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Abstract In 1992, the Brugada syndrome (BrS) was recognized as a disease responsible for sudden cardiac death, characterized by a right bundle-branch block with ST segment elevation in the leads V1 and V2. This syndrome is highly associated with sudden cardiac death, especially in young males. BrS is currently diagnosed in patients with ST-segment elevation showing type 1 morphology ≥ 2 mm in ≥1 leads among the right precordial leads V1 or V2 positioned in the 2nd, 3rd, or 4th intercostal space, and occurring either spontaneously or after a provocative drug test by the intravenous administration of Class I antiarrhythmic drugs. With accumulated findings, the BrS inheritance model is believed to be an autosomal dominant inheritable model with incomplete penetrance, although most patients with BrS were sporadic cases. SCN5A , which was identified as the first BrS-associated gene in 1998, has emerged as the most common gene associated with BrS, and more than 10 BrS-associated genes have been identified thereafter. Mutation-specific genetic testing is recommended for the family members and appropriate relatives following the identification of BrS-causative mutations in an index patient. In addition, comprehensive or BrS1 ( SCN5A ) targeted genetic testing could be useful for patients in whom a cardiologist has established a clinical index of suspicion for BrS based on the patient׳s clinical history, family history, and the expressed electrocardiographic (resting 12-lead ECGs and/or provocative drug challenge testing) phenotype. Over the past 20 years, extensive research in this field has allowed better understanding of the pathophysiology, genetic background, and management of BrS even though controversies still exist. In this review article, a background of genetics, the genetic background of BrS, the genotype and phenotype relationship, the role of genetic screening in clinical practice, and the interpretation of the identified genetic variants have been addressed based on this understanding.

ObjectiveThe long-term predictive value of the new proposed algorithm in the updated 2016 guidelines of the European Association of Cardiovascular Imaging to assess diastolic dysfunction (DD) in patients with heart failure with preserved ejection fraction (HFpEF) has not been validated.MethodsThe analysis included 451 patients who were diagnosed with HFpEF as confirmed via echocardiography. The endpoints were mortality and hospitalization for HF. The Kaplan–Meier curves and Cox regression models were generated to determine the risk of all-cause mortality based on the 2016 and 2009 DD grading algorithm, respectively. We evaluated the net reclassification index of outcomes on the basis of 2009 DD grade after abiding by the 2016 recommendations.ResultsAfter a follow-up of 2976 days, 119 patients (26.4%) died. According to the 2016 DD grading, grade III DD was associated with a significantly higher risk of mortality (hazard ratio [HR], 2.209; 95% CI 1.144–4.266) and HF hospitalization (HR, 2.047; 95% CI 1.348–3.870), as compared with grade I DD. Grade II DD was also associated with a higher risk of mortality (HR, 1.538; 95% CI 1.313–1.924). However, only grade III DD was independently associated with worse mortality based on 2009 DD grading. The net reclassification index for mortality increased significantly after grading by 2016 algorithm (10.6%, p < 0.001).ConclusionsThe 2016 DD grading algorithm showed improved prognostic value of long-term mortality in patients with HFpEF. Based on the findings of the study, the appropriate grading of DD is important in the prognostication of patients with HFpEF.Key Points• The application of the 2016 European Association of Cardiovascular Imaging recommendations diastolic dysfunction (DD) grading algorithm improves the predictive value for mortality.• Our analysis suggests DD grades II and III based on 2016 guidelines is associated with poor outcomes as compared with grade I. The echocardiographic indices of the new algorithm should be obtained and applied to effectively evaluate DD.

Brugada syndrome (BrS) is a rare cardiac arrhythmia with a complex and largely unexplained genetic basis. In this study, we analysed genomic data from 214 Taiwanese BrS cases and 1316 controls to uncover susceptibility loci using genome-wide association study (GWAS), copy number variation (CNV) analysis, and rare-variant association test (RVAT). Imputation with a population-specific Merged-TWN-panel yielded the highest accuracy across SNP categories. GWAS identified four genome-wide significant SNPs across three loci, including SCN10A, ZNF451, and RP11-510I5, with the ZNF451 locus showing a strong association (OR = 9.845, P = 6.8e-11). The total SNP-heritability for BrS was estimated at 0.18 (SE = 0.20), and SNPs located in the 3 risk loci regions accounted for 0.13 (SE = 0.02) of the phenotypic variance. Functional annotation revealed several regulatory non-coding SNPs, and gene-based analysis confirmed SCN10A as significant. Notably, ZNF451-AS1, a non-coding RNA gene overlapping the ZNF451 region, was identified via RVAT, suggesting that both common and rare variants at this locus contribute to BrS risk. CNV analysis further identified potential case-enriched regions, including a duplication involving HRAS. These findings underscore the importance of population-specific genomic resources and highlight ZNF451 as a key susceptibility locus, bridging both common and rare-variant contributions to BrS.

Objective Late‐onset hereditary transthyretin amyloidosis with polyneuropathy (ATTRv‐PN) is often associated with heart involvement. Recent advances in cardiac imaging allow the detection of cardiac amyloidosis. This study aimed to explore cardiomyopathy by cardiac imaging and its clinical correlates with polyneuropathy in late‐onset ATTRv‐PN. Methods Polyneuropathy was assessed by intraepidermal nerve fiber (IENF) density, nerve conduction study (NCS), autonomic function tests, quantitative sensory testing, and clinical questionnaires. Cardiomyopathy was evaluated by echocardiography, 99mTc‐pyrophosphate (PYP) single‐photon emission computed tomography (SPECT) imaging, cardiac magnetic resonance imaging (CMR), and serum Pro‐B‐type natriuretic peptide. Healthy controls and patients with Brugada syndrome were enrolled for comparison of CMR. Results Fifty late‐onset ATTRv‐PN patients (38 men, 46 with p. A117S mutation), aged 63.7 ± 5.5 years, of polyneuropathy disability stage 1–4 were enrolled. All patients presented polyneuropathy in NCS, and 74.5% of patients had reduced IENF density in distal legs. All patients showed significant radiotracer uptake in the heart on 99mTc‐PYP SPECT imaging, and 87.8% of patients had abnormally increased left ventricular (LV) septum thickness on echocardiography. CMR showed longer myocardial native T1, larger extracellular volume, greater LV mass index, and higher LV mass to end‐diastolic volume ratio in ATTRv‐PN patients than healthy controls and patients with Brugada syndrome. These CMR parameters were associated with skin denervation, absent sympathetic skin responses, elevated thermal thresholds, worsened NCS profiles, and functional deficits of polyneuropathy. Interpretation Late‐onset ATTRv‐PN coexisted with cardiomyopathy regardless of the clinical severity of polyneuropathy. The cardiac amyloid burden revealed by CMR was correlated with pathophysiology and clinical disability of nerve degeneration.

YKL-40 is significantly associated with the prevalence and severity of coronary artery disease (CAD). YKL-40 levels are significantly associated with variations in the CHI3L1 and TRIB1 genes. We investigated candidate genes for YKL-40 levels and evaluated the prognostic value of this biomarker and corresponding variants for long-term outcomes in patients with CAD. We included 4664 and 521 participants from the Taiwan Biobank (TWB) and CAD cohorts, respectively. Candidate variants for circulating YKL-40 levels were investigated using genome-wide association study (GWAS) data from the TWB cohort, and the results were validated in the CAD cohort. The primary endpoint was all-cause mortality. The secondary endpoint was major adverse cardiac events (MACEs), which included the composite endpoints of all-cause mortality, nonfatal acute coronary syndrome, hospitalization for heart failure, and nonfatal stroke. According to the GWAS data from the TWB cohort, three CHI3L1 variants (rs4950928, rs10399931, and rs872129) and one TRIB1 variant (rs6982502) were independently associated with YKL-40 levels. These findings were validated in the CAD cohort. The combined CHI3L1 and TRIB1 weighted genetic risk scores (WGRSs) were not associated with the long-term outcomes (median follow-up period of 3.7 years) in patients with CAD. Conversely, patients with YKL-40 levels in the upper tertile had the highest rates of all-cause mortality and MACEs (log-rank p  = 9.58 × 10 −8 for all-cause mortality and 1.34 × 10 −7 for MACEs). Furthermore, YKL-40 levels predicted poor clinical outcomes only in patients with multivessel CAD (log-rank p  = 3.0 × 10 −6 for all-cause mortality and 1.10 × 10 −5 for MACEs) and not in patients with single-vessel CAD. This study revealed that YKL-40 levels but not the combined CHI3L1 and TRIB1 WGRSs were found to be independent predictors of poor clinical outcomes in patients with multivessel CAD.

Irritable bowel syndrome (IBS) is one of the most widely recognized functional bowel disorders (FBDs) with a genetic component. SCN5A gene and SCN1B loci have been identified in population-based IBS cohorts and proposed to have a mechanistic role in the pathophysiology of IBS. These same genes have been associated with Brugada syndrome (BrS). The present study examines the hypothesis that these two inherited syndromes are linked. Prevalence of FBDs over a 12 months period were compared between probands with BrS/drug-induced type 1 Brugada pattern (DI-Type 1 BrP) (n = 148) and a control group (n = 124) matched for age, female sex, presence of arrhythmia and co-morbid conditions. SCN5A/SCN1B genes were screened in 88 patients. Prevalence of IBS was 25% in patients with BrS/DI-Type 1 BrP and 8.1% in the control group (p = 2.34 × 10−4). On stepwise logistic regression analysis, presence of current and/or history of migraine (OR of 2.75; 95% CI: 1.08 to 6.98; p = 0.033) was a predictor of underlying BrS/DI-Type 1 BrP among patients with FBDs. We identified 8 putative SCN5A/SCN1B variants in 7 (12.3%) patients with BrS/DI-Type 1 BrP and 1 (3.2%) patient in control group. Five out of 8 (62.5%) patients with SCN5A/SCN1B variants had FBDs. In conclusion, IBS is a common co-morbidity in patients with BrS/DI-Type 1 BrP. Presence of current and/or history of migraine are a predictor of underlying BrS/DI-Type 1 BrP among patients with FBDs. Frequent co-existence of IBS and BrS/DI-Type 1 BrP necessitates cautious use of certain drugs among the therapeutic options for IBS that are known to exacerbate the Brugada phenotype.

Background Availability of next generation sequencing data, allows low-frequency and rare variants to be studied through strategies other than the commonly used genome-wide association studies (GWAS). Rare variants are important keys towards explaining the heritability for complex diseases that remains to be explained by common variants due to their low effect sizes. However, analysis strategies struggle to keep up with the huge amount of data at disposal therefore creating a bottleneck. This study describes CLIN_SKAT, an R package, that provides users with an easily implemented analysis pipeline with the goal of (i) extracting clinically relevant variants (both rare and common), followed by (ii) gene-based association analysis by grouping the selected variants. Results CLIN_SKAT offers four simple functions that can be used to obtain clinically relevant variants, map them to genes or gene sets, calculate weights from global healthy populations and conduct weighted case–control analysis. CLIN_SKAT introduces improvements by adding certain pre-analysis steps and customizable features to make the SKAT results clinically more meaningful. Moreover, it offers several plot functions that can be availed towards obtaining visualizations for interpretation of the analyses results. CLIN_SKAT is available on Windows/Linux/MacOS and is operative for R version 4.0.4 or later. It can be freely downloaded from https://github.com/ShihChingYu/CLIN_SKAT , installed through devtools::install_github(\"ShihChingYu/CLIN_SKAT\", force=T) and executed by loading the package into R using library(CLIN_SKAT). All outputs (tabular and graphical) can be downloaded in simple, publishable formats. Conclusions Statistical association analysis is often underpowered due to low sample sizes and high numbers of variants to be tested, limiting detection of causal ones. Therefore, retaining a subset of variants that are biologically meaningful seems to be a more effective strategy for identifying explainable associations while reducing the degrees of freedom. CLIN_SKAT offers users a one-stop R package that identifies disease risk variants with improved power via a series of tailor-made procedures that allows dimension reduction, by retaining functionally relevant variants, and incorporating ethnicity based priors. Furthermore, it also eliminates the requirement for high computational resources and bioinformatics expertise.

ObjectiveTo retrospectively investigate the clinical spectrum, genetic profiles and outcomes of survivors of paediatric sudden cardiac arrest (SCA).Design and patientsAll 66 patients (aged 1–20 years), with unexpected SCA or syncope related to ventricular tachycardia (VT)/fibrillation and who survived to discharge from a tertiary centre, were enrolled from 1995 to 2018. Of these, 30 with underlying diseases prior to the events were excluded. Whole-exome sequencing targeting 384 channelopathy and cardiomyopathy-related genes (composite panel) was conducted to identify the possible genetic variants/mutations.ResultsA total of 36 patients were enrolled. Male adolescents predominated (66.7%), and the median age at onset was 13.3 years. Events occurred most often during exercise and daily activities. The yield rate of the genetic test was 84.6% (22/26); 14 had pathogenic variants; and 8 had likely pathogenic variants. The most common diagnoses were long QT in nine (25%), catecholaminergic polymorphic VT in six patients (16.7%), but other long QT and cardiomyopathy genes were also detected in eight patients (30.7%). The 10-year transplantation-free survival rate was 87.8% and was better for those who received genetic tests initially at the disease onset. An implantable cardioverter–defibrillator was implanted in 55.6% of the patients, with an appropriate shock rate of 61.1%. The defibrillator shock rate was lower for those who received composite panel initially.ConclusionSurvivors of SCA in the paediatric population had favourable long-term outcomes aided by genetic test. A broad composite genetic panel brings extra diagnostic value in the investigation of ventricular fibrillation/sudden cardiac death.

Resistin and soluble suppression of tumorigenicity 2 (sST2) are useful predictors in patients with coronary artery disease (CAD). Their serum levels are significantly attributed to variations in RETN and IL1RL1 loci. We investigated candidate variants in the RETN locus for resistin levels and those in the IL1RL1 locus for sST2 levels and evaluated the prognostication of these two biomarkers and the corresponding variants for long-term outcomes in the patients with CAD. We included 4652, 557, and 512 Chinese participants from the Taiwan Biobank (TWB), cardiovascular health examination (CH), and CAD cohorts, respectively. Candidate variants in RETN and IL1RL1 were investigated using whole-genome sequence (WGS) and genome-wide association study (GWAS) data in the TWB cohort. The weighted genetic risk scores (WGRS) of RETN and IL1RL1 with resistin and sST2 levels were calculated. Kaplan–Meier curves were used to analyze the prognostication of resistin and sST2 levels, WGRS of RETN and IL1RL1, and their combinations. Three RETN variants (rs3219175, rs370006313, and rs3745368) and two IL1RL1 variants (rs10183388 and rs4142132) were independently associated with resistin and sST2 levels as per the WGS and GWAS data in the TWB cohort and were further validated in the CH and CAD cohorts. In combination, these variants explained 53.7% and 28.0% of the variation in resistin and sST2 levels, respectively. In the CAD cohort, higher resistin and sST2 levels predicted higher rates of all-cause mortality and major adverse cardiac events (MACEs) during long-term follow-up, but WGRS of RETN and IL1RL1 variants had no impact on these outcomes. A synergistic effect of certain combinations of biomarkers with RETN and IL1RL1 variants was found on the prognostication of long-term outcomes: Patients with high resistin levels/low RETN WGRS and those with high sST2 levels/low IL1RL1 WGRS had significantly higher all-cause mortality and MACEs rates, and those with both these combinations had the poorest outcomes. Both higher resistin and sST2 levels, but not RETN and IL1RL1 variants, predict poor long-term outcomes in patients with CAD. Furthermore, combining resistin and sST2 levels with the WGRS of RETN and IL1RL1 genotyping exerts a synergistic effect on the prognostication of CAD outcomes. Future studies including a large sample size of participants with different ethnic populations are needed to verify this finding.

Background Transthyretin cardiac cardiomyopathy (ATTR-CM) is a rare but life-threatening disease. Tafamidis is an effective treatment for patients with ATTR-CM, however its long-term effects on cardiac remodeling and cardiac amyloid deposition are unknown. This study aimed to used cardiac magnetic resonance (CMR) to investigate the effects of tafamidis on patients with hereditary A97S ATTR-CM. Methods We retrospectively analyzed a prospective cohort of ATTR-CM patients, including 14 with hereditary A97S ATTR-CM and 17 healthy controls with baseline CMR data. All ATTR-CM patients received tafamidis treatment and received CMR with extracellular volume (ECV) at baseline and after 1 year of follow-up. Results Baseline N-terminal pro-B-type natriuretic peptide, left ventricular (LV) mass, LV ejection fraction, global radial, circumferential and longitudinal strain, T1 mapping and ECV were significantly worse in the patients with ATTR-CM compared with the healthy controls. After 1 year of tafamidis treatment, ECV decreased from 51.5 ± 8.9% to 49.0 ± 9.4% (P = 0.041), however there were no significant changes in LV mass, LV ejection fraction, global radial strain, global circumferential strain, global longitudinal strain and T1 mapping. Conclusions After a one-year treatment period, tafamidis exhibited subtle but statistically significant reductions in ECV, potentially indicating a decrease in amyloid deposition among patients diagnosed with hereditary A97S ATTR-CM.