Next-generation sequencing and bioinformatics to identify genetic causes of malignant hyperthermia.

BACKGROUND/PURPOSE: Malignant hyperthermia (MH) is a life-threatening pharmacogenetic disease with only two known causative genes, RYR1 and CACNA1S. Both are huge genes containing numerous exons, and they reportedly only account for 50-70% of known MH patients. Next-generation sequencing (NGS) technology and bioinformatics could help delineate the genetic diagnosis of MH and several MH-like clinical presentations. METHODS: We established a capture-based targeted NGS sequencing framework to examine the whole genomic regions of RYR1, CACNA1S and the 16.6 Kb mitochondrial genome, as well as 12 other genes related to excitation-contraction coupling and/or skeletal muscle calcium homeostasis. We applied bioinformatics analyses to the variants identified in this study and also to the 48 documented RYR1 pathogenic variants. RESULTS: The causative variants were identified in seven of the eight (87.5%) MH families, but in none of the 10 individuals classified as either normal controls (N = 2) or patients displaying MH-like clinical features later found to be caused by other etiologies (N = 8). We showed that RYR1 c.1565A>G (p.Tyr522Cys)(rs118192162) could be a genetic hot spot in the Taiwanese population. Bioinformatics analyses demonstrated low population frequencies and predicted damaging effects from all known pathogenic RYR1 variants. We estimated that more than one in 1149 individuals worldwide carry MH pathogenic variants at RYR1. CONCLUSION: NGS and bioinformatics are sensitive and specific tools to examine RYR1 and CACNA1S for the genetic diagnosis of MH. Pathogenic variants in RYR1 can be found in the majority of MH patients in Taiwan.

The effect and molecular mechanism of statins on the expression of human anti-coagulation genes.

Statins are potent lipid-lowering drugs. Large prospective clinical trials have shown the anti-thrombotic effect of statins, e.g., preventing deep vein thrombosis. However, the mechanism underlying the beneficial effect of statins in reducing thrombus formation remains to be established. We, thus, conduct this study to investigate the potential molecular mechanisms. The cultured human hepatoma cells (HepG2) were used as the in vitro model. The human protein C gene promoter was cloned into the luciferase reporter to study the transcriptional regulation of human protein C gene. Wistar rats fed with simvastatin (5 mg/kg day) were used as the in vivo model. We found that simvastatin increased the expression of protein C in hepatocytes (361 ± 64% and 313 ± 59% after 2 h and 6 h of stimulation, respectively, both p < 0.01). In the animal study, the serum protein C levels were increased in the simvastatin-treated group (7 ± 2.2 unit/ml vs 23.4 ± 19.3 unit/ml and 23.4 ± 18.2 unit/ml and 1 and 2 weeks of treatment, respectively, both p < 0.05). Regarding the possible molecular mechanism, we found that the level of hepatocyte nuclear factor 1α (HNF1α) was also increased in both the in vivo and in vitro models. We found that the protein C promoter activity was increased by simvastatin, and this effect was inhibited by HNF1α knockdown and constitutively active Rac1. Therefore, stains may modulate protein C expression through small GTPase Rac 1 and HNF1α.

Medical students' affective reactions to workplace experiences: qualitative investigation in a Chinese cultural context.

BACKGROUND: Compassion fatigue, unprofessional behavior, and burnout are prompting educators to examine medical students' affective reactions to workplace experiences. Attributes of both students and learning environments are influenced by their socio-cultural backgrounds. To prevent 'educational cultural hegemony', opinion leaders have advocated research in under-represented cultural contexts, of which Asia is a prime example. This study aimed to broaden the discourse of medical education by answering the question: how do students react affectively to workplace experiences in a Chinese cultural context? METHODS: In 2014, the authors recruited five female and seven male Taiwanese clerkship students to make 1-2 audio-diary recordings per week for 12 weeks describing affective experiences, to which they had consciously reacted. The authors analyzed transcripts of these recordings thematically in the original Mandarin and prepared a thick description of their findings, including illustrative extracts. An English-speaking education researcher helped them translate this into English, constantly comparing the interpretation with the original, untranslated data. RESULTS: (Mis) matches between their visions of future professional life and clerkship experiences influenced participants' affective reactions, thoughts, and behaviors. Participants managed these reactions by drawing on a range of personal and social resources, which influenced the valence, strength, and nature of their reactions. This complex set of interrelationships was influenced by culturally determined values and norms, of which this report provides a thick description. CONCLUSION: To avoid educational cultural hegemony, educators need to understand professional behavior in terms of complex interactions between culturally-specific attributes of individual students and learning environments. TRIAL REGISTRATION: The ethics committee of the National Taiwan University (NTU) Hospital gave research ethics approval ( 20130864RINB ).

Atrial flutter/fibrillation in patients receiving transcatheter closure of atrial septal defect.

BACKGROUND/PURPOSE: Atrial flutter/fibrillation (AFL/Af) is a common late complication in atrial septal defect (ASD) patients even after occluder implantation. We try to delineate the risk factors of persistent AFL/Af. METHODS: From 1998 to 2010, all patients older than 18 years of age who received ASD occluder implantation in our hospital were enrolled, and their records were retrospectively reviewed. In addition, renin-angiotensin system gene polymorphisms including angiotensinogen gene, A1166C polymorphism on the angiotensin II type I receptor gene, and insertion/deletion (I/D) patterns on the angiotensin-converting enzyme gene were checked using direct sequencing. RESULTS: A total of 517 patients (male/female 127/390) were enrolled. The mean age of patients receiving occluder deployment was 41.5 ± 14.5 years. Prior to occluder deployment, 3.9% of patients had persistent Af, 3.1% of patients had paroxysmal Af, and 0.8% had AFL. After a follow-up of 1894 patient-years, 3.5% had persistent Af and 1.9% of patients had paroxysmal Af. The greatest risk factors of AFL/Af genesis included age, occluder size, presence of multiple ASDs, and underlying thyroid or mitral valve disorder (p < 0.001, p < 0.001, p = 0.033, p = 0.016, and p = 0.012, respectively). Preoperative AFL/Af status is the most important factor in determining AFL/Af resolution and progression after an intervention. The renin-angiotensin system gene polymorphisms had no association with AFL/Af genesis, and progression or resolution after intervention. CONCLUSION: AFL/Af is common after ASD occluder implantation, and predisposed by older age, larger and multiple ASDs, and underlying disorders. Preoperative atrial arrhythmia status is the most important predictor of AFL/Af progression or resolution. Renin-angiotensin system gene polymorphisms had no association with AFL/Af.

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.

A Double-Blind, Randomized, Placebo-Controlled Study to Evaluate the Efficacy and Safety of STA-2 (Green Tea Polyphenols) in Patients with Chronic Stable Angina.

BACKGROUND: Green tea intake has been shown to improve endurance capacity in animal studies, but whether it has a similar effect on humans remains unclear. A randomized, double-blinded, parallel-controlled study was conducted to evaluate the short-term effect of STA-2, a pharmaceutical preparation of green tea polyphenols, in patients with effort-induced angina and documented positive exercise tolerance test. METHODS: A total of 79 patients recruited from three medical centers were randomly assigned to receive 2 STA-2 250 mg capsules, each containing 100 mg green tea polyphenols, three times daily, or placebo for six weeks after two consecutive symptom-limited treadmill exercise tests to ascertain the reproducibility of exercise tolerance. RESULTS: There was no difference in total exercise tolerance time from baseline to Week 6 between two groups (p = 0.639). There were also no observed improvements in subgroup analyses stratified by age, gender, and BMI categories. However, a significant reduction in low-density lipoprotein levels was shown in patients in the STA-2 group (-8.99 ± 19.18 mg/dL) versus the placebo group (0.57 ± 19.77 mg/dL), p = 0.037, with greater benefits in patients not taking antihyperlipidemic drugs (STA-2: -9.10 ± 19.96 mg/dL vs. placebo: 4.42 ± 15.08 mg/dL, p = 0.037). CONCLUSIONS: STA-2 treatment for 6 weeks did not increase exercise time as measured on a treadmill. However, this study also indicated that STA-2 treatment could have potential beneficial effects on LDL-cholesterol concentrations.

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.

Acute effects of biventricular pacing in heart failure patients with a normal ejection fraction and mechanical dyssynchrony.

OBJECTIVES: We tested the acute effects of resynchronization in heart failure patients with a normal (>50%) left ventricular (LV) ejection fraction (HFNEF) and mechanical dyssynchrony. METHODS: Twenty-four HFNEF patients (72 ± 6 years, 5 male) with mechanical dyssynchrony (standard deviation of electromechanical time delay among 12 LV segments >35 ms) were studied with temporary pacing catheters in the right atrium, LV, and right ventricle (RV), and high-fidelity catheters for pressure recording. Using selected atrioventricular (AV) intervals of 60, 90, 120, 150, and 180 ms to optimize transmitral flow during simultaneous biventricular pacing, the RV-LV (VV) interval was then evaluated at RV30, RV15, 0, LV15, LV30, and LV45 (RV or LV indicates which ventricle was paced first, the number indicates by how many ms). RESULTS: During simultaneous pacing, longer AV intervals were associated with improved LV pressure-derivative minimums and increased aortic pressures (p < 0.05 vs. normal sinus rhythm). In the VV interval from RV30 to LV45, there was a graded increase in the aortic velocity time integral and a decrease in dyssynchrony during simultaneous or LV-first pacing (p < 0.05 vs. normal sinus rhythm). CONCLUSIONS: For HFNEF patients with mechanical dyssynchrony, acute simultaneous biventricular or LV-first pacing with longer AV intervals reduced mechanical dyssynchrony and improved diastolic and systolic hemodynamics.

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.

Association of Small-Conductance Calcium-Activated Potassium Channels and Atrial Fibrillation - How Far Have We Gone?

UNLABELLED: Atrial fibrillation (AF) is the most common sustained and most important arrhythmia in clinical practice. The mechanisms underlying AF initiation and maintenance are known to be complex and heterogeneous. The general understanding of the detailed molecular basis of AF is still incomplete. Recently, these is increasing evidence that small conductance calcium-activated potassium (SK) channels are associated with atrial action potential repolarization and the pathogenesis of AF. Although the functional role of SK channels in the genesis of AF is not entirely clear, new insights into the basic pathophysiological mechanism of AF have been provided. Besides, genome-wide association studies also implicate that genes coding for SK channels are related to the risk of developing AF. This article reviews recent work on the association of SK channels and AF, genetic studies of SK channels, and discuss future investigation and developments regarding this field. KEY WORDS: Atrial fibrillation; Genetics; Small conductance calcium-activated potassium channels.

Sex-based differences in obstructive sleep apnea and atrial fibrillation: Implication of atrial fibrillation burden.

Background: Obstructive sleep apnea (OSA) is a risk factor for atrial fibrillation (AF); however, it is unclear whether AF increases the risk of OSA. Furthermore, sex differences among patients with both AF and OSA remain unclear. We aimed to determine the association between an increased AF burden and OSA and investigate the differences in clinical characteristics between women and men with AF and OSA. Methods: This was a descriptive, cross-sectional analysis from a prospective cohort study. Patients with non-valvular AF were recruited from the cardiac electrophysiology clinic of a tertiary center; they underwent a home sleep apnea test and 14-day ambulatory electrocardiography. Moderate-to-severe OSA was defined as an apnea-hypopnea index of ≥15. Results: Of 320 patients with AF, 53.4% had moderate-to-severe OSA, and the mean body mass index (BMI) was 25.6 kg/m2. Less women (38.2%) had moderate-to-severe OSA than men (59.3%) (p < 0.001). In the multivariate analysis, age, being a man, and BMI were significantly associated with moderate-to-severe OSA. AF burden was associated with moderate-to-severe OSA only in men (odds ratio: 1.008; 95% confidence interval: 1.001-1.014). Women and men with OSA had similar BMI (p = 0.526) and OSA severity (p = 0.754), but women were older than men (70.1 ± 1.3 vs. 63.1 ± 0.9 years, p < 0.001). Women with moderate-to-severe OSA had a lower AF burden than men did (27.6 ± 7.1 vs. 49.5 ± 3.9%, p = 0.009). Conclusions: AF burden is a sex-specific risk factor for OSA and is limited to men. In contrast, women with both AF and OSA have a lower AF burden than men, despite being older and having similar OSA severity and body habitus. Thus, AF may develop later in women with OSA than in men.

Predicting impaired cardiopulmonary exercise capacity in patients with atrial fibrillation using a simple echocardiographic marker.

BACKGROUND: Exercise intolerance is a common symptom associated with atrial fibrillation (AF). However, echocardiographic markers that can predict impaired exercise capacity are lacking. OBJECTIVE: This study aimed to investigate the association between echocardiographic parameters and exercise capacity assessed by cardiopulmonary exercise testing in patients with AF. METHODS: This single-center prospective study enrolled patients with AF who underwent echocardiography and cardiopulmonary exercise testing to evaluate exercise capacity at a tertiary center for AF management from 2020 to 2022. Patients with valvular heart disease, reduced left ventricular ejection fraction, or documented cardiomyopathy were excluded. RESULTS: Of the 188 patients, 134 (71.2%) exhibited impaired exercise capacity (peak oxygen consumption ≤85%), including 4 (2.1%) having poor exercise capacity (peak oxygen consumption <50%). Echocardiographic findings revealed that these patients had an enlarged left atrial end-systolic diameter (LA); smaller left ventricular end-diastolic diameter (LVEDD); and increased relative wall thickness, tricuspid regurgitation velocity, and LA/LVEDD and E/e' ratios. In addition, they exhibited lower peak systolic velocity of the mitral annulus and LA reservoir strain. In the multivariate regression model, LA/LVEDD remained the only significant echocardiographic parameter after adjustment for age, sex, and body mass index (P = .020). This significance persisted even after incorporation of heart rate reserve, N-terminal pro-B-type natriuretic peptide level, and beta-blocker use into the model. CONCLUSION: In patients with AF, LA/LVEDD is strongly associated with exercise capacity. Further follow-up and validation are necessary to clarify its clinical implications in patient care.

Soluble ST2 as a biomarker for detecting stable heart failure with a normal ejection fraction in hypertensive patients.

BACKGROUND: We investigated the measurement of soluble ST2 (sST2) in stable heart failure (HF) with a normal ejection fraction (HFNEF) in hypertensive patients. METHODS AND RESULTS: Echocardiography and serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) and sST2 concentrations were evaluated in 107 hypertensive patients (65 ± 12 years, 57 male) with ejection fraction (EF) >50%. Among them, 68 patients with stable HF in functional class II and III were the HFNEF group. We found that the area under the receiver operating characteristic curve (AUC) for sST2 was 0.80 (95% CI 0.70-0.89; P < .001), relatively better than that for NT-proBNP (AUC 0.70, 95% CI 0.58-0.79; P = .003) to detect HFNEF. However, the NT-proBNP concentration, rather than sST2, was higher in HFNEF patients with functional class III (562 ± 891 vs 185 ± 242 pg/mL in functional class II; P = .009), and correlated better with mitral E/e' (annular early diastolic velocity) (r = 0.327; P = .008) than sST2 concentrations in HFNEF patients. Multivariate analysis showed that sST2 >13.5 ng/mL was independently associated with HFNEF in hypertensive patients (odds ratio 11.7, 95% CI = 2.9-47.4; P = .001). CONCLUSIONS: sST2 measurement provides diagnostic aid of stable HFNEF for hypertensive patients. Addition of NT-proBNP to sST2 could give further information regarding HF functional class and diastolic abnormality.

Outcome of Circumferential Pulmonary Vein Isolation for Ablation of Atrial Fibrillation: A Single Center Experience.

BACKGROUND: Atrial fibrillation (AF) is the most common heart rhythm disorder in adults. Currently, use of the circumferential pulmonary vein isolation (CPVI) technique is the cornerstone of ablation therapy for paroxysmal atrial fibrillation. In this report, we described our ablation strategy and outcomes when treating a limited number of AF patients. METHODS: This study enrolled patients with paroxysmal or persistent AF that were resistant to at least one anti-arrhythmia drug. We used the CARTO XP system for electro-anatomic mapping, facilitated by left atrium multi-slice computed tomography imaging. The ablation strategy was to obtain CPVI by using an irrigation catheter and the end-point was complete entry and exit block at each pulmonary veins. AF recurrence was defined through review of symptoms and AF documentation via electrocardiography (ECG) or Holter ECG. RESULTS: From 2007 to 2011, 108 patients (76% paroxysmal AF) received ablation by means of our standard procedures, and the AF recurrence rate was 22% during a mean follow up of 20.6 ± 10.2 months. The major complication rate was less than 3% in all the patients that received AF ablation in our center. CONCLUSIONS: Our AF ablation results were comparable to those results reported in major electrophysiology centers, with acceptable complication rates. KEY WORDS: Ablation; Atrial fibrillation; Pulmonary vein isolation.

Prevalence of Atrial Fibrillation in Patients with Brugada Syndrome in Taiwan.

PURPOSE: The aim of this study was to assess the prevalence of atrial fibrillation (AF) in patients with Brugada syndrome (BrS) and their clinical characteristics in Taiwan. METHODS: The patient group consisted of 47 symptomatic BrS patients consecutively enrolled from 2000 to 2010. The definition of BrS patients with AF was a BrS patient with at least one episode of AF in a 12-lead electrogram or 24-hour holter (permanent, persistent or paroxysmal) during follow-up, or before diagnosis of BrS. RESULTS: Six BrS patients were identified with AF, and all of them were male. Two experienced sudden cardiac death (SCD), 2 presented with seizure and 4 with syncope. The mean age at onset of BrS was 47 ± 16 years, similar to those BrS patients without AF (45 ± 14, p = 0.67). Compared to those BrS patients without AF, significantly higher percentages of the BrS patients with AF presented with seizure and documented ventricular tachyarrhythmia (p = 0.02 and 0.03, respectively). Five of them had spontaneous Brugada type I electrogram, similar to those BrS patients without AF (p = 0.9). The SCN5A mutation rate is similar between BrS patients with AF and those without AF (p = 0.69). The prevalence of AF in BrS patients in Taiwan was 12.7% (6/47, 95% confidence interval 0.06-0.19) which is not significantly lower than the 20% prevalence found in the Caucasian population (p = 0.16). CONCLUSIONS: BrS patients with AF had distinct clinical features from those patients without AF in Taiwan. KEY WORDS: Atrial fibrillation; Brugada syndrome; Taiwan.

Next-Generation Sequencing in the Genetics of Human Atrial Fibrillation.

UNLABELLED: The International Human Genome Sequencing Consortium published the first draft of the human genome in the journal Nature in February 2001, providing the sequence of the entire genome's three billion base pairs. The Human Genome Project involves a concerted effort to better understand the human DNA sequence through identification of all the genes. The knowledge that can be derived from the genome could result in the development of novel diagnostic assays, targeted therapies and the improved ability to predict the onset, severity and progression of diseases. This has been made possible by many parallelized, high-throughput technologies such as next-generation sequencing. In this review, we discuss the possible application of next-generation sequencing in finding the susceptibility gene(s) or disease mechanism of an important human arrhythmia called atrial fibrillation. KEY WORDS: Arrhythmia; Atrial fibrillation; Genetics, Next-generation sequencing.

Association between atrial fibrillation burden and cognitive function in patients with atrial fibrillation.

BACKGROUND: Accumulating evidence has demonstrated an association between clinical atrial fibrillation (AF) and cognitive impairment. This study aimed to further clarify the impact of AF burden on cognitive function based on detailed electrophysiological recordings and standardized assessments of cognitive function. METHODS: This prospective cohort study, conducted at the Cardiac Electrophysiology Clinic of a tertiary center, included patients with non-valvular AF. AF burden was evaluated using 14-day patch-based electrocardiography. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). RESULTS: Enrolled patients (n = 253) were grouped according to the median AF burden (13.52%). Patients with higher AF burden were significantly older and had larger left atrium size, a worse ejection fraction, and a lower MoCA score than those with lower AF burden. Predictors of MoCA score included age, CHA2DS2-VASc score, AF burden, and Center for Epidemiologic Studies Depression Scale scores. The association between MoCA scores and AF burden remained significant after adjustment for demographic characteristics, underlying diseases, and echocardiographic parameters (standardized beta coefficient: -0.159, 95% confidence interval: -0.020 to -0.004, p = 0.004). CONCLUSION: AF burden is associated with cognitive function in patients with AF. Further studies are required to determine whether reducing AF burden can preserve cognitive function in these patients.

Genotype-phenotype correlation in Taiwanese children with diazoxide-unresponsive congenital hyperinsulinism.

Objective: Congenital hyperinsulinism (CHI) is a group of clinically and genetically heterogeneous disorders characterized by dysregulated insulin secretion. The aim of the study was to elucidate genetic etiologies of Taiwanese children with the most severe diazoxide-unresponsive CHI and analyze their genotype-phenotype correlations. Methods: We combined Sanger with whole exome sequencing (WES) to analyze CHI-related genes. The allele frequency of the most common variant was estimated by single-nucleotide polymorphism haplotype analysis. The functional effects of the ATP-sensitive potassium (KATP) channel variants were assessed using patch clamp recording and Western blot. Results: Nine of 13 (69%) patients with ten different pathogenic variants (7 in ABCC8, 2 in KCNJ11 and 1 in GCK) were identified by the combined sequencing. The variant ABCC8 p.T1042QfsX75 identified in three probands was located in a specific haplotype. Functional study revealed the human SUR1 (hSUR1)-L366F KATP channels failed to respond to intracellular MgADP and diazoxide while hSUR1-R797Q and hSUR1-R1393C KATP channels were defective in trafficking. One patient had a de novo dominant mutation in the GCK gene (p.I211F), and WES revealed mosaicism of this variant from another patient. Conclusion: Pathogenic variants in KATP channels are the most common underlying cause of diazoxide-unresponsive CHI in the Taiwanese cohort. The p.T1042QfsX75 variant in the ABCC8 gene is highly suggestive of a founder effect. The I211F mutation in the GCK gene and three rare SUR1 variants associated with defective gating (p.L366F) or traffic (p.R797Q and p.R1393C) KATP channels are also associated with the diazoxide-unresponsive phenotype.

Impact of ventricular dyssynchrony on postexercise accommodation of systolic myocardial motion in hypertensive patients with heart failure and a normal ejection fraction: a tissue-Doppler echocardiography study.

BACKGROUND: We hypothesized left ventricular (LV) dyssynchrony would affect postexercise accommodation of regional myocardial motion in patients with heart failure and a normal ejection fraction (HFNEF). METHODS AND RESULTS: Tissue-Doppler echocardiography was studied in 100 hypertensive patients with LV ejection fraction >50%. Among them, 70 HFNEF patients were classified into the systolic dyssynchrony (Dys: >65 ms difference of electromechanical delay between septal and lateral segments) (43 patients) and nondyssynchrony (Ndys: 27 patients) groups, and the other 30 patients were as the control (Ctrl). The systolic myocardial velocities (Sm) of 6-basal LV segments at baseline and after exercise were analyzed. When compared with the Ctrl group, the baseline lower mean Sm of 6 LV segments in the Ndys group could increase to a similar postexercise level as that in the Ctrl group, whereas that in the Dys group remained lower after exercise (7.8 ± 1.3 versus Ndys: 8.6 ± 1.5 and Ctrl: 8.9 ± 1.2 cm/s, P < .05, respectively). This is mainly due to a much higher percentage increase of lateral Sm after exercise in the Ndys group (Ndys: 49 versus Dys: 29%, P < .05). CONCLUSIONS: Dyssynchrony-related regional myocardial contractile abnormality after exercise in HFNEF patients suggested the detrimental impact of electromechanical uncoupling on HF symptoms.

Significant association of rs13376333 in KCNN3 on chromosome 1q21 with atrial fibrillation in a Taiwanese population.

BACKGROUND: A recent study in individuals of European ancestry demonstrated a significant association of the single nucleotide polymorphism (SNP) rs13376333 in potassium intermediate/small conductance calcium-activated channel, subfamily N, member 3 (KCNN3) on chromosome 1q21 with lone atrial fibrillation (AF), indicating a common genetic basis for AF. The aim of the present study was to investigate whether this association between SNP rs13376333 and AF also exists in Taiwanese subjects. METHODS AND RESULTS: The SNP rs13376333 was compared in 214 lone AF patients (58.3±11.4 years) vs. 214 controls (57.7±13.2 years), and in 322 structural AF patients (69.6±13.7 years) vs. 322 controls (68.4±14.2 years) in a Taiwanese population, in a case-control design. The associations between SNP rs13376333 in KCNN3 and structural or lone AF were significant. In the lone AF group, the frequency of the minor allele of SNP rs13376333 was 8.6% compared with 3.0% in the controls (P<0.001; odds ratio [OR], 3.02; 95% confidence interval [CI]: 1.54-6.29). The frequency of the minor allele of SNP rs13376333 was 6.5% in structural AF patients compared with 3.1% in controls (P=0.004; OR, 2.18; 95%CI: 1.23-3.96). CONCLUSIONS: There are significant associations between SNP rs13376333 and the risk of developing both lone and structural AF in the Taiwanese population. The minor allele frequency of SNP rs13376333 was much lower in the Taiwanese population compared to that in the Caucasian population.