Hyperactivation of ATF4/TGF-ß1 signaling contributes to the progressive cardiac fibrosis in Arrhythmogenic cardiomyopathy caused by DSG2 Variant.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized with progressive cardiac fibrosis and heart failure. However, the exact mechanism driving the progression of cardiac fibrosis and heart failure in ACM remains elusive. This study aims to investigate the underlying mechanisms of progressive cardiac fibrosis in ACM caused by newly identified Desmoglein-2 (DSG2) variation. METHODS: We identified homozygous DSG2F531C variant in a family with 8 ACM patients using whole-exome sequencing and generated Dsg2F536C knock-in mice. Neonatal and adult mouse ventricular myocytes isolated from Dsg2F536C knock-in mice were used. We performed functional, transcriptomic and mass spectrometry analyses to evaluate the mechanisms of ACM caused by DSG2F531C variant. RESULTS: All eight patients with ACM were homozygous for DSG2F531C variant. Dsg2F536C/F536C mice displayed cardiac enlargement, dysfunction, and progressive cardiac fibrosis in both ventricles. Mechanistic investigations revealed that the variant DSG2-F536C protein underwent misfolding, leading to its recognition by BiP within the endoplasmic reticulum, which triggered endoplasmic reticulum stress, activated the PERK-ATF4 signaling pathway and increased ATF4 levels in cardiomyocytes. Increased ATF4 facilitated the expression of TGF-ß1 in cardiomyocytes, thereby activating cardiac fibroblasts through paracrine signaling and ultimately promoting cardiac fibrosis in Dsg2F536C/F536C mice. Notably, inhibition of the PERK-ATF4 signaling attenuated progressive cardiac fibrosis and cardiac systolic dysfunction in Dsg2F536C/F536C mice. CONCLUSIONS: Hyperactivation of the ATF4/TGF-ß1 signaling in cardiomyocytes emerges as a novel mechanism underlying progressive cardiac fibrosis in ACM. Targeting the ATF4/TGF-ß1 signaling may be a novel therapeutic target for managing ACM.

Majority of transferred mosaic embryos developed healthy live births revealed by a preclinical study using embryonic morphology assessment and noninvasive PGT-A on cell-free DNA in blastocoel fluid.

PURPOSE: This preclinical study aimed to evaluate whether using transferred mosaic embryos (primarily selected by embryonic morphology assessment (EMA) and compared by the noninvasive preimplantation genetic testing for aneuploidy (niPGT-A) on cell-free DNA in blastocoel fluid (BF)) increases the rates of clinical pregnancies (CPs) and healthy live births (HLBs) and to investigate whether niPGT-A could provide valuable genetic information for the EMA-selected transferred mosaic embryos. METHODS: This study collected 215 blastocyst culture samples and 182 BF samples. Cell-free DNA from the BF was amplified and examined by next-generation sequencing-based niPGT-A. All 182 patients underwent EMA. However, only 147 underwent in vitro fertilization and embryo transfer, and only 113 clinical outcomes were followed up. Comprehensive chromosome screening for the chorionic villus sampling of spontaneous miscarriages and noninvasive prenatal testing for ongoing pregnancies were also performed. RESULTS: The implantation rate was 77.55% in 147 transferred high-quality embryos selected by EMA. Among 113 CPs, 16 led to spontaneous miscarriage (14.16%), and 97 resulted in HLBs (85.84%). According to the niPGT-A results for 113 patients with clinical outcomes, 80.4% had CP (euploid, 20.54%; single aneuploid, 1.79%; mosaic chromosome aneuploid and/or segmental aneuploid, 58.04%). Of all the mosaic aneuploids, 90.76% were false positive, transforming to euploid. CONCLUSIONS: Transferred EMA-selected embryos showed higher implantation rates. The niPGT-A of BF provided valuable genetic status ("-ploid") information, which helped reduce aneuploid-induced implantation failure and miscarriage, thereby increasing the CP and HLB rates. Additionally, majority of the transferred embryos with complex/chaotic mosaic aneuploid would likely develop HLBs.

Clinical characteristics and therapeutic strategy of frequent accelerated idioventricular rhythm.

BACKGROUND: Accelerated idioventricular rhythm (AIVR) is often transient, considered benign and requires no treatment. This observational study aims to investigate the clinical manifestations, treatment, and prognosis of frequent AIVR. METHODS: Twenty-seven patients (20 male; mean age 32.2 ± 17.0 years) diagnosed with frequent AIVR were enrolled in our study. Inclusion criteria were as follows: (1) at least three recordings of AIVR on 24-h Holter monitoring with an interval of over one month between each recording; and (2) resting ectopic ventricular rate between 50 to 110 bpm on ECG. Electrophysiological study (EPS) and catheter ablation were performed in patients with distinct indications. RESULTS: All 27 patients experienced palpitation or chest discomfort, and two had syncope or presyncope on exertion. Impaired left ventricular ejection fraction (LVEF) was identified in 5 patients, and LVEF was negatively correlated with AIVR burden (P < 0.001). AIVR burden of over 73.8%/day could predict impaired LVEF with a sensitivity of 100% and specificity of 94.1%. Seventeen patients received EPS and ablation, five of whom had decreased LVEF. During a median follow-up of 60 (32, 84) months, LVEF of patients with impaired LV function returned to normal levels 6 months post-discharge, except one with dilated cardiomyopathy (DCM). Two patients died during follow-up. The DCM patient died due to late stage of heart failure, and another patient who refused ablation died of AIVR over-acceleration under fever. CONCLUSIONS: Frequent AIVR has unique clinical manifestations. AIVR patients with burden of over 70%, impaired LVEF, and/or symptoms of syncope or presyncope due to over-response to sympathetic tone should be considered for catheter ablation.

2020 APHRS/HRS expert consensus statement on the investigation of decedents with sudden unexplained death and patients with sudden cardiac arrest, and of their families.

This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.

2020 APHRS/HRS expert consensus statement on the investigation of decedents with sudden unexplained death and patients with sudden cardiac arrest, and of their families.

This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.

A Novel Gain-of-Function KCND3 Variant Associated with Brugada Syndrome.

Brugada syndrome (BrS) is a known cause of sudden cardiac death (SCD) characterized by abnormal electrocardiograms and fatal arrhythmias. The variants in KCND3 encoding the KV4.3 potassium-channel (the α-subunit of the Ito) have seldom been reported in BrS. This study aimed to identify novel KCND3 variants associated with BrS and elucidate BrS pathogenesis. High-depth targeted sequencing was performed and the electrophysiological properties of the variants were detected by whole-cell patch-clamp methods in a cultured-cell expressing system. The transcriptional levels of KV4.3 in different genotypes were studied by real-time PCR. Western blot was used to assess channel protein expression. A novel KCND3heterozygous variant, c.1292G>A (Arg431His, R431H), was found in the proband. Whole-cell patch-clamp results revealed a gain-of-function phenotype in the variant, with peak Ito current density increased and faster recovery from inactivation. The expression of mutant Kv4.3 membrane protein increased and the cytoplasmic protein decreased, demonstrating that the membrane/cytoplasm ratio was significantly different. In conclusion, a novel KCND3 heterozygous variant was associated with BrS. The increased Ito current explained the critical role of KCND3 in the pathogenesis of BrS. Genetic screening for KCND3 could be useful for understanding the pathogenesis of BrS and providing effective risk stratification in the clinic.

Knockout of SORBS2 Protein Disrupts the Structural Integrity of Intercalated Disc and Manifests Features of Arrhythmogenic Cardiomyopathy.

Background Sorbs2b (sorbin and SH3 domain-containing 2b) was recently identified as a cardiomyopathy gene from a zebrafish mutagenesis screen. However, cardiac functions of its mammalian ortholog remain elusive. Methods and Results We conducted a detailed expression and subcellular localization analysis of Sorbs2 ortholog in mice and a phenotypic characterization in Sorbs2 knockout mice. Sorbs2 is highly expressed in the mouse heart and encodes an adhesion junction/desmosome protein that is mainly localized to the intercalated disc. A mutation with near complete depletion of the Sorbs2 protein in mice results in phenotypes characteristic of human arrhythmogenic cardiomyopathy (ACM), including right ventricular dilation, right ventricular dysfunction, spontaneous ventricular tachycardia, and premature death. Sorbs2 is required to maintain the structural integrity of intercalated disc. Its absence resulted in profound cardiac electrical remodeling with impaired impulse conduction and action potential derangements. Targeted sequencing of human patients with ACM identified 2 rare splicing variants classified as likely pathogenic were in 2 unrelated individuals with ACM from a cohort of 59 patients with ACM. Conclusions The Sorbs2 knockout mouse manifests several key features reminiscent of human ACM. Although the candidacy of SORBS2 as a new ACM-susceptibility gene is supported by preliminary human genetics study, future validation in larger cohorts with ACM is needed.

Whole-exome sequencing identifies a de novo PDE3A variant causing autosomal dominant hypertension with brachydactyly type E syndrome: a case report.

BACKGROUND: Autosomal dominant hypertension with brachydactyly type E syndrome caused by pathogenic variants in the PDE3A gene was first reported in 2015. To date, there are only a few reports of this kind of syndrome. Other patients still lack a genetic diagnosis. CASE PRESENTATION: Whole-exome sequencing was performed in an 18-year-old female proband with a clinical diagnosis of hypertension with brachydactyly syndrome. Quantitative real-time PCR was used to identify pathogenic copy number variations (CNVs). After bioinformatics analysis and healthy control database filtering, we revealed a heterozygous missense PDE3A variant (c.1346G > A, p.Gly449Asp). The variant was absent in the ExAC database and located in a highly evolutionarily conserved cluster of reported PDE3A pathogenic variants. Importantly, this variant was predicted to affect protein function by both SIFT (score = 0) and PolyPhen-2 (score = 1). After Sanger sequencing, the variant was determined to be absent in the healthy parents of the proband as well as 800 ethnically and geographically matched healthy controls. CONCLUSION: We present a report linking a de novo PDE3A variant to autosomal dominant hypertension with brachydactyly type E syndrome.

Genetic arrhythmias complicating patients with dilated cardiomyopathy.

BACKGROUND: Sudden cardiac death due to malignant arrhythmias is a common cause of death in dilated cardiomyopathy (DCM). Whether genetic variants increase the risk of arrhythmias in DCM is unknown. OBJECTIVE: The purpose of this study was to investigate the genetic causes of arrhythmias in DCM patients. METHODS: Whole-exome sequencing and high-depth targeted next-generation sequencing (142-gene panel) were used. Eight specific DCM pedigrees with arrhythmias and 2 separate cohorts of 1232 consecutive unrelated sporadic DCM patients from 3 medical centers (550 in the discovery cohort, 682 in the replication cohort) were analyzed; 470 (250 in the discovery cohort, 220 in the replication cohort) suffered from arrhythmias (DCM-A group) and 762 (300 in the discovery cohort, 462 in the replication cohort) did not (DCM-NA group). All identified causative variants were Sanger sequenced to eliminate false-positive results and then screened in 700 unrelated matched arrhythmia- and DCM-free healthy controls. RESULTS: We identified long QT syndrome (LQTS)-causative variants that independently cosegregated in 2 unrelated DCM-LQTS pedigrees. Pathogenic variants in arrhythmia-related genes (ion channelopathies) were identified in 4.9% (23/470) of sporadic DCM-A patients (4.0% in the discovery cohort, 5.9% in the replication cohort) but only 0.1% (1/762) of sporadic DCM-NA patients (P = 2.16 × 10-9). These arrhythmia-related pathogenic variants included long QT syndrome, atrial fibrillation, sick sinus syndrome, cardiac conduction disease, and Brugada syndrome. CONCLUSION: Some arrhythmias in DCM patients are caused by arrhythmia-related pathogenic variants. For DCM patients with explicit arrhythmias, arrhythmia-causative genetic screening may help to explain the etiology and decision-making.

A PLN nonsense variant causes severe dilated cardiomyopathy in a novel autosomal recessive inheritance mode.

BACKGROUND: Pathogenic variants in human phospholamban coding gene (PLN) are known to cause hereditary dilated cardiomyopathy with heart failure in an autosomal dominant mode. METHODS: We performed high-depth targeted next-generation sequencing using a cardiomyopathy-panel containing 80 disease-related genes in 650 unrelated patients with non-ischemic cardiomyopathy to identify potential pathogenic PLN variants. To comprehensively evaluate the genetic cause of the proband and his pedigree, whole-exome sequencing and Sanger sequencing were performed. RESULTS: A novel homozygous nonsense variant (p.Glu2Ter, c.4G>T) in PLN was identified in a 36-year-old male suffering from dilated cardiomyopathy with severe heart failure. No more cardiomyopathy-causing variant or likely pathogenic copy number variation was identified. This variant was not detected in 800 unrelated healthy controls. Furthermore, the variant is not in the Exome Aggregation Consortium or the Genome Aggregation databases. Western blots showed that this variant significantly reduced the expression of phospholamban. Furthermore, in pedigree analysis, we found that all five heterozygous PLN-p.Glu2Ter carriers (including four elder relatives) had normal heart size and cardiac function, which revealed a novel autosomal recessive inheritance mode. CONCLUSIONS: Our study identified a novel pathogenic variant of PLN, and revealed a novel pathogenic inheritance mode of PLN causing dilated cardiomyopathy with heart failure.

Ranolazine prevents pressure overload-induced cardiac hypertrophy and heart failure by restoring aberrant Na+ and Ca2+ handling.

BACKGROUND: Cardiac hypertrophy and heart failure are characterized by increased late sodium current and abnormal Ca2+ handling. Ranolazine, a selective inhibitor of the late sodium current, can reduce sodium accumulation and Ca 2+ overload. In this study, we investigated the effects of ranolazine on pressure overload-induced cardiac hypertrophy and heart failure in mice. METHODS AND RESULTS: Inhibition of late sodium current with the selective inhibitor ranolazine suppressed cardiac hypertrophy and fibrosis and improved heart function assessed by echocardiography, hemodynamics, and histological analysis in mice exposed to chronic pressure overload induced by transverse aortic constriction (TAC). Ca2+ imaging of ventricular myocytes from TAC mice revealed both abnormal SR Ca 2+ release and increased SR Ca 2+ leak. Ranolazine restored aberrant SR Ca 2+ handling induced by pressure overload. Ranolazine also suppressed Na + overload induced in the failing heart, and restored Na + -induced Ca 2+ overload in an sodium-calcium exchanger (NCX)-dependent manner. Ranolazine suppressed the Ca 2+ -dependent calmodulin (CaM)/CaMKII/myocyte enhancer factor-2 (MEF2) and CaM/CaMKII/calcineurin/nuclear factor of activated T-cells (NFAT) hypertrophy signaling pathways triggered by pressure overload. Pressure overload also prolonged endoplasmic reticulum (ER) stress leading to ER-initiated apoptosis, while inhibition of late sodium current or NCX relieved ER stress and ER-initiated cardiomyocyte apoptosis. CONCLUSIONS: Our study demonstrates that inhibition of late sodium current with ranolazine improves pressure overload-induced cardiac hypertrophy and systolic and diastolic function by restoring Na+ and Ca 2+ handling, inhibiting the downstream hypertrophic pathways and ER stress. Inhibition of late sodium current may provide a new treatment strategy for cardiac hypertrophy and heart failure.

A targeted sequencing approach to find novel pathogenic genes associated with sporadic aortic dissection.

Aortic dissection (AD) is a heterogeneous genetic disease of the aorta with high mortality and poor prognosis. However, only few genetic causes of AD have been explored till date. After conducting a broad literature review focused on identifying potential pathogenic pathways, we designed a panel containing 152 AD-associated genes to conduct massively parallel targeted next-generation sequencing of 702 sporadic aortic dissection patients and 163 matched healthy controls. After validation by Sanger sequencing, we identified 21 definitely pathogenic and 635 likely pathogenic variants in 61.25% (430/702) of patients. In these patients, 34.88% (150/430) harbored more than one variant that was either definitely or likely to be pathogenic. Among the candidate genes, we identified 546 likely pathogenic variants in 47.72% (335/702) of patients. Importantly, we identified 94 loss-of-function (LOF) variants in 45 genes in AD patients, but only five LOF variants in the controls (P=1.34×10-4). With a burden test, we highlighted RNF213 as an important new gene for AD pathogenesis. We also performed transcriptome sequencing of human aorta tissues to evaluate the expression levels of these newly identified genes. Our study has compiled a comprehensive genetic map of sporadic AD in the Han Chinese population. We believe it will facilitate risk predicting and genetic diagnosis of this severe disease in the future.

Idiopathic isolated fibrotic atrial cardiomyopathy underlies unexplained scar-related atrial tachycardia in younger patients.

Aims: Unexplained scar-related atrial tachycardia (AT) has been frequently encountered in clinical practice. We hypothesized that idiopathic, isolated fibrotic atrial cardiomyopathy (ACM) underlies this rhythm disorder. This study was aimed to characterize the underlying substrate and to explore the aetiology of this unexplained scar-related AT. Methods and results: Twenty-six (11 men, aged 46 ± 13 years) of 52 non-surgical scar-related AT patients identified by three-dimensional voltage mapping were enrolled in this prospective observational study. Multimodality image examinations (echocardiography, cardiac magnetic resonance, 99Tc single-photon emission computed tomography), ventricular voltage mapping, and intracardiac pressure curve recording ruled out ventricular involvement. Catheter ablation was acutely successful for all the patients, and pacemaker implantation was performed in seven patients who presented sinus node dysfunction or atrial standstill after termination of the AT. In three patients with multiple AT recurrences, the diseased areas of the right atrium were resected and dechannelled via mini-invasive surgical interventions. Histological examinations revealed profound fibrosis without amyloidosis or adipose deposition. Viral and familial investigations yielded negative results. Fibrosis progression over a median of 45 (5-109) months of follow-up manifested as atrial arrhythmia recurrence in seven patients and atrial lead non-capture due to newly developed atrial standstill in two patients. Two patients suffered four ischaemic stroke events before receiving anticoagulation treatment. Conclusion: Isolated, fibrotic ACM may underlie the idiopathic scar-related ATs. This novel cardiomyopathy has unique clinical characteristics with high morbidity including stroke and warrants specific therapeutic strategies. Further investigations are required to determine the aetiology and mechanism.

Variants of genes encoding collagens and matrix metalloproteinase system increased the risk of aortic dissection.

Aortic dissection (AD) is a devastating, heterogeneous condition of aorta. The homeostasis between collagens and matrix metalloproteases (MMPs)/tissue inhibitors of MMPs (TIMPs) system in the extracellular matrix plays an important role for structure and functions of aorta. However, our knowledge on association between variants of genes in this system and pathogenesis of AD is very limited. We analyzed all yet known coding human genes of collagens (45 genes), MMPs/TIMPs (27 genes) in 702 sporadic AD patients and in 163 matched healthy controls, by using massively targeted next-generation and Sanger sequencing. To define the pathogenesis of potential disease-causing candidate genes, we performed transcriptome sequencing and pedigree co-segregation analysis in some genes and generated Col5a2 knockout rats. We identified 257 pathogenic or likely pathogenic variants which involved 88.89% (64/72) genes in collagens-MMPs/TIMPs system and accounted for 31.05% (218/702) sporadic AD patients. In them, 84.86% patients (185/218) carried one variant, 12.84% two variants and 2.30% more than two variants. Importantly, we identified 52 novel probably pathogenic loss-of-function (LOF) variants (20 nonsense, 16 frameshift, 14 splice sites, one stop-loss, one initiation codon) in 11.06% (50/452) AD patients, which were absent in 163 controls (P=2.5×10-5). Transcriptome sequencing revealed that identified variants induced dyshomeostasis in expression of collagens-TIMPs/MMPs systems. The Col5a2 -/- rats manifested growth retardation and aortic dysplasia. Our study provides a first comprehensive map of genetic alterations in collagens-MMPs/TIMPs system in sporadic AD patients and suggests that variants of these genes contribute largely to AD pathogenesis.

Rapid molecular genetic diagnosis of hypertrophic cardiomyopathy by semiconductor sequencing.

BACKGROUND: Rapidly determining the complex genetic basis of Hypertrophic cardiomyopathy (HCM) is vital to better understanding and optimally managing this common polygenetic cardiovascular disease. METHODS: A rapid custom Ion-amplicon-resequencing assay, covering 30 commonly affected genes of HCM, was developed and validated in 120 unrelated patients with HCM to facilitate genetic diagnosis of this disease. With this HCM-specific panel and only 20 ng of input genomic DNA, physicians can, for the first time, go from blood samples to variants within a single day. RESULTS: On average, this approach gained 595628 mapped reads per sample, 95.51% reads on target (64.06 kb), 490-fold base coverage depth and 93.24% uniformity of base coverage in CDS regions of the 30 HCM genes. After validation, we detected underlying pathogenic variants in 87% (104 of 120) samples. Tested seven randomly selected HCM genes in eight samples by Sanger sequencing, the sensitivity and false-positive-rate of this HCM panel was 100% and 5%, respectively. CONCLUSIONS: This Ion amplicon HCM resequencing assay provides a currently most rapid, comprehensive, cost-effective and reliable measure for genetic diagnosis of HCM in routinely obtained samples.

[Clinical characteristics and genetic analysis of three pediatric patients with idiopathic restrictive cardiomyopathy].

OBJECTIVE: Restrictive cardiomyopathy (RCM) is rare in children, and little is known about the molecular basis of RCM. The aim of this study was to investigate the clinical and myopathological characteristics and to detect mutations on cardiac sarcomere protein genes in three idiopathic pediatric RCMs. METHODS: Detailed clinical characteristics and familiar history were obtained in three idiopathic pediatric RCMs. One hundred healthy pediatric individuals were recruited as controls. Histological evaluation was performed with heart tissue retrieved at catheterization in case-1 and case-2. The entire coding sequences of four cardiac sarcomere protein genes, including cardiac troponin T (TNNT2), cardiac troponin I(TNNI3), ß-myosin heavy chain (MYH7), and α-actin (ACTC)were screened for mutations. Sequence variants were then tested in the family as well as in 100 healthy control DNAs. RESULTS: All three index cases were diagnosed as primary RCMs without family history, and their clinical conditions deteriorated rapidly. Case-1 was in combination with ventricular septal defect. Case-2 was in combination with mid- and inferoseptal hypertrophy. In case-1, myocardial biopsies displayed extensive an isomorphism and disarray of cardiomyocytes; electron microscopy showed large stacks of severely dysmorphic megamitochondria and focal Z-disc streaming. In case-2, endomyocardial biopsy revealed moderate myocyte hypertrophy with mild interstitial fibrosis; transmission electron microscopy showed misalignment of Z-bands and unequal Z-Z band distances. Genetic analysis identified two heterozygous missense mutations in TNNI3, with R204H in case-1 and R192H in case-3 respectively. A de novo heterozygous deletion in TNNT2 (p. Asn100_Glu101del) was identified in case-2. Sequence analysis shows that all three mutations are located in a position highly conserved across many species. The three mutations were negative for their parents and controls. CONCLUSION: The clinical conditions in all three index cases are deteriorated rapidly after diagnosed as primary RCM. Three heterozygous mutations including two in TNNI3 and one in TNNT2 gene are identified in the three RCMs respectively, which are considered as causative mutations. These findings provide new insights into the molecular etiology responsible for pediatric RCM.

Establishment and evaluation of a swine model of acute myocardial infarction and reperfusion-ventricular fibrillation-cardiac arrest using the interventional technique.

BACKGROUND: Ventricular fibrillation is the main cause of sudden cardiac death among patients with acute myocardial infarction (AMI). Substantial benefits could be obtained by both researchers and practitioners if an AMI reperfusion-ventricular fibrillation-cardiac arrest model were established. METHODS: Twenty swine were anesthetized and underwent occlusion of the left anterior descending branch for 90 minutes prior to blood reperfusion. Throughout this process, continuous 12-lead electrocardiography (ECG) was used to monitor heart rate, rhythm, and electrocardiogram alteration. Thereafter, AMI was confirmed by ECG and left ventricular angiography. Heart tissue was collected for pathological analysis, and for evaluation of the establishment of a model of AMI reperfusion. RESULTS: Seven swine died during the model establishment, and the 13 surviving swine were proven to have myocardial infarction; nine of those survivors had ventricular fibrillation-cardiac arrest after reperfusion based on the electrocardiograph and pathological examination. CONCLUSION: Blocking the left anterior descending branch by inflation of an over-the-wire coronary balloon catheter in swine can result in successful establishment of a swine model of AMI and reperfusion-ventricular fibrillation-cardiac arrest, with good reproducibility and a high survival rate.

ß1-Adrenoceptor blocker aggravated ventricular arrhythmia.

OBJECTIVES: To assess the impact of ß1 -adrenoceptor blockers (ß1 -blocker) and isoprenaline on the incidence of idiopathic repetitive ventricular arrhythmia that apparently decreases with preprocedural anxiety. METHODS: From January 2010 to July 2012, six patients were identified who had idiopathic ventricular arrhythmias that apparently decreased (by greater than 90%) with preprocedural anxiety. The number of ectopic ventricular beats per hour (VPH) was calculated from Holter or telemetry monitoring to assess the ectopic burden. The mean VPH of 24 hours from Holter before admission (VPH-m) was used as baseline (100%) for normalization. ß1 -Blockers, isoprenaline, and/or aminophylline were administrated successively on the ward and catheter lab to evaluate their effects on the ventricular arrhythmias. RESULTS: Among 97 consecutive patients with idiopathic ventricular arrhythmias, six had reduction in normalized VPHs in the hour before the scheduled procedure time from (104.6 ± 4.6%) to (2.8 ± 1.6%) possibly due to preprocedural anxiety (P < 0.05), then increased to (97.9 ± 9.7%) during ß1 -blocker administration (P < 0.05), then quickly reduced to (1.6 ± 1.0%) during subsequent isoprenaline infusion. Repeated ß1 -blocker quickly counteracted the inhibitory effect of isoprenaline, and VPHs increased to (120.9 ± 2.4%) from (1.6 ± 1.0%; P < 0.05). Isoprenaline and ß1 -blocker showed similar effects on the arrhythmias in catheter lab. CONCLUSIONS: In some patients with structurally normal heart and ventricular arrhythmias there is a marked reduction of arrhythmias associated with preprocedural anxiety. These patients exhibit a reproducible sequence of ß1 -blocker aggravation and catecholamine inhibition of ventricular arrhythmias, including both repetitive ventricular premature beats and monomorphic ventricular tachycardia.

Circulating microRNAs, novel biomarkers of acute myocardial infarction: a systemic review.

BACKGROUND: MicroRNAs (MiRNA) are a novel class of non-coding RNAs involved in the regulation of gene expression post-transcriptionally by cleavage or translational repression of their specific target miRNAs. Numerous studies have demonstrated that circulating miRNAs are stable and abundant in blood and aberrantly expressed under pathological conditions, including cardiovascular diseases. The implications of circulating miRNAs in acute myocardial infarction have recently been recognized. This review will highlight the potential role of miRNA as a novel class of biomarkers in acute myocardial infarction. METHODS: This systemic review is based on our own work and other related reports. RESULTS: During diseases circulating miRNAs are derived from not only circulating blood cells but also other tissues affected by ongoing diseases. These disease-related miRNAs in the blood can serve as potential biomarkers. CONCLUSION: The circulating miRNAs can be used as novel biomarkers potentially offering more sensitive and specific tests than those currently available for diagnosis of acute myocardial infarction.