Classification, Epidemiology, and Global Burden of Cardiomyopathies

A predictive model for dilated cardiomyopathy with pulmonary hypertension

Aims

Dilated cardiomyopathy (DCM) is defined as a serious cardiac disorder caused by the presence of left ventricular dilatation and contractile dysfunction in the absence of severe coronary artery disease and abnormal loading conditions. The incidence of cardiac death is markedly higher in patients with DCM with pulmonary hypertension (PH) than in DCM patients without PH. No previous studies have constructed a predictive model to predict PH in patients with DCM.

Methods

Data from 218 DCM patients (68.3% man; mean age 57.33) were collected. Patients were divided into low, intermediate and high PH‐risk groups based on the echocardiographic assessment at the tricuspid regurgitation peak velocity (TRV) in conjunction with the presence of echocardiographic signs from at least two different categories. Basic information, vital signs, comorbidities and biochemical data of each patient were determined. The impact of each parameter on PH probability was analysed by univariable and multivariable analyses, the data from which were employed to establish a predictive model. Finally, the discriminability, calibration ability and clinical efficacy of the model were verified for both the modelling group and the external validation group.

Results

We successfully applied a history of chronic obstructive pulmonary disease (COPD) or chronic bronchitis, systolic murmur (SM) at the tricuspid area, SM at the apex and brain natriuretic peptide (BNP) level to establish a model for predicting PH probability in DCM. The model was proven to have high accuracy and good discriminability (area under the receiver operating characteristic curve 0.889), calibration ability and clinical application value.

Conclusions

A model for predicting PH probability in patients with DCM was successfully established. The new model is reliable for predicting PH probability in DCM and has good clinical applicability.

Clinical Characteristics, Cardiac Magnetic Resonance Features, and Outcomes of Patients with Dilated Cardiomyopathy - An Experience from a South Asian Country

Objectives:

The objectives of the study were to evaluate the clinical presentation, cardiac magnetic resonance (CMR) features, and outcomes of patients with dilated cardiomyopathy (DCM).

Material and Methods:

A retrospective study was conducted at a tertiary care center of Pakistan. All patients who underwent CMR for further evaluation of DCM during the period of 2011–2019 and in whom CMR confirmed the diagnosis of DCM, were included in the study. Patients were followed up in the year 2020 for all-cause mortality and cardiovascular hospitalizations.

Results:

A total of 75 patients were included in the study. The mean age was 38.7 ± 13 with the majority (n = 57, 76%) being male. Dyspnea was the most common presenting symptom (n = 68, 90.7%). The mean left ventricle ejection fraction (LVEF) by CMR was 29.3 ± 12 and mean left ventricle stroke volume (LVSV) was 66.5 ± 31. Late gadolinium enhanced (LGE) was present in 28 (37.3%) patients. Follow-up was available in 61 patients with the mean follow-up duration of 39.7 ± 27 months. Most patients (40, 65.6%) experienced all-cause major adverse cardiovascular events (MACE) during the follow-up and mortality was observed in 10 (16.4%) patients. LVSV by CMR (P = 0.03), LVEF by CMR (P = 0.02), and presence of pericardial effusion (PE) (P = 0.01) were significantly associated with all-cause MACE. On multiregression analysis, SV by CMR was associated with all cause MACE (P = 0.048). The presence of LGE was associated with higher mortality (P = 0.03).

Conclusion:

LVSV, LVEF by CMR, and PE were significantly associated with all-cause MACE. LGE was associated with higher mortality. Our cohort had a relatively younger age of presentation and diagnosis, and a greater mortality on follow-up, when compared with other regions of the world.

Stem cell therapy for dilated cardiomyopathy

BACKGROUND

Stem cell therapy (SCT) has been proposed as an alternative treatment for dilated cardiomyopathy (DCM), nonetheless its effectiveness remains debatable.

OBJECTIVES

To assess the effectiveness and safety of SCT in adults with non-ischaemic DCM.

SEARCH METHODS

We searched CENTRAL in the Cochrane Library, MEDLINE, and Embase for relevant trials in November 2020. We also searched two clinical trials registers in May 2020.

SELECTION CRITERIA

Eligible studies were randomized controlled trials (RCT) comparing stem/progenitor cells with no cells in adults with non-ischaemic DCM. We included co-interventions such as the administration of stem cell mobilizing agents. Studies were classified and analysed into three categories according to the comparison intervention, which consisted of no intervention/placebo, cell mobilization with cytokines, or a different mode of SCT. The first two comparisons (no cells in the control group) served to assess the efficacy of SCT while the third (different mode of SCT) served to complement the review with information about safety and other information of potential utility for a better understanding of the effects of SCT.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references for eligibility, assessed trial quality, and extracted data. We undertook a quantitative evaluation of data using random-effects meta-analyses. We evaluated heterogeneity using the I² statistic. We could not explore potential effect modifiers through subgroup analyses as they were deemed uninformative due to the scarce number of trials available. We assessed the certainty of the evidence using the GRADE approach. We created summary of findings tables using GRADEpro GDT. We focused our summary of findings on all-cause mortality, safety, health-related quality of life (HRQoL), performance status, and major adverse cardiovascular events.

MAIN RESULTS

We included 13 RCTs involving 762 participants (452 cell therapy and 310 controls). Only one study was at low risk of bias in all domains. There were many shortcomings in the publications that did not allow a precise assessment of the risk of bias in many domains. Due to the nature of the intervention, the main source of potential bias was lack of blinding of participants (performance bias). Frequently, the format of the continuous data available was not ideal for use in the meta-analysis and forced us to seek strategies for transforming data in a usable format. We are uncertain whether SCT reduces all-cause mortality in people with DCM compared to no intervention/placebo (mean follow-up 12 months) (risk ratio (RR) 0.84, 95% confidence interval (CI) 0.54 to 1.31; I² = 0%; studies = 7, participants = 361; very low-certainty evidence). We are uncertain whether SCT increases the risk of procedural complications associated with cells injection in people with DCM (data could not be pooled; studies = 7; participants = 361; very low-certainty evidence). We are uncertain whether SCT improves HRQoL (standardized mean difference (SMD) 0.62, 95% CI 0.01 to 1.23; I² = 72%; studies = 5, participants = 272; very low-certainty evidence) and functional capacity (6-minute walk test) (mean difference (MD) 70.12 m, 95% CI -5.28 to 145.51; I² = 87%; studies = 5, participants = 230; very low-certainty evidence). SCT may result in a slight functional class (New York Heart Association) improvement (data could not be pooled; studies = 6, participants = 398; low-certainty evidence). None of the included studies reported major adverse cardiovascular events as defined in our protocol. SCT may not increase the risk of ventricular arrhythmia (data could not be pooled; studies = 8, participants = 504; low-certainty evidence). When comparing SCT to cell mobilization with granulocyte-colony stimulating factor (G-CSF), we are uncertain whether SCT reduces all-cause mortality (RR 0.46, 95% CI 0.16 to 1.31; I² = 39%; studies = 3, participants = 195; very low-certainty evidence). We are uncertain whether SCT increases the risk of procedural complications associated with cells injection (studies = 1, participants = 60; very low-certainty evidence). SCT may not improve HRQoL (MD 4.61 points, 95% CI -5.62 to 14.83; studies = 1, participants = 22; low-certainty evidence). SCT may improve functional capacity (6-minute walk test) (MD 140.14 m, 95% CI 119.51 to 160.77; I² = 0%; studies = 2, participants = 155; low-certainty evidence). None of the included studies reported MACE as defined in our protocol or ventricular arrhythmia. The most commonly reported outcomes across studies were based on physiological measures of cardiac function where there were some beneficial effects suggesting potential benefits of SCT in people with non-ischaemic DCM. However, it is unclear if this intermediate effects translates into clinical benefits for these patients. With regard to specific aspects related to the modality of cell therapy and its delivery, uncertainties remain as subgroup analyses could not be performed as planned, making it necessary to wait for the publication of several studies that are currently in progress before any firm conclusion can be reached.

AUTHORS' CONCLUSIONS

We are uncertain whether SCT in people with DCM reduces the risk of all-cause mortality and procedural complications, improves HRQoL, and performance status (exercise capacity). SCT may improve functional class (NYHA), compared to usual care (no cells). Similarly, when compared to G-CSF, we are also uncertain whether SCT in people with DCM reduces the risk of all-cause mortality although some studies within this comparison observed a favourable effect that should be interpreted with caution. SCT may not improve HRQoL but may improve to some extent performance status (exercise capacity). Very low-quality evidence reflects uncertainty regarding procedural complications. These suggested beneficial effects of SCT, although uncertain due to the very low certainty of the evidence, are accompanied by favourable effects on some physiological measures of cardiac function. Presently, the most effective mode of administration of SCT and the population that could benefit the most is unclear. Therefore, it seems reasonable that use of SCT in people with DCM is limited to clinical research settings. Results of ongoing studies are likely to modify these conclusions.

TEAD1 protects against necroptosis in postmitotic cardiomyocytes through regulation of nuclear DNA-encoded mitochondrial genes

The Hippo signaling effector, TEAD1 plays an essential role in cardiovascular development. However, a role for TEAD1 in postmitotic cardiomyocytes (CMs) remains incompletely understood. Herein we reported that TEAD1 is required for postmitotic CM survival. We found that adult mice with ubiquitous or CM-specific loss of Tead1 present with a rapid lethality due to an acute-onset dilated cardiomyopathy. Surprisingly, deletion of Tead1 activated the necroptotic pathway and induced massive cardiomyocyte necroptosis, but not apoptosis. In contrast to apoptosis, necroptosis is a pro-inflammatory form of cell death and consistent with this, dramatically higher levels of markers of activated macrophages and pro-inflammatory cytokines were observed in the hearts of Tead1 knockout mice. Blocking necroptosis by administration of necrostatin-1 rescued Tead1 deletion-induced heart failure. Mechanistically, genome-wide transcriptome and ChIP-seq analysis revealed that in adult hearts, Tead1 directly activates a large set of nuclear DNA-encoded mitochondrial genes required for assembly of the electron transfer complex and the production of ATP. Loss of Tead1 expression in adult CMs increased mitochondrial reactive oxygen species, disrupted the structure of mitochondria, reduced complex I-IV driven oxygen consumption and ATP levels, resulting in the activation of necroptosis. This study identifies an unexpected paradigm in which TEAD1 is essential for postmitotic CM survival by maintaining the expression of nuclear DNA-encoded mitochondrial genes required for ATP synthesis.

Genetic evaluation of cardiomyopathies in Qatar identifies enrichment of pathogenic sarcomere gene variants and possible founder disease mutations in the Arabs

Background

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are serious inherited heart diseases with various causative mutations identified. The full spectrum of causative mutations remains to be discovered, especially in understudied populations.

Methods

Here, we established the DOHA Registry and Biobank for cardiomyopathies in Qatar, followed by sequencing of 174 genes on 51 HCM and 53 DCM patients, and 31 relatives.

Results

In HCM, the analysis of 25 HCM‐associated genes showed that 20% of HCM cases had putative pathogenic variants for cardiomyopathy, mainly in sarcomere genes. Additional 49% of HCM cases had variants of uncertain significance, while 31% of HCM cases had likely benign variant(s) or had no variants identified within the analyzed HCM genes. In DCM, 56 putative DCM genes were analyzed. Eight percent of DCM cases had putative pathogenic variants for DCM, in the TTN gene while 70% of cases had variants of uncertain significance, in the analyzed DCM genes, that will need further pathogenicity assessment. Moreover, 22% of DCM cases remain unexplained, by having likely benign variant(s) or having no variants detected in any of the analyzed DCM genes.

Conclusion

We identified or replicated at least four recurrent variants among cardiomyopathy patients, which could be founder disease mutations in the Arabic population, including a frameshift variant (c.1371_1381dupTATCCAGTTAT) of unknown significance in the FKTN gene which seems to cause DCM in homozygosity, and HCM in heterozygosity. In vivo and/or in vitro functional validation need to be pursued in order to assess the pathogenicity of the identified variants.

A review of the underlying genetics and emerging therapies for canine cardiomyopathies

Cardiomyopathies such as dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy are common in large breed dogs and carry an overall poor prognosis. Research shows that these diseases have strong breed predilections, and selective breeding has historically been recommended to reduce the disease prevalence in affected breeds. Treatment of these diseases is typically palliative and aimed at slowing disease progression and managing clinical signs of heart failure as they develop. The discovery of specific genetic mutations underlying cardiomyopathies, such as the striatin mutation in Boxer arrhythmogenic right ventricular cardiomyopathy and the pyruvate dehydrogenase kinase 4 and titin mutations in Doberman Pinschers, has strengthened our ability to screen and selectively breed individuals in an attempt to produce unaffected offspring. The discovery of these disease-linked mutations has also opened avenues for the development of gene therapies, including gene transfer and genome-editing approaches. This review article discusses the known genetics of cardiomyopathies in dogs, reviews existing gene therapy strategies and the status of their development in canines, and discusses ongoing challenges in the clinical translation of these technologies for treating heart disease. While challenges remain in using these emerging technologies, the exponential growth of the gene therapy field holds great promise for future clinical applications.

ACR Appropriateness Criteria® Nonischemic Myocardial Disease with Clinical Manifestations (Ischemic Cardiomyopathy Already Excluded)

Nonischemic cardiomyopathies encompass a broad spectrum of myocardial disorders with mechanical or electrical dysfunction without evidence of ischemia. There are five broad variants of nonischemic cardiomyopathies; hypertrophic cardiomyopathy (Variant 1), restrictive or infiltrative cardiomyopathy (Variant 2), dilated or unclassified cardiomyopathy (Variant 3), arrhythmogenic cardiomyopathy (Variant 4), and inflammatory cardiomyopathy (Variant 5). For variants 1, 3, and 4, resting transthoracic echocardiography, MRI heart function and morphology without and with contrast, and MRI heart function and morphology without contrast are the usually appropriate imaging modalities. For variants 2 and 5, resting transthoracic echocardiography and MRI heart function and morphology without and with contrast are the usually appropriate imaging modalities. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Hypertrophic Cardiomyopathy and Primary Restrictive Cardiomyopathy: Similarities, Differences and Phenocopies

Hypertrophic cardiomyopathy (HCM) and primary restrictive cardiomyopathy (RCM) have a similar genetic background as they are both caused mainly by variants in sarcomeric genes. These “sarcomeric cardiomyopathies” also share diastolic dysfunction as the prevalent pathophysiological mechanism. Starting from the observation that patients with HCM and primary RCM may coexist in the same family, a characteristic pathophysiological profile of HCM with restrictive physiology has been recently described and supports the hypothesis that familiar forms of primary RCM may represent a part of the phenotypic spectrum of HCM rather than a different genetic cardiomyopathy. To further complicate this scenario some infiltrative (amyloidosis) and storage diseases (Fabry disease and glycogen storage diseases) may show either a hypertrophic or restrictive phenotype according to left ventricular wall thickness and filling pattern. Establishing a correct etiological diagnosis among HCM, primary RCM, and hypertrophic or restrictive phenocopies is of paramount importance for cascade family screening and therapy.

Clinical Insights Into Heritable Cardiomyopathies

Cardiomyopathies (CMs) encompass a heterogeneous group of structural and functional abnormalities of the myocardium. The phenotypic characteristics of these myocardial diseases range from silent to symptomatic heart failure, to sudden cardiac death due to malignant tachycardias. These diseases represent a leading cause of cardiovascular morbidity, cardiac transplantation, and death. Since the discovery of the first locus associated with hypertrophic cardiomyopathy 30 years ago, multiple loci and molecular mechanisms have been associated with these cardiomyopathy phenotypes. Conversely, the disparity between the ever-growing landscape of cardiovascular genetics and the lack of awareness in this field noticeably demonstrates the necessity to update training curricula and educational pathways. This review summarizes the current understanding of heritable CMs, including the most common pathogenic gene variants associated with the morpho-functional types of cardiomyopathies: dilated, hypertrophic, arrhythmogenic, non-compaction, and restrictive. Increased understanding of the genetic/phenotypic associations of these heritable diseases would facilitate risk stratification to leveraging appropriate surveillance and management, and it would additionally provide identification of family members at risk of avoidable cardiovascular morbidity and mortality.

Cardiac MRI in cardiomyopathies

Heart failure affects 1-2% of the adult population and one of the main contributors to its development is cardiomyopathy. Assessing a patient's risk for adverse events in heart failure is challenging and made more difficult by the heterogenous phenotypic expression of the disease. Cardiac MRI has long been a gold standard measure of myocardial function and anatomy due to its high spatial and temporal resolution. More recently, it has been posited to play a more critical role in the diagnosis and prognosis of cardiomyopathy-related heart failure. Given the limitations of more commonly used imaging modalities, increasing the clinical use of cardiac magnetic resonance imaging could potentially improve the prognosis of specific subgroups of patients at risk of adverse cardiac events.

Massively Parallel Sequencing of 43 Arrhythmia Genes in a Selected SUDI Cohort from Cape Town

Sudden unexpected death in infants (SUDI) is a devastating event, and unfortunately occurs frequently in developing countries. The emerging molecular autopsy has added value to post-mortem investigations, where genetic variants were able to explain the unexpected demise. Many of these variants have been found in genes involved in arrythmia pathways. The aim of this study was to sequence 43 genes previously associated with cardiac arrhythmia in a selected cohort of SUDI cases (n = 19) in South Africa. A total of 335 variants were found among the 19 infants, of which four were novel. The variants were classified as “likely pathogenic” (n = 1), “variant of unknown significance” (n = 54), “likely benign” (n = 56) or “benign” (n = 224). The likely pathogenic variant was LMNA NM_170707.2:c.1279C > T (p.Arg427Cys) and was found in a 3-week-old male infant of African ancestry. Variants in LMNA have previously been associated with dilated cardiomyopathy, with a typical age of onset in adulthood; therefore, this may be the first report in an infant. The yield of pathogenic or likely pathogenic variants in the classic genes typically associated with channelopathies and sudden death, was less in this study compared with other settings. This finding highlights the importance of population-specific research to develop a molecular autopsy which is locally relevant.

Left and right ventricular strain using fast strain-encoded cardiovascular magnetic resonance for the diagnostic classification of patients with chronic non-ischemic heart failure due to dilated, hypertrophic cardiomyopathy or cardiac amyloidosis

AIMS

To compare the ability of left ventricular (LV) and right ventricular (RV) strain measured by fast-strain encoded cardiovascular magnetic resonance (CMR) (fast-SENC) with LV- and RV-ejection fraction for the diagnostic classification of patients with different stages of chronic heart failure (stages A-D based on American College of Cardiology/American Heart Association guidelines) due to non-ischemic cardiomyopathies.

METHODS

Our study population consisted of 276 consecutive patients who underwent CMR for clinical reasons, and 19 healthy subjects. Wall motion score index and non-infarct related late gadolinium enhancement (LGE), LV ejection fraction (LVEF) and RV ejection fraction (RVEF) and global LV- and RV-longitudinal (GLS) and circumferential strain (GCS) based on fast-SENC acquisitions, were calculated in all subjects. The percentage of LV and RV myocardial segments with strain ≤ - 17% (%normal LV and RV myocardium) was determined in all subjects.

RESULTS

LVEF and RVEF, LV-GLS, LV-GCS, RV-GLS, RV-GCS and %normal LV- and RV myocardium depressed with increasing heart failure stage (p < 0.001 for all by ANOVA). By multivariable analysis, %normal LV and RV myocardium exhibited closer associations to heart failure stages than LVEF and RVEF (r_partial = 0.79 versus r_partial = 0.21 for %normal LV myocardium versus LVEF and r_partial = 0.64 versus r_partial = 0.20 for %normal RV myocardium versus RVEF, respectively). Furthermore, %normal LV and RV myocardium exhibited incremental value for the identification of patients (i) with subclinical myocardial dysfunction and (ii) with symptomatic heart failure, surpassing that provided by LVEF and RVEF (ΔAUC = 0.22 for LVEF and ΔAUC = 0.19 for RVEF with subclinical dysfunction, and ΔAUC = 0.19 for LVEF and ΔAUC = 0.22 for RVEF with symptomatic heart failure, respectively, p < 0.001 for all). %normal LV myocardium reclassified 11 of 31 (35%) patients judged as having no structural heart disease by clinical and imaging data to stage B, i.e., subclinical LV-dysfunction.

CONCLUSIONS

In patients with non-ischemic cardiomyopathy, %normal LV and RV myocardium, by fast-SENC, enables improved identification of asymptomatic patients with subclinical LV-dysfunction. This technique may be useful for the early identification of such presumably healthy subjects at risk for heart failure and for monitoring LV and RV deformation during pharmacologic interventions in future studies.

Left and right ventricular strain using fast strain-encoded cardiovascular magnetic resonance for the diagnostic classification of patients with chronic non-ischemic heart failure due to dilated, hypertrophic cardiomyopathy or cardiac amyloidosis

AIMS

To compare the ability of left ventricular (LV) and right ventricular (RV) strain measured by fast-strain encoded cardiovascular magnetic resonance (CMR) (fast-SENC) with LV- and RV-ejection fraction for the diagnostic classification of patients with different stages of chronic heart failure (stages A-D based on American College of Cardiology/American Heart Association guidelines) due to non-ischemic cardiomyopathies.

METHODS

Our study population consisted of 276 consecutive patients who underwent CMR for clinical reasons, and 19 healthy subjects. Wall motion score index and non-infarct related late gadolinium enhancement (LGE), LV ejection fraction (LVEF) and RV ejection fraction (RVEF) and global LV- and RV-longitudinal (GLS) and circumferential strain (GCS) based on fast-SENC acquisitions, were calculated in all subjects. The percentage of LV and RV myocardial segments with strain ≤ - 17% (%normal LV and RV myocardium) was determined in all subjects.

RESULTS

LVEF and RVEF, LV-GLS, LV-GCS, RV-GLS, RV-GCS and %normal LV- and RV myocardium depressed with increasing heart failure stage (p < 0.001 for all by ANOVA). By multivariable analysis, %normal LV and RV myocardium exhibited closer associations to heart failure stages than LVEF and RVEF (rpartial = 0.79 versus rpartial = 0.21 for %normal LV myocardium versus LVEF and rpartial = 0.64 versus rpartial = 0.20 for %normal RV myocardium versus RVEF, respectively). Furthermore, %normal LV and RV myocardium exhibited incremental value for the identification of patients (i) with subclinical myocardial dysfunction and (ii) with symptomatic heart failure, surpassing that provided by LVEF and RVEF (ΔAUC = 0.22 for LVEF and ΔAUC = 0.19 for RVEF with subclinical dysfunction, and ΔAUC = 0.19 for LVEF and ΔAUC = 0.22 for RVEF with symptomatic heart failure, respectively, p < 0.001 for all). %normal LV myocardium reclassified 11 of 31 (35%) patients judged as having no structural heart disease by clinical and imaging data to stage B, i.e., subclinical LV-dysfunction.

CONCLUSIONS

In patients with non-ischemic cardiomyopathy, %normal LV and RV myocardium, by fast-SENC, enables improved identification of asymptomatic patients with subclinical LV-dysfunction. This technique may be useful for the early identification of such presumably healthy subjects at risk for heart failure and for monitoring LV and RV deformation during pharmacologic interventions in future studies.

The Implementation Science for Genomic Health Translation (INSIGHT) Study in Epilepsy: Protocol for a Learning Health Care System

BACKGROUND

Genomic medicine is poised to improve care for common complex diseases such as epilepsy, but additional clinical informatics and implementation science research is needed for it to become a part of the standard of care. Epilepsy is an exemplary complex neurological disorder for which DNA diagnostics have shown to be advantageous for patient care.

OBJECTIVE

We designed the Implementation Science for Genomic Health Translation (INSIGHT) study to leverage the fact that both the clinic and testing laboratory control the development and customization of their respective electronic health records and clinical reporting platforms. Through INSIGHT, we can rapidly prototype and benchmark novel approaches to incorporating clinical genomics into patient care. Of particular interest are clinical decision support tools that take advantage of domain knowledge from clinical genomics and can be rapidly adjusted based on feedback from clinicians.

METHODS

Building on previously developed evidence and infrastructure components, our model includes the following: establishment of an intervention-ready genomic knowledge base for patient care, creation of a health informatics platform and linking it to a clinical genomics reporting system, and scaling and evaluation of INSIGHT following established implementation science principles.

RESULTS

INSIGHT was approved by the Institutional Review Board at the University of Texas Health Science Center at Houston on May 15, 2020, and is designed as a 2-year proof-of-concept study beginning in December 2021. By design, 120 patients from the Texas Comprehensive Epilepsy Program are to be enrolled to test the INSIGHT workflow. Initial results are expected in the first half of 2023.

CONCLUSIONS

INSIGHT's domain-specific, practical but generalizable approach may help catalyze a pathway to accelerate translation of genomic knowledge into impactful interventions in patient care.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/25576.

Prospective follow-up in various subtypes of cardiomyopathies: insights from the ESC EORP Cardiomyopathy Registry

AIMS

The European Society of Cardiology (ESC) European Observational Research Programme (EORP) Cardiomyopathy Registry is a prospective multinational registry of consecutive patients with cardiomyopathies. The objective of this report is to describe the short-term outcomes of adult patients (≥18 years old).

METHODS AND RESULTS

Out of 3208 patients recruited, follow-up data at 1 year were obtained in 2713 patients (84.6%) [1420 with hypertrophic (HCM); 1105 dilated (DCM); 128 arrhythmogenic right ventricular (ARVC); and 60 restrictive (RCM) cardiomyopathies]. Improvement of symptoms (dyspnoea, chest pain, and palpitations) was globally observed over time (P < 0.05 for each). Additional invasive procedures were performed: prophylactic implantation of implantable cardioverter-defibrillator (ICD) (5.2%), pacemaker (1.2%), heart transplant (1.1%), ablation for atrial or ventricular arrhythmia (0.5% and 0.1%). Patients with atrial fibrillation increased from 28.7% to 32.2% of the cohort. Ventricular arrhythmias (VF/ventricular tachycardias) in ICD carriers (primary prevention) at 1 year were more frequent in ARVC, then in DCM, HCM, and RCM (10.3%, 8.2%, 7.5%, and 0%, respectively). Major cardiovascular events (MACE) occurred in 29.3% of RCM, 10.5% of DCM, 5.3% of HCM, and 3.9% of ARVC (P < 0.001). MACE were more frequent in index patients compared to relatives (10.8% vs. 4.4%, P < 0.001), more frequent in East Europe centres (13.1%) and least common in South Europe (5.3%) (P < 0.001). Subtype of cardiomyopathy, geographical region, and proband were predictors of MACE on multivariable analysis.

CONCLUSIONS

Despite symptomatic improvement, patients with cardiomyopathies remain prone to major clinical events in the short term. Outcomes were different not only according to cardiomyopathy subtypes but also in relatives vs. index patients, and according to European regions.

The Time Has Come to Explore Plasma Biomarkers in Genetic Cardiomyopathies

For patients with hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM), screening for pathogenic variants has become standard clinical practice. Genetic cascade screening also allows the identification of relatives that carry the same mutation as the proband, but disease onset and severity in mutation carriers often remains uncertain. Early detection of disease onset may allow timely treatment before irreversible changes are present. Although plasma biomarkers may aid in the prediction of disease onset, monitoring relies predominantly on identifying early clinical symptoms, on imaging techniques like echocardiography (Echo) and cardiac magnetic resonance imaging (CMR), and on (ambulatory) electrocardiography (electrocardiograms (ECGs)). In contrast to most other cardiac diseases, which are explained by a combination of risk factors and comorbidities, genetic cardiomyopathies have a clear primary genetically defined cardiac background. Cardiomyopathy cohorts could therefore have excellent value in biomarker studies and in distinguishing biomarkers related to the primary cardiac disease from those related to extracardiac, secondary organ dysfunction. Despite this advantage, biomarker investigations in cardiomyopathies are still limited, most likely due to the limited number of carriers in the past. Here, we discuss not only the potential use of established plasma biomarkers, including natriuretic peptides and troponins, but also the use of novel biomarkers, such as cardiac autoantibodies in genetic cardiomyopathy, and discuss how we can gauge biomarker studies in cardiomyopathy cohorts for heart failure at large.

The p.Ala2430Val mutation in filamin C causes a "hypertrophic myofibrillar cardiomyopathy"

Hypertrophic cardiomyopathy (HCM) often leads to heart failure. Mutations in sarcomeric proteins are most frequently the cause of HCM but in many patients the gene defect is not known. Here we report on a young man who was diagnosed with HCM shortly after birth. Whole exome sequencing revealed a mutation in the FLNC gene (c.7289C > T; p.Ala2430Val) that was previously shown to cause aggregation of the mutant protein in transfected cells. Myocardial tissue from patients with this mutation has not been analyzed before and thus, the underlying etiology is not well understood. Myocardial tissue of our patient obtained during myectomy at the age of 23 years was analyzed in detail by histochemistry, immunofluorescence staining, electron microscopy and western blot analysis. Cardiac histology showed a pathology typical for myofibrillar myopathy with myofibril disarray and abnormal protein aggregates containing BAG3, desmin, HSPB5 and filamin C. Analysis of sarcomeric and intercalated disc proteins showed focally reduced expression of the gap junction protein connexin43 and Xin-positive sarcomeric lesions in the cardiomyocytes of our patient. In addition, autophagy pathways were altered with upregulation of LC3-II, WIPI1 and HSPB5, 6, 7 and 8. We conclude that the p.Ala2430Val mutation in FLNC most probably is associated with HCM characterized by abnormal intercalated discs, disarray of myofibrils and aggregates containing Z-disc proteins similar to myofibrillar myopathy, which supports the pathological effect of the mutation.

A Novel Titin Truncation Variant Linked to Familial Dilated Cardiomyopathy Found in a Japanese Family and Its Functional Analysis in Genome-Edited Model Cells

Dilated cardiomyopathy (DCM) is a common cause of heart failure. TTN, which encodes titin protein, is a representative causative gene of DCM, and is presented mainly as a truncation variant. However, TTN truncation variants are also found in healthy individuals, and it is therefore important to evaluate the pathogenicity of each variant. In this study, we analyzed 67 cardiomyopathy-associated genes in a male Japanese patient who was hospitalized for recurrent severe heart failure and identified a novel truncation variant, TTN Ser17456Arg fs*14. This TTN truncation variant was located in the A-band region. Moreover, the patient's mother with heart failure harbored the same variant, whereas the father and brother without heart failure did not harbor the variant. To examine the functional changes associated with the truncation variant, H9c2 cells were subjected to genome editing to generate cells with a homologous truncation variant. The cells were differentiated using all-trans-retinoic acid, and the mRNA expression of skeletal actin and cardiac actin were found to be increased and decreased, respectively, consistent with known changes in patients with DCM or heart failure. In contrast, another cell with the titin truncation variant used as a control showed no changes in heart failure-related genes. In summary, we found a novel TTN truncation variant in familial DCM patients and confirmed its functional changes using a relatively simple cell model. The novel truncation variant was identified as a pathogenic and disease-causing mutation.

Diagnosis and Risk Prediction of Dilated Cardiomyopathy in the Era of Big Data and Genomics

Dilated cardiomyopathy (DCM) is a leading cause of heart failure and life-threatening ventricular arrhythmias (LTVA). Work-up and risk stratification of DCM is clinically challenging, as there is great heterogeneity in phenotype and genotype. Throughout the last decade, improved genetic testing of patients has identified genotype-phenotype associations and enhanced evaluation of at-risk relatives leading to better patient prognosis. The field is now ripe to explore opportunities to improve personalised risk assessments. Multivariable risk models presented as "risk calculators" can incorporate a multitude of clinical variables and predict outcome (such as heart failure hospitalisations or LTVA). In addition, genetic risk scores derived from genome/exome-wide association studies can estimate an individual's lifetime genetic risk of developing DCM. The use of clinically granular investigations, such as late gadolinium enhancement on cardiac magnetic resonance imaging, is warranted in order to increase predictive performance. To this end, constructing big data infrastructures improves accessibility of data by using electronic health records, existing research databases, and disease registries. By applying methods such as machine and deep learning, we can model complex interactions, identify new phenotype clusters, and perform prognostic modelling. This review aims to provide an overview of the evolution of DCM definitions as well as its clinical work-up and considerations in the era of genomics. In addition, we present exciting examples in the field of big data infrastructures, personalised prognostic assessment, and artificial intelligence.

Circular RNAs in Sudden Cardiac Death Related Diseases: Novel Biomarker for Clinical and Forensic Diagnosis

The prevention and diagnosis of sudden cardiac death (SCD) are among the most important keystones and challenges in clinical and forensic practice. However, the diagnostic value of the current biomarkers remains unresolved issues. Therefore, novel diagnostic biomarkers are urgently required to identify patients with early-stage cardiovascular diseases (CVD), and to assist in the postmortem diagnosis of SCD cases without typical cardiac damage. An increasing number of studies show that circular RNAs (circRNAs) have stable expressions in myocardial tissue, and their time- and tissue-specific expression levels might reflect the pathophysiological status of the heart, which makes them potential CVD biomarkers. In this article, we briefly introduced the biogenesis and functional characteristics of circRNAs. Moreover, we described the roles of circRNAs in multiple SCD-related diseases, including coronary artery disease (CAD), myocardial ischemia or infarction, arrhythmia, cardiomyopathy, and myocarditis, and discussed the application prospects and challenges of circRNAs as a novel biomarker in the clinical and forensic diagnosis of SCD.

Malignant Arrhythmogenic Role Associated with RBM20: A Comprehensive Interpretation Focused on a Personalized Approach

The RBM20 gene encodes the muscle-specific splicing factor RNA-binding motif 20, a regulator of heart-specific alternative splicing. Nearly 40 potentially deleterious variants in RBM20 have been reported in the last ten years, being found to be associated with highly arrhythmogenic events in familial dilated cardiomyopathy. Frequently, malignant arrhythmias can be a primary manifestation of disease. The early recognition of arrhythmic genotypes is crucial in avoiding lethal episodes, as it may have an impact on the adoption of personalized preventive measures. Our study performs a comprehensive update of data concerning rare variants in RBM20 that are associated with malignant arrhythmogenic phenotypes with a focus on personalized medicine.

Global, Regional, and National Burden of Myocarditis and Cardiomyopathy, 1990-2017

Objective: To estimate the burden of myocarditis (MC), alcoholic cardiomyopathy (AC), and other cardiomyopathy (OC) for 195 countries and territories from 1990 to 2017. Methods: We collected detailed information on MC, AC, and OC between 1990 and 2017 from the Global Burden of Disease study 2017, which was designed to provide a systematic assessment of health loss due to diseases and injuries in 21 regions, covering 195 countries and territories. Estimates of MC, AC, and OC burden were produced using a standard Cause of Death Ensemble model and a Bayesian mixed-effects meta-regression tool, and included prevalence, deaths, years lived with disability (YLDs), and years of life lost (YLLs). All estimates were presented as counts, age-standardized rates per 100,000 people and percentage change, with 95% uncertainty intervals (UIs). Results: Worldwide, there were 1.80 million (95% UI 1.64-1.98) cases of MC, 1.62 million (95% UI 1.37-1.90) cases of AC and 4.21 million (95% UI 3.63-4.87) cases of OC, contributing to 46,486 (95% UI 39,709-51,824), 88,890 (95% UI 80,935-96,290), and 233,159 (95% UI 213,677-248,289) deaths in 2017, respectively. Furthermore, globally, there were 131,376 (95% UI 90,113-183,001) YLDs and 1.26 million (95% UI 1.10-1.42) YLLs attributable to MC, 139,087 (95% UI 95,134-196,130) YLDs and 2.84 million (95% UI 2.60-3.07) YLLs attributable to AC, and 353,325 (95% UI 237,907-493,908) YLDs and 5.51 million (95% UI 4.95-5.99) YLLs attributable to OC in 2017. At the national level, the age-standardized prevalence rates varied by 10.4 times for MC, 252.6 times for AC and 38.1 times for OC; the age-standardized death rates varied by 43.9 times for MC, 531.0 times for AC and 43.3 times for OC; the age-standardized YLD rates varied by 12.4 times for MC, 223.7 times for AC, and 34.1 times for OC; and the age-standardized YLL rates varied by 38.4 times for MC, 684.8 times for AC, and 36.2 times for OC. Between 1990 and 2017, despite the decreases in age-standardized rates, the global numbers of prevalent cases, deaths, YLDs, and YLLs have increased for all the diseases. Conclusion: Accurate assessment of the burden of MC, AC, and OC is essential for formulating effective preventative prevention and treatment programs and optimizing health system resource allocation. Our results suggest that MC, AC, and OC remain important global public health problems with increasing numbers of prevalent cases, deaths, YLDs, and YLLs over the past decades, and there are significant geographic variations in the burden of these diseases. Further research is warranted to expand our knowledge of potential risk factors and to improve the prevention, early detection and treatment of these diseases.

A long noncoding RNA CHAIR protects the heart from pathological stress

Mammalian genomes have been found to be extensively transcribed. In addition to classic protein coding genes, a large numbers of long noncoding genes (lncRNAs) have been identified, while their functions, especially in heart diseases, remain to be established. We hypothesized that heart failure progression is controlled by tissue-specific lncRNAs. In the present study, we found that the cardiac-enriched lncRNA 4632428C04Rik, named as cardiomyocyte hypertrophic associated inhibitory RNA (CHAIR), is dynamically regulated during heart development, is expressed at low levels in embryonic hearts and accumulated at high levels in adult hearts. More interestingly, the lncRNA was down-regulated during cardiac hypertrophy and failure both in mice and humans. Importantly, loss of lncRNA CHAIR has no effects on normal hearts, whereas it results in accelerated heart function decline, increased hypertrophy, and exacerbated heart failure in response to stress. In contrast, restoring the expression of lncRNA CHAIR rescued the hearts from hypertrophy and failure. DNMT3A was recruited to CHAIR promoter during heart failure to suppress its expression. Reciprocally, CHAIR interacted with DNMT3A to inhibit its DNA-binding activity. Taken together, our data revealed a new cardioprotective lncRNA that represses heart failure through an epigenetic mechanism.

Risk Factors and Prevalence of Dilated Cardiomyopathy in Sub-Saharan Africa: Protocol for a Systematic Review

Background

Cardiomyopathies, defined as diseases involving mainly the heart muscles, are linked to an estimated 5.9 of 100,000 deaths globally. In sub-Saharan Africa, cardiomyopathies constitute 21.4% of heart failure cases, with dilated cardiomyopathy (DCM) being the most common form. The etiology of DCM is heterogeneous and is broadly categorized as genetic or nongenetic, as well as a mixed disease in which genetics interact with intrinsic and environmental factors. Factors such as age, gender, family history, and ethnicity are nonmodifiable, whereas modifiable risk factors include poor nutrition, physical inactivity, and excessive alcohol consumption, among others. However, the relative contribution of the different risk factors to the etiology of DCM is not known in sub-Saharan Africa, and the prevalence of DCM among heart failure patients has not been systematically studied in the region.

Objective

The aim of this review is to synthesize available literature from sub-Saharan Africa on the prevalence of DCM among patients with heart failure, as well as the literature on factors associated with DCM. This paper outlines the protocol that will be followed to conduct the systematic review.

Methods

A limited search of the PubMed database will be performed to identify relevant keywords contained in the title, abstract, and subject descriptors using initial search terms “heart failure,” “cardiomyopathy,” and “sub-Saharan Africa.” These search terms and their synonyms will then be used in an extensive search in PubMed, and will address the first research question on prevalence. To address the second research question on risk factors, the terms “heart failure,” “cardiomyopathy,” and “cardiovascular risk factors” in “Sub-Saharan Africa” will be used, listing them one by one. Articles published from 2000 and in the English language will be included. Indexed articles in PubMed and Embase will be included, as well as the first 300 articles retrieved from a Google Scholar search. Collected data will be organized in Endnote and then uploaded to the Rayyan web app for systematic reviews. Two reviewers will independently select articles against the inclusion criteria. Discrepancies in reviewer selections will be resolved by an arbitrator. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for reporting systematic reviews will be applied. A map of sub-Saharan Africa with colors to show disease prevalence in each country will be included. For quantitative data, where possible, odds ratios (for categorical outcome data) or standardized mean differences (for continuous data) and their 95% CIs will be calculated.

Results

The primary outcomes will be the prevalence of DCM among patients with heart failure and cardiovascular risk factors associated with DCM in sub-Saharan Africa. The literature search will begin on January 1, 2021, and data analysis is expected to be completed by April 30, 2021.

Conclusions

This review will provide information on the current status of the prevalence and associated factors of DCM, and possibly identify gaps, including paucity of data or conflicting results that need to be addressed to improve our understanding of DCM in sub-Saharan Africa.

International Registered Report Identifier (IRRID)

PRR1-10.2196/18229

Plasminogen activator inhibitor-1 reduces cardiac fibrosis and promotes M2 macrophage polarization in inflammatory cardiomyopathy

Plasminogen activator inhibitor-1 (PAI-1) has a cardioprotective function in mice by repressing cardiac fibrosis through TGF-β and plasminogen-mediated pathways. In addition it is known to be involved in the recruitment and polarization of monocytes/macrophages towards a M2 phenotype in cancer. Here, we investigated the expression of PAI-1 in human dilated cardiomyopathy (DCM) and inflammatory dilated cardiomyopathy (DCMi) and its effect on cardiac fibrosis and macrophage polarization. We retrospectively analyzed endomyocardial biopsies (EMBs) of patients with DCM or DCMi for PAI-1 expression by immunohistochemistry. Furthermore, EMBs were evaluated for the content of fibrotic tissue, number of activated myofibroblasts, TGF-β expression, as well as for M1 and M2 macrophages. Patients with high-grade DCMi (DCMi-high, CD3⁺ lymphocytes > 30 cells/mm²) had significantly increased PAI-1 levels compared to DCM and low-grade DCMi patients (DCMi-low, CD3⁺ lymphocytes = 14-30 cells/mm²) (15.5 ± 0.4% vs. 1.0 ± 0.1% and 4.0 ± 0.1%, p ≤ 0.001). Elevated PAI-1 expression in DCMi-high subjects was associated with a diminished degree of cardiac fibrosis, decreased levels of TGF-β and reduced number of myofibroblasts. In addition, DCMi-high patients revealed an increased proportion of non-classical M2 macrophages towards classical M1 macrophages, indicating M2 macrophage-favoring properties of PAI-1 in inflammatory cardiomyopathies. Our findings give evidence that elevated expression of cardiac PAI-1 in subjects with high-grade DCMi suppresses fibrosis by inhibiting TGF-β and myofibroblast activation. Moreover, our data indicate that PAI-1 is involved in the polarization of M2 macrophages in the heart. Thus, PAI-1 could serve as a potential prognostic biomarker and as a possible therapeutic target in inflammatory cardiomyopathies.

Systems pharmacology reveals the multi-level synergetic mechanism of action of Ginkgo biloba L. leaves for cardiomyopathy treatment

ETHNOPHARMACOLOGICAL RELEVANCE

Cardiomyopathy is a common cause of heart failure and may lead to increased risk of sudden cardiac death, lacking simple, safe and effective treatment strategies due to unclear pathogenesis. Ginkgo biloba L. leaves (GBLs), a traditional Chinese medicine (TCM), has been widely used in clinical medicine for improving blood circulation, and was demonstrated to be effective on cardiomyopathy in preclinical studies. However, because of the widely known holistic therapeutic philosophy via multi-target and multi-pathway effect for most TCMs, to explore its underlying molecular mechanisms of action (MoA) remains a great challenge.

AIM OF STUDY

Decipher the underlying MoA of GBLs for cardiomyopathy treatment: Study design and methods: An integrated systems pharmacology framework was employed to screen potential active compounds, identify therapeutic targets, explore the action pathways and verify mechanisms of GBLs with in vitro experiments.

RESULTS

We firstly confirmed the therapeutic effect of GBLs on cardiomyopathy and subsequently screened 27 active compounds from GBLs according to their pharmacokinetic properties. Then Probability Ensemble Approach was applied to identify the compound combinations that exert synergetic effect from GBLs. Network analysis and functional enrichment analysis demonstrated that these compounds exhibit synergistic therapeutic effect by acting on multiple targets and thereby regulating multiple pathways mainly involved in pro-survival, anti-apoptotic and anti-inflammatory processes. Finally, using a doxorubicin-induced myocardial injury model, therapeutic effect of ginkgolide A, ginkgolide B, isorhamnetin, as well as their synergistic effect on PI3K-AKT and NF-κB signaling pathways were validated in vitro. Importantly, we demonstrated that Ginkgo diterpene lactone meglumine injection (GDJ), an approved injection derived from GBLs, could be a promising agent for cardiomyopathy treatment.

CONCLUSION

Collectively, the multi-level synergetic mechanism of GBLs on cardiomyopathy treatment was demonstrated with systems pharmacology approach, providing a paradigm for deciphering the complicated MoA of TCMs.

Overview of Cardiomyopathies in Childhood

Paediatric cardiomyopathies are a heterogenous group of rare disorders, characterised by mechanical and electrical abnormalities of the heart muscle. The overall annual incidence of childhood cardiomyopathies is estimated at about 1 per 100,000 children and is significantly higher during the first 2 years of life. Dilated cardiomyopathies account for approximately half of the cases. Hypertrophic cardiomyopathies form the second largest group, followed by the less common left ventricular non-compaction and restrictive phenotypes. Infectious, metabolic, genetic, and syndromic conditions account for the majority of cases. Congestive heart failure is the typical manifestation in children with dilated cardiomyopathy, whereas presenting symptoms are more variable in other phenotypes. The natural history is largely influenced by the type of cardiomyopathy and its underlying aetiology. Results from a national population-based study revealed 10-year transplant-free survival rates of 80, 62, and 48% for hypertrophic, dilated and left ventricular non-compaction cardiomyopathies, respectively. Long-term survival rates of children with a restrictive phenotype have largely been obscured by early listing for heart transplantation. In general, the majority of adverse events, including death and heart transplantation, occur during the first 2 years after the initial presentation. This review provides an overview of childhood cardiomyopathies with a focus on epidemiology, natural history, and outcomes.

Hypertrophic Cardiomyopathy: Diverse Pathophysiology Revealed by Genetic Research, Toward Future Therapy

Hypertrophic cardiomyopathy (HCM) is an intractable disease that causes heart failure mainly due to unexplained severe cardiac hypertrophy and diastolic dysfunction. HCM, which occurs in 0.2% of the general population, is the most common cause of sudden cardiac death in young people. HCM has been studied extensively using molecular genetic approaches. Genes encoding cardiac β-myosin heavy chain, cardiac myosin-binding protein C, and troponin complex, which were originally identified as causative genes, were subsequently reported to be frequently implicated in HCM. Indeed, HCM has been considered a disease of sarcomere gene mutations. However, fewer than half of patients with HCM have mutations in sarcomere genes. The others have been documented to have mutations in cardiac proteins in various other locations, including the Z disc, sarcoplasmic reticulum, plasma membrane, nucleus, and mitochondria. Next-generation sequencing makes it possible to detect mutations at high throughput, and it has become increasingly common to identify multiple cardiomyopathy-causing gene mutations in a single HCM patient. Elucidating how mutations in different genes contribute to the disease pathophysiology will be a challenge. In studies using animal models, sarcomere mutations generally tend to increase myocardial Ca²⁺ sensitivity, and some mutations increase the activity of myosin ATPase. Clinical trials of drugs to treat HCM are ongoing, and further new therapies based on pathophysiological analyses of the causative genes are eagerly anticipated.

Cardiomyopathies in China: A 2018-2019 state-of-the-art review

Cardiomyopathies are diseases of the cardiac muscle and are often characterized by ventricular dilation, hypertrophy, and cardiac arrhythmia. Patients with cardiomyopathies often experience sudden death and cardiac failure and require cardiac transplantation during the course of disease progression. Early diagnosis, differential diagnosis, and genetic consultation depend on imaging techniques, genetic testing, and new emerging diagnostic tools such as serum biomarkers. The molecular genetics of cardiomyopathies has been widely studied recently. The discovery of mechanisms underlying heterogeneity and overlapping of the phenotypes of cardiomyopathies has revealed the existence of disease modifiers, and this has led to the emergence of novel disease-modifying therapy. This 2018-2019 state-of-the-art review outlines the pathogenesis, diagnosis, and treatment of cardiomyopathies in China.

Hereditary Hypertrophic Cardiomyopathy in Children and Young Adults-The Value of Reevaluating and Expanding Gene Panel Analyses

Introduction: Sudden cardiac death (SCD) and early onset cardiomyopathy (CM) in the young will always lead to suspicion of an underlying genetic disorder. Incited by the rapid advances in genetic testing for disease we have revisited families, which previously tested “gene-negative” for familial predominantly pediatric CM, in hopes of finding a causative gene variant. Methods: 10 different families with non-syndromic pediatric CM or hypertrophic cardiomyopathy (HCM) with severe disease progression and/or heredity for HCM/CM related SCD with “gene-negative” results were included. The index patient underwent genetic testing with a recently updated gene panel for CM and SCD. In case of failure to detect a pathogenic variant in a relevant gene, the index patient and both parents underwent clinical (i.e., partial) exome sequencing (trio-exome) in order to catch pathogenic variants linked to the disease in genes that were not included in the CM panel. Results: The mean age at clinical presentation of the 10 index cases was 12.5 years (boys 13.4 years, n = 8; girls 9 years, n = 2) and the family history burden was 33 HCM/CM cases including 9 HCM-related SCD and one heart transplantation. In 5 (50%) families we identified a genetic variant classified as pathogenic or likely pathogenic, in accordance with the American College of Medical Genetics and Genomics (ACMG) criteria, in MYH7 (n = 2), RBM20, ALPK3, and PGM1, respectively, and genetic variants of unknown significance (VUS) segregating with the disease in an additional 3 (30%) families, in MYBPC3, ABCC9, and FLNC, respectively. Conclusion: Our results show the importance of renewed thorough clinical assessment and the necessity to challenge previous genetic test results with more comprehensive updated gene panels or exome sequencing if the initial test failed to identify a causative gene for early onset CM or SCD in children. In pediatric cardiomyopathy cases when the gene panel still fails to detect a causative variant, a trio exome sequencing strategy might resolve some unexplained cases, especially if a multisystemic condition is clinically missed.

Efficacy and Mode of Action of Mesenchymal Stem Cells in Non-Ischemic Dilated Cardiomyopathy: A Systematic Review

Non-ischemic dilated cardiomyopathy (NIDCM) constitutes one of the most common causes to non-ischemic heart failure. Despite treatment, the disease often progresses, causing severe morbidity and mortality, making novel treatment strategies necessary. Due to the regenerative actions of mesenchymal stem cells (MSCs), they have been proposed as a treatment for NIDCM. This systematic review aims to evaluate efficacy and mode of action (MoA) of MSC-based therapies in NIDCM. A systematic literature search was conducted in Medline (Pubmed) and Embase. A total of 27 studies were included (3 clinical trials and 24 preclinical studies). MSCs from different tissues and routes of delivery were reported, with bone marrow-derived MSCs and direct intramyocardial injections being the most frequent. All included clinical trials and 22 preclinical trials reported an improvement in cardiac function following MSC treatment. Furthermore, preclinical studies demonstrated alterations in tissue structure, gene, and protein expression patterns, primarily related to fibrosis and angiogenesis. Consequently, MSC treatment can improve cardiac function in NIDCM patients. The MoA underlying this effect involves anti-fibrosis, angiogenesis, immunomodulation, and anti-apoptosis, though these processes seem to be interdependent. These encouraging results calls for larger confirmatory clinical studies, as well as preclinical studies utilizing unbiased investigation of the potential MoA.

Cardiotoxicity of immune checkpoint inhibitors: An updated review

The immune checkpoint molecules are involved in the regulation of T cells in order to prevent them from attacking to sell tissues and play a role in the immune response homeostasis. Application of the immune checkpoint inhibitors (ICIs) has provided a promising therapeutic approach in pathologies where the immune system is suppressed. The extended utilization of ICIs in several cancers has caused immune-related side effects in the cardiovascular system like cardiomyopathy and myocarditis. Cardiac toxicity, one of the main side effects of the ICIs based therapeutic approach has less been concerned; however, during the last years, many cases of fatal heart failure and myocarditis have been reported in patients treated with ICIs. In this review article, we attempted to discuss the cardiac adverse effects of inhibiting different immune checkpoint molecules. This article is protected by copyright. All rights reserved.

A missense mutation in the RSRSP stretch of Rbm20 causes dilated cardiomyopathy and atrial fibrillation in mice

Dilated cardiomyopathy (DCM) is a fatal heart disease characterized by left ventricular dilatation and cardiac dysfunction. Recent genetic studies on DCM have identified causative mutations in over 60 genes, including RBM20, which encodes a regulator of heart-specific splicing. DCM patients with RBM20 mutations have been reported to present with more severe cardiac phenotypes, including impaired cardiac function, atrial fibrillation (AF), and ventricular arrhythmias leading to sudden cardiac death, compared to those with mutations in the other genes. An RSRSP stretch of RBM20, a hotspot of missense mutations found in patients with idiopathic DCM, functions as a crucial part of its nuclear localization signals. However, the relationship between mutations in the RSRSP stretch and cardiac phenotypes has never been assessed in an animal model. Here, we show that Rbm20 mutant mice harboring a missense mutation S637A in the RSRSP stretch, mimicking that in a DCM patient, demonstrated severe cardiac dysfunction and spontaneous AF and ventricular arrhythmias mimicking the clinical state in patients. In contrast, Rbm20 mutant mice with frame-shifting deletion demonstrated less severe phenotypes, although loss of RBM20-dependent alternative splicing was indistinguishable. RBM20^S637A protein cannot be localized to the nuclear speckles, but accumulated in cytoplasmic, perinuclear granule-like structures in cardiomyocytes, which might contribute to the more severe cardiac phenotypes.

Left Ventricular Pressure-Strain Loop-Based Quantitative Examination of the Global and Regional Myocardial Work of Patients with Dilated Cardiomyopathy

The aim of our prospective pilot study was to explore the distribution characteristics of myocardial work (MW) of patients with dilated cardiomyopathy (DCM) and their clinical value in evaluation of therapeutic effects. Thirty patients with DCM were enrolled in the case group, and 30 healthy patients were randomly allocated to the control group. Global myocardial work (GMW) and regional myocardial work (RMW) of the control and case groups before and after therapy were evaluated by using left ventricular pressure-strain loops and then compared. We found significant differences in GMW and RMW between the control and case groups (p < 0.05). Compared with before therapy, the global work index and 6-min walking distance increased, but LV ejection fraction and global longitudinal strain did not significantly change after therapy. GMW was significantly correlated with LV ejection fraction and global longitudinal strain (p < 0.01). Bland-Altman plot analysis revealed that GMW values were consistent between and within the groups. The results suggest that LV MW values were diffusely impaired in patients with DCM and that the global work index may be used as an indicator in evaluation of therapeutic effects.

Anesthesia Management in a Patient with Unclassified Cardiomyopathy for Transureteral Lithotripsy Surgery

Anesthesia management has always been challenging in cardiac patients, especially patients with cardiomyopathy. There are a variety of cardiomyopathies such as unclassified cardiomyopathy as a complex type that can occur in many forms like left ventricular noncompaction (LVNC) that is an uncommon primary genetic cardiomyopathy typified by noticeable trabeculation of the left ventricular (LV) wall and intertrabecular recesses. We report anesthesia management in a 53-year-old female patient who admitted to the hospital for the transureteral lithotripsy surgery due to dysuria and urolithiasis with a medical history, and echocardiographic examination indicated the diagnosis of hypertension and unclassified cardiomyopathy (LVNC).

Role of CMR Mapping Techniques in Cardiac Hypertrophic Phenotype

Non-ischemic cardiomyopathies represent a heterogeneous group of myocardial diseases potentially leading to heart failure, life-threatening arrhythmias, and eventually death. Myocardial dysfunction is associated with different underlying pathological processes, ultimately inducing changes in morphological appearance. Thus, classification based on presenting morphological phenotypes has been proposed, i.e., dilated, hypertrophic, restrictive, and right ventricular cardiomyopathies. In light of the key diagnostic and prognostic role of morphological and functional features, cardiovascular imaging has emerged as key element in the clinical workflow of suspected cardiomyopathies, and above all, cardiovascular magnetic resonance (CMR) represents the ideal technique to be used: thanks to its physical principles, besides optimal spatial and temporal resolutions, incomparable contrast resolution allows to assess myocardial tissue abnormalities in detail. Traditionally, weighted images and late enhancement images after gadolinium-based contrast agent administration have been used to perform tissue characterization, but in the last decade quantitative assessment of pre-contrast longitudinal relaxation time (native T1), post-contrast longitudinal relaxation time (post-contrast T1) and transversal relaxation time (T2), all displayed with dedicated pixel-wise color-coded maps (mapping), has contributed to give precious knowledge insight, with positive influence of diagnostic accuracy and prognosis assessment, mostly in the setting of the hypertrophic phenotype. This review aims to describe the available evidence of the role of mapping techniques in the assessment of hypertrophic phenotype, and to suggest their integration in the routine CMR evaluation of newly diagnosed cardiomyopathies with increased wall thickness.

Cardiac magnetic resonance in hypertrophic and dilated cardiomyopathies

Cardiomyopathies are a heterogeneous entity. The progress in the field of genetics has allowed over the years to determine its origin more and more often. The classification of these pathologies has changed over the years; it has been updated with new knowledge. Imaging allows to define the phenotypic characteristics of the different forms of cardiomyopathy. Cardiac magnetic resonance (CMR) allows a morphological evaluation of the associated (and sometimes pathognomonic) cardiac findings of any form of cardiomyopathy. The tissue characterization sequences also make magnetic resonance imaging unique in its ability to detect changes in myocardial tissue. This review aims to define the features that can be highlighted by CMR in hypertrophic and dilated forms and the possible differential diagnoses. In hypertrophic forms, CMR provides: precise evaluation of wall thickness in all segments, ventricular function and size and evaluation of possible presence of areas of fibrosis as well as changes in myocardial tissue (measurement of T1 mapping and extracellular volume values). In dilated forms, cardiac resonance is the gold standard in the assessment of ventricular volumes. CMR highlights also the potential alterations of the myocardial tissue.

Myocardial Energy Metabolism in Non-ischemic Cardiomyopathy

As the most metabolically demanding organ in the body, the heart must generate massive amounts of energy adenosine triphosphate (ATP) from the oxidation of fatty acids, carbohydrates and other fuels (e.g., amino acids, ketone bodies), in order to sustain constant contractile function. While the healthy mature heart acts omnivorously and is highly flexible in its ability to utilize the numerous fuel sources delivered to it through its coronary circulation, the heart’s ability to produce ATP from these fuel sources becomes perturbed in numerous cardiovascular disorders. This includes ischemic heart disease and myocardial infarction, as well as in various cardiomyopathies that often precede the development of overt heart failure. We herein will provide an overview of myocardial energy metabolism in the healthy heart, while describing the numerous perturbations that take place in various non-ischemic cardiomyopathies such as hypertrophic cardiomyopathy, diabetic cardiomyopathy, arrhythmogenic cardiomyopathy, and the cardiomyopathy associated with the rare genetic disease, Barth Syndrome. Based on preclinical evidence where optimizing myocardial energy metabolism has been shown to attenuate cardiac dysfunction, we will discuss the feasibility of myocardial energetics optimization as an approach to treat the cardiac pathology associated with these various non-ischemic cardiomyopathies.

Advanced Nuclear Medicine and Molecular Imaging in the Diagnosis of Cardiomyopathy

OBJECTIVE. The purpose of this article is to summarize the protocol, interpretation, and diagnostic performance of nuclear medicine and molecular imaging in imaging two distinctive, underdiagnosed cardiomyopathies: cardiac amyloidosis and cardiac sarcoidosis. CONCLUSION. Emerging new radiotracers and advanced molecular imaging modalities enable us to noninvasively characterize certain types of cardiomyopathies, including cardiac amyloidosis and cardiac sarcoidosis, with great confidence. We expect to improve recognition and promote the application of such advanced techniques in the imaging and management of these potentially lethal cardiomyopathies.

Epidemiology of the inherited cardiomyopathies

In the absence of contemporary, population-based epidemiological studies, estimates of the incidence and prevalence of the inherited cardiomyopathies have been derived from screening studies, most often of young adult populations, to assess cardiovascular risk or to detect the presence of disease in athletes or military recruits. The global estimates for hypertrophic cardiomyopathy (1/500 individuals), dilated cardiomyopathy (1/250) and arrhythmogenic right ventricular cardiomyopathy (1/5,000) are probably conservative given that only individuals who fulfil diagnostic criteria would have been included. This caveat is highly relevant because a substantial minority or even a majority of individuals who carry disease-causing genetic variants and are at risk of disease complications have incomplete and/or late-onset disease expression. The genetic literature on cardiomyopathy, which is often focused on the identification of genetic variants, has been biased in favour of pedigrees with higher penetrance. In clinical practice, an abnormal electrocardiogram with normal or non-diagnostic imaging results is a common finding for the sarcomere variants that cause hypertrophic cardiomyopathy, the titin and sarcomere variants that cause dilated cardiomyopathy and the desmosomal variants that cause either arrhythmogenic right ventricular cardiomyopathy or dilated cardiomyopathy. Therefore, defining the genetic epidemiology is also challenging given the overlapping phenotypes, incomplete and age-related expression, and highly variable penetrance even within individual families carrying the same genetic variant.

Laboratory medicine: health evaluation in elite athletes

The need to evaluate the health status of an athlete represents a crucial aim in preventive and protective sports science in order to identify the best diagnostic strategy to improve performance and reduce risks related to physical exercise. In the present review we aim to define the main biochemical and haematological markers that vary significantly during and after sports training to identify risk factors, at competitive and professional levels and to highlight the set up of a specific parameter's panel for elite athletes. Moreover, we also intend to consider additional biomarkers, still under investigation, which could further contribute to laboratory sports medicine and provide reliable data that can be used by athlete's competent staff in order to establish personal attitudes and prevent sports injuries.

Current Understanding of the Role of Cytoskeletal Cross-Linkers in the Onset and Development of Cardiomyopathies

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

T1 and T2 mapping to detect chronic inflammation in cardiac magnetic resonance imaging in heart failure with reduced ejection fraction

Aims

The purpose of this retrospective single‐centre study was to evaluate the non‐invasive detection of endomyocardial biopsy (EMB)‐established chronic myocardial inflammation in patients with heart failure with reduced ejection fraction (HFrEF) using T1 and T2 mapping.

Methods and results

The study population consisted of 52 retrospectively identified HFrEF patients who underwent EMB and cardiac magnetic resonance imaging at 3 Tesla. EMB was defined according to the position statement of the European Society of Cardiology and served as reference to identify inflammation in all patients. A control group of healthy volunteers with prior cardiac magnetic resonance imaging studies (n = 58) was also identified. Global and segmental T1 and T2 values as well as septal measurements and tissue heterogeneity parameters were calculated.

Out of the 52 patients with HFrEF, 33 patients had myocardial inflammation detected by EMB, while 19 patients were EMB negative for inflammation. Mean left ventricular ejection fraction was 31% in both groups (P = 0.97). Global T1 and T2 values in HFrEF patients were significantly higher compared with healthy controls (T1 1275 ± 69 ms vs. 1,175 ± 44 ms, P < 0.001; T2 40.0 ± 3.4 ms vs. 37.9 ± 1.6 ms, P < 0.001). The distribution of T1 and T2 values between patients with and without EMB‐proven chronic myocardial inflammation was not statistically different when regarding global (T1 1292 ± 71 ms vs. 1266 ± 67 ms, P = 0.26; T2 40.0 ± 2.6 ms vs. 40.0 ± 3.9 ms, P = 1.0), septal (T1 1299 ± 63 ms vs. 1289 ± 76 ms, P = 0.76; T2 40.1 ± 3.5 ms vs 40.0 ± 6.4 ms, P = 0.49) or maximum segmental values (T1 1414 ± 111 ms vs. 1363 ± 88 ms, P = 0.15; T2 47.3 ± 5.2 ms vs. 48.8 ± 11.8 ms, P = 0.53). Mean absolute deviation of segmental T1 and T2 values and log‐transformed pixel‐wise standard deviation as parameters of tissue heterogeneity did not reveal statistical significant differences between inflammation‐positive and inflammation‐negative HFrEF patients (all P > 0.4).

Conclusions

Conventionally performed quantitative T1 and T2 mapping values significantly correlated with prevalence of HFrEF but did not discriminate HFrEF patients with or without chronic myocardial inflammation in our cohort. This suggests that EMB is the preferred method to detect chronic myocardial inflammation in HFrEF.

Cells, Materials, and Fabrication Processes for Cardiac Tissue Engineering

Cardiovascular disease is the number one killer worldwide, with myocardial infarction (MI) responsible for approximately 1 in 6 deaths. The lack of endogenous regenerative capacity, added to the deleterious remodelling programme set into motion by myocardial necrosis, turns MI into a progressively debilitating disease, which current pharmacological therapy cannot halt. The advent of Regenerative Therapies over 2 decades ago kick-started a whole new scientific field whose aim was to prevent or even reverse the pathological processes of MI. As a highly dynamic organ, the heart displays a tight association between 3D structure and function, with the non-cellular components, mainly the cardiac extracellular matrix (ECM), playing both fundamental active and passive roles. Tissue engineering aims to reproduce this tissue architecture and function in order to fabricate replicas able to mimic or even substitute damaged organs. Recent advances in cell reprogramming and refinement of methods for additive manufacturing have played a critical role in the development of clinically relevant engineered cardiovascular tissues. This review focuses on the generation of human cardiac tissues for therapy, paying special attention to human pluripotent stem cells and their derivatives. We provide a perspective on progress in regenerative medicine from the early stages of cell therapy to the present day, as well as an overview of cellular processes, materials and fabrication strategies currently under investigation. Finally, we summarise current clinical applications and reflect on the most urgent needs and gaps to be filled for efficient translation to the clinical arena.

Sex-Related Differences in Dilated Cardiomyopathy with a Focus on Cardiac Dysfunction in Oncology

PURPOSE OF REVIEW

The aim of this report is to describe the main aspects of sex-related differences in non-ischemic dilated cardiomyopathies (DCM), focusing on chemotherapy-induced heart failure (HF) and investigating the possible therapeutic implications and clinical management applications in the era of personalized medicine.

RECENT FINDINGS

In cardio-oncology, molecular and multimodality imaging studies confirm that sex differences do exist, affecting the therapeutic cardioprotective strategies and, therefore, the long-term outcomes. Interestingly, compelling evidences suggest that sex-specific characteristics in drug toxicity might predict differences in the therapeutic response, most likely due to the tangled interplay between cancer and HF, which probably share common underlying mechanisms. Cardiovascular diseases show many sex-related differences in prevalence, etiology, phenotype expression, and outcomes. Complex molecular mechanisms underlie this diverse pathological manifestations, from sex-determined differential gene expression to sex hormone interaction with their receptors in the heart. Non-ischemic DCM is an umbrella definition that incorporates several etiologies, including chemotherapy-induced cardiomyopathies. The role of sex as a risk factor for cardiotoxicity is poorly explored. However, understanding the various features of disease manifestation and outcomes is of paramount importance for a prompt and tailored evaluation.

ESC EORP Cardiomyopathy Registry: real-life practice of genetic counselling and testing in adult cardiomyopathy patients

Aims

Cardiomyopathies comprise a heterogeneous group of diseases, often of genetic origin. We assessed the current practice of genetic counselling and testing in the prospective European Society of Cardiology EURObservational Research Programme Cardiomyopathy Registry.

Methods and results

A total of 3208 adult patients from 69 centres in 18 countries were enrolled. Genetic counselling was performed in 60.8% of all patients [75.4% in hypertrophic cardiomyopathy (HCM), 39.2% in dilated cardiomyopathy (DCM), 70.8% in arrhythmogenic right ventricular cardiomyopathy (ARVC), and 49.2% in restrictive cardiomyopathy (RCM), P < 0.001]. Comparing European geographical areas, genetic counselling was performed from 42.4% to 83.3% (P < 0.001). It was provided by a cardiologist (85.3%), geneticist (15.1%), genetic counsellor (11.3%), or a nurse (7.5%) (P < 0.001). Genetic testing was performed in 37.3% of all patients (48.8% in HCM, 18.6% in DCM, 55.6% in ARVC, and 43.6% in RCM, P < 0.001). Index patients with genetic testing were younger at diagnosis and had more familial disease, family history of sudden cardiac death, or implanted cardioverter defibrillators but less co‐morbidities than those not tested (P < 0.001 for each comparison). At least one disease‐causing variant was found in 41.7% of index patients with genetic testing (43.3% in HCM, 33.3% in DCM, 51.4% in ARVC, and 42.9% in RCM, P = 0.13).

Conclusions

This is the first detailed report on the real‐life practice of genetic counselling and testing in cardiomyopathies in Europe. Genetic counselling and testing were performed in a substantial proportion of patients but less often than recommended by European guidelines and much less in DCM than in HCM and ARVC, despite evidence for genetic background.

A case series on inflammatory cardiomyopathy and suspected cardiac sarcoidosis: role of cardiac PET in management

Background

Presentation of life-threatening arrhythmias concomitantly with a new-onset non-ischaemic cardiomyopathy raises concern for an inflammatory cardiomyopathy such as cardiac sarcoidosis or cardiac manifestations of connective tissue disease. Comprehensive workup for specific aetiologies may be unrevealing except for signs of myocardial inflammation identified on cardiac positron emission tomography (PET). Here, we present five cases of such subjects and their clinical course.

Case summary

We collected clinical, imaging, pathological, and follow-up data of five subjects presenting with arrhythmias and unexplained new-onset cardiomyopathy. Mean age was 56.2 ± 5.8 years. Three subjects presented with ventricular tachycardia and two with atrial arrhythmias. Echocardiography showed a mean left ventricular ejection fraction of 37 ± 9%_. Significant coronary artery disease was ruled out in all cases as the cause of the cardiomyopathy. All patients underwent cardiac magnetic resonance imaging (MRI) and PET scan at presentation and follow-up. In all patients, cardiac MRI revealed hyperenhancement in epicardial and mid-myocardial pattern in a non-coronary distribution, while PET scan revealed fluorodeoxyglucose (FDG) mismatch defects in multiple foci in a non-coronary distribution. Right ventricular biopsy was obtained in all patients and revealed interstitial fibrosis and cardiomyocyte hypertrophy. On median follow-up of 210 days, all subjects had improvement in both heart failure symptoms and arrhythmias and repeat PET in four out of five patients showed decreased inflammation.

Discussion

A high level of suspicion for inflammatory cardiomyopathy is needed in patients presenting with new unexplained cardiomyopathy and arrhythmias. A cardiac FDG-PET should be considered for diagnosis if cardiac inflammation is in the differential. This can inform further decisions regarding targeted immunomodulation therapy that may be helpful in this cohort.

Prevalence of sudden arrhythmic death syndrome-related genetic mutations in an Asian cohort of whole genome sequence

AIMS

Recently, the spectrum of background mutation in the genes implicated in sudden arrhythmic death syndrome (SADS), has been elucidated in the Caucasian populations. However, this information is largely unknown in the Asian populations.

METHODS AND RESULTS

We assessed the background rare variants (minor allele frequency < 0.01) of major SADS genes in whole genome sequence data of 1514 healthy Taiwanese subjects from the Taiwan Biobank. We found up to 45% of healthy subjects have a rare variant in at least one of the major SADS genes. Around 3.44% of healthy subjects had multiple mutations in one or multiple genes. The background mutation rates in long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and arrhythmogenic right ventricular cardiomyopathy genes were similar, but those in Brugada syndrome (BrS) (SCN5A) and hypertrophic cardiomyopathy (HCM) genes (MYBPC3, MYH7, and TNNT2) were higher, compared to those reported in the Caucasian populations. Furthermore, the rate of incidental pathogenic variant was highest in MYBPC3 gene. Finally, the number of variant was proportional to the exon length of the gene (R2 = 0.486, P = 0.0056) but not related to its functional or evolutionary importance (degree of evolutionary conservation) (R2 = 0.0008, P = 0.9218), suggesting that the mutation was random. The ratio of variant number over exon nucleotide length was highest in MYBPC3, MYH7, and TNNT2 genes.

CONCLUSION

Unique features of background SADS gene mutation in the Asian populations include higher prevalence of incidental variant in HCM, BrS, and long QT 3 (SCN5A) genes. HCM genes have the highest variant number per exon length.