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Background: Idiopathic ventricular tachycardia (VT) occurs in structurally normal hearts and accounts for a significant number of all types of VT. The genome-wide association study is the most effective strategy for identifying novel genetic variants for common diseases. However, no genome-wide association study has been reported for idiopathic VT. Methods: We conducted the first genome-wide association study for idiopathic VT in the Chinese Han population using a discovery population with 246 cases and 648 controls and a replication population with 222 cases and >4072 controls. Candidate VT genes were functionally characterized in zebrafish. Real-time RT-PCR analysis was used to determine the effects of candidate genes on expression of ion channels and regulators. Patch-clamping was used to record L-type calcium current from neonatal rat cardiomyocytes with overexpression of candidate genes. Results: We identified 4 significant loci represented by rs78960694 (minor allele frequency [MAF]=5.02% in cases and 1.84% in controls; P =4.30×10 − 12, odds ratio [OR]=3.91) and rs2229095 (MAF=3.25% in cases and 1.63% in controls; P =1.02×10 − 7, OR=3.44) near and in CCR7 , respectively, rs68126098 in NELL1 (MAF=40.98% in cases and 32.07% in controls; P= 2.40×10 − 8, OR=1.53), rs2390325 between PKN2 and LMO4 (MAF=21.19% in cases and 15.12% in controls; P =1.92×10 − 7, OR=1.62), and rs270065 in CSMD1 (MAF=33.63% in cases and 40.25% in controls; P =9.51×10 − 7, OR=0.69). Note that the associations of idiopathic VT for CCR7 variant rs78960694 and NELL1 variant rs68126098 reach genome-wide significance ( P − 8). Overexpression of either PKN2 or CCR7 increased the heart rate in zebrafish, and enhanced expression of CACNA1C, RYR2 , or NOS1AP in zebrafish embryos, HEK293, and AC16 cardiomyocytes. Overexpression of either PKN2 or CCR7 significantly increased L-type Ca2+ current density. Conclusions: The first genome-wide association study identifies 4 novel loci and 2 risk genes ( PKN2 and CCR7 ) for idiopathic VT. These findings identify new molecular determinants for cardiac calcium homeostasis and rhythm maintenance and provide novel targets for diagnosis and treatment for idiopathic VT.

The importance of the local sequence context in determining how efficiently aminoglycosides rescue nonsense mutations has been established previously in disease models. Different stop codons appear to facilitate the termination process with differing efficiencies. Furthermore, the efficiency with which termination is suppressed may also be influenced by the local sequence context surrounding the stop codon. The strongest bias has usually been identified with the nucleotide base that immediately follows the stop codon in the majority of experiments. However, how the sequence context influences the efficiency of aminoglycosides in rescuing the human ether-a-go-go-related (HERG) protein in mammalian cells remains to be fully elucidated. Therefore, the present study was devised to examine the susceptibility of different termination codons on the HERG gene and the +4 nucleotide immediately following them to be suppressed by aminoglyco-sides in 293 cells. The 293 cells were transiently transfected with the wild-type or mutant genes. The read-through effect was subsequently examined by adding aminoglycoside G418 into the culture medium, followed by incubation of the cells for 24 h. An immunofluorescence method was then used to observe the protein expression of HERG prior to and following drug treatment. Patch clamping was performed to evaluate the function of the HERG protein. These experiments revealed that stop codons TGA and TAA in the R1014X mutant were more susceptible to treatment with the drug G418. Similar results were observed with the W927X-TGA and W927X-TAA mutants. Subsequently, R1014X-TGAC, R1014X-TGAG and R1014X-TGAA mutants were constructed based on the R1014X-TGAT mutant. The level of red fluorescence was observed prior to and following the administration of G418 using antibodies targeting the N- or C-terminus of the HERG protein. However, the tail current density was found only to increase with the R1014X-TGAT mutant following G418 treatment. Taken together, the results of the present study suggest that the type of premature stop codon and the context of the nucleotide immediately following at the +4 position, may determine the pharmacological rescue efficiency of the HERG gene.

Ventricular tachycardia (VT) causes sudden cardiac death, however, the majority of risk genes for VT remain unknown. SCN4B encodes a β-subunit, Na(v)β4, for the voltage-gated cardiac sodium channel complex involved in generation and conduction of the cardiac action potential. We hypothesized that genomic variants in SCN4B increase the risk of VT. We used high-resolution melt analysis followed by Sanger sequencing to screen 199 VT patients to identify nonsynonymous variants in SCN4B. Two nonsynonymous heterozygous variants in SCN4B were identified in VT patients, including p.Gly8Ser in four VT patients and p.Ala145Ser in one VT patient. Case–control association studies were used to assess the association between variant p.Gly8Ser and VT in two independent populations for VT (299 VT cases vs. 981 controls in population 1 and 270 VT patients vs. 639 controls in population 2). Significant association was identified between p.Gly8Ser and VT in population 1 (P = 1.21 × 10(−4), odds ratio or OR = 11.04), and the finding was confirmed in population 2 (P = 0.03, OR = 3.62). The association remained highly significant in the combined population (P = 3.09 × 10(−5), OR = 6.17). Significant association was also identified between p.Gly8Ser and idiopathic VT (P = 1.89 × 10(−5), OR = 7.27). Functional analysis with Western blotting showed that both p.Gly8Ser and p.Ala145Ser variants significantly reduced the expression level of Na(v)β4. Based on 2015 ACMG Standards and Guidelines, p.Gly8Ser and p.Ala145Ser can be classified as the pathogenic and likely pathogenic variant, respectively. Our data suggest that SCN4B is a susceptibility gene for common VT and idiopathic VT and link rare SCN4B variants with large effects (OR = 6.17–7.27) to common VT.

Right ventricular apical (RVA) pacing can lead to progressive left ventricular dysfunction and heart failure (HF), even in patients with normal cardiac structure and function. Our study conducted candidate gene screening and lentivirus transfected neonatal rat cardiomyocytes (NRCMs) to explore the genetic and pathogenic mechanisms of RVA pacing induced cardiomyopathy in third degree atrioventricular block (III AVB) patients. We followed 887 III AVB patients with baseline normal cardiac function and RVA pacing. After a median follow-up of 2.5 years, 10 patients (four males, mean age 47.6 ± 10.0 years) were diagnosed with RVA pacing induced HF with left ventricular ejection fraction (LVEF) reducing dramatically to 37.8 ± 7.1% (P

DTNA encoding dystrobrevin-α (α-DB) is a putative causal gene associated with left ventricular noncompaction cardiomyopathy (LVNC). The aim of the study was to investigate the causal role of DTNA in LVNC using a transgenic mouse model.A missense mutation (c.146A > G, p.N49S) of DTNA was identified in a patient with LVNC by Sanger sequencing. Six independent lines of transgenic mice expressing the mutant DTNA under a myosin heavy chain 6 (Myh6) promoter were generated (Myh6:DtnaN49S). Phenotypic characteristics of DTNA-p.N49S mutations were evaluated by echocardiography, histological observation, and immunoblotting. Multiple trabeculation and a higher ratio of non-compacted to compact myocardial layer were found in the Myh6:DtnaN49S mice compared to the controls. The transgenic mice also showed left ventricular (LV) dilation and cardiac systolic dysfunction. In conclusion, overexpression of the DTNA-p.N49S mutation in a mouse heart can be responsible for the phenotype of deep trabeculation, dilated cardiomyopathy, and cardiac dysfunction, which resembles the phenotype of LVNC.

Background Robust data regarding genotype–phenotype correlations in left ventricular noncompaction cardiomyopathy (LVNC) are lacking. Methods About 72 cardiomyopathy‐related genes were comprehensively screened in a cohort of LVNC patients using targeted sequencing. Baseline and follow‐up data were collected. The primary endpoint was a composite of death and heart transplantation. Results A total of 83 unrelated adult patients were included in analyses. Following stringent classification according to the American College of Medical Genetics and Genomics (ACMG) guidelines, 36 pathogenic variants of 14 genes were detected in 32 patients. Among them, 12 patients carried at least one nonsarcomere variant (NSV). At baseline, NSV carriers had a higher frequency of atrial fibrillation, but lower left ventricular ejection fraction, than did noncarriers. During a median follow‐up of 4.2 years, NSV carriers experienced a higher rate of the primary endpoint compared with noncarriers. There was no significant difference in the rate between carriers of sarcomere variant (SV) and noncarriers, as well as between carriers of SV and NSV. The presence of NSV was associated with an increased risk of the primary endpoint independent of age, sex, and cardiac function (hazard ratio: 3.61, 95% confidence interval: 1.42–9.19, p = .002). Conclusion NSV may act as a genetic modifier and worsen the clinical phenotype in patients with LVNC.

Coronary heart disease (CHD) is associated with complex metabolic disorders, but its molecular aetiology remains unclear. Using a novel nontargeted metabolomics approach, we explored the global metabolic perturbation profile for CHD. Blood samples from 150 patients with severe obstructive CHD and 150 angiographically normal controls were collected. Metabolic fingerprinting was performed by ultra-high performance liquid chromatography coupled to quadruple time-of-flight mass spectrometry (UHPLC-QTOF/MS) technique. After adjusting for CHD traditional risk factors and metabolic batch, a comprehensive list of 105 metabolites was found to be significantly altered in CHD patients. Among the metabolites identified, six metabolites were discovered to have the strongest correlation with CHD after adjusting for multiple testing: palmitic acid (β = 0.205; p

DTNA encoding dystrobrevin-α (α-DB) is a putative causal gene associated with left ventricular noncompaction cardiomyopathy (LVNC). The aim of the study was to investigate the causal role of DTNA in LVNC using a transgenic mouse model.A missense mutation (c.146AG, p.N49S) of DTNA was identified in a patient with LVNC by Sanger sequencing. Six independent lines of transgenic mice expressing the mutant DTNA under a myosin heavy chain 6 (Myh6) promoter were generated (Myh6:Dtna

Aims Two LMNA mutations (R644C and R190W) have been associated with familial and sporadic left ventricular non-compaction (LVNC). However, the mechanisms underlying these associations have not been elucidated. Methods and results Genomic DNA was isolated from peripheral blood leucocytes and analysed by direct sequencing. Human embryonic kidney 293 cells were transfected with either wild type or mutant LMNA and SCN5A for whole-cell patch-clamp experiment and fluorescence microscopy. Point mutation modeling for mutant LMNA was also performed. One novel LVNC-associated mutation (V445E) in β2 sheet of immunoglobulin (Ig)-like fold was found in the proband and his father. We also found that the peak current of sodium channel was markedly reduced in mutant LMNA compared with WT while the activation, inactivation, and recovery curves were not significantly altered. The mutant lamin A/C were aggregated into multiple highlighted particles. Three β sheets and multiple side chains in Ig-like fold were altered due to the replacement of a valine by glutamic acid. Conclusion Our data associated a novel lamin A/C mutation (V445E) with a sudden death form of familial LVNC. The reduced sodium current in mutant LMNA may account for the advent of malignant ventricular arrhythmias. The altered structures of three β sheets and side chains may partially explain the aggregation of lamin A/C protein subjacent to the nuclear envelope.

Although N-terminal pro-brain natriuretic peptide (NT-proBNP) is a useful screening test of impaired right ventricular (RV) function in conditions affecting the right-sided cardiac muscle, the role of NT-proBNP remains unclear in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study was designed to clarify the relation between the plasma NT-proBNP level and the RV function evaluated by cardiovascular magnetic resonance (CMR) imaging. We selected 56 patients with confirmed ARVC only when their blood specimens for NT-proBNP measurements were collected within 48 hours of a CMR scan. The NT-proBNP level was significantly higher in patients with RV dysfunction than in patients without RV dysfunction (median of 655.3 [interquartile range 556.4 to 870.0] vs 347.0 [interquartile range 308.0 to 456.2] pmol/L, p0.001). The NT-proBNP levels were positively correlated with RV end-diastolic and end-systolic volume indices (r = 0.49 and 0.70, respectively) and negatively correlated with RV ejection fraction (r = -0.76, all p0.001), which remained significant after adjustment for age, gender, and body mass index. The area under the receiver-operating characteristic curve for NT-proBNP was 0.91 (95% confidence interval 0.80 to 0.97, p0.001). The cut-off value of NT-proBNP (458 pmol/L) was associated with sensitivity, specificity, and positive and negative predictive values of 91%, 89%, 67%, and 98%, respectively. In conclusion, NT-proBNP is a useful marker for the detection of RV dysfunction and associated with extent of RV dilatation and dysfunction determined by CMR in patients with ARVC.

Background Idiopathic ventricular tachycardia ( VT ) is a type of cardiac arrhythmia occurring in structurally normal hearts. The heritability of idiopathic VT remains to be clarified, and numerous genetic factors responsible for development of idiopathic VT are as yet unclear. Variations in FGF 12 (fibroblast growth factor 12), which is expressed in the human ventricle and modulates the cardiac Na + channel Na V 1.5, may play an important role in the genetic pathogenesis of VT . Methods and Results We tested the hypothesis that genetic variations in FGF 12 are associated with VT in 2 independent Chinese cohorts and resequenced all the exons and exon–intron boundaries and the 5′ and 3′ untranslated regions of FGF 12 in 320 unrelated participants with idiopathic VT . For population‐based case–control association studies, we chose 3 single‐nucleotide polymorphisms—rs1460922, rs4687326, and rs2686464—which included all the exons of FGF 12 . The results showed that the single‐nucleotide polymorphism rs1460922 in FGF 12 was significantly associated with VT after adjusting for covariates of sex and age in 2 independent Chinese populations: adjusted P =0.015 (odds ratio: 1.54 [95% CI, 1.09–2.19]) in the discovery sample, adjusted P =0.018 (odds ratio: 1.64 [95% CI, 1.09–2.48]) in the replication sample, and adjusted P =2.52E‐04 (odds ratio: 1.59 [95% CI, 1.24–2.03]) in the combined sample. After resequencing all amino acid coding regions and untranslated regions of FGF 12 , 5 rare variations were identified. The result of western blotting revealed that a de novo functional variation, p.P211Q (1.84% of 163 patients with right ventricular outflow tract VT), could downregulate FGF 12 expression significantly. Conclusions In this study, we observed that rs1460922 of FGF 12 was significantly associated with VT and identified that a de novo variation of FGF 12 may be an important genetic risk factor for the pathogenesis of VT .

Purpose: Readthrough of nonsense mutation are used as gene-specific treatment in some genetic disease. Response to readthrough treatment is determined by readthrough efficiency of various nonsense mutations. In this manuscript, we aimed to explore the harmful effect of nonsense mutation suppressions. Methods: HEK293 cells were transfected with two SCN5A (encode cardiac Na+ channel) nonsense mutations, p.R1623X and p.S1812X. We applied two readthrough-enhancing methods (either aminoglycosides or by a siRNA targeting eukaryotic release factor eRF3a (a GTPase that binds eRF1)) to suppress these SCN5A nonsense mutations. When either of readthrough methods was used, the sodium channel proteins were tested by western blot, immunoblotting and record by whole cell patch clamp to observe the functional characterization of restored channels. Results: With readthrough treatment the sodium currents form the mutant cDNAs were restored. These mutations reduced the protein level of full-length sodium channel; the sodium currents were reduced to 3% of wild-type. The sodium currents from mutant cDNAs were increased to 30% of wild-type, and the full-length proteins also increased. However, the functional characterization of these channels from cDNA carrying p.R1623X and p.S1812X exhibited abnormal biophysical properties, including a negative shift of steady-state sodium channel inactivation, a positive shift of sodium channel activation and robust late sodium currents. Ramp test showed prolongation of QT interval. Conclusions: These results demonstrated that readthrough-enhancing methods effectively suppressed nonsense mutations in SCN5A and restored the expression of full-length channels. But the restored channels may increase the risk of arrhythmia. The strategies for nonsense mutations suppression provides potential evidence for personalized medicine for the treatment of genetic disorders.

Background Ventricular arrhythmias (VA) arising from arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) and idiopathic right ventricular outflow tract ventricular arrhythmias (RVOT-VA) share the pattern of left bundle branch block (LBBB)/inferior axis. The existence of QRS notching showed a discriminating effect of the two conditions in recent research; however, there are little data regarding the difference in the distribution of QRS notching. The aim of this study was to compare the VA morphology between the two conditions, especially evaluating the diagnostic role of QRS notching. Methods Electrocardiographic (ECG) recordings of VA episode with LBBB/inferior axis of 16 ARVD/C and 45 idiopathic RVOT-VA patients (30 originated from the septum, 15 from the free-wall) were gathered and compared. Results ARVD/C had longer mean QRS duration in all 12 leads, and significant differences existed in leads Ⅰ,Ⅱ,Ⅲ, aVL, aVF, and V1 (P < 0.05). Lead Ⅰ had the largest mean difference of 25.1 ± 5.8 ms. In addition, ARVD/C had more R-wave transition in lead V5 or later (37.5% vs 8.9%, P < 0.01).The presence of QRS notching (15/16 [93.8%] vs 36/45 [80.0%], P = 0.20) and the total number of leads expressing notching (2.88 ± 2.0 vs 2.80 ± 2.0, P = 0.90) were not different between ARVD/C and idiopathic RVOT-VA. However, QRS notching existing simultaneously in leads I and aVL was more common in ARVD/C (43.8% vs13.3%, P = 0.011). Conclusion Longer QRS duration, later precordial R/S transition, and QRS notching in lateral leads (leads Ⅰ and aVL) are useful in discriminating ARVD/C from idiopathic RVOT-VA.

OBJECTIVES The variation of the substrates of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT) was not understood. The purpose of this study was to investigate the variation of electroanatomic substrate [slow conduction zone (SCZ) and left ventricular conduction system (LVCS)] in ILVT and control individuals and markers of successful ablation. METHODS Electroanatomical mapping was performed during sinus rhythm in 20 ILVT patients and 26 control individuals with paroxysmal supraventricular tachycardia. LVCS and SCZ were tagged in geometry and the anatomic aspects were investigated. RESULTS According to the distribution of Purkinje potential, LVCS was distinguished into three types: left bundle branch (LBB) was divided into two discrete fascicles without interconnections; divided into three separate fascicles; and fanlike structure distribution over septum broadly. The length of LBB and its fascicles in patients with ILVT were slightly longer than those of controls (P > 0.05). In the ILVT group, the SCZ was located at the inferoposterior septum in 17, inferior apical septum in one and two SCZs were located at the posterior and mid-septal in the other two patients, which were greater in size and longer in length than those of six controls (P < 0.05). At the crossover junction area with diastolic potential and Purkinje potential, with the size of 1.5 ± 0.4 cm(2), concealed entertainment and ablation were obtained successfully in all patients with ILVT. CONCLUSION The anatomy of the LVCS and SCZ is highly variable in patients with ILVT, and the crossover junction area with diastolic potential and Purkinje potential might be a marker of ablation.

To compare cardiovascular magnetic resonance (CMR) characteristics between arrhythmogenic right ventricular cardiomyopathy (ARVC) patients with syncope and without syncope and explore CMR parameters related with syncope. A consecutive series of 80 patients with ARVC were divided in two groups according to history of syncope prior to CMR examinations. The biventricular function and volumes were calculated and indexed by body surface area. Fatty infiltration and late-gadolinium enhancement (LGE) were self-quantitatively analyzed according to segmental model. Patients with syncope had statistically significant greater left ventricular end-diastolic volume index (LVEDVI) (79.6 ± 23.0 vs. 69.0 ± 17.9 mL/m(2), P = 0.030), right ventricular end-diastolic volume index (RVEDVI) (122.0 ± 30.0 vs. 107.4 ± 21.8 mL/m(2), P = 0.017), and LGE incidence (52.2 vs. 21.1 %, P = 0.006) than that of patients without syncope. Patients with syncope had a trend towards greater number of segments with LGE (8.6 ± 4.2 vs. 6.6 ± 3.1, P = 0.199) than that of patients without syncope in subgroup analyses of patients with LGE, but no statistical significance was reached. Multivariate regression analysis showed the presence of LGE was independently associated with syncope in patients with ARVC (odds ratios 8.827, 95 % confidence interval 1.945-40.068, P = 0.005). CMR is helpful in detection and management of the patients with ARVC. Patients with syncope had significantly higher LVEDVI, RVEDVI and LGE incidence, and larger studies with follow-up data are needed to elucidate the relationship between LGE and syncope in patients with ARVC.

To evaluate the efficacy and safety of Shensong Yangxin (SSYX) in patients with bradycardia arrhythmias, a randomized, double-blind, and placebo-controlled study was conducted. Patients with bradycardia were randomly assigned to receive either SSYX (trial group,n=115) or placebo (control group,n=104) for 4 weeks. ECG, 24-hour continuous ECG recording, echocardiography, and hepatic and renal function were evaluated at baseline and after treatment. Results showed that the average heart rate, the fastest heart rate, and the lowest heart rate in the trial group were all significantly higher than those in the control group at the end of treatment (P<0.05or 0.01, resp.). Compared with pretreatment, the average heart rate, the fastest heart rate, and the lowest heart rate in the trial group all increased significantly after treatment (P<0.05or 0.01, resp.). Both the efficacy and the symptom scores in the trial group were significantly better than those in the control group after treatment (both havingP<0.01). No severe adverse effects were reported. In conclusion, SSYX treatment significantly increased the heart rate in patients with bradycardia without severe side effects. The exact mechanisms remain to be further explored.

The genetic background of early repolarization syndrome (ERS) has not been fully understood. In this study, we identified a missense SCN5A mutation and a polymorphism in a patient with ERS and characterized the functional consequences of the two variants. The functional consequences of mutant channels were investigated with the patch-clamp technique, immunocytochemical studies and real-time PCR. A 19-year-old female proband with recurrent syncope had a documented electrocardiogram with ventricular fibrillation (VF) proceeded by large J waves in leads I, II, III, aVF and V2-V6. Genetic analysis revealed that the patient carried a missense mutation of c.4297 G>C and a synonymous polymorphism of T5457C on the same allele of the SCN5A gene. Patch-clamp experiments demonstrated that the c.4297 G>C mutation significantly reduced the sodium current (INa) density and altered the channel kinetics. Immunocytochemical studies demonstrated that the mutation dramatically inhibited the expression of sodium channels in the cell membrane and in the cytoplasm, although the mRNA levels remained in the normal range. Noteworthy, the reduction in INa density may be partially restored from the co-existence of the T5457C polymorphism on the same allele by the upregulation of mRNA levels. In conclusion, our study indicated that the c.4297 G>C mutation caused the 'loss-of-function' of sodium channels that may account for the clinical phenotype of ERS. The reduction in INa density was due to a decreased number of sodium channels caused by abnormal translation processes. The T5457C polymorphism partially rescued the INa density of the mutant channels by the upregulation of mRNA levels.

SCN5A and SNTA1 are reported susceptible genes for long QT syndrome (LQTS). This study was designed to elucidate a plausible pathogenic arrhythmia mechanism for the combined novel mutations R800L-SCN5A and A261V-SNTA1 on cardiac sodium channels. A Caucasian family with syncope and marginally prolonged QT interval was screened for LQTS-susceptibility genes and found to harbor the R800L mutation in SCN5A and A261V mutation in SNTA1, and those with both mutations had the strongest clinical phenotype. The mutations were engineered into the most common splice variant of human SCN5A and SNTA1 cDNA, respectively, and sodium current ( INa) was characterized in human embryonic kidney 293 cells cotransfected with neuronal nitric oxide synthase (nNOS) and the cardiac isoform of the plasma membrane Ca-ATPase (PMCA4b). Peak INa densities were unchanged for wild-type (WT) and for mutant channels containing R800L-SCN5A, A261V-SNTA1, or R800L-SCN5A plus A261V-SNTA1. However, late INa for either single mutant was moderately increased two- to threefold compared with WT. The combined mutations of R800L-SCN5A plus A261V-SNTA1 significantly enhanced the INa late/peak ratio by 5.6-fold compared with WT. The time constants of current decay of combined mutant channel were markedly increased. The gain-of-function effect could be blocked by the NG-monomethyl-l-arginine, a nNOS inhibitor. We conclude that novel mutations in SCN5A and SNTA1 jointly exert a nNOS-dependent gain-of-function on SCN5A channels, which may consequently prolong the action potential duration and lead to LQTS phenotype.

Aims This study was to use implantable cardioverter defibrillator (ICD) home monitoring (HM) feature to evaluate the role of mean night-time heart rate (MNHR) in the occurrence of ventricular arrhythmias (VAs) and mortality. Methods and results This study retrospectively analysed clinical and ICD device data in 318 ICD patients. Data of the first 30-day MNHR (recorded 02:00–06:00 am) by HM were collected. The average and standard deviation of 30-day MNHR (AVHR and SDHR, respectively) were then determined in each patient. The primary endpoint was appropriate ICD treatment of VAs. The secondary endpoint was all-cause mortality. During a mean follow-up period of 32 ± 10 months, 179 of the 318 patients (56.3%) experienced VAs, 123 patients (38.7%) were treated by ICD shocks, and 37 patients (11.6%) died. The overall SDHR in this study cohort was 4.5 ± 3.0 bpm. Based on the receiver operating characteristic curve, the cut-off value of SDHR = 3.685 bpm was identified to predict VAs. In the Kaplan–Meier survival, SDHR ≥ 3.685 bpm was associated with increased VAs [hazard ratio (HR) = 1.885; 95% confidence interval (CI) = 1.362–2.609; P < 0.001], shock events (HR = 1.637; 95% CI = 1.11–2.414; P = 0.013), all-cause mortality (HR = 2.42; 95% CI = 1.266–4.627; P = 0.008), and the combined endpoints (HR = 1.872; 95% CI = 1.365–2.567; P < 0.001). In univariate and multivariate Cox models (adjusting for clinical factors), SDHR ≥ 3.685 bpm was still an independent predictor for all endpoints. Conclusion In ICD population, SDHR ≥ 3.685 bpm was an independent predictor for VAs and all-cause mortality.

Aims. The molecular mechanisms of Chinese traditional medicine Wenxin Keli (WXKL) were unknown. This study was aimed at exploring the effects of WXKL on the gene expression profile and pathological alteration of rabbits with myocardial infarction.Methods. Twenty male adult rabbits were randomly divided into 4 groups: sham, model, WXKL, and captopril groups. Model, WXKL, and captopril groups underwent the ligation of the left anterior descending coronary artery while sham group went through an identical procedure without ligation. WXKL (817 mg/kg/d), captopril (8 mg/kg/d), and distilled water (to model and sham groups) were administered orally to each group. After 4 weeks, the rabbits were examined with echocardiography and the hearts were taken for expression chip and pathological staining (H&E, Masson, and Tunel) studies.Results. The data revealed that WXKL downregulated genes associated with inflammation (CX3CR1, MRC1, and FPR1), apoptosis (CTSC and TTC5), and neurohumoral system (ACE and EDN1) and upregulated angiogenesis promoting genes such as RSPO3. Moreover, the results also showed that WXKL improved cardiac function and prevented histopathological injury and apoptosis.Conclusion. The present study demonstrated that WXKL might play an important role in inhibiting inflammation, renin-angiotensin system, and apoptosis. It might be a promising Chinese medicine in the treatment of patients with myocardial infarction.

Aims Clinical and animal studies suggest that beta1-adrenergic and M2 muscarinic receptor autoantibodies (beta1-AAbs and M2-AAbs) play important roles in the pathophysiological process of chronic heart failure (CHF). Removal of these autoantibodies improved haemodynamic parameters and left ventricular ejection fraction patients with CHF. The goal of this project is to evaluate whether beta1-AAbs and M2-AAbs predict prognosis and sudden cardiac death (SCD) in CHF. Methods and results A total of 2062 patients with CHF and 824 control subjects were recruited. Beta1-AAbs and M2-AAbs were detected by the enzyme-linked immunosorbent assay (ELISA) method, and the correlation between these autoantibodies and the prognosis of CHF was analysed. During a median follow-up period of 36 months (0.40 ± 65 months), 379 (21.56%) cases died—164 had dilated cardiomyopathy (DCM) and 215 had ischaemic cardiomyopathy (ICM). Of these, SCD occurred in 69 cases (40.37%) of DCM and in 84 cases (39.07%) of ICM. Positivity for beta1-AAbs in DCM and ICM was significantly higher than for the controls (8.1% and 8.25% v.s 2.2%, both P < 0.01). However, positive M2-AAbs did not show any statistical difference between the three groups. Cox regression analysis revealed that positive beta1-AAbs were associated with higher mortality in CHF and that it predicted SCD for DCM [hazard ratio (HR) 4.51, 95% confidence interval (CI) 2.405–8.471] and ICM (HR 3.749, 95% CI 2.389–5.884) patients, but not non-SCD (NSCD) patients. Conclusions The rates of positive beta1-AAbs were higher in CHF patients than in the controls. Positive beta1-AAbs might serve as an independent predictor for SCD in patients with CHF.

Objective To describe the clinical characteristics of idiopathic ventricular fibrillation (IVF) with fragmented QRS complex (f-QRS) and J wave in resting electrocardiogram.

Identification of the Slow Conduction Zone in a Macroreentry. Background: Although idiopathic left ventricular tachycardia (ILVT) has been shown to possess a slow conduction zone (SCZ), the details of the electrophysiological and anatomic aspects are still not well understood. Objective: We hypothesized that the SCZ can be identified using a 3-dimensional electroanatomic (EA) mapping system. Methods : Ten patients with ILVT were mapped using a 3-dimensional electroanatomic (EA) mapping system. After a 3-dimensional endocardial geometry of the left ventricular was created, the conduction system with left Purkinje potential (PP) and the SCZ with diastolic potential (DP) in LV were mapped during sinus rhythm (SR) and ventricular tachycardia (VT) and were tagged as special landmarks in the geometry. The electrophysiological and anatomic aspects of it were investigated. Results: EA mapping during SR and VT was successfully performed in 7 patients, during VT in 3 patients. The SCZ with DPs located at the inferoposterior septum was found in 7 patients during SR and all patients during VT. The length of the SCZ was 25.2 ± 2.3 mm with conduction velocity 0.08 ± 0.01 m/s. No differences in these parameters were found between patients during SR and VT (P > 0.05). An area with PP was found within the posterior septum. A crossover junction area with DP and PP was found in 7 patients during SR and VT. This area with DP and PP during SR coincided or were in proximity to such area during VT and radiofrequency ablation targeting the site within the area abolished VT in all patients. Conclusion: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified and can be used to guide the ablation of ILVT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 840-845, August 2012)

Objective Recent studies have revealed that microRNAs (miRNAs) are involved in the regulation of cardiac development, physiologic, and pathologic processes via post-transcriptional control of gene expression. The stable circulating miRNAs offer unique opportunities for the early diagnosis of several diseases. In this study, we examined the circulating miR-133 and miR-328 levels from patients with acute myocardial infarction (AMI). Patients and Methods Twenty-eight control subjects and fifty-one consecutive AMI patients were enrolled. The plasma and whole blood samples from AMI patients were obtained within 24 hours (n=51) and 7 days (n=6) after the onset of AMI symptoms. The circulating miR-133 and miR-328 levels were analyzed using quantitative real-time PCR. Results The miR-133 levels in plasma from AMI patients exhibited a 4.4-fold increase compared with control subjects (p=0.006). Moreover, the increased miR-133 levels in whole blood were comparable with those in plasma samples. In contrast, the miR-328 levels in plasma and whole blood of AMI patients were markedly increased by 10.9-fold and 16.1-fold, respectively, compared to those in control subjects (p=0.033 and p

Ca 2+ cycling plays a critical role in heart failure and lethal arrhythmias. As susceptibility to sudden cardiac death is considered to be a heritable trait in general population, we have therefore investigated whether potentially functional variants of genes encoding RyR2 (ryanodine receptor 2) and the L-type Ca 2+ channel are related to the risk of ventricular arrhythmias and sudden cardiac death in CHF (chronic heart failure) in a case-control study. We found that the A allele of rs3766871 in RYR2 was associated with an increased risk of ventricular arrhythmias in patients with CHF {odds ratio, 1.66 [95% CI (confidence interval), 1.21–2.26]; P =0.002}. During a median follow-up period of 32 months in 1058 (85.0%) patients, 296 (28.0%) patients died from heart failure, of whom 141 (47.6%) had sudden cardiac death. After adjustment for age, gender and suspected risk factors, patients carrying the A allele of rs3766871 had an increased risk of cardiac death {HR (hazard ratio), 1.53 [95% CI, 1.11–2.12]; P =0.010} and sudden cardiac death [HR, 1.92 (95% CI, 1.25–2.94); P =0.003]. Patients carrying the A allele of rs790896 in RYR2 had a reduced risk of sudden cardiac death [HR, 0.65 (95% CI, 0.45–0.92); P =0.015]. In conclusion, the A allele of rs3766871 in RYR2 not only associates with ventricular arrhythmias, but also serves as an independent predictor of sudden cardiac death, and the A allele of rs790896 in RYR2 is a protective factor against sudden cardiac death in patients with CHF.

Aims This study was to evaluate perioperative anticoagulation therapy in patients with mechanic heart valve(s) undergoing pacemaker implantation. Methods and resluts A total of 109 patients with mechanical heart valve(s) undertaking pacemaker implantation were studied. Fifty-one patients with warfarin suspended 3 days before surgery were classified into Group 1 and 58 patients with warfarin suspended

Sildenafil has been suggested to be a cost-effective treatment for pulmonary arterial hypertension (PAH). On account of the lack of data confirming its benefit in PAH patients, sildenafil has not been adopted in China for the treatment of PAH. The purpose of this study was to evaluate the efficacy, safety and 1-year survival of Chinese patients with PAH treated with sildenafil. Sixty Chinese patients with PAH were enrolled in this preliminary study. Their 6-min walk distance, WHO functional class and hemodynamic parameters (such as right atrial pressure, pulmonary arterial pressure, cardiac index and pulmonary vascular resistance) at both baseline and 16 weeks after initiation of sildenafil treatment were recorded. In addition, 1-year overall survival was assessed in this cohort. The 6-min walk distance improved from 392.13+/-91.35 to 467.22+/-80.38 m during the course of treatment (P

Vardenafil is a new phosphodiesterase-5 inhibitor that has shown some efficacy in the treatment of pulmonary arterial hypertension (PAH).To examine the long-term effects of vardenafil in patients with PAH.A multicentre, open-label study of 1-year's duration was undertaken in 45 patients with PAH to determine the long-term safety and efficacy of vardenafil (5 mg once daily for the first 4 weeks, then 5 mg twice daily) and make a preliminary assessment of its monthly acquisition cost compared with other PAH-active treatments. The patients' clinical features, exercise capacity, WHO functional class and haemodynamic variables were measured at baseline and at 3 and at least 9 months after initiating vardenafil treatment.At the 3 months and a mean (SD) of 14 (3) months (range 9-18) follow-up assessments, the 6 min walking distance was significantly increased from baseline by 70.7 (78.4) m (p0.001) and 83.4 (91.8) m (p0.001), respectively. Furthermore, long-term treatment with vardenafil for a mean duration of1 year was also associated with improvements in haemodynamic parameters, WHO functional class and serum uric acid concentrations. Overall, vardenafil treatment was well tolerated. No patients were withdrawn owing to adverse events and none died during the course of the study.Long-term treatment with vardenafil is well tolerated and has sustained beneficial effects on PAH, as measured by patients' exercise capacity, WHO functional class and haemodynamic parameters.

Pharmacologic restoration of the trafficking defects of HERG missense mutations has been documented. However, whether correction of HERG nonsense mutations is possible is unknown.The purpose of this study was to investigate the effect of aminoglycoside antibiotics on the expression of nonsense mutants expected to produce truncated HERG channels.HERG channel and mutant currents were recorded by whole-cell patch clamp techniques. Pharmacologic rescue was applied by culturing the cells in 400 microg/mL G-418 or gentamicin for 24 hours.Current densities were significantly reduced in cells expressing R1014X and W927X mutants compared to those of cells expressing wild-type (WT) HERG. R863X and E698X mutants failed to generate any typical HERG currents. Mean peak tail current density of R1014X mutant was significantly lower than that of WT (3.9 +/- 1.4 pA/pF, n = 8, vs 47.8 +/- 6.3 pA/pF, n = 12, P.05) and increased to 12.7 +/- 3.3 pA/pF (n = 7, P.05) and 18.3 +/- 3.7 pA/pF (n = 8, P.05) after G-418 and gentamicin treatment. The voltage dependence of activation of R1014X was also restored after drug treatment. Furthermore, expression of full-length proteins for R1014X induced by drugs was detected by western blot and confocal imaging. Similar results were observed in W927X. For R863X and E698X, however, gentamicin treatment had no effect. In the cells cotransfected with WT/R1014X, gentamicin and G-418 demonstrated different results: gentamicin, but not G-418, increased the current density by 2.2-fold (n = 12, P.05).The study findings provide proof of principle that interventions designed to read through premature stop mutations may at least partially reverse the LQT2 phenotype in vitro.

Many drugs cause severe side-effects such as long QT syndromes by blocking the human ether-a-go-go related gene (HERG) K(+) channels and/or disrupting HERG protein trafficking. Acehytisine hydrochloride is an anti-arrhythmic drug in phase IV clinical trial. To study whether acehytisine hydrochloride affects HERG channel activity and protein trafficking, we expressed HERG in human embryonic kidney 293 (HEK293) cells and recorded HERG channel currents with a whole-cell patch clamp technique. We also measured the protein levels by Western blot analysis. We found that acehytisine hydrochloride inhibited HERG step current (I(HERG)) in a concentration-dependent manner. However, it had little effect on the tail current (I(tail)). In addition, acehytisine hydrochloride accelerated channel inactivation and slowed recovery from inactivation. In contrast, it did not inhibit HERG protein (135 and 155 kD) trafficking, although it reduced the 155 kD band density at 2500 microM. Moreover, the F656C mutation in the S6 domain abolished acehytisine hydrochloride inhibition on the I(HERG) and enhanced the inhibitive effects on the trafficking of the 155 kD band. Acehytisine hydrochloride interrupted HERG protein trafficking at 1000 and 2500 microM. Our data showed that acehytisine hydrochloride could inhibit I(HERG), but had no effects on I(tail) until the concentration was above 1000 microM. Therefore, acehytisine hydrochloride may not induce QT interval prolongation and could be a promising anti-arrhythmic drug without severe side-effects.

Structural remodelling plays an important role in the genesis and maintenance of atrial fibrillation (AF). Although some studies that associate structural remodelling with atrial dilation have been reported, structural pulmonary venous (PV) remodelling due to chronic atrial dilation remains unclear.Six sham dogs and five mitral regurgitation (MR) dogs (three months after partial mitral valve avulsion) were studied. Separate cryosections from the PV and left atrium (LA) were immunolabelled with antibodies against connexin (Cx) 40 and Cx43 and analyzed by confocal laser scanning microscopy. Tissue samples from the PV and LA were stained with hematoxylin and eosin, and Masson's trichrome.In MR models, a decrease in Cx40 (0.57+/-0.2% versus 1.18+/-0.3%, P0.05) and Cx43 (0.48+/-0.2% versus 1.56+/-0.5%, P0.05) expression was observed compared with sham dogs. The distribution pattern of Cx40 and Cx43 changed from homogeneous to heterogeneous. Gap junction remodelling was not observed in the LA. In Masson's trichrome-stained sections from MR dogs, regions with increased interstitial fibrosis were present in the PV. Thickness in the PV and the PV-LA junction did not change in the MR group.The present study demonstrated a decrease in Cx40 and Cx43 expression and increased interstitial fibrosis in PV due to MR. These changes may potentially be a mechanism that renders the dilated atria more susceptible to AF.

BACKGROUND Shensong Yangxin (SSYX) is one of the compound recipe of Chinese materia medica. This study was conducted to investigate the effects of SSYX on sodium current (I(Na)), L-type calcium current (I(Ca, L)), transient outward potassium current (I(to)), delayed rectifier current (I(K)), and inward rectifier potassium currents (I(K1)) in isolated ventricular myocytes. METHODS Whole cell patch-clamp technique was used to study ion channel currents in enzymatically isolated guinea pig or rat ventricular myocytes. RESULTS SSYX decreased peak I(Na) by (44.84 +/- 7.65)% from 27.21 +/- 5.35 to 14.88 +/- 2.75 pA/pF (n = 5, P < 0.05). The medicine significantly inhibited the I(Ca, L). At concentrations of 0.25, 0.50, and 1.00 g/100 ml, the peak I(Ca, L) was reduced by (19.22 +/- 1.10)%, (44.82 +/- 6.50)% and (50.69 +/- 5.64)%, respectively (n = 5, all P < 0.05). SSYX lifted the I - V curve of both I(Na) and I(Ca, L) without changing the threshold, peak and reversal potentials. At the concentration of 0.5%, the drug blocked the transient component of I(to) by 50.60% at membrane voltage of 60 mV and negatively shifted the inactive curve and delayed the recovery from channel inactivation. The tail current density of I(K) was decreased by (30.77 +/- 1.11)% (n = 5, P < 0.05) at membrane voltage of 50 mV after exposure to the medicine and the time-dependent activity of I(K) was also inhibited. Similar to the effect on I(K), the SSYX inhibited I(K1) by 33.10% at the test potential of -100 mV with little effect on reversal potential and the rectification property. CONCLUSIONS The experiments revealed that SSYX could block multiple ion channels such as I(Na) I(Ca, L), I(k), I(to) and I(K1), which may change the action potential duration and contribute to some of its antiarrhythmic effects.

BACKGROUND Atrial fibrillation is a common arrhythmia with multi-factorial pathogenesis. Recently, a single nucleotide polymorphism (G/T) at position 1057 in the KCNE4 gene, resulting in a glutamic acid (Glu, E)/aspartic acid (Asp, D) substitution at position 145 of the KCNE4 peptide, was found in our laboratory to be associated with idiopathic atrial fibrillation (atrial fibrillation more frequent with KCNE4 145D). However, the functional effect of the KCNE4 145E/D polymorphism is still unknown. METHODS We constructed KCNE4 (145E/D) expression plasmids and transiently co-transfected them with the KCNQ1 gene into Chinese hamster ovary-K1 cells and performed whole-cell patch-clamping recording to identify the possible functional consequences of the single nucleotide polymorphism. Quantitative data were analyzed by Student;s t test. Probability values less than 0.05 were considered statistically significant. RESULTS A slowly activating, non-inactivating voltage-dependent current ((24.0 +/- 2.9) pA/pF, at +60 mV)) could be recorded in the cells transfected with KCNQ1 alone. Co-expression of wild type KCNE4 inhibited the KCNQ1 current ((7.3 +/- 1.1) pA/pF)). By contrast, co-expression of KCNE4 (145D) augment the KCNQ1 current ((42.9 +/- 7) pA/pF)). The V(1/2) of activation for the KCNQ1/KCNE4 (145D) current was shifted significantly towards the depolarizing potential compared to that for the KCNQ1 current ((-2.3 +/- 0.2) mv vs (-13.0 +/- 1.5) mv, P < 0.01)) without changing the slope factorkappa. Furthermore, KCNE4 (145D) also affected the activation and deactivation kinetics of KCNQ1 channels. CONCLUSION We provide experimental evidence that the KCNE4 (145E/D) polymorphism exerts the effect of "gain of function" on the KCNQ1 channel. It may underlie the genetic mechanism of atrial fibrillation. Further studies on the functional association between I(Ks) and KCNE4 (145D) polymorphism in cardiac myocytes are suggested.

Several genetic variants have been associated with early repolarization syndrome (ERS). However, the lack of functional validations of the mutant effects has limited the interpretation of genetic tests. In the present study, we identified and characterized a novel sodium channel, voltage gated, type V alpha subunit (SCN5A) mutation that was associated with ERS. A 67-year-old male proband suffering from recurrent syncope underwent a documented electrocardiogram (ECG) for polymorphic ventricular tachycardia (VT). It was noted that baseline 12-lead ECG exhibited a predominantly elevated ST-segment which mimicked acute myocardial ischemia in lead V2–V6, and the ECG also demonstrated J waves in lead II, III, aVF and V2–V6. Using genetic analysis, we noted that the proband carried a novel heterozygous missense mutation of A1055G in the SCN5A gene. Whole-cell configuration of patch-clamp analysis revealed that the mutation significantly decreased peak sodium current (INa) density and shifted the steady-state inactivation curve of INa to a more negative potential. Confocal imaging suggested that in the mutant channel a defect of protein expression both on the cell membrane and in cytoplasm was present. The present study demonstrated that a novel heterozygous missense mutation of A1055G in SCN5A led to 'loss-of function' of the sodium channels, and we suggest that it accounts for the arrhythmogenic characteristics of ERS.

Background Although cardiovascular magnetic resonance (CMR) is showing increasingly diagnostic potential in left ventricular non-compaction (LVNC), relatively little research relevant to CMR is conducted in children with LVNC. This study was performed to characterize and compare CMR features and clinical outcomes in children with LVNC with and without late gadolinium enhancement (LGE). Methods A cohort of 40 consecutive children (age, 13.7 ± 3.3 years; 29 boys and 11 girls) with isolated LVNC underwent a baseline CMR scan with subsequent clinical follow-up. Short-axis cine images were used to calculate left ventricular (LV) ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), myocardial mass, ratio of non-compacted-to-compacted myocardial thickness (NC/C ratio), and number of non-compacted segments. The LGE images were analyzed to assess visually presence and patterns of LGE. The primary end point was a composite of cardiac death and heart transplantation. Results The LGE was present in 10 (25 %) children, and 46 (27 %) segments were involved, including 23 non-compacted segments and 23 normal segments. Compared with LGE- cohort, LGE+ cohort had significantly lower LVEF (23.8 ± 10.7 % vs. 42.9 ± 16.7 %, p

Objectives: Genetic testing, a gold standard for long QT syndrome (LQTS) diagnosis, is time-consuming and costly when all the 15 candidate genes are screened. Since genotype-specific ECG patterns are present in most LQT1-3 mutation carriers, we tested the utility of ECG-guided genotyping in a large cohort of Chinese LQTS patients. Methods and Results: We enrolled 230 patients (26 ± 17 years, 66% female) with a clinical diagnosis of LQTS. Genotypes were predicted as LQT1-3 based on the presence of ECG patterns typical for each genotype in 200 patients (85 LQT1, 110 LQT2 and 5 LQT3). Family-based genotype prediction was also conducted if gene-specific ECG patterns were found in other affected family members. Mutational screening identified 104 mutations (44% novel), i.e. 46 KCNQ1, 54 KCNH2 and 4 SCN5A mutations. The overall predictive accuracy of ECG-guided genotyping was 79% (157/200) and 79% (67/85), 78% (86/110) and 80% (4/5) for LQT1, LQT2 and LQT3, respectively. The predictive accuracy was 98% (42/43) when family-based ECG assessment was performed. Conclusions: From this large-scale genotyping study, we found that LQT2 is the most common genotype among the Chinese. Family-based ECG-guided genotyping is highly accurate. ECG-guided genotyping is time- and cost-effective. We therefore recommend it as an optimal approach for the genetic diagnosis of LQTS.