Takeru Makiyama

Kyoto University, Kioto, Kyōto, Japan

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Publications (68)318.45 Total impact

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    ABSTRACT: Balloon aortic valvuloplasty (BAV) has played a limited role in the management of patients with severe aortic stenosis. However, BAV is being performed more frequently these days with the emergence of transcatheter aortic valve implantation (TAVI). We previously described a technique named "looped Inoue balloon technique" to simplify the antegrade transvenous BAV by making a loop in the left atrium using two stylets. We present a case in which the looped Inoue balloon technique was successfully applied. The patient was an 83-year-old woman with progressive dyspnea due to severe aortic stenosis. The aortic valve area was 0.39 cm(2) with a mean transvalvular gradient of 46 mmHg. The patient was deemed high risk for surgical aortic valve replacement or TAVI in view of the multiple comorbidities and frailty. Antegrade BAV using the looped Inoue balloon technique was performed. The procedure was successful without any complications. The post procedural aortic valve area increased to 1.15 cm(2) with a mean pressure gradient of 23 mmHg. This is the first report of clinical use of the looped Inoue balloon technique for antegrade BAV.
    Heart and vessels. 07/2014;
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    ABSTRACT: The prevalence, intensity, safety, and efficacy of oral anticoagulation (OAC) in addition to dual antiplatelet therapy (DAPT) in "real-world" patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI) have not yet been fully evaluated. In the Coronary REvascularization Demonstrating Outcome Study in Kyoto registry cohort-2, a total of 1,057 patients with AF (8.3%) were identified among 12,716 patients undergoing first PCI. Cumulative 5-year incidence of stroke was higher in patients with AF than in no-AF patients (12.8% vs 5.8%, p <0.0001). Although most patients with AF had CHADS2 score ≥2 (75.2%), only 506 patients (47.9%) received OAC with warfarin at hospital discharge. Cumulative 5-year incidence of stroke in the OAC group was not different from that in the no-OAC group (13.8% vs 11.8%, p = 0.49). Time in therapeutic range (TTR) was only 52.6% with an international normalized ratio of 1.6 to 2.6, and only 154 of 409 patients (37.7%) with international normalized ratio data had TTR ≥65%. Cumulative 5-year incidence of stroke in patients with TTR ≥65% was markedly lower than that in patients with TTR <65% (6.9% vs 15.1%, p = 0.01). In a 4-month landmark analysis in the OAC group, there was a trend for higher cumulative incidences of stroke and major bleeding in the on-DAPT (n = 286) than in the off-DAPT (n = 173) groups (15.1% vs 6.7%, p = 0.052 and 14.7% vs 8.7%, p = 0.10, respectively). In conclusion, OAC was underused and its intensity was mostly suboptimal in real-world patients with AF undergoing PCI, which lead to inadequate stroke prevention. Long-term DAPT in patients receiving OAC did not reduce stroke incidence.
    The American journal of cardiology. 07/2014; 114(1):70-8.
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    ABSTRACT: Treatment of coronary artery disease has significantly changed over the past decade including an introduction of drug-eluting stents and a more stringent adherence to evidence-based medications. However, the impact of these advanced treatment methods on the practice patterns and long-term outcomes in patients undergoing coronary revascularization in the real world has not been yet fully evaluated. The present study population consisted of the 2 groups of patients who underwent their first coronary revascularization in the Coronary REvascularization Demonstrating Outcome Study in Kyoto Registry Cohort-1 (bare-metal stent era: January 2000 to December 2002, n = 8,986) and Cohort-2 (drug-eluting stent era: January 2005 to December 2007, n = 10,339). Compared with Cohort-1, the proportion of patients treated with percutaneous coronary intervention significantly increased in Cohort-2 (73% vs 81%, p <0.001), particularly for 3-vessel disease (50% vs 61%, p <0.001) and left main disease (18% vs 36%, p <0.001). Evidence-based medications were more frequently used in Cohort-2. The cumulative 2-year incidence of and the adjusted risk for all-cause death were not significantly different between Cohort-1 and Cohort-2 (6.2% vs 6.4%, p = 0.69, and hazard ratio [HR] 0.91, 95% confidence interval [CI] 0.81 to 1.03, p = 0.15). Adjusted risks for both myocardial infarction and repeated coronary revascularization were significantly reduced in Cohort-2 compared with Cohort-1 (HR 0.80, 95% CI 0.67 to 0.96, p = 0.02, and HR 0.73, 95% CI 0.69 to 0.77, p <0.001, respectively). In conclusion, despite changes in treatment methods over time, the long-term mortality of patients undergoing coronary revascularization in the real-world clinical practice has not been changed, although there was a significant reduction of myocardial infarction and repeated coronary revascularization.
    The American journal of cardiology 05/2014; 113(10):1652-9. · 3.58 Impact Factor
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    ABSTRACT: Background: Recent randomized clinical trials have reported favorable clinical outcomes after the use of drug-eluting stents (DES) in patients with acute coronary syndrome (ACS). However, the long-term efficacy and safety outcomes, bleeding outcome in particular, after DES implantation in ACS patients have not been thoroughly evaluated in a real-world population. Methods and Results: We evaluated long-term clinical outcomes in 565 consecutive ACS patients who underwent DES implantation in an emergency setting between 2004 and 2011 (ST-segment elevation acute myocardial infarction [STEMI]: n=269, non-STEMI/unstable angina pectoris: n=296). Mean clinical follow-up period in this study was 4.6±2.0 years. The cumulative incidence of all-cause death, cardiac death, myocardial infarction, stent thrombosis and target-lesion revascularization was 6.9%, 4.0%, 2.2%, 1.3% and 8.4% at 1 year, and 19.6%, 6.7%, 5.6%, 3.0% and 13.9% at 5 years, respectively. The cumulative 5-year incidence of major bleeding events was 8.4% (n=42). Fatal bleeding events, however, occurred in only 4 patients, even including 2 patients who required resuscitation upon arrival at the hospital. Of the 42 patients with major bleeding events, 39 were taking dual antiplatelet therapy (DAPT) at the time of bleeding. Conclusions: DES implantation provided favorable long-term clinical outcomes with an acceptably low incidence of fatal bleeding in a real-world population of ACS patients. However, prolonged DAPT seems to be associated with major bleeding after DES implantation.
    Circulation Journal 05/2014; · 3.58 Impact Factor
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    ABSTRACT: -Sick sinus syndrome (SSS) is a common arrhythmia often associated with aging or organic heart diseases, but may also occur in a familial form with a variable mode of inheritance. Despite the identification of causative genes, including cardiac sodium channel (SCN5A), the etiology and molecular epidemiology of familial SSS remain undetermined primarily because of its rarity. -We genetically screened 48 members of 15 SSS families for mutations in several candidate genes, and determined the functional properties of mutant sodium (Na) channels using whole-cell patch clamping. We identified six SCN5A mutations including a compound heterozygous mutation. Heterologously expressed mutant Na channels showed loss-of-function properties of reduced or no Na current density in conjunction with gating modulations. Among 19 family members with SCN5A mutations, QT prolongation and Brugada syndrome were associated in four and two individuals, respectively. Age of onset in probands carrying SCN5A mutations was significantly younger (12.4 ± 4.6 years, n=5, mean±SE) than that of SCN5A-negative probands (47.0 ± 4.6 years, n=10; p<0.001) or non-familial SSS (74.3 ± 0.4 years, n=538; p<0.001). Meta-analysis of SSS probands carrying SCN5A mutations (n=29) indicated profound male predominance (79.3%) resembling Brugada syndrome but with a considerably earlier age of onset (20.9 ± 3.4 years). -The notable pathophysiological overlap between familial SSS and Na channelopathy indicates that familial SSS with SCN5A mutations may represent a subset of cardiac Na channelopathy with strong male predominance and early clinical manifestations.
    Circulation Arrhythmia and Electrophysiology 04/2014; · 5.95 Impact Factor
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    ABSTRACT: The aim of this study was to clarify myocardial involvement and its clinical implications in subjects with spinal and bulbar muscular atrophy (SBMA), a neuromuscular disease affecting both neuronal and nonneuronal tissues. Two independent cardiologists evaluated ECGs from a total of 144 consecutive subjects with SBMA. We performed immunohistochemical, immunoblot, and quantitative real-time PCR analyses of autopsied myocardium. Abnormal ECGs were detected in 70 (48.6%) of 144 subjects. The most frequent findings were ST-segment abnormalities in V1-3 (19.4%), followed by ST-segment abnormalities in V5-6 (18.1%). We detected Brugada-type ECGs in 17 of 28 subjects with ST-segment abnormalities in V1-3. Of those, one subject presented with syncope that required an implantable cardioverter defibrillator and led to eventual sudden death, and another subject also died suddenly. No subjects with Brugada-type ECGs had mutations in SCN5A, CACNA1C, or CACNB2 genes. In autopsied cases, we detected nuclear accumulation of the mutant androgen receptor protein and decreased expression levels of SCN5A in the myocardium. Subjects with SBMA often show Brugada-type ECG. The accumulation of the pathogenic androgen receptor may have a role in the myocardial involvement in SBMA.
    Neurology 04/2014; · 8.25 Impact Factor
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    ABSTRACT: CACNA1C mutations have been reported to cause LQTS type 8 (LQT8; Timothy syndrome), which exhibits severe phenotypes, although the frequency of patients with LQT8 exhibiting only QT prolongation is unknown. This study aimed to elucidate the frequency of CACNA1C mutations in patients with long QT syndrome (LQTS), except those with Timothy syndrome and investigate phenotypic variants.METHODS AND RESULTS: CACNA1C gene screening was performed in 278 probands negative for LQTS-related gene mutations. Functional analysis of mutant channels using a whole-cell patch-clamp technique was also performed. Using genetic screening, we identified five novel CACNA1C mutations: P381S, M456I, A582D, R858H, and G1783C in seven (2.5%) unrelated probands. Seven mutation carriers showed alternative clinical phenotypes. Biophysical assay of CACNA1C mutations revealed that the peak calcium currents were significantly larger in R858H mutant channels than those of wild-type (WT). In contrast, A582D mutant channels displayed significantly slower inactivation compared with WT. The two mutant channels exerted different gain-of-function effects on calcium currents.CONCLUSION: In patients with LQTS, the frequency of CACNA1C mutations was higher than reported. Even without typical phenotypes of Timothy syndrome, CACNA1C mutations may cause QT prolongation and/or fatal arrhythmia attacks.
    Europace 04/2014; · 2.77 Impact Factor
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    ABSTRACT: Andersen-Tawil syndrome (ATS) is an inherited disease characterized by ventricular arrhythmias, periodic paralysis, and dysmorphic features. It results from a heterozygous mutation of KCNJ2, but little is known about mosaicism in ATS. We performed genetic analysis of KCNJ2 in 32 ATS probands and their family members and identified KCNJ2 mutations in 25 probands, 20 families of whom underwent extensive genetic testing. These tests revealed that 7 probands carried de novo mutations while 13 carried inherited mutations from their parents. We then specifically assessed a single proband and the respective family. The proband was a 9-year-old girl who fulfilled the ATS triad and carried an insertion mutation (p.75_76insThr). We determined that the proband's mother carried a somatic mosaicism and that the proband's younger brother also carried the ATS phenotype with the same insertion mutation. The mother, who exhibited mosaicism, was asymptomatic, although she exhibited Q(T)U prolongation. Mutant allele frequency was 11% as per TA cloning and 17.3% as per targeted deep sequencing. Our observations suggest that targeted deep sequencing is useful for the detection of mosaicism and that the detection of mosaic mutations in parents of apparently sporadic ATS patients can help in the process of genetic counseling.
    Clinical Genetics 02/2014; · 4.25 Impact Factor
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    ABSTRACT: Background: Loss-of-function mutations in the HCN4 gene have been shown to be associated with sinus dysfunction, but there are no reports on HCN4-mediated atrioventricular (AV) block. A novel missense HCN4 mutation G1097W was identified in a 69 year-old Japanese male with AV block, and we characterized the functional consequences of If-like channels reconstituted with the heterozygous HCN4 mutation. Methods and Results: Wild-type (WT) HCN4 or/and HCN4-G1097W were expressed in a heterologous cell expression system. A functional assay using a whole-cell patch-clamp demonstrated that the mutant If-like currents were activated at more negative voltages compared to WT currents, while they retained the sensitivity to changes in intracellular cyclic adenosine monophosphate (cAMP) levels. Co-expression of G1097W with WT channels showed dominant-negative effects, including a reduction in peak currents and a negative voltage shifting on reconstituted currents. Conclusions: The HCN4-G1097W mutant channels displayed a loss-of-function type modulation on cardiac If channels and thus could predispose them to AV nodal dysfunction. These data provide a novel insight into the genetic basis for the AV block.
    Circulation Journal 01/2014; · 3.58 Impact Factor
  • International journal of cardiology 01/2014; · 6.18 Impact Factor
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    ABSTRACT: Brugada syndrome (BrS) is an inherited disease characterized by right precordial ST-segment elevation on electrocardiograms (ECG) that predisposes patients to sudden cardiac death as a result of polymorphic ventricular tachyarrhythmia or ventricular fibrillation (VF). In BrS patients, except for SCN5A, mutations in other responsible genes are poorly elucidated. We identified four KCNH2 mutations, T152I, R164C, W927G, and R1135H, in 236 consecutive probands with BrS or Brugada-like ECG. Three of these mutation carriers showed QTc intervals shorter than 360 ms(1/2) and one experienced VF. We performed patch-clamp analyses on IKr reconstituted with the KCNH2 mutations in Chinese hamster ovary (CHO) cells and compared the phenotypes of the patients with different genotypes. Three mutations, R164C, W927G, and R1135H, increased IKr densities. Three mutations, T152I, R164C, and W927G, caused a negative shift in voltage-dependent activation curves. Only the R1135H mutant channel prolonged the deactivation time constants. We also identified 20 SCN5A and five CACNA1C mutation carriers in our cohort. Comparison of probands' phenotypes with three different genotypes revealed that KCNH2 mutation carriers showed shorter QTc intervals and SCN5A mutation carriers had longer QRS durations. All KCNH2 mutations that we identified in probands with BrS exerted gain-of-function effects on IKr channels, which may partially explain the ECG findings in our patients. This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 01/2014; · 3.48 Impact Factor
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    ABSTRACT: Ryanodine receptor gene (RYR2) mutations are well known to cause catecholaminergic polymorphic ventricular tachycardia (CPVT). Recently, RYR2 exon 3 deletion has been identified in patients with dilated cardiomyopathy (DCM) and/or CPVT. This study aimed to screen for the RYR2 exon 3 deletion in CPVT probands, characterize its clinical pathology, and confirm the genomic rearrangement.METHODS AND RESULTS: Our cohort consisted of 24 CPVT probands. Polymerase chain reaction (PCR)-based conventional genetic analysis did not identify any mutations in coding exons of RYR2 in these probands. They were screened using multiplex ligation-dependent probe amplification (MLPA). In probands identified with RYR2 exon 3 deletion, the precise location of the deletion was identified by quantitative PCR and direct sequencing methods. We identified two CPVT probands from unrelated families who harboured a large deletion including exon 3. The probands were 9- and 17-year-old girls. Both probands had a history of syncope related to emotional stress or exercise, exhibited bradycardia, and were diagnosed with left ventricular non-compaction (LVNC). We examined 10 family members and identified six more RYR2 exon 3 deletion carriers. In total, there were eight carriers, of which seven were diagnosed with LVNC (87.5%). Two carriers under the age of 4 years remained asymptomatic, although they were diagnosed with LVNC. Using quantitative PCR and direct sequencing, we confirmed that the deletions were 1.1 and 37.7 kb in length.CONCLUSION: RYR2 exon 3 deletion is frequently associated with LVNC. Therefore, detection of the deletion offers a new modality for predicting the prognosis of patients with LVNC with ventricular/atrial arrhythmias, particularly in children.
    Europace 01/2014; · 2.77 Impact Factor
  • Journal of the American College of Cardiology 01/2014; 63(12):A7. · 14.09 Impact Factor
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    ABSTRACT: The influence of pre-infarction angina pectoris (AP) on long-term clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) remains controversial. Among 5429 patients with acute myocardial infarction (AMI) enrolled in the CREDO-Kyoto AMI Registry, the current study population consisted of 3476 STEMI patients who underwent primary PCI within 24 hours of symptom onset and in whom the data on pre-infarction AP was available. Pre-infarction AP defined as AP occurring within 48 hours of hospital arrival was present in 675 patients (19.4%). Patients with pre-infarction AP was younger and more often had anterior AMI, and longer total ischemic time, while they less often had history of heart failure, atrial fibrillation, and shock presentation. The infarct size estimated by peak creatinine phosphokinase was significantly smaller in patients with than in patients without pre-infarction AP (median [interquartile range]: 2141[965-3867] IU/L versus 2462[1257-4495] IU/L, P<0.001). The cumulative 5-year incidence of death was significantly lower in patients with pre-infarction AP (12.4% versus 20.7%, P<0.001) with median follow-up interval of 1845 days. After adjusting for confounders, pre-infarction AP was independently associated with a lower risk for death (hazard ratio 0.69, 95% confidence interval 0.54-0.86, P=0.001). The lower risk for 5-year mortality in patients with pre-infarction AP was consistently observed across subgroups stratified by total ischemic time, initial Thrombolysis in Myocardial Infarction flow grade, hemodynamic status, infarct location, and diabetes mellitus. In conclusion, pre-infarction AP was independently associated with lower 5-year mortality in STEMI patients undergoing primary PCI.
    The American Journal of Cardiology. 01/2014;
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    ABSTRACT: Atrial fibrillation (AF) is one of the most common cardiac arrhythmias, and in some patients, the disease is inheritable. Hereditary aspects of AF, however, remain not fully elucidated. The purpose of this study was to identify genetic backgrounds that contributed to juvenile-onset AF and to define the mechanism. In 30 consecutive juvenile-onset AF patients (onset age <50 year-old), we screened AF-related genes (KCNQ1, KCNH2, KCNE1-3 and 5, KCNJ2, and SCN5A). We analyzed the function of mutant channels using whole-cell patch-clamp techniques and computer simulations. Among the juvenile-onset AF patients, we identified three mutations (10%), SCN5A-M1875T, KCNJ2-M301K, and KCNQ1-G229D. Since KCNQ1 variant (G229) identified in a 16-year-old boy was novel, we focused on the proband. The G229D-IKs was found to induce a large instantaneous activating component without deactivation after repolarization to -50 mV. In addition, WT/G229D-IKs (WT and mutant co-expression) displayed both instantaneous and time-dependent activating currents. Compared to WT-IKs, the tail current densities in WT/G229D-IKs were larger at test potentials between -130 and -40 mV, but smaller at test potentials between 20 and 50 mV. Moreover, WT/G229D-IKs resulted in a negative voltage shift for current activation (-35.2 mV) and slower deactivation. WT/G229D-IKs conducted a large outward current induced by an atrial action potential waveform, and computer simulation incorporating the WT/G229D-IKs results revealed that the mutation shortened atrial but not ventricular action potential. A novel KCNQ1-G229D mutation identified in a juvenile-onset AF patient altered the IKs activity and kinetics, thereby increasing the arrhythmogenicity to AF.
    Heart rhythm: the official journal of the Heart Rhythm Society 10/2013; · 4.56 Impact Factor
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    ABSTRACT: Fatal ventricular arrhythmias in the early period of life have been associated with cardiac channelopathies for decades, and postmortem analyses in SIDS victims have provided evidence of this association. However, the prevalence and functional properties of cardiac ion channel mutations in infantile fatal arrhythmia cases are not clear. Seven infants with potentially lethal arrhythmias at age < 1 year (5 males, age of onset 44.1 ± 72.1 days) were genetically analyzed for KCNQ1, KCNH2, KCNE1-5, KCNJ2, SCN5A, GJA5, and CALM1 by using denaturing high-performance liquid chromatography and direct sequencing. Whole-cell currents of wildtype and mutant channels were recorded and analyzed in Chinese hamster ovary cells transfected with SCN5A and KCNH2 cDNA. In 5 of 7 patients, we identified 4 mutations (p.N1774D, p.T290fsX53, p.F1486del and p.N406K) in SCN5A, and 1 mutation (p.G628D) in KCNH2. N1774D, F1486del, and N406K in SCN5A displayed tetrodotoxin-sensitive persistent late Na(+) currents. By contrast, SCN5A-T290fsX53 was nonfunctional. KCNH2-G628D exhibited loss of channel function. Genetic screening of 7 patients was used to demonstrate the high prevalence of cardiac channelopathies. Functional assays revealed both gain and loss of channel function in SCN5A mutations, as well as loss of function associated with the KCNH2 mutation.
    Journal of Cardiovascular Electrophysiology 08/2013; · 3.48 Impact Factor
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    ABSTRACT: Background: The genetic background of catecholaminergic polymorphic ventricular tachycardia (CPVT) has been extensively investigated for the last decade in Western countries, but it remains unstudied in the Asian population. Methods and Results: In 50 Japanese probands from unrelated families who satisfied clinical criteria for CPVT, genetic testing was conducted in all exons on 3 CPVT-related genes: cardiac ryanodine receptor 2 (RYR2), calsequestrin 2 (CASQ2) and inward rectifier potassium channel 2 (KCNJ2), and the clinical features between RYR2-genotyped and -non-genotyped patient groups were compared. Genetic and clinical evaluation was also done in 46 family members. In the genetic screening, 28 (18 novel) RYR2 (56.0%), 1 compound heterozygous CASQ2 (2.0%) and 1 KCNJ2 (2.0%) mutation carriers were identified. In the RYR2 mutation-positive group, the frequency of bidirectional ventricular tachycardia and the use of β-blockers were significantly higher than in the mutation-negative group. In contrast, there was no significant difference in supraventricular arrhythmias between the 2 groups. With regard to disease penetrance, the number of family members of RYR2-genotyped probands with a clinical diagnosis of CPVT was high. Conclusions: Thirty gene mutation carriers were found for 3 genes in 50 probands clinically diagnosed as having CPVT. The penetrance of CPVT phenotype was significantly higher in RYR2 mutation carriers, thus RYR2 gene screening in CPVT patients would be indispensable to prevent unexpected cardiac sudden death of young family members.
    Circulation Journal 04/2013; · 3.58 Impact Factor
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    ABSTRACT: Background: Mutations in genes encoding the L-type cardiac calcium channel (LTCC) are associated with various types of inherited arrhythmias, including Brugada syndrome (BrS). However, the frequency in Asian populations remains unknown. This study aimed to elucidate disease-causing mutations in LTCC-related genes in Japanese patients diagnosed as BrS or idiopathic ventricular fibrillation (IVF), early repolarization syndrome, short QT syndrome, and compare them with those carrying SCN5A mutations. Methods and Results: We screened CACNA1C and CACNB2b in 312 probands and compared the clinical characteristics between probands with gene mutations in CACNA1C or SCN5A. In results, we identified 6 CACNA1C mutations in 7 unrelated probands and SCN5A mutations in 20 probands. There were no CACNB2b mutation carriers. In topology, half of the mutations were located in the C-terminus. Among 7 CACNA1C mutation carriers, 2 were female and 3 were symptomatic; 2 patients were resuscitated from ventricular fibrillation, and 1 patient had syncope. Compared with SCN5A mutation carriers, there were no significant differences in the ECG characteristics. 2 of 3 symptomatic CACNA1C patients were female, but all female SCN5A mutation carriers remained asymptomatic. Conclusions: We identified 6 CACNA1C mutations in BrS and IVF patients and their phenotypes were varied. Although mutation frequency was not high, screening of LTCC channel genes may be clinically important to prevent unexpected sudden death.
    Circulation Journal 04/2013; · 3.58 Impact Factor
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    ABSTRACT: Background: Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a heart muscle disease caused by desmosomal gene mutations, and presents as ventricular tachycardia and sudden cardiac death. Although the mean age at onset or diagnosis of ARVC/D are reported to be around the 30-40s, the age-dependent clinical and genetic differences remain unknown. Methods and Results: A total of 35 consecutive Japanese probands (23 male) who were clinically diagnosed with ARVC/D were enrolled in the present study, and genetic analysis of PKP2, DSP, DSG2, and DSC2 was done. The mean age at the first symptom and at diagnosis was 38.6±14.8 years and 40.5±17.7 years, respectively. Probands in whom the onset was cardiopulmonary arrest were significantly younger (22.3±15.3 years) than those with arrhythmia (41.1±13.2 years) or congestive heart failure (45.7±8.5 years). On genetic screening, 19 mutation carriers were identified. Although there was no age dependence for each gene mutation carrier, carriers with PKP2 premature stop codon developed the disease at a significantly younger age than other mutation carriers. Conclusions: The initial clinical manifestations in some young probands were very severe, and PKP2 mutations with a premature stop codon would be associated with disease onset at a younger age.
    Circulation Journal 03/2013; · 3.58 Impact Factor
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    ABSTRACT: Background: In the short- to mid-term, cardiomyocytes generated from human-induced pluripotent stem cells (hiPSC-CMs) have been reported to be less mature than those of adult hearts. However, the maturation process in a long-term culture remains unknown. Methods and Results: A hiPSC clone generated from a healthy control was differentiated into CMs through embryoid body (EB) formation. The ultrastructural characteristics and gene expressions of spontaneously contracting EBs were analyzed through 1-year of culture after cardiac differentiation was initiated. The 14-day-old EBs contained a low number of myofibrils, which lacked alignment, and immature high-density Z-bands lacking A-, H-, I-, and M-bands. Through the long-term culture up to 180 days, the myofibrils became more tightly packed and formed parallel arrays accompanied by the appearance of mature Z-, A-, H-, and I-bands, but not M-bands. Notably, M-bands were finally detected in 360-day-old EBs. The expression levels of the M-band-specific genes in hiPSC-CMs remained lower in comparison with those in the adult heart. Immunocytochemistry indicated increasing number of MLC2v-positive/MLC2a-negative cells with decreasing number of MLC2v/MLC2a double-positive cells, indicating maturing of ventricular-type CMs. Conclusions: The structural maturation process of hiPSC-CMs through 1-year of culture revealed ultrastructural sarcomeric changes accompanied by delayed formation of M-bands. Our study provides new insight into the maturation process of hiPSC-CMs.
    Circulation Journal 02/2013; · 3.58 Impact Factor

Publication Stats

568 Citations
318.45 Total Impact Points

Institutions

  • 2007–2014
    • Kyoto University
      • Department of Cardiovascular Medicine
      Kioto, Kyōto, Japan
  • 2013
    • Tenri Yorozu Hospital
      Тэнри, Nara, Japan
  • 2008–2013
    • Shiga University of Medical Science
      • Department of Cardiovascular and Respiratory Medicine
      Ōtu, Shiga, Japan
  • 2011
    • Niigata University
      • Division of Cardiology
      Niahi-niigata, Niigata, Japan
  • 2006
    • Tongji Hospital
      Wu-han-shih, Hubei, China