathogenic variants were associated with sigmoid septum and VSB.

CONCLUSIONS

These findings provide novel phenotypic evidence to clinicians that may offer incremental diagnostic value in counseling families in ambiguous NSML/NS cases.

IMPACT

Characteristics of the ventricular septum are linked to specific gene variants that cause NSML and NS. Sigmoid septum and VSB are associated with NSML. This novel echocardiographic association may help clinicians distinguish NSML from NS in ambiguous cases. Early distinction between the two may be important, as syndrome-specific therapies may become available in the near future. This study may encourage further research into genotype-phenotype associations in other forms of HCM.

Genetics of Cardiomyopathy: Clinical and Mechanistic Implications for Heart Failure

Genetic cardiomyopathies are an important cause of sudden cardiac death across all age groups. Genetic testing in heart failure clinics is useful for family screening and providing individual prognostic insight. Obtaining a family history of at least three generations, including the creation of a pedigree, is recommended for all patients with primary cardiomyopathy. Additionally, when appropriate, consultation with a genetic counsellor can aid in the success of a genetic evaluation. Clinical screening should be performed on all first-degree relatives of patients with genetic cardiomyopathy.

Genetics has played an important role in the understanding of different cardiomyopathies, and the field of heart failure (HF) genetics is progressing rapidly. Much research has also focused on distinguishing markers of risk in patients with cardiomyopathy using genetic testing. While these efforts currently remain incomplete, new genomic technologies and analytical strategies provide promising opportunities to further explore the genetic architecture of cardiomyopathies, afford insight into the early manifestations of cardiomyopathy, and help define the molecular pathophysiological basis for cardiac remodeling. Cardiovascular physicians should be fully aware of the utility and potential pitfalls of incorporating genetic test results into pre-emptive treatment strategies for patients in the preliminary stages of HF. Future work will need to be directed towards elucidating the biological mechanisms of both rare and common gene variants and environmental determinants of plasticity in the genotype-phenotype relationship. This future research should aim to further our ability to identify, diagnose, and treat disorders that cause HF and sudden cardiac death in young patients, as well as prioritize improving our ability to stratify the risk for these patients prior to the onset of the more severe consequences of their disease.

Septal myectomy in the era of genetic testing

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is one of the most common genetic cardiac diseases and encompasses an array of clinical presentations. Little is known about the impact of genetic background on outcomes after septal myectomy (SM). The aim of this study was to evaluate the effect of specific genetic mutations on midterm outcomes in adults undergoing SM for HOCM.

METHODS

From 2003 to 2020, a total of 59 patients (male = 66%, mean age = 52 ± 13) underwent SM after a preoperative genetic test. Patients were divided into two groups according to their test result (positive or negative). Preoperative echocardiograms were examined to identify phenotypical characteristics of each mutation.

RESULTS

A total of thirty-one patients (53%) had a positive genetic test. MYBPC3 was the most common mutation (15/31 patients). Four different phenotypes were identified on preoperative echocardiograms. Overall, Type 1 phenotype was the most common (37% of the cohort). Type 3 was found exclusively in patients with a positive genetic test. Following SM, none of the patients required a redo myectomy or septal ablation. At 10 years, the survival was 97 ± 3% and 100% in patients with a positive and negative genetic test (p = .33), respectively.

CONCLUSION

Although our results suggest that the multiple gene mutations present with different characteristics and phenotypes, midterm results of SM appear to be good regardless of genetic mutation presence.

Deep learning algorithm to improve hypertrophic cardiomyopathy mutation prediction using cardiac cine images

OBJECTIVES

The high variability of hypertrophic cardiomyopathy (HCM) genetic phenotypes has prompted the establishment of risk-stratification systems that predict the risk of a positive genetic mutation based on clinical and echocardiographic profiles. This study aims to improve mutation-risk prediction by extracting cardiovascular magnetic resonance (CMR) morphological features using a deep learning algorithm.

METHODS

We recruited 198 HCM patients (48% men, aged 47 ± 13 years) and divided them into training (147 cases) and test (51 cases) sets based on different genetic testing institutions and CMR scan dates (2012, 2013, respectively). All patients underwent CMR examinations, HCM genetic testing, and an assessment of established genotype scores (Mayo Clinic score I, Mayo Clinic score II, and Toronto score). A deep learning (DL) model was developed to classify the HCM genotypes, based on a nonenhanced four-chamber view of cine images.

RESULTS

The areas under the curve (AUCs) for the test set were Mayo Clinic score I (AUC: 0.64, sensitivity: 64.29%, specificity: 47.83%), Mayo Clinic score II (AUC: 0.70, sensitivity: 64.29%, specificity: 65.22%), Toronto score (AUC: 0.74, sensitivity: 75.00%, specificity: 56.52%), and DL model (AUC: 0.80, sensitivity: 85.71%, specificity: 69.57%). The combination of the DL and the Toronto score resulted in a significantly higher predictive performance (AUC = 0.84, sensitivity: 83.33%, specificity: 78.26%), compared with Mayo I (p = 006), Mayo II (p = 022), and Toronto score (p = 0.029).

CONCLUSIONS

The combination of the DL model, based on nonenhanced cine CMR images and the Toronto score yielded significantly higher diagnostic performance in detecting HCM mutations.

KEY POINTS

• Deep learning method could enable the extraction of image features from cine images. • Deep learning method based on cine images performed better than established scores in identifying HCM patients with positive genotypes. • The combination of the deep learning method based on cine images and the Toronto score could further improve the performance of the identification of HCM patients with positive genotypes.

Palpitation was associated with clinical outcomes in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disease with diversified clinical presentation and it is important to identify new predictors of clinical outcomes and survival in HCM patients. In our study, 206 HCM patients were compared with respect to major adverse cardiovascular and cerebrovascular events. By multivariable logistic analysis, we determined that palpitation, together with chronic heart failure (CHF) > 1 year, was an independent predictor of major adverse cardiovascular and cerebral events (MACCE) in HCM patients (OR 3.24, 95% CI 1.60–6.57, P = 0.001). Specially, palpitation was related to higher prevalence of rehospitalization (OR 3.86, 95% CI 2.08–7.08, P < 0.001), cardiac death (OR 2.96, 95% CI 1.05–8.32, P = 0.04) and heart failure exacerbation (OR 4.07, 95% CI 2.04–8.13, P < 0.001). However, patients presented with palpitation did not show a significantly different cardiac phenotype and function. Finally, palpitation predicted a poor prognosis in HCM patients without atrial fibrillation by utilizing Kaplan–Meier analysis (P = 0.041). In conclusion, palpitation could be a new predictor of clinical outcomes and overall survival in HCM patients.

The role of echocardiography for diagnosis and prognostic stratification in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most frequent cardiac disease with genetic substrate, affecting about 0.2-0.5% of the population. While most of the patients with HCM have a relatively good prognosis, some are at increased risk of adverse events. Identifying such patients at risk is important for optimal treatment and follow-up. While clinical and electrocardiographic information plays an important role, echocardiography remains the cornerstone in assessing patients with HCM. In this review, we discuss the role of echocardiography in diagnosing HCM, the key features that differentiate HCM from other diseases and the use of echocardiography for risk stratification in this setting (risk of sudden cardiac death, heart failure, atrial fibrillation and stroke). The use of modern echocardiographic techniques (deformation imaging, 3D echocardiography) refines the diagnosis and prognostic assessment of patients with HCM. The echocardiographic data need to be integrated with clinical data and other information, including cardiac magnetic resonance, especially in challenging cases or when there is incomplete information, for the optimal management of these patients.

The Surgeon's View of the Left Ventricular Outflow Tract in Congenital Heart Surgery

Left ventricular outflow tract (LVOT) obstruction is a component of many forms of congenital heart disease, including hypertrophic cardiomyopathy, membranous subaortic stenosis, tunnel subaortic stenosis, and outflow tract obstruction related to atrioventricular septal defects. We have gained a particularly extensive experience with the diagnosis and treatment of hypertrophic cardiomyopathy, having performed septal myectomy in over 3,800 patients. In the setting of this review of LVOT obstruction, we use hypertrophic cardiomyopathy as a template by which other pathologies causing LVOT obstruction can be understood. We review important surgical issues in patient selection, diagnostic evaluation, interpretation of imaging, and operative management. To this end, the review focuses on obstructive hypertrophic cardiomyopathy and then broadens to discuss other pathologies causing LVOT obstruction, with important similarities and differences in their management. These other pathologies share some similar presentations and operative techniques, and at times can be confused with hypertrophic cardiomyopathy, but also have important distinctions of which the surgeon should be aware.

Effectiveness of Bokeria-Boldyrev ACH Solution in Surgerical Treatment of Adult Patients with Obstructive Hypertrophic Cardiomyopathy

The study examined effectiveness of pharmaco-cold cardioplegia employing solutions of enhanced buffer capacity during surgery of obstructive hypertrophic cardiomyopathy in adult patients (N=51) operated during 2013-2018. In group 1 (N=28), the cardioplegia was performed with HTK (Custodiol) solution, whereas in group 2 (N=23), it was carried out with Bokeria-Boldyrev ACH solution. The mean, minimum, and maximum ages in group 1 were 46, 21, and 64 years, respectively; in group 2 - 42, 14, and 70 years, respectively. In both groups, the patients were subjected to myoectomy of exit pathway in the left ventricle according to Bokeria-Morrow operation and annuloplasty of tricuspid valve accompanied by reconstructive surgery (or replacement) of mitral valve. Atrial fibrillation (if any) was suppressed with cryoablation (-60°С) of the openings of the right and left pulmonary veins. The surgery was carried out in hypothermic mode at 28°C. The significant intergroup differences were observed in the asystole latent period after the onset of antegrade or retrograde injection of cardioplegic solution. In group 1, the asystole latent periods determined after antegrade or retrograde injection were 53±7 or 170±30 sec, respectively; in group 2 - 32±6 and 97±11 sec (p<0.0001), respectively. The mean times of aortic cross-clumping in groups 1 and 2 were 66±8 and 64±6 min, respectively; the electromechanical action of the heart restored after aortic unclamping in 35±7 and 30±6 sec, respectively. The biochemical and clinical data revealed no significant intergroup differences. Overall, novel Bokeria-Boldyrev ACH cardioplegic solution secured effective protection of the myocardium against intraoperative ischemia in adult patients with obstructive hypertrophic cardiomyopathy and significantly decreased the asystole latent period.

Molecular mechanisms of action of resveratrol in modulation of diabetic and non-diabetic cardiomyopathy

Cardiomyopathy is among the major clinical manifestations of heart diseases that triggers malfunctioning of the cardiovascular system. Some of the major causal factors of cardiomyopathy includes myocardial ischemia, drug-toxicity, genetic aberrations, abnormal depositions of essential elements, and redox imbalance. Diabetes, being the major comorbid of cardiovascular diseases and vice versa, further contributes to the progression of cardiomyopathy. The molecular mechanisms of action suggest that oxidative stress is among the primary factors that triggers cascading impact on cardiomyopathy. Resveratrol, a phenolic antioxidant, has the potential to quench the excessive free radicals. It is a potent antioxidant supplement that may as well be a therapeutic molecule. The review focuses on the various molecular mechanisms of action that resveratrol potentiates in reversing or attenuating the progress of diabetic and non-diabetic cardiomyopathy triggered by wide range of factors. Additionally, resveratrol also tends to preserve the healthy heart from potential damage that may be triggered by oxidative stress.

Genotype-Related Clinical Characteristics and Myocardial Fibrosis and their Association with Prognosis in Hypertrophic Cardiomyopathy

BACKGROUND

The spectrum of genetic variants and their clinical significance of Hypertrophic cardiomyopathy (HCM) have been poorly studied in Asian patients. The objectives of this study were to assess the spectrum of genetic variants and genotype-phenotype relationships within a Korean HCM population.

METHODS

Eighty-nine consecutive unrelated HCM patients were included. All patients underwent genotypic analysis for 23 HCM-associated genes. Clinical parameters including echocardiographic and cardiac magnetic resonance (CMR) parameters were evaluated. A composite of major adverse cardiac and cerebrovascular events was assessed.

RESULTS

Genetic variants were detected in 55 of 89 subjects. Pathogenic variants or likely pathogenic variants were identified in 27 of HCM patients in MYBPC3, TNNI3, MYH7, and MYL7. Variants of uncertain significance were identified in 28 patients. There were significant differences in the presence of non-sustained ventricular tachycardia (p = 0.030) and myocardial fibrosis on CMR (p = 0.029) in the detected compared to the not-detected groups. Event-free survival was superior in the not-detected group (p = 0.006).

CONCLUSION

Genetic variants in patients with HCM are relatively common and are associated with adverse clinical events and myocardial fibrosis on CMR. Genotypic analysis may add important information to clinical variables in the assessment of long-term risk for HCM patients.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease. The disease is characterized by marked variability in morphological expression and natural history, ranging from asymptomatic to heart failure or sudden cardiac death. Left ventricular hypertrophy and abnormal ventricular configuration result in dynamic left ventricular outflow obstruction in most patients. The goal of pharmacological therapy in HCM is to alleviate the symptoms, and it includes pharmacotherapies and septal reduction therapies. In this review, we summarize the relevant clinical issues and treatment options of HCM.