Brugada syndrome in Japan and Europe: a genome-wide association study reveals shared genetic architecture and new risk loci.

BACKGROUND AND AIMS: Brugada syndrome (BrS) is an inherited arrhythmia with a higher disease prevalence and more lethal arrhythmic events in Asians than in Europeans. Genome-wide association studies (GWAS) have revealed its polygenic architecture mainly in European populations. The aim of this study was to identify novel BrS-associated loci and to compare allelic effects across ancestries. METHODS: A GWAS was conducted in Japanese participants, involving 940 cases and 1634 controls, followed by a cross-ancestry meta-analysis of Japanese and European GWAS (total of 3760 cases and 11 635 controls). The novel loci were characterized by fine-mapping, gene expression, and splicing quantitative trait associations in the human heart. RESULTS: The Japanese-specific GWAS identified one novel locus near ZSCAN20 (P = 1.0 × 10-8), and the cross-ancestry meta-analysis identified 17 association signals, including six novel loci. The effect directions of the 17 lead variants were consistent (94.1%; P for sign test = 2.7 × 10-4), and their allelic effects were highly correlated across ancestries (Pearson's R = .91; P = 2.9 × 10-7). The genetic risk score derived from the BrS GWAS of European ancestry was significantly associated with the risk of BrS in the Japanese population [odds ratio 2.12 (95% confidence interval 1.94-2.31); P = 1.2 × 10-61], suggesting a shared genetic architecture across ancestries. Functional characterization revealed that a lead variant in CAMK2D promotes alternative splicing, resulting in an isoform switch of calmodulin kinase II-δ, favouring a pro-inflammatory/pro-death pathway. CONCLUSIONS: This study demonstrates novel susceptibility loci implicating potentially novel pathogenesis underlying BrS. Despite differences in clinical expressivity and epidemiology, the polygenic architecture of BrS was substantially shared across ancestries.

2024 Guidelines of the Taiwan Society of Cardiology for the Diagnosis and Treatment of Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a multi-organ systemic syndrome that involves cardiac and extra-cardiac pathophysiological abnormalities. Its growing prevalence causes a major public concern worldwide. HFpEF is usually associated with multiple comorbidities, and non-cardiovascular death is common in patients with HFpEF. In Asia, patients with HFpEF has a younger age, higher prevalence of diabetes and chronic kidney disease than Western countries. A 2-step diagnostic algorithm is recommended in this guideline. In the first step, the diagnosis of HFpEF can be made if patients have symptoms and/or signs of heart failure, left ventricular ejection fraction ≥ 50%, increased natriuretic peptide, and objective evidence of left atrial or left ventricular abnormalities or raised left ventricular filling pressure. If diagnosis is still uncertain, invasive or noninvasive stress test can be performed in the second step. Comorbidities need to be controlled in HFpEF. Weight reduction for obesity and supervised exercise training are recommended for HFpEF. For pharmacological therapy, diuretic is used to relieve congestion and sodium-glucose cotransporter 2 inhibitor, empagliflozin or dapagliflozin, is recommended to improve prognosis of HFpEF. The research on HFpEF is advancing at a rapid pace. It is expected that newer modalities for diagnosis and management of HFpEF could appear in the near future.

Predictors of Left Ventricular Ejection Fraction Improvement in Patients with Early-Stage Heart Failure with Reduced Ejection Fraction.

Objectives: To identify the predictors of left ventricular ejection fraction (LVEF) recovery in patients with heart failure with reduced ejection fraction (HFrEF) and compare the mortality rate between patients with HFrEF and heart failure with improved ejection fraction (HFimpEF). Methods: Patients in a post-acute care program from 2018 to 2021 were enrolled. A series of echocardiograms were arranged during follow-up. Mortality, cardiovascular death and sudden cardiac death events were recorded. A total of 259 patients were enrolled and followed for at least 1 year; 158 (61%) patients fulfilled the criteria of HFimpEF, 87 (33.6%) were defined as having persistent HFrEF, and 14 (5.4%) were defined as having heart failure with mildly reduced ejection fraction. The patients with HFimpEF and persistent HFrEF were included for analysis. Results: The mean follow-up duration was 1090 ± 414 days, and the median time to LVEF recovery was 159 days (IQR 112-289 days). Multivariate logistic regression analysis showed that beta-blocker prescription was the only independent predictor of HFimpEF [odds ratio (OR) 2.11, 95% confidence interval (CI) 1.10-4.08, p = 0.03]. Diagnosis of ischemic cardiomyopathy (ICM) and QRS duration ≥ 110 ms were negative predictors of HFimpEF (OR 0.49, 95% CI 0.27-0.88, p = 0.02, and OR 0.4, 95% CI 0.21-0.77, p = 0.005, respectively). The patients with HfimpEF had a significantly better prognosis with lower mortality (hazard ratio 0.2, 95% CI 0.08-0.50, log-rank p < 0.001) than the patients with persistent HFrEF. Conclusions: Beta-blocker prescription was an independent predictor of HFimpEF, while the diagnosis of ICM and QRS duration ≥ 110 ms were negative predictors of HFimpEF. Patients with HfimpEF had a significantly lower mortality rate compared to those with persistent HFrEF.

CLIN_SKAT: an R package to conduct association analysis using functionally relevant variants.

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.

Synergistic Effects of Weighted Genetic Risk Scores and Resistin and sST2 Levels on the Prognostication of Long-Term Outcomes in Patients with Coronary Artery Disease.

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.

Epidemiology of Cardiomyopathy in Taiwanese Population Aged Younger Than 65 Years.

Background: Few studies have investigated the epidemiology of cardiomyopathy (CMP) in the general population in Taiwan. The aim of this study was to investigate this issue. Methods: We identified patients aged < 65 years and diagnosed with CMP between 2001 and 2014 from the National Health Insurance Database of Taiwan 2000-2014. Those with known or presumed causes of CMP were further identified. Results: We identified 38,868 CMP patients (male/female = 2.13). Half had known or presumed causes of CMP, including coronary artery disease (23.6%), congenital heart disease (1.6%), metabolic disease (8.4%), conduction disturbance/dyssynchrony (2.2%), myocarditis (0.5%), muscular dystrophy (1.42%), Kawasaki disease (0.2%), nutrition problems or alcoholism (2.9%), and unspecified causes (12.4%). The incidence rates of CMP without known causes were 1.13 and 8.70 per 100,000 person-years in pediatric (0-19 years) and adult (20-64 years) populations, respectively. After an initial peak during infancy (9.16 per 100,000 person-years), the incidence declined to a nadir in those aged from 5 to 14 years, and then steadily increased during adulthood (26.51 per 100,000 person-years in those aged 60-64 years). Although mortality was higher in the pediatric (11.4%) than in the adult (1.5%) patients, the proportion of sudden death to all deaths was similar in the pediatric (9.9%) and adult (10.5%) patients. Conclusions: This study provides an epidemiological continuum of CMP in a Taiwanese population aged < 65 years. The results revealed an initial peak during infancy, followed by a decline in adolescence and a subsequent steady rise. The prognosis was poorer in the pediatric patients, and poorest in the infants. However, the risk of sudden death was the same in the adult and pediatric patients.

Combined corrected QT interval and growth differentiation factor-15 level has synergistic predictive value for long-term outcome of angiographically confirmed coronary artery disease.

BACKGROUND: The corrected QT interval (QTc) predicts prognosis for the general population and patients with coronary artery disease (CAD). Growth differentiation factor-15 (GDF-15) is a biomarker of myocardial fibrosis and left ventricular (LV) remodelling. The interaction between these two parameters is unknown. SUBJECTS AND METHODS: This study included 487 patients with angiographically confirmed CAD. QTc was calculated using the Bazett formula. Multiple biochemistries and GDF-15 levels were measured. The primary endpoint was total mortality, and the secondary endpoints comprised the combination of total mortality, myocardial infarction and hospitalisation for heart failure and stroke. RESULTS: The mean follow-up period was 1029 ± 343 days (5-1692 days), during which 21 patients died and 47 had secondary endpoints. ROC curve analysis for the optimal cut-off value of primary endpoint is 1.12 ng/mL for GDF-15 (AUC = 0.787, P = 9.0 × 10-6 ) and 438.5 msec for QTc (AUC = 0.698, P = .002). Utilising linear regression, QTc has a positive correlation with Log-GDF-15 (r = .216, P = 1.0 × 10-6 ). Utilising Kaplan-Meier analysis, both QTc interval and GDF-15 level are significant predictors for primary end point (P = .000194, P = 2.0 × 10-6 , respectively) and secondary endpoint (P = .00028, P = 6.15 × 10-8 , respectively). When combined these two parameters together, a significant synergistic predictive power was noted for primary and secondary endpoint (P = 2.31 × 10-7 , P = 1.26 × 10-8 , respectively). This combined strategy also showed significant correlation with the severity of CAD (P < .001). CONCLUSION: In Chinese patient with angiographically confirmed CAD, a combined strategy utilising an ECG parameter (QTc) and a circulating biomarker (GDF-15) has good correlation with the severity of CAD, and improves the predictive power for total mortality.

Application of the newest European Association of Cardiovascular Imaging Recommendation regarding the long-term prognostic relevance of left ventricular diastolic function in heart failure with preserved ejection fraction.

OBJECTIVE: The 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. METHODS: The 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. RESULTS: After 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). CONCLUSIONS: The 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.

Is a timely assessment of the hematocrit necessary for cardiovascular magnetic resonance-derived extracellular volume measurements?

BACKGROUND: Cardiovascular magnetic resonance (CMR)-derived extracellular volume (ECV) requires a hematocrit (Hct) to correct contrast volume distributions in blood. However, the timely assessment of Hct can be challenging and has limited the routine clinical application of ECV. The goal of the present study was to evaluate whether ECV measurements lead to significant error if a venous Hct was unavailable on the day of CMR. METHODS: 109 patients with CMR T1 mapping and two venous Hcts (Hct0: a Hct from the day of CMR, and Hct1: a Hct from a different day) were retrospectively identified. A synthetic Hct (Hctsyn) derived from native blood T1 was also assessed. The study used two different ECV methods, (1) a conventional method in which ECV was estimated from native and postcontrast T1 maps using a region-based method, and (2) an inline method in which ECV was directly measured from inline ECV mapping. ECVs measured with Hct0, Hct1, and Hctsyn were compared for each method, and the reference ECV (ECV0) was defined using the Hct0. The error between synthetic (ECVsyn) and ECV0was analyzed for the two ECV methods. RESULTS: ECV measured using Hct1 and Hctsyn were significantly correlated with ECV0 for each method. No significant differences were observed between ECV0 and ECV measured with Hct1 (ECV1; 28.4 ± 6.6% vs. 28.3 ± 6.1%, p = 0.789) and between ECV0 and ECV calculated with Hctsyn (ECVsyn; 28.4 ± 6.6% vs. 28.2 ± 6.2%, p = 0.45) using the conventional method. Similarly, ECV0 was not significantly different from ECV1 (28.5 ± 6.7% vs. 28.5 ± 6.2, p = 0.801) and ECVsyn (28.5 ± 6.7% vs. 28.4 ± 6.0, p = 0.974) using inline method. ECVsyn values revealed relatively large discrepancies in patients with lower Hcts compared with those with higher Hcts. CONCLUSIONS: Venous Hcts measured on a different day from that of the CMR examination can still be used to measure ECV. ECVsyn can provide an alternative method to quantify ECV without needing a blood sample, but significant ECV errors occur in patients with severe anemia.

The 10-Year Prognosis and Prevalence of Brugada-Type Electrocardiograms in Elderly Women: A Longitudinal Nationwide Community-Based Prospective Study.

BACKGROUND: Brugada syndrome is a disorder associated with sudden cardiac death and characterized by an abnormal electrocardiogram (ECG). Previous studies were predominantly conducted in men, and the data on long-term prognosis are limited. Information about women, especially elderly women, is lacking. OBJECTIVE: The aim of this study was to investigate the long-term prognosis of the Brugada ECG pattern in elderly women. METHOD: We investigated the 10-year prognosis of the Brugada ECG pattern in elderly women in a nationwide community-based population in Taiwan. Community-dwelling women older than 55 years were prospectively recruited from December 2008 to March 2013 by a stratified random sampling method. All enrolled individuals were followed up annually until April 2019, and the cause of death was documented by citizen death records. RESULTS: Among 2597 women, 60 (2.31%) had a Brugada-type ECG, and this prevalence was higher than the mean global prevalence of 0.23%. One woman had a type 1 ECG (0.04%), whereas 15 (0.58%) and 44 (1.70%) women had type 2 and type 3 ECG patterns, respectively. Cox survival analysis revealed that all-cause mortality and cardiac mortality were similar in the individuals with and without a Brugada-type ECG during a mean follow-up of 96.1 ± 20.5 months. CONCLUSIONS: Our findings suggest that Brugada ECG patterns are not infrequent in elderly women but are not associated with increased risk of mortality in long-term follow-up; these findings may help reduce unnecessary anxiety for physicians, nurses, allied health caregivers, and patients.

Circulating Chemerin Levels, but not the RARRES2 Polymorphisms, Predict the Long-Term Outcome of Angiographically Confirmed Coronary Artery Disease.

Chemerin, a novel adipokine, has been associated with metabolic, inflammatory, and atherosclerotic diseases. We aimed to determine the genetic basis of chemerin levels by conducting a genome-wide association study (GWAS) and to investigate the role of RARRES2 polymorphisms and circulating chemerin levels in the long-term outcome of coronary artery disease (CAD). A total of 2197 participants from the Taiwan Biobank (TWB) were recruited for the GWAS analysis, and 481 patients with angiographically confirmed CAD were enrolled for long-term outcome analysis. One locus of genome-wide significance with a single independent association signal was identified in the GWAS for chemerin levels with the peak association at the RARRES2 gene promoter region polymorphism rs3735167 (p = 2.35 × 10-21). In the CAD population, borderline significance was noted between RARRES2 polymorphisms and chemerin levels, whereas high chemerin levels were associated with obesity, female sex, diabetes mellitus, hypertension, current smoking, high platelet and leukocyte counts, anemia, impaired renal function, high C-reactive protein (CRP) levels, and multi-vessel disease. Kaplan⁻Meier survival curves indicated that the patients with high chemerin and CRP levels, but not those with RARRES2 polymorphisms, had a lower survival rate and higher combined cerebral and cardiovascular event rates. Combined chemerin and CRP levels further revealed a stepwise increase in poor clinical outcomes from low- to high-risk subgroups. In conclusion, rs3735167 is the lead RARRES2 polymorphism for chemerin levels in Taiwanese. Chemerin levels, but not the rs3735167 genotypes, predicted the long-term outcome of CAD, especially when combined with CRP levels.

An automated microfluidic DNA microarray platform for genetic variant detection in inherited arrhythmic diseases.

In this study, we developed an automated microfluidic DNA microarray (AMDM) platform for point mutation detection of genetic variants in inherited arrhythmic diseases. The platform allows for automated and programmable reagent sequencing under precise conditions of hybridization flow and temperature control. It is composed of a commercial microfluidic control system, a microfluidic microarray device, and a temperature control unit. The automated and rapid hybridization process can be performed in the AMDM platform using Cy3 labeled oligonucleotide exons of SCN5A genetic DNA, which produces proteins associated with sodium channels abundant in the heart (cardiac) muscle cells. We then introduce a graphene oxide (GO)-assisted DNA microarray hybridization protocol to enable point mutation detection. In this protocol, a GO solution is added after the staining step to quench dyes bound to single-stranded DNA or non-perfectly matched DNA, which can improve point mutation specificity. As proof-of-concept we extracted the wild-type and mutant of exon 12 and exon 17 of SCN5A genetic DNA from patients with long QT syndrome or Brugada syndrome by touchdown PCR and performed a successful point mutation discrimination in the AMDM platform. Overall, the AMDM platform can greatly reduce laborious and time-consuming hybridization steps and prevent potential contamination. Furthermore, by introducing the reciprocating flow into the microchannel during the hybridization process, the total assay time can be reduced to 3 hours, which is 6 times faster than the conventional DNA microarray. Given the automatic assay operation, shorter assay time, and high point mutation discrimination, we believe that the AMDM platform has potential for low-cost, rapid and sensitive genetic testing in a simple and user-friendly manner, which may benefit gene screening in medical practice.

Genome-wide methylation profiles in coronary artery ectasia.

Coronary artery ectasia (CAE) is a disease characterized by abnormally dilated coronary arteries. The mechanism of CAE remains unclear, and its treatment is limited. Previous studies have shown that risk factors for CAE were related to changes in DNA methylation. However, no systematic investigation of methylation profiles has been performed. Therefore, we compared methylation profiles between 12 CAE patients and 12 propensity-matched individuals with normal coronary arteries using microarrays. Wilcoxon's rank sum tests revealed 89 genes with significantly different methylation levels (P<0.05 and Δß > |0.1|). Functional characterization using the DAVID database and gene set enrichment analysis indicated that these genes were involved in immune and inflammatory responses. Of these genes 6 were validated in 29 CAE patients and 87 matched individuals with CAE, using pyro-sequencing. TLR6 and NOTCH4 showed significant differences in methylation between the two groups, and lower protein levels of toll-like receptor 6 (TLR6) were detected in CAE patients. In conclusion, this genome-wide analysis of methylation profiles in CAE patients showed that significant changes in both methylation and expression of TLR6 deserve further study to elucidate their roles in CAE.

Clinical Outcomes of Repetition of Drug-Coated Balloon for Femoropopliteal Restenosis After Drug-Coated Balloon Treatment.

BACKGROUND: To compare the clinical outcomes of patients undergoing repeated drug-coated balloon (DCB) treatment for femoropopliteal (FP) DCB restenosis with those of patients without repetition-DCB.Methods and Results:From March 2013 to September 2014, 102 patients (118 affected legs) underwent DCB for symptomatic FP disease; 47 patients had restenosis, and 37 underwent reintervention over a 45-month follow-up. We compared the outcomes of repetition-DCB for DCB restenosis with those of patients without repetition. The baseline patient and lesion characteristics were similar between groups. The mean lesion length was 200.8±113.1 and 195.2±134.6 mm, P=0.894, respectively. In addition, the procedural and follow-up outcomes were not different. The rates of freedom from binary restenosis (70% vs. 14%, P=0.001) and clinically driven target lesion revascularization (CD-TLR) (78% vs. 38%, P=0.026) at 1 year were statistically different between groups. Cox regression analysis showed that repetition of DCB was the only predictor for freedom from binary restenosis (hazard ratio [HR]: 6.15, 95% confidence interval (CI) 1.60 to 23.6, P=0.008) and CD-TLR (HR: 5.37, 95% CI 1.32-22.0, P=0.019). CONCLUSIONS: For FP DCB restenosis, repetition of DCB can potentially improve vessel patency and significantly reduce the need for reintervention compared with conventional treatment. However, these observations require further confirmation in larger scale studies.

Growth Differentiation Factor 15 May Predict Mortality of Peripheral and Coronary Artery Diseases and Correlate with Their Risk Factors.

Plasma GDF15 concentrations were measured in 612 Taiwanese individuals without overt systemic disease. Clinical parameters, GDF15 genetic variants, and 22 biomarker levels were analyzed. We further enrolled 86 patients with PAD and 481 patients with CAD, who received endovascular intervention and coronary angiography, respectively, to examine the role of GDF15 level in predicting all-cause mortality. Significant associations were found between GDF15 genotypes/haplotypes and GDF15 levels. The circulating GDF15 level was positively associated with age, smoking, hypertension, and diabetes mellitus as well as circulating levels of lipocalin 2 and various biomarkers of inflammation and oxidative stress. Kaplan-Meier survival analysis showed that baseline GDF15 levels of above 3096 pg/mL and 1123 pg/mL were strong predictors of death for patients with PAD and CAD, respectively (P = 0.011 and P < 0.001). GDF15 more accurately reclassified 17.3% and 29.2% of patients with PAD and CAD, respectively (P = 0.0046 and P = 0.0197), compared to C-reactive protein. Both genetic and nongenetic factors, including cardiometabolic and inflammatory markers and adipokines, were significantly associated with GDF15 level. A high level of GDF15 was significantly associated with an increase of all-cause mortality in patients with high-risk PAD and in patients with angiographically documented CAD.

Next-generation sequencing of nine atrial fibrillation candidate genes identified novel de novo mutations in patients with extreme trait of atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Genome-wide association studies (GWAS) have identified common variants in nine genomic regions associated with AF (KCNN3, PRRX1, PITX2, WNT8A, CAV1, C9orf3, SYNE2, HCN4 and ZFHX3 genes); however, the genetic variability of these risk variants does not explain the entire genetic susceptibility to AF. Rare variants missed by GWAS may also contribute to genetic risk of AF. METHODS: We used an extreme trait design to sequence carefully selected probands with extreme phenotypes and their unaffected parents to identify rare de novo variants or mutations. Based on the hypothesis that common and rare variants may colocate in the same disease susceptibility gene, we used next-generation sequencing to sequence these nine published AF susceptibility genes identified by GWAS (a total of 179 exons) in 20 trios, 200 unrelated patients with AF and 200 non-AF controls. RESULTS: We identified a novel mutation in the 5' untranslated region of the PITX2 gene, which localised in the transcriptionally active enhancer region. We also identified one missense exon mutation in KCNN3, two in ZFHX3 and one in SYNE2. None of these mutations were present in other unrelated patients with AF, healthy controls, unaffected parents and are thus novel and de novo (p<10(-4)). Functional study showed that the mutation in the 5' untranslated region of the PITX2 gene significantly downregulated PITX2 expression in atrial myocytes, either in basal condition or during rapid pacing. In silico analysis showed that the missense mutation in ZFHX3 results in damage of the ZFHX3 protein structure. CONCLUSIONS: The genetic architecture of subjects with extreme phenotypes of AF is similar to that of rare or Mendelian diseases, and mutations may be the underlying cause.

Prevalence and prognosis of Brugada electrocardiogram patterns in an elderly Han Chinese population: a nation-wide community-based study (HALST cohort).

AIMS: The exact world-wide prevalence of Brugada electrocardiogram (ECG) pattern is still unclear, especially in adults aged 55 years and older. METHODS AND RESULTS: The study was conducted as part of the Healthy Aging Longitudinal Study in Taiwan (HALST). Using a stratified random sampled method, a sample of community-dwelling subjects was recruited from seven community-based regions across Taiwan. All enrolled subjects were follow-up annually and cause of death was documented by citizen death records. A total of 5214 subjects were enrolled (male/female: 2530/2684) with a mean age of 69 ± 8 years. The overall prevalence of Brugada ECG patterns was 3.32%. Four subjects carried spontaneous Type 1 Brugada ECG pattern, 68 carried Type 2, and 101 carried Type 3. Compared with the world-wide average prevalence of Brugada ECG patterns, the prevalence of spontaneous Type 1 Brugada ECG pattern in subjects from the HALST cohort was similar (0.077 vs. 0.07%) and the combined prevalence of Types 2 and 3 Brugada ECG pattern was 10 times higher (3.24 vs. 0.28%) even the mean age of study subjects was significantly higher (69 ± 8 vs. 35 ± 8, P < 0.001). However, all-cause mortality and cardiac mortality rates were not significantly different between subjects with and without Brugada ECG patterns during the 4-year follow-up (log-rank test, P = 0.21, 0.32, respectively). CONCLUSION: The prevalence of Brugada ECG pattern in adults aged 55 years and older in Taiwan was higher than the average world-wide prevalence but was not associated with increased mortality.

Unique clinical characteristics and SCN5A mutations in patients with Brugada syndrome in Taiwan.

BACKGROUND/PURPOSE: Brugada syndrome (BrS) is a hereditable sudden cardiac death (SCD). Mutations in the SCN5A gene (the most common BrS-causing gene) are responsible for 20-25% of this disease in Caucasian populations. However, the prevalence of SCN5A mutations in patients with BrS in the Chinese Han population in Taiwan remains unknown. Therefore, in this study, we investigated the prevalence of the SCN5A mutation in the largest BrS cohort in Taiwan. METHODS: We consecutively enrolled 47 unrelated patients with BrS from medical centers and hospitals in Taiwan between 2000 and 2010. Mutations within all the 27 translated exons, and exon-intron boundaries of the SCN5A-encoded cardiac sodium channel were screened in all patients with BrS using direct sequencing. A total of 500 unrelated healthy volunteers with a normal electrocardiogram were genotyped as a control group. RESULTS: SCN5A genetic variants were identified in 14 of the 47 patients with BrS and four of the 14 patients with BrS had missense mutations (1651 G>A, 1776 C>G, 3578 G>A). The prevalence rate of SCN5A mutations was approximately 8% (4/47), which was significantly lower than that reported in Caucasian populations (20-25%; p = 0.0007). The average age of these 14 BrS patients with SCN5A variants at diagnosis (12 men and 2 women) was 40 ± 13 years. Four patients experienced SCD, and six presented with seizure or syncope. Only three patients (3/14, 21.4%) had a family history of SCD. CONCLUSION: The prevalence of SCN5A mutations in the Chinese Han population in Taiwan may be lower than that reported in the Caucasian populations. In addition, most patients with BrS did not have a family history of SCD.

Case Report: Lacosamide unmasking SCN5A-associated Brugada syndrome in a young female with epilepsy.

Background: Lacosamide is frequently used as a mono- or adjunctive therapy for the treatment of adults with epilepsy. Although lacosamide is known to act on both neuronal and cardiac sodium channels, potentially leading to cardiac arrhythmias, including Brugada syndrome (BrS), its adverse effects in individuals with genetic susceptibility are less understood. Case: We report a 33-year-old female with underlying epilepsy who presented to the emergency department with a four-day history of seizure clusters, and was initially treated with lacosamide therapy. During the intravenous lacosamide infusion, the patient developed sudden cardiac arrest caused by ventricular arrhythmias necessitating resuscitation. Of note, the patient had a family history of sudden cardiac death. Workup including routine laboratory results, 12-lead electrocardiogram (ECG), echocardiogram, and coronary angiogram was non-specific. However, a characteristic type 1 Brugada ECG pattern was identified by ajmaline provocation testing; thus, confirming the diagnosis of BrS. Subsequently, the genotypic diagnosis was confirmed by Sanger sequencing, which revealed a heterozygous mutation (c.2893C>T, p.Arg965Cys) in the SCN5A gene. Eventually, the patient underwent implantable cardioverter-defibrillator implantation and was discharged with full neurological recovery. Conclusion: This case highlights a rare but lethal adverse event associated with lacosamide treatment in patients with genetic susceptibility. Further research is warranted to investigate the interactions between lacosamide and SCN5A variants.