BACKGROUND: Symptomatic children with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for recurrent arrhythmic events. β-Blockers decrease this risk, but studies comparing individual β-blockers in sizeable cohorts are lacking. We aimed to assess the association between risk for arrhythmic events and type of β-blocker in a large cohort of symptomatic children with CPVT. METHODS: From 2 international registries of patients with CPVT, RYR2 variant-carrying symptomatic children (defined as syncope or sudden cardiac arrest before β-blocker initiation and age at start of β-blocker therapy <18 years), treated with a β-blocker were included. Cox regression analyses with time-dependent covariates for β-blockers and potential confounders were used to assess the hazard ratio (HR). The primary outcome was the first occurrence of sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter-defibrillator shock, or syncope. The secondary outcome was the first occurrence of any of the primary outcomes except syncope. RESULTS: We included 329 patients (median age at diagnosis, 12 [interquartile range, 7-15] years, 35% females). Ninety-nine (30.1%) patients experienced the primary outcome and 74 (22.5%) experienced the secondary outcome during a median follow-up of 6.7 (interquartile range, 2.8-12.5) years. Two-hundred sixteen patients (66.0%) used a nonselective β-blocker (predominantly nadolol [n=140] or propranolol [n=70]) and 111 (33.7%) used a β1-selective β-blocker (predominantly atenolol [n=51], metoprolol [n=33], or bisoprolol [n=19]) as initial β-blocker. Baseline characteristics did not differ. The HRs for both the primary and secondary outcomes were higher for β1-selective compared with nonselective β-blockers (HR, 2.04 [95% CI, 1.31-3.17]; and HR, 1.99 [95% CI, 1.20-3.30], respectively). When assessed separately, the HR for the primary outcome was higher for atenolol (HR, 2.68 [95% CI, 1.44-4.99]), bisoprolol (HR, 3.24 [95% CI, 1.47-7.18]), and metoprolol (HR, 2.18 [95% CI, 1.08-4.40]) compared with nadolol, but did not differ from propranolol. The HR of the secondary outcome was only higher in atenolol compared with nadolol (HR, 2.68 [95% CI, 1.30-5.55]). CONCLUSIONS: β1-selective β-blockers were associated with a significantly higher risk for arrhythmic events in symptomatic children with CPVT compared with nonselective β-blockers, specifically nadolol. Nadolol, or propranolol if nadolol is unavailable, should be the preferred β-blocker for treating symptomatic children with CPVT.

• Klíčová slova
• atenolol, child, death, sudden, cardiac, metoprolol, nadolol, polymorphic catecholergic ventricular tachycardia, propranolol,
• MeSH
• beta blokátory farmakologie   terapeutické užití   MeSH
• dítě MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• kohortové studie MeSH
• komorová tachykardie farmakoterapie   MeSH
• lidé MeSH
• mladiství MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• beta blokátory MeSH

BACKGROUND: In severely affected patients with catecholaminergic polymorphic ventricular tachycardia, beta-blockers are often insufficiently protective. The purpose of this study was to evaluate whether flecainide is associated with a lower incidence of arrhythmic events (AEs) when added to beta-blockers in a large cohort of patients with catecholaminergic polymorphic ventricular tachycardia. METHODS: From 2 international registries, this multicenter case cross-over study included patients with a clinical or genetic diagnosis of catecholaminergic polymorphic ventricular tachycardia in whom flecainide was added to beta-blocker therapy. The study period was defined as the period in which background therapy (ie, beta-blocker type [beta1-selective or nonselective]), left cardiac sympathetic denervation, and implantable cardioverter defibrillator treatment status, remained unchanged within individual patients and was divided into pre-flecainide and on-flecainide periods. The primary end point was AEs, defined as sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter defibrillator shock, and arrhythmic syncope. The association of flecainide with AE rates was assessed using a generalized linear mixed model assuming negative binomial distribution and random effects for patients. RESULTS: A total of 247 patients (123 [50%] females; median age at start of flecainide, 18 years [interquartile range, 14-29]; median flecainide dose, 2.2 mg/kg per day [interquartile range, 1.7-3.1]) were included. At baseline, all patients used a beta-blocker, 70 (28%) had an implantable cardioverter defibrillator, and 21 (9%) had a left cardiac sympathetic denervation. During a median pre-flecainide follow-up of 2.1 years (interquartile range, 0.4-7.2), 41 patients (17%) experienced 58 AEs (annual event rate, 5.6%). During a median on-flecainide follow-up of 2.9 years (interquartile range, 1.0-6.0), 23 patients (9%) experienced 38 AEs (annual event rate, 4.0%). There were significantly fewer AEs after initiation of flecainide (incidence rate ratio, 0.55 [95% CI, 0.38-0.83]; P=0.007). Among patients who were symptomatic before diagnosis or during the pre-flecainide period (n=167), flecainide was associated with significantly fewer AEs (incidence rate ratio, 0.49 [95% CI, 0.31-0.77]; P=0.002). Among patients with ≥1 AE on beta-blocker therapy (n=41), adding flecainide was also associated with significantly fewer AEs (incidence rate ratio, 0.25 [95% CI, 0.14-0.45]; P<0.001). CONCLUSIONS: For patients with catecholaminergic polymorphic ventricular tachycardia, adding flecainide to beta-blocker therapy was associated with a lower incidence of AEs in the overall cohort, in symptomatic patients, and particularly in patients with breakthrough AEs while on beta-blocker therapy.

• Klíčová slova
• catecholaminergic polymorphic ventricular tachycardia, sudden cardiac death, ventricular arrhythmias,
• MeSH
• beta blokátory škodlivé účinky   MeSH
• defibrilátory implantabilní * MeSH
• flekainid škodlivé účinky   MeSH
• incidence MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• klinické křížové studie MeSH
• komorová tachykardie * diagnóza   farmakoterapie   epidemiologie   MeSH
• lidé MeSH
• mladiství MeSH
• náhlá srdeční smrt epidemiologie   etiologie   prevence a kontrola   MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• beta blokátory MeSH
• flekainid MeSH

BACKGROUND: Children with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for sudden death, and a risk stratification tool does not exist. OBJECTIVE: The purpose of this study was to determine whether proband status, age at symptom onset, and/or sex are independent predictors of cardiac events. METHODS: A multicenter, ambispective, cohort of pediatric CPVT patients was categorized by sex, proband status, and age at symptom onset (D1: first decade of life [symptom onset <10 years] or D2: second decade of life [symptom onset 10-18 years, inclusive]). Demographics, therapy, genetics, and outcomes were compared between groups. RESULTS: A total of 133 patients were included and stratified into 58 D1 and 75 D2 patients (68 female and 65 male; 106 probands and 27 relatives). Localization of RYR2 variants to hotspots differed based on proband status and age at symptom onset. The cardiac event rate was 33% (n = 44/133), inclusive of a 3% (n = 4/133) mortality rate, over a median of 6 years (interquartile range 3-11) after time of symptom onset. Proband status, rather than age at of symptom onset or sex, was an independent predictor of time to first cardiac event (P = .008; hazard ratio = 4.4). The 5-, 10- and 15-year event-free survival rates for probands were 77%, 56%, and 46%, respectively, and for relatives were 96%, 91%, and 86%, respectively. Event risk after diagnosis was 48% (32/67) in patients on β-blocker or flecainide alone vs 10% (5/48) in patients on β-blocker plus flecainide and/or left cardiac sympathetic denervation (P <.001). CONCLUSION: Proband status, but not age at symptom onset or male sex, independently predicted an earlier onset of cardiac events. A larger sample size would enable a comprehensive investigation of other risk factors.

• Klíčová slova
• Catecholaminergic polymorphic ventricular tachycardia, Inherited arrhythmia, Pediatrics, Risk predictors, Ryanodine receptor,
• MeSH
• dítě MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• komorová tachykardie epidemiologie   terapie   MeSH
• lidé MeSH
• mladiství MeSH
• rizikové faktory MeSH
• sexuální faktory MeSH
• stupeň závažnosti nemoci MeSH
• věk při počátku nemoci MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Kanada epidemiologie   MeSH
• Spojené státy americké epidemiologie   MeSH

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) may cause sudden cardiac death (SCD) despite medical therapy. Therefore, implantable cardioverter-defibrillators (ICDs) are commonly advised. However, there is limited data on the outcomes of ICD use in children. OBJECTIVE: The purpose of this study was to compare the risk of arrhythmic events in pediatric patients with CPVT with and without an ICD. METHODS: We compared the risk of SCD in patients with RYR2 (ryanodine receptor 2) variants and phenotype-positive symptomatic CPVT patients with and without an ICD who were younger than 19 years and had no history of sudden cardiac arrest at phenotype diagnosis. The primary outcome was SCD; secondary outcomes were composite end points of SCD, sudden cardiac arrest, or appropriate ICD shocks with or without arrhythmic syncope. RESULTS: The study included 235 patients, 73 with an ICD (31.1%) and 162 without an ICD (68.9%). Over a median follow-up of 8.0 years (interquartile range 4.3-13.4 years), SCD occurred in 7 patients (3.0%), of whom 4 (57.1%) were noncompliant with medications and none had an ICD. Patients with ICD had a higher risk of both secondary composite outcomes (without syncope: hazard ratio 5.85; 95% confidence interval 3.40-10.09; P < .0001; with syncope: hazard ratio 2.55; 95% confidence interval 1.50-4.34; P = .0005). Thirty-one patients with ICD (42.5%) experienced appropriate shocks, 18 (24.7%) inappropriate shocks, and 21 (28.8%) device-related complications. CONCLUSION: SCD events occurred only in patients without an ICD and mostly in those not on optimal medical therapy. Patients with an ICD had a high risk of appropriate and inappropriate shocks, which may be reduced with appropriate device programming. Severe ICD complications were common, and risks vs benefits of ICDs need to be considered.

• Klíčová slova
• Catecholaminergic polymorphic ventricular tachycardia, Implantable cardioverter-defibrillator, Inherited arrhythmia, Ryanodine receptor, Sudden cardiac death, Ventricular tachycardia,
• MeSH
• defibrilátory implantabilní * MeSH
• dítě MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• komorová tachykardie * terapie   patofyziologie   MeSH
• lidé MeSH
• mladiství MeSH
• náhlá srdeční smrt * prevence a kontrola   etiologie   MeSH
• následné studie MeSH
• předškolní dítě MeSH
• retrospektivní studie MeSH
• ryanodinový receptor vápníkového kanálu genetika   MeSH
• výsledek terapie MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• Názvy látek
• ryanodinový receptor vápníkového kanálu MeSH

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare hereditary arrhythmia. The onset of clinical symptoms usually occurs during childhood, and is typically related to exercise. The aim of our study was to describe the clinical characteristics of seven Czech families with CPVT and the results of mutational analysis of the RyR2 gene in these families. METHODS: The subjects and their relatives were investigated at the participating departments. They underwent basic clinical investigation, and history was focused on possible CPVT symptoms, that is, syncopes during exercise. Bicycle ergometry was performed to obtain electrocardiogram recording during adrenergic stimulation. In all the investigated individuals, blood samples were taken for mutation analysis of the RyR2 gene. RESULTS: To date, seven families have been investigated, comprising 11 adults and 13 children. In seven CPVT patients, the indication for examination was syncope during exercise. Diagnosis was confirmed by bicycle ergometry-induced polymorphic ventricular tachycardia. In one relative, polymorphic ventricular tachycardia was also induced. All eight affected individuals were treated with β-blockers and in two, a cardioverter-defibrillator was implanted due to recurrent syncopi. Coding variants of the RyR2 gene were found in four probands. CONCLUSIONS: This is a systematic description of CPVT families in the Czech Republic. Our data support the importance of exercise testing for the diagnosis of CPVT. In addition, RyR2 gene coding variants were found in 50% of affected individuals.

• MeSH
• dítě MeSH
• dospělí MeSH
• genetická predispozice k nemoci genetika   MeSH
• heterozygot MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• komorová tachykardie diagnóza   genetika   MeSH
• lidé MeSH
• mladý dospělý MeSH
• mutace genetika   MeSH
• rodokmen MeSH
• ryanodinový receptor vápníkového kanálu genetika   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• ryanodinový receptor vápníkového kanálu MeSH

Human induced pluripotent stem cell (iPSC) lines were generated from peripheral blood mononuclear cells (PBMCs) isolated from two related patients diagnosed with either idiopathic ventricular fibrillation or catecholaminergic polymorphic ventricular tachycardia, carrying an unknown variant in the RYR2 gene, c.14201A>G (p.Y4734C) and one healthy related individual. Reprogramming was done using a commercially available Epi5 Reprogramming Kit. The pluripotency of the iPSC lines was verified by the expression of pluripotency markers and by their capacity to differentiate into all three embryonic germ layers in vitro. These iPSC lines are available for functional analysis and in vitro studies of RYR2 channelopathy.

• MeSH
• buněčná diferenciace MeSH
• buněčné linie MeSH
• dospělí MeSH
• fibrilace komor * genetika   MeSH
• indukované pluripotentní kmenové buňky * metabolismus   MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• komorová tachykardie * genetika   metabolismus   MeSH
• lidé MeSH
• ryanodinový receptor vápníkového kanálu * genetika   metabolismus   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ryanodinový receptor vápníkového kanálu * MeSH
• RyR2 protein, human MeSH Prohlížeč

AIMS: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an ion channelopathy characterized by ventricular arrhythmia during exertion or stress. Mutations in RYR2-coded Ryanodine Receptor-2 (RyR2) and CASQ2-coded Calsequestrin-2 (CASQ2) genes underlie CPVT1 and CPVT2, respectively. However, prognostic markers are scarce. We sought to better characterize the phenotypic and genotypic spectrum of CPVT, and utilize molecular modelling to help account for clinical phenotypes. METHODS AND RESULTS: This is a Pediatric and Congenital Electrophysiology Society multicentre, retrospective cohort study of CPVT patients diagnosed at <19 years of age and their first-degree relatives. Genetic testing was undertaken in 194 of 236 subjects (82%) during 3.5 (1.4-5.3) years of follow-up. The majority (60%) had RyR2-associated CPVT1. Variant locations were predicted based on a 3D structural model of RyR2. Specific residues appear to have key structural importance, supported by an association between cardiac arrest and mutations in the intersubunit interface of the N-terminus, and the S4-S5 linker and helices S5 and S6 of the RyR2 C-terminus. In approximately one quarter of symptomatic patients, cardiac events were precipitated by only normal wakeful activities. CONCLUSION: This large, multicentre study identifies contemporary challenges related to the diagnosis and prognostication of CPVT patients. Structural modelling of RyR2 can improve our understanding severe CPVT phenotypes. Wakeful rest, rather than exertion, often precipitated life-threatening cardiac events.

• MeSH
• dědičnost MeSH
• dítě MeSH
• fenotyp MeSH
• genetická predispozice k nemoci MeSH
• genetické markery MeSH
• kalsekvestrin genetika   MeSH
• katecholaminergní polymorfní komorová tachykardie MeSH
• komorová tachykardie diagnóza   genetika   mortalita   patofyziologie   MeSH
• konformace proteinů MeSH
• lidé MeSH
• mladiství MeSH
• molekulární modely MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• náhlá srdeční smrt epidemiologie   MeSH
• prognóza MeSH
• registrace MeSH
• retrospektivní studie MeSH
• rizikové faktory MeSH
• rodokmen MeSH
• ryanodinový receptor vápníkového kanálu chemie   genetika   metabolismus   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH
• Názvy látek
• CASQ2 protein, human MeSH Prohlížeč
• genetické markery MeSH
• kalsekvestrin MeSH
• ryanodinový receptor vápníkového kanálu MeSH
• RyR2 protein, human MeSH Prohlížeč