The clinical features, outcomes and genetic characteristics of hypertrophic cardiomyopathy patients with severe right ventricular hypertrophy

Unveiling the Spectrum of Minor Genes in Cardiomyopathies: A Narrative Review

Hereditary cardiomyopathies (CMPs), including arrhythmogenic cardiomyopathy (ACM), dilated cardiomyopathy (DCM), and hypertrophic cardiomyopathy (HCM), represent a group of heart disorders that significantly contribute to cardiovascular morbidity and mortality and are often driven by genetic factors. Recent advances in next-generation sequencing (NGS) technology have enabled the identification of rare variants in both well-established and minor genes associated with CMPs. Nowadays, a set of core genes is included in diagnostic panels for ACM, DCM, and HCM. On the other hand, despite their lesser-known status, variants in the minor genes may contribute to disease mechanisms and influence prognosis. This review evaluates the current evidence supporting the involvement of the minor genes in CMPs, considering their potential pathogenicity and clinical significance. A comprehensive analysis of databases, such as ClinGen, ClinVar, and GeneReviews, along with recent literature and diagnostic guidelines provides a thorough overview of the genetic landscape of minor genes in CMPs and offers guidance in clinical practice, evaluating each case individually based on the clinical referral, and insights for future research. Given the increasing knowledge on these less understood genetic factors, future studies are essential to clearly assess their roles, ultimately leading to improved diagnostic precision and therapeutic strategies in hereditary CMPs.

Mavacamten in Right Ventricular Outflow Tract Obstruction

Right ventricular outflow tract (RVOT) obstruction is a rare complication of ventricular hypertrophy in patients with hypertrophic cardiomyopathy (HCM). This study presents an unusual case of a patient with HCM with severe RVOT obstruction that was relieved successfully through the use of mavacamten.

Clinical Significance of Physical Examination for Hypertrophic Cardiomyopathy

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) show various physical findings, but their clinical significance has not been systematically evaluated.

METHODS AND RESULTS

This study evaluated 105 consecutive patients with HCM who had undergone phonocardiography and external pulse recording. Physical examinations included a visible jugular a-wave (Jug-a), audible 4th sound (S4), and double or sustained apex beat. The primary outcome was a composite of all-cause death and hospitalization for cardiovascular disease. A total of 104 non-HCM subjects served as controls. The prevalence of visible Jug-a in the seated or supine position, audible S4, and a sustained or double apex beat in patients with HCM were 10%, 71%, 70%, 42%, and 27%, respectively, all of which were significantly higher than in the controls (0%, 20%, 11%, 17%, and 2%; P<0.001 for all comparisons). The combination of visible Jug-a in the supine position and audible S4 yielded a specificity of 94% and sensitivity of 57%. During a follow-up period of 6.6 years, 6 patients died and 10 were hospitalized. The absence of audible S4 was a predictor of cardiovascular events (hazard ratio, 3.91; 95% confidence interval, 1.41 to 10.8; P=0.005).

CONCLUSIONS

Detection of these findings has clinical importance in the diagnosis and risk stratification of HCM prior to the use of advanced imaging techniques.

Implications of structural right ventricular involvement in patients with hypertrophic cardiomyopathy

AIMS

In the clinical practice, the right ventricular (RV) manifestations have received less attention in hypertrophic cardiomyopathy (HCM). This paper aimed to evaluate the risk prediction value and genetic characteristics of RV involvement in HCM patients.

METHODS AND RESULTS

A total of 893 patients with HCM were recruited. RV hypertrophy, RV obstruction, and RV late gadolinium enhancement were evaluated by echocardiography and/or cardiac magnetic resonance. Patients with any of the above structural abnormalities were identified as having RV involvement. All patients were followed with a median follow-up time of 3.0 years. The primary endpoint was cardiovascular death; the secondary endpoints were all-cause death and heart failure (HF)-related death. Survival analyses were conducted to evaluate the associations between RV involvement and the endpoints. Genetic testing was performed on 669 patients. RV involvement was recognized in 114 of 893 patients (12.8%). Survival analyses demonstrated that RV involvement was an independent risk factor for cardiovascular death (P = 0.002), all-cause death (P = 0.011), and HF-related death (P = 0.004). These outcome results were then confirmed by a sensitivity analysis. Genetic testing revealed a higher frequency of genotype-positive in patients with RV involvement (57.0% vs. 31.0%, P < 0.001), and the P/LP variants of MYBPC3 were more frequently identified in patients with RV involvement (30.4% vs. 12.0%, P < 0.001). Logistic analyses indicated the independent correlation between RV involvement and these genetic factors.

CONCLUSION

RV involvement was an independent risk factor for cardiovascular death, all-cause death and HF-related death in HCM patients. Genetic factors might contribute to RV involvement in HCM.

The role of the M-band myomesin proteins in muscle integrity and cardiac disease

Transversal structural elements in cross-striated muscles, such as the M-band or the Z-disc, anchor and mechanically stabilize the contractile apparatus and its minimal unit—the sarcomere. The ability of proteins to target and interact with these structural sarcomeric elements is an inevitable necessity for the correct assembly and functionality of the myofibrillar apparatus. Specifically, the M-band is a well-recognized mechanical and signaling hub dealing with active forces during contraction, while impairment of its function leads to disease and death. Research on the M-band architecture is focusing on the assembly and interactions of the three major filamentous proteins in the region, mainly the three myomesin proteins including their embryonic heart (EH) isoform, titin and obscurin. These proteins form the basic filamentous network of the M-band, interacting with each other as also with additional proteins in the region that are involved in signaling, energetic or mechanosensitive processes. While myomesin-1, titin and obscurin are found in every muscle, the expression levels of myomesin-2 (also known as M-protein) and myomesin-3 are tissue specific: myomesin-2 is mainly expressed in the cardiac and fast skeletal muscles, while myomesin-3 is mainly expressed in intermediate muscles and specific regions of the cardiac muscle. Furthermore, EH-myomesin apart from its role during embryonic stages, is present in adults with specific cardiac diseases. The current work in structural, molecular, and cellular biology as well as in animal models, provides important details about the assembly of myomesin-1, obscurin and titin, the information however about the myomesin-2 and -3, such as their interactions, localization and structural details remain very limited. Remarkably, an increasing number of reports is linking all three myomesin proteins and particularly myomesin-2 to serious cardiovascular diseases suggesting that this protein family could be more important than originally thought. In this review we will focus on the myomesin protein family, the myomesin interactions and structural differences between isoforms and we will provide the most recent evidence why the structurally and biophysically unexplored myomesin-2 and myomesin-3 are emerging as hot targets for understanding muscle function and disease.

CSRP3, p.Arg122*, is responsible for hypertrophic cardiomyopathy in a Chinese family

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a hereditary disease manifested by a thickened ventricular wall. Cysteine and glycine-rich protein 3 (CSRP3), the gene encoding muscle LIM protein, is important for initiating hypertrophic gene expression. The mutation of CSRP3 causes dilated cardiomyopathy or HCM.

METHODS

In the present study, we enrolled a Chinese family with HCM across three generations. Whole-exome sequencing (WES) was performed in the proband to detect the candidate genes of the family. Sanger sequencing was performed for mutational analysis and confirmation of cosegregation.

RESULTS

Through histopathological and imaging examinations, an obvious left ventricular hypertrophy was found in the proband. After WES data filtering, bioinformatic prediction and co-segregation analysis, a nonsense mutation (NM_003476.5:c.364C>T; NP_003467.1:p.Arg122*) of CSRP3 was identified in this family. This variant was predicted to be disease-causing and resulted in a truncated protein.

CONCLUSIONS

This is the first HCM family case of CSRP3 (p.Arg122*) variation in Asia. The finding here not only contributes to the genetic diagnosis and counseling of the family, but also provides a new case with detailed phenotypes that may be caused by the CSRP3 variant.

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.

Severe right ventricular hypertrophy in hypertrophic cardiomyopathy: Serious symptoms, complex surgical procedures, and poor prognosis in Fuwai Hospital

OBJECTIVE

Severe right ventricular hypertrophy (SRVH) in hypertrophic cardiomyopathy (HCM) is rare. We studied the clinical characteristics and prognosis of 36 patients with HCM and SRVH in a Chinese cohort.

METHODS

Patients with HCM and SRVH were enrolled between 2013 and 2017. The clinical characteristics, treatment therapies, and clinical outcomes of the 36 patients were retrospectively studied and compared with those of 128 patients without SRVH.

RESULTS

Patients in the group with SRVH were younger than those in the group without SRVH (27.58±15.09 years vs 40.34±13.21 years, respectively; p<0.001). Patients with SRVH had more serious clinical symptoms and a higher New York Heart Association functional class than those without SRVH. Most patients in the group with SRVH exhibited diffuse RV hypertrophy, and 13 patients presented with biventricular outflow tract obstruction. Maximal left ventricular (LV) wall thickness (27.29±7.95 mm vs 24.33±5.85 mm, respectively; p=0.027) and LV outflow tract gradient (80.83±24.41 mm Hg vs 42.3±5.7 mm Hg, respectively; p=0.000) were significantly greater in patients with SRVH than in those without SRVH. A total of 30 patients in the group with SRVH underwent surgical correction. During a median follow-up period of 48 months, six patients with SRVH reached primary clinical endpoints (four sudden cardiac deaths, one heart failure-related death, and one heart transplantation), whereas only two deaths occurred in the patients without SRVH.

CONCLUSION

We conclude that patients with HCM and SRVH exhibit serious symptoms and have complex surgical requirements and poor clinical outcomes.

Right ventricular involvement in hypertrophic cardiomyopathy: evidence and implications from current literature

Objectives. In current guidelines, hypertrophic cardiomyopathy (HCM) is defined by hypertrophy of the left ventricle (LV). Less attention has been given to the right ventricle (RV) in patients with HCM. We wanted to provide an overview of current literature on RV involvement in HCM. Design. We performed a systematic search in PubMed and added additional articles by manual screening of references. The quality of the articles was assessed according to the GRADE system. Results. We identified 35 original articles on RV involvement in HCM. Based on these publications, RV hypertrophy occurs in 28-44% of HCM patients, depending on the cut-off value for hypertrophy and the method for assessment. Histological studies show the same structural changes in RV as are typically described in the LV cardiomyocyte hypertrophy and disarray, as well as fibrosis. These changes are similar, but less pronounced in the RV than in the LV. We discuss how HCM can impact the RV, either through a primary involvement similar to the LV or secondary to hemodynamic effects resulting from LV dysfunction. RV dysfunction in HCM is associated with higher mortality, partly due to an increased risk of ventricular tachycardia and sudden cardiac death. Conclusions. The evidence for RV involvement in HCM is limited. Multimodal imaging assessment of the RV should be included in the work-up of patients with HCM, and the added value of including RV function in the risk stratification algorithm should be further explored.

Role of Cardiac Magnetic Resonance in Detecting Biventricular Apical Hypertrophic Cardiomyopathy

Apical Hypertrophic Cardiomyopathy (ApHCM) is a rare variant of hypertrophic cardiomyopathy with a low prevalence in the general population. ApHCM with right ventricular involvement (BiApHCM) is largely unreported and may not be detected with conventional transthoracic echocardiogram (TTE) alone. Cardiac Magnetic Resonance (CMR) has been demonstrated to be a proficient imaging modality to diagnose BiApHCM. We present a case of BiApHCM that was diagnosed with TTE and further characterized by CMR. This imaging modality may be utilized more in the future to help diagnose and detect the prevalence of BiApHCM.

Prevalence, functional characteristics, and clinical significance of right ventricular involvement in patients with hypertrophic cardiomyopathy

We sought to investigate the prevalence, functional characteristics, and clinical significance of right ventricular (RV) involvement in patients with hypertrophic cardiomyopathy (HCM). A total of 256 patients with HCM who underwent both cardiac magnetic resonance (CMR) imaging and transthoracic echocardiography within 6 months of each other were retrospectively analysed. RV involvement was defined as an increased RV wall thickness ≥ 7 mm on CMR in the segments of the RV free wall. Primary outcomes were defined as the composite of all-cause death, heart transplantation, and unplanned cardiovascular admission. Thirty-seven (14.4%) patients showed RV involvement. Patients with RV involvement showed a significantly higher left ventricular (LV) maximal wall thickness and left atrial volume index. Multivariate Cox model revealed that RV involvement was independently associated with primary outcomes (HR: 2.30, p = 0.024). In a subgroup analysis of patients with speckle tracking echocardiography (n = 190), those with RV involvement had significantly more impaired RV strain, which was independently associated with primary outcomes. RV involvement in patients with HCM correlated with more advanced LV structure and biventricular dysfunction, suggesting an indicator of severe HCM. RV involvement and impaired RV strain have a prognostic value related to clinical adverse events in patients with HCM.

Possible Azithromycin-Induced Life-Threatening Arrhythmia Requiring Extracorporeal Membrane Oxygenation Support: A Case Report

Patient: Female, 37-year-old

Final Diagnosis: Ventricular arrhythmia

Symptoms: Arrhythmia

Medication: Azithromycin

Clinical Procedure: ECMO insertion

Specialty: Cardiac surgery • Cardiology • Critical Care Medicine

Arrhythmic risk stratification by cardiac magnetic resonance tissue characterization: disclosing the arrhythmic substrate within the heart muscle

Sudden cardiac death (SCD) is a pivotal health problem worldwide. The identification of subjects at increased risk of SCD is crucial for the accurate selection of candidates for implantable cardioverter defibrillator (ICD) therapy. Current strategies for arrhythmic stratification largely rely on left ventricular (LV) ejection fraction (EF), mostly measured by echocardiography, and New York Heart Association functional status for heart failure with reduced EF. For specific diseases, such as hypertrophic and arrhythmogenic cardiomyopathy, some risk scores have been proposed; however, these scores take into account some parameters that are a partial reflection of the global arrhythmic risk and show a suboptimal accuracy. Thanks to a more comprehensive evaluation, cardiac magnetic resonance (CMR) provides insights into the heart muscle (the so-called tissue characterization) identifying cardiac fibrosis as an arrhythmic substrate. Combining sequences before and after administration of contrast media and mapping techniques, CMR is able to characterize the myocardial tissue composition, shedding light on both intracellular and extracellular alterations. Over time, late gadolinium enhancement (LGE) emerged as solid prognostic marker, strongly associated with major arrhythmic events regardless of LVEF, adding incremental value over current strategy in ischemic heart disease and non-ischemic cardiomyopathies. The evidence on a potential prognostic role of mapping imaging is promising. However, mapping techniques require further investigation and standardization. Disclosing the arrhythmic substrate within the myocardium, CMR should be considered as part of a multiparametric approach to personalized arrhythmic stratification.

Right ventricular phenotype, function, and failure: a journey from evolution to clinics

The right ventricle has long been perceived as the "low pressure bystander" of the left ventricle. Although the structure consists of, at first glance, the same cardiomyocytes as the left ventricle, it is in fact derived from a different set of precursor cells and has a complex three-dimensional anatomy and a very distinct contraction pattern. Mechanisms of right ventricular failure, its detection and follow-up, and more specific different responses to pressure versus volume overload are still incompletely understood. In order to fully comprehend right ventricular form and function, evolutionary biological entities that have led to the specifics of right ventricular physiology and morphology need to be addressed. Processes responsible for cardiac formation are based on very ancient cardiac lineages and within the first few weeks of fetal life, the human heart seems to repeat cardiac evolution. Furthermore, it appears that most cardiogenic signal pathways (if not all) act in combination with tissue-specific transcriptional cofactors to exert inductive responses reflecting an important expansion of ancestral regulatory genes throughout evolution and eventually cardiac complexity. Such molecular entities result in specific biomechanics of the RV that differs from that of the left ventricle. It is clear that sole descriptions of right ventricular contraction patterns (and LV contraction patterns for that matter) are futile and need to be addressed into a bigger multilayer three-dimensional picture. Therefore, we aim to present a complete picture from evolution, formation, and clinical presentation of right ventricular (mal)adaptation and failure on a molecular, cellular, biomechanical, and (patho)anatomical basis.

Soluble ST2, Galectin-3 and clinical prognosis of patients with hypertrophic cardiomyopathy undergoing ventricular septal myectomy: a correlation analysis

Background

Hypertrophic cardiomyopathy (HCM) is the most common chromosomal abnormal heart disease. The pathophysiological mechanism of HCM is complex. Several studies have suggested that the level of Soluble ST2 (sST2) may be a biomarker of chronic systolic heart failure, however, the role of sST2 in HCM remains unclear. So we performed this study to analyze the role of Soluble ST2 (sST2), Galectin-3 (Gal-3) and its correlations with clinical prognosis of patients with hypertrophic cardiomyopathy (HCM) undergoing ventricular septal myectomy.

Methods

HCM patients who underwent modified Morrow surgery in our hospital during June 2016-June 2018 were included. We divided the patients into different groups stratified by sST2 and Gal-3 level. Besides, we included volunteers without heart disease for medical examination as normal controls. Biochemical analyses were conducted to identify the biomarkers difference. The predictive value of sST2 and Gal-3 on all-cause mortality was evaluated with Cox regression analysis.

Results

A total of 125 HCM patients were included in this present study. The sST2 and Gal-3 levels in HCM patients were significantly higher than that in control group (all P<0.001); there were significant differences in the incidence of all-cause mortality for HCM patients stratified by the sST2 and Gal-3 level; Cox univariate regression survival analysis showed that the hypertension (HR =1.19, 95% CI: 1.01-1.38), maximum wall thickness (HR =1.48, 95% CI: 1.04-1.98), Log sST2 (HR =1.02, 95% CI: 1.01-1.05), Log Gal-3 (HR =1.17, 95% CI: 1.09-1.32) were the predictors for all-cause mortality in patients with HCM, and Cox multivariate risk regression showed that maximum wall thickness was the independent predictors of all-cause mortality in patients with HCM (HR =1.63, 95% CI: 1.35-1.97).

Conclusions

Even through sST2 and Gal-3 were not associated with clinical prognosis of patients with HCM undergoing ventricular septal myectomy, it may be involved in the progress of HCM, more studies are warranted to identify the potential mechanism and reverence value.

Combining Nanomaterials and Developmental Pathways to Design New Treatments for Cardiac Regeneration: The Pulsing Heart of Advanced Therapies

The research for heart therapies is challenged by the limited intrinsic regenerative capacity of the adult heart. Moreover, it has been hampered by the poor results obtained by tissue engineering and regenerative medicine attempts at generating functional beating constructs able to integrate with the host tissue. For this reason, organ transplantation remains the elective treatment for end-stage heart failure, while novel strategies aiming to promote cardiac regeneration or repair lag behind. The recent discovery that adult cardiomyocytes can be ectopically induced to enter the cell cycle and proliferate by a combination of microRNAs and cardioprotective drugs, like anti-oxidant, anti-inflammatory, anti-coagulants and anti-platelets agents, fueled the quest for new strategies suited to foster cardiac repair. While proposing a revolutionary approach for heart regeneration, these studies raised serious issues regarding the efficient controlled delivery of the therapeutic cargo, as well as its timely removal or metabolic inactivation from the site of action. Especially, there is need for innovative treatment because of evidence of severe side effects caused by pleiotropic drugs. Biocompatible nanoparticles possess unique physico-chemical properties that have been extensively exploited for overcoming the limitations of standard medical therapies. Researchers have put great efforts into the optimization of the nanoparticles synthesis and functionalization, to control their interactions with the biological milieu and use as a viable alternative to traditional approaches. Nanoparticles can be used for diagnosis and deliver therapies in a personalized and targeted fashion. Regarding the treatment of cardiovascular diseases, nanoparticles-based strategies have provided very promising outcomes, in preclinical studies, during the last years. Efficient encapsulation of a large variety of cargos, specific release at the desired site and improvement of cardiac function are some of the main achievements reached so far by nanoparticle-based treatments in animal models. This work offers an overview on the recent nanomedical applications for cardiac regeneration and highlights how the versatility of nanomaterials can be combined with the newest molecular biology discoveries to advance cardiac regeneration therapies.

Right ventricular involvement in hypertrophic cardiomyopathy: Patterns and implications

Although hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy worldwide, the criteria for its definition and most of the literature concern the left ventricle, thus confirming the theory that the right ventricle is the neglected one. Right ventricular (RV) involvement includes structural and functional changes with significant impact on clinical presentation and prognosis. The pattern of RV hypertrophy can be variable with possible dynamic obstruction. Histological findings suggest similar pathogenetic changes in both ventricles supporting the common myopathic process with sarcomeric mutations. Systolic dysfunction of the RV is subtle, and the classical echocardiographic indices are usually within normal limits, while global longitudinal strain is significantly impaired. Diastolic dysfunction of the RV is also evident in patients with HCM possibly due to fibrosis of the RV free wall and/or the obstruction of the RV filling with significant prognostic implications. RV involvement in HCM is associated with increased incidence of supraventricular and ventricular arrhythmias, severe dyspnea, pulmonary thromboembolism, progressive heart failure, and increased risk of sudden cardiac death. Therefore, the RV should be routinely included in the detailed assessment of patients with HCM.

Isolated Severe Right Ventricular Hypertrophic Cardiomyopathy

A 26-year-old woman with a diagnosis of congenital heart disease was admitted to the hospital with exertional dyspnea, cyanotic complexion, and bilateral lower limb edema. All tests revealed isolated severe right ventricular hypertrophy. She was in poor condition, with a diminishing chance for routine surgical treatment, so she was scheduled for orthotopic homologous heart transplantation. After the operation, isolated severe right ventricular hypertrophic cardiomyopathy was confirmed histologically and pathologically. After the operation, the patient's cardiac function was normal. Exertional dyspnea, cyanotic complexion, and bilateral lower limb edema all improved postoperatively.

Phenotypic diversity identified by cardiac magnetic resonance in a large hypertrophic cardiomyopathy family with a single MYH7 mutation

Limited data is available on phenotypic variations with the same genotype in hypertrophic cardiomyopathy (HCM). The present study aims to explore the relationship between genotype and phenotype characterized by cardiovascular magnetic resonance (CMR) in a large Chinese family. A proband diagnosed with HCM from a multigenerational family underwent next-generation sequencing based on a custom sureSelect panel, including 117 candidate pathogenic genes associated with cardiomyopathies. All genetic results were confirmed by the Sanger sequencing method. All confirmed mutation carriers underwent CMR exam and myocardial tissue characterization using T1 mapping and late gadolinium enhancement (LGE) on a 3T scanner (Siemens Trio, Gemany). After clinical and genetic screening of 36 (including the proband) members of a large Chinese family, nineteen family members are determined to carry the single p.T1377M (c.4130C>T) mutation in the MYH7 gene. Of these 19 mutation carriers, eight are diagnosed with HCM, one was considered as borderline affected and ten are not clinically or phenotypically affected. Different HCM phenotypes are present in the nine affected individuals in this family. In addition, we have found different tissue characteristics assessed by T1 mapping and LGE in these individuals. We describe a family that demonstrates the diverse HCM phenotypes associated with a single MYH7 mutation.