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Balestra E, Bobbo M, Cittar M, Chicco D, D’Agata Mottolese B, Barbi E, Caiffa T. Congenital Long QT Syndrome in Children and Adolescents: A General Overview. CHILDREN (BASEL, SWITZERLAND) 2024; 11:582. [PMID: 38790576 PMCID: PMC11119491 DOI: 10.3390/children11050582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 04/24/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024]
Abstract
Congenital long QT syndrome (LQTS) represents a disorder of myocardial repolarization characterized by a prolongation of QTc interval on ECG, which can degenerate into fast polymorphic ventricular arrhythmias. The typical symptoms of LQTS are syncope and palpitations, mainly triggered by adrenergic stimuli, but it can also manifest with cardiac arrest. At least 17 genotypes have been associated with LQTS, with a specific genotype-phenotype relationship described for the three most common subtypes (LQTS1, -2, and -3). β-Blockers are the first-line therapy for LQTS, even if the choice of the appropriate patients needing to be treated may be challenging. In specific cases, interventional measures, such as an implantable cardioverter-defibrillator (ICD) or left cardiac sympathetic denervation (LCSD), are useful. The aim of this review is to highlight the current state-of-the-art knowledge on LQTS, providing an updated picture of possible diagnostic algorithms and therapeutic management.
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Affiliation(s)
- Elia Balestra
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34127 Trieste, Italy;
| | - Marco Bobbo
- Institute for Maternal and Child Health, IRCCS “Burlo Garofolo”, 34127 Trieste, Italy; (M.B.); (D.C.); (B.D.M.); (T.C.)
| | - Marco Cittar
- Cardiovascular Department, Centre for Diagnosis and Management of Cardiomyopathies, Azienda Sanitaria Universitaria Integrata di Trieste, University of Trieste, 34127 Trieste, Italy;
| | - Daniela Chicco
- Institute for Maternal and Child Health, IRCCS “Burlo Garofolo”, 34127 Trieste, Italy; (M.B.); (D.C.); (B.D.M.); (T.C.)
| | - Biancamaria D’Agata Mottolese
- Institute for Maternal and Child Health, IRCCS “Burlo Garofolo”, 34127 Trieste, Italy; (M.B.); (D.C.); (B.D.M.); (T.C.)
| | - Egidio Barbi
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34127 Trieste, Italy;
- Institute for Maternal and Child Health, IRCCS “Burlo Garofolo”, 34127 Trieste, Italy; (M.B.); (D.C.); (B.D.M.); (T.C.)
| | - Thomas Caiffa
- Institute for Maternal and Child Health, IRCCS “Burlo Garofolo”, 34127 Trieste, Italy; (M.B.); (D.C.); (B.D.M.); (T.C.)
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Tonko JB, Lambiase PD. The proarrhythmogenic role of autonomics and emerging neuromodulation approaches to prevent sudden death in cardiac ion channelopathies. Cardiovasc Res 2024; 120:114-131. [PMID: 38195920 PMCID: PMC10936753 DOI: 10.1093/cvr/cvae009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/06/2023] [Accepted: 11/30/2023] [Indexed: 01/11/2024] Open
Abstract
Ventricular arrhythmias in cardiac channelopathies are linked to autonomic triggers, which are sub-optimally targeted in current management strategies. Improved molecular understanding of cardiac channelopathies and cellular autonomic signalling could refine autonomic therapies to target the specific signalling pathways relevant to the specific aetiologies as well as the central nervous system centres involved in the cardiac autonomic regulation. This review summarizes key anatomical and physiological aspects of the cardiac autonomic nervous system and its impact on ventricular arrhythmias in primary inherited arrhythmia syndromes. Proarrhythmogenic autonomic effects and potential therapeutic targets in defined conditions including the Brugada syndrome, early repolarization syndrome, long QT syndrome, and catecholaminergic polymorphic ventricular tachycardia will be examined. Pharmacological and interventional neuromodulation options for these cardiac channelopathies are discussed. Promising new targets for cardiac neuromodulation include inhibitory and excitatory G-protein coupled receptors, neuropeptides, chemorepellents/attractants as well as the vagal and sympathetic nuclei in the central nervous system. Novel therapeutic strategies utilizing invasive and non-invasive deep brain/brain stem stimulation as well as the rapidly growing field of chemo-, opto-, or sonogenetics allowing cell-specific targeting to reduce ventricular arrhythmias are presented.
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Affiliation(s)
- Johanna B Tonko
- Institute of Cardiovascular Science, University College London, 5 University Street, London WC1E 6JF, London, UK
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, 5 University Street, London WC1E 6JF, London, UK
- Department for Cardiology, Bart’s Heart Centre, West Smithfield EC1A 7BE, London, UK
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3
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Comollo TW, Zou X, Zhang C, Kesters D, Hof T, Sampson KJ, Kass RS. Exploring mutation specific beta blocker pharmacology of the pathogenic late sodium channel current from patient-specific pluripotent stem cell myocytes derived from long QT syndrome mutation carriers. Channels (Austin) 2022; 16:173-184. [PMID: 35949058 PMCID: PMC9373745 DOI: 10.1080/19336950.2022.2106025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The congenital long QT syndrome (LQTS), one of the most common cardiac channelopathies, is characterized by delayed ventricular repolarization underlying prolongation of the QT interval of the surface electrocardiogram. LQTS is caused by mutations in genes coding for cardiac ion channels or ion channel-associated proteins. The major therapeutic approach to LQTS management is beta blocker therapy which has been shown to be effective in treatment of LQTS variants caused by mutations in K+ channels. However, this approach has been questioned in the treatment of patients identified as LQTS variant 3(LQT3) patients who carry mutations in SCN5A, the gene coding for the principal cardiac Na+ channel. LQT3 mutations are gain of function mutations that disrupt spontaneous Na+ channel inactivation and promote persistent or late Na+ channel current (INaL) that delays repolarization and underlies QT prolongation. Clinical investigation of patients with the two most common LQT3 mutations, the ΔKPQ and the E1784K mutations, found beta blocker treatment a useful therapeutic approach for managing arrhythmias in this patient population. However, there is little experimental data that reveals the mechanisms underlying these antiarrhythmic actions. Here, we have investigated the effects of the beta blocker propranolol on INaL expressed by ΔKPQ and E1784K channels in induced pluripotent stem cells derived from patients carrying these mutations. Our results indicate that propranolol preferentially inhibits INaL expressed by these channels suggesting that the protective effects of propranolol in treating LQT3 patients is due in part to modulation of INaL.
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Affiliation(s)
- Thomas W. Comollo
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA
| | - Xinle Zou
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA
| | - Chuangeng Zhang
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA
| | - Divya Kesters
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA
| | - Thomas Hof
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA
| | - Kevin J. Sampson
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA
| | - Robert S. Kass
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, Columbia, NY, USA,CONTACT Robert S. Kass
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Proshlyakov AY, Chomakhidze PS, Novikova NA. Comparative Characteristics of Beta-Blockers in Patients with Congenital Long QT Syndrome. RATIONAL PHARMACOTHERAPY IN CARDIOLOGY 2021. [DOI: 10.20996/1819-6446-2021-06-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Congenital long QT syndrome is a pathology that requires special attention and knowledge about the safety and effectiveness of various medications. Prolongation of the QT interval due to congenital or acquired causes is an important factor in the development of an unfavorable life forecast with the formation of an elongated QT syndrome. With an unfavorable course, patients suffer from loss of consciousness, episodes of tachycardia. Often, stable polymorphic ventricular tachycardia develops. The risk of sudden cardiac death in this pathology can vary from 0.33% to 5%. In people who have suffered an episode of cardiac arrest, and do not have a permanent prescribed antiarrhythmic therapy, the mortality rate reaches 50% within 15 years. Preventive administration of antiarrhythmic drugs is not always effective. A positive result of treatment depends on the severity of long QT syndrome and its genotype. Beta-blockers are often prescribed to patients of different ages with various cardiac pathologies, including for the prevention of arrhythmia in long QT syndrome. Beta-blockers differ in various pharmacokinetic and pharmacodynamic parameters (lipophilicity/hydrophilicity, selectivity, presence/absence of internal sympathomimetic activity), which, along with the variant of the disease genotype, can affect their effectiveness and safety in the considered pathology. This review article presents the results of major studies on the safety and effectiveness of different groups of beta blockers in various variants of long QT syndrome. The preferred beta-blockers for various genotypes of the syndrome were determined, and a comparative characteristic of beta-blockers for their safety and preventive effectiveness was given.
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Affiliation(s)
- A. Yu. Proshlyakov
- I.M. Sechenov First Moscow State Medical University (Sechenov University)
| | - P. Sh. Chomakhidze
- I.M. Sechenov First Moscow State Medical University (Sechenov University)
| | - N. A. Novikova
- I.M. Sechenov First Moscow State Medical University (Sechenov University)
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González-Garrido A, Domínguez-Pérez M, Jacobo-Albavera L, López-Ramírez O, Guevara-Chávez JG, Zepeda-García O, Iturralde P, Carnevale A, Villarreal-Molina T. Compound Heterozygous KCNQ1 Mutations Causing Recessive Romano-Ward Syndrome: Functional Characterization by Mutant Co-expression. Front Cardiovasc Med 2021; 8:625449. [PMID: 33693037 PMCID: PMC7937651 DOI: 10.3389/fcvm.2021.625449] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022] Open
Abstract
Next Generation Sequencing has identified many KCNQ1 genetic variants associated with type 1 long QT or Romano-Ward syndrome, most frequently inherited in an autosomal dominant fashion, although recessive forms have been reported. Particularly in the case of missense variants, functional studies of mutants are of aid to establish variant pathogenicity and to understand the mechanistic basis of disease. Two compound heterozygous KCNQ1 mutations (p.A300T and p.P535T) were previously found in a child who suffered sudden death. To provide further insight into the clinical significance and basis for pathogenicity of these variants, different combinations of wildtype, A300T and P535T alleles were co-expressed with the accessory β-subunit minK in HEK293 cells, to analyze colocalization with the plasma membrane and some biophysical phenotypes of homo and heterotetrameric channels using the patch-clamp technique. A300T homotetrameric channels showed left-shifted activation V1/2 as previously observed in Xenopus oocytes, decreased maximum conductance density, slow rise-time300ms, and a characteristic use-dependent response. A300T slow rise-time300ms and use-dependent response behaved as dominant biophysical traits for all allele combinations. The P535T variant significantly decreased maximum conductance density and Kv7.1-minK-plasma membrane colocalization. P535T/A300T heterotetrameric channels showed decreased colocalization with plasma membrane, slow rise-time300ms and the A300T characteristic use-dependent response. While A300T left shifted activation voltage dependence behaved as a recessive trait when co-expressed with WT alleles, it was dominant when co-expressed with P535T alleles. Conclusions: The combination of P535T/A300T channel biophysical properties is compatible with recessive Romano Ward syndrome. Further analysis of other biophysical traits may identify other mechanisms involved in the pathophysiology of this disease.
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Affiliation(s)
- Antonia González-Garrido
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico City, Mexico.,Cátedras CONACyT, Consejo Nacional de Ciencia y Tecnología, Mexico City, Mexico
| | - Mayra Domínguez-Pérez
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Leonor Jacobo-Albavera
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Omar López-Ramírez
- Department of Neurobiology, University of Chicago, Chicago, IL, United States
| | - José Guadalupe Guevara-Chávez
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Oscar Zepeda-García
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Pedro Iturralde
- Departamento de Electrofisiología, Instituto Nacional de Cardiología "Ignacio Chávez", Mexico, Mexico
| | - Alessandra Carnevale
- Laboratorio de Enfermedades Mendelianas, Instituto Nacional de Medicina Genómica, Mexico, Mexico
| | - Teresa Villarreal-Molina
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
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Abstract
Long QT syndrome (LQTS) is a cardiovascular disorder characterized by an abnormality in cardiac repolarization leading to a prolonged QT interval and T-wave irregularities on the surface electrocardiogram. It is commonly associated with syncope, seizures, susceptibility to torsades de pointes, and risk for sudden death. LQTS is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. The availability of therapy for this lethal disease emphasizes the importance of early and accurate diagnosis. Additionally, understanding of the molecular mechanisms underlying LQTS could help to optimize genotype-specific treatments to prevent deaths in LQTS patients. In this review, we briefly summarize current knowledge regarding molecular underpinning of LQTS, in particular focusing on LQT1, LQT2, and LQT3, and discuss novel strategies to study ion channel dysfunction and drug-specific therapies in LQT1, LQT2, and LQT3 syndromes.
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Affiliation(s)
| | - Isabelle Deschênes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
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Han L, Liu F, Li Q, Qing T, Zhai Z, Xia Z, Li J. The Efficacy of Beta-Blockers in Patients With Long QT Syndrome 1-3 According to Individuals' Gender, Age, and QTc Intervals: A Network Meta-analysis. Front Pharmacol 2021; 11:579525. [PMID: 33381033 PMCID: PMC7768040 DOI: 10.3389/fphar.2020.579525] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/13/2020] [Indexed: 02/02/2023] Open
Abstract
Long QT syndrome (LQTS) is an arrhythmic heart disease caused by congenital genetic mutations, and results in increased occurrence rates of polymorphic ventricular tachyarrhythmias and sudden cardiac death (SCD). Clinical evidence from numerous previous studies suggested that beta blockers (BBs), including atenolol, propranolol, metoprolol, and nadolol, exhibit different efficacies for reducing the risk of cardiac events (CEs), such as syncope, arrest cardiac arrest (ACA), and SCD, in patients with LQTS. In this study, we identified relevant studies in MEDLINE, PubMed, embase, and Cochrane databases and performed a meta-analysis to assess the relationship between the rate of CEs and LQTS individuals with confounding variables, including different gender, age, and QTc intervals. Moreover, a network meta-analysis was not only established to evaluate the effectiveness of different BBs, but also to provide the ranked efficacies of BBs treatment for preventing the recurrence of CEs in LQT1 and LQT2 patients. In conclusion, nadolol was recommended as a relatively effective strategy for LQT2 in order to improve the prognosis of patients during a long follow-up period.
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Affiliation(s)
- Lu Han
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Fuxiang Liu
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qing Li
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Tao Qing
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zhenyu Zhai
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zirong Xia
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Juxiang Li
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, China
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8
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Long QT Syndrome and Electrical Storm: Is Implanted Cardiac Defibrillator the Final Destination in Long QT Syndrome Management? COR ET VASA 2020. [DOI: 10.33678/cor.2020.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Long QT syndrome type 1 and 2 patients respond differently to arrhythmic triggers: The TriQarr in vivo study. Heart Rhythm 2020; 18:241-249. [PMID: 32882399 DOI: 10.1016/j.hrthm.2020.08.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/21/2020] [Accepted: 08/27/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND In patients with long QT syndrome (LQTS), swimming and loud noises have been identified as genotype-specific arrhythmic triggers in LQTS type 1 (LQTS1) and LQTS type 2 (LQTS2), respectively. OBJECTIVE The purpose of this study was to compare LQTS group responses to arrhythmic triggers. METHODS LQTS1 and LQTS2 patients were included. Before and after beta-blocker intake, electrocardiograms were recorded as participants (1) were exposed to a loud noise of ∼100 dB; and (2) had their face immersed into cold water. RESULTS Twenty-three patients (9 LQTS1, 14 LQTS2) participated. In response to noise, LQTS groups showed similarly increased heart rate, but LQTS2 patients had corrected QT interval (Fridericia formula) (QTcF) prolonged significantly more than LQTS1 patients (37 ± 8 ms vs 15 ± 6 ms; P = .02). After intake of beta-blocker, QTcF prolongation in LQTS2 patients was significantly blunted and similar to that of LQTS1 patients (P = .90). In response to simulated diving, LQTS groups experienced a heart rate drop of ∼28 bpm, which shortened QTcF similarly in both groups. After intake of beta-blockers, heart rate dropped to 28 ± 2 bpm in LQTS1 patients and 20 ± 3 bpm in LQTS2, resulting in a slower heart rate in LQTS1 compared with LQTS2 (P = .01). In response, QTcF shortened similarly in LQTS1 and LQTS2 patients (57 ± 9 ms vs 36 ± 7 ms; P = .10). CONCLUSION When exposed to noise, LQTS2 patients had QTc prolonged significantly more than did LQTS1 patients. Importantly, beta-blockers reduced noise-induced QTc prolongation in LQTS2 patients, thus demonstrating the protective effect of beta-blockers. In response to simulated diving, LQTS groups responded similarly, but a slower heart rate was observed in LQTS1 patients during simulated diving after beta-blocker intake.
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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Policarová M, Novotný T, Bébarová M. Impaired Adrenergic/Protein Kinase A Response of Slow Delayed Rectifier Potassium Channels as a Long QT Syndrome Motif: Importance and Unknowns. Can J Cardiol 2019; 35:511-522. [DOI: 10.1016/j.cjca.2018.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 12/29/2022] Open
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Shah SR, Park K, Alweis R. Long QT Syndrome: A Comprehensive Review of the Literature and Current Evidence. Curr Probl Cardiol 2018; 44:92-106. [PMID: 29784533 DOI: 10.1016/j.cpcardiol.2018.04.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/29/2018] [Indexed: 01/02/2023]
Abstract
Long QT syndrome (LQT) represents a heterogeneous family of cardiac electrophysiologic disorders characterized by QT prolongation and T-wave abnormalities on the electrocardiogram. It is commonly associated with syncope, however, sudden cardiac death can occur due to torsades de pointes. LQT is a clinical diagnosis and should be suspected in individuals on the basis of clinical presentation, family history and ECG characteristics. Management is focused on the prevention of syncope and ultimately sudden death. Complete cessation of symptoms is the goal. Life-style modification, beta blockers and ICD implantation are the most important therapeutic modalities in proper management of patients with LQT. Awareness should be raised regarding possible circumstances that could increase the risk of QT prolongation. Advanced age, hypokalemia, a history of heart failure, and structural heart disease are often mentioned in this context. Prudent consideration is needed before making a decision to recommend an ICD implantation in a young, active patient. Medical and/or device therapy still represent important therapeutic modalities in the management of patients with LQT with careful clinical judgement for the substrate of patients who will benefit. Insights from benchside to bedside have facilitated progress toward better therapeutic strategies, there also remains a need for tailoring management toward individuals in a mechanism-specific manner to optimize care. In addition, continued progress toward fundamental understanding of mechanisms of ion channel function and drug-channel interaction will guide the development of more effective, mechanism-based molecular agents in the treatment of LQT.
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Ion Channel Disorders and Sudden Cardiac Death. Int J Mol Sci 2018; 19:ijms19030692. [PMID: 29495624 PMCID: PMC5877553 DOI: 10.3390/ijms19030692] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 12/19/2022] Open
Abstract
Long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia are inherited primary electrical disorders that predispose to sudden cardiac death in the absence of structural heart disease. Also known as cardiac channelopathies, primary electrical disorders respond to mutations in genes encoding cardiac ion channels and/or their regulatory proteins, which result in modifications in the cardiac action potential or in the intracellular calcium handling that lead to electrical instability and life-threatening ventricular arrhythmias. These disorders may have low penetrance and expressivity, making clinical diagnosis often challenging. However, because sudden cardiac death might be the first presenting symptom of the disease, early diagnosis becomes essential. Genetic testing might be helpful in this regard, providing a definite diagnosis in some patients. Yet important limitations still exist, with a significant proportion of patients remaining with no causative mutation identifiable after genetic testing. This review aims to provide the latest knowledge on the genetic basis of cardiac channelopathies and discuss the role of the affected proteins in the pathophysiology of each one of these diseases.
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Non-sustained microvolt level T-wave alternans in congenital long QT syndrome types 1 and 2. J Electrocardiol 2017; 51:303-308. [PMID: 29183619 DOI: 10.1016/j.jelectrocard.2017.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 11/23/2022]
Abstract
BACKGROUND Patients with long QT syndrome (LQTS) are predisposed to polymorphic ventricular tachycardia (VT) during adrenergic stimulation. Microvolt T-wave alternans (MTWA) is linked to vulnerability to VT in structural heart disease. The prevalence of non-sustained MTWA (NS-MTWA) in LQTS is unknown. METHODS 31 LQT1, 42 LQT2, and 80 controls underwent MTWA testing during exercise. MTWA tests were classified per standardized criteria, and re-analyzed according to the modified criteria to account for NS-MTWA. RESULTS LQT1 and LQT2 patients had a significantly higher frequency of late NS-MTWA (26% and 12%) compared to controls (0%). There was no significant difference between the groups with respect to sustained and early NS-MTWA. Late NS-MTWA was significantly associated with QTc. CONCLUSION LQT1 and LQT2 patients had a higher prevalence of late NS-MTWA during exercise than matched controls. NS-MTWA likely reflects transient adrenergically mediated dispersion of repolarization, and could be a marker of arrhythmic risk in LQTS.
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Ahn J, Kim HJ, Choi JI, Lee KN, Shim J, Ahn HS, Kim YH. Effectiveness of beta-blockers depending on the genotype of congenital long-QT syndrome: A meta-analysis. PLoS One 2017; 12:e0185680. [PMID: 29059199 PMCID: PMC5653191 DOI: 10.1371/journal.pone.0185680] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 09/17/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Beta-blockers are first-line therapy in patients with congenital long-QT syndrome (LQTS). OBJECTIVE This study sought to determine the differences in effectiveness of beta-blockers on risk reduction according to LQTS genotype. METHODS We searched MEDLINE, EMBASE, and CENTRAL databases to investigate the use of beta-blockers (atenolol, nadolol, propranolol, and metoprolol) in patients with LQTS. Hazard ratio (HR) and relative risk (RR) were extracted or calculated from studies reporting cardiac events (syncope, aborted cardiac arrest (ACA), or sudden cardiac death (SCD)). RESULTS Among 2,113 articles searched, 10 studies (7 registry-based cohort studies (Cohort) and 3 interrupted time series studies (ITS)) involving 9,727 patients were included. In a meta-analysis using a random-effect model, the use of beta-blocker was associated with significant risk reduction of all cardiac events (HR 0.49, p<0.001 in Cohort; RR 0.39, p<0.001 in ITS) and serious cardiac events (ACA or SCD) (HR 0.47, p<0.001 in Cohort). In both LQT1 and LQT2, the risk was reduced with beta-blocker therapy in Cohort (HR 0.59 in LQT1; HR 0.39 in LQT2) as well as ITS (RR 0.29 in LQT1; RR 0.48 in LQT2). Among the beta-blockers, nadolol showed a significant risk reduction in both LQT1 and LQT2 (HR 0.47 and 0.27, respectively), whereas atenolol and propranolol decreased the risk only in LQT1 (HR 0.36 and 0.46, respectively). Metoprolol showed no significant reduction in either genotype. In LQT3, beta-blocker therapy was not as effective as LQT1 or LQT2; however, it was inconclusive due to data insufficiency. CONCLUSION This meta-analysis showed that beta-blockers were effective in reducing risk of cardiac events in patients with LQTS. Among them, nadolol was effective in LQT1 and LQT2, whereas other drugs showed different effectiveness depending on LQT genotype.
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Affiliation(s)
- Jinhee Ahn
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Center, Seoul, Republic of Korea
- Division of Cardiology, Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea
| | - Hyun Jung Kim
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Jong-Il Choi
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Center, Seoul, Republic of Korea
| | - Kwang No Lee
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Center, Seoul, Republic of Korea
| | - Jaemin Shim
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Center, Seoul, Republic of Korea
| | - Hyeong Sik Ahn
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Young-Hoon Kim
- Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Center, Seoul, Republic of Korea
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16
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Bartos DC, Morotti S, Ginsburg KS, Grandi E, Bers DM. Quantitative analysis of the Ca 2+ -dependent regulation of delayed rectifier K + current I Ks in rabbit ventricular myocytes. J Physiol 2017; 595:2253-2268. [PMID: 28008618 DOI: 10.1113/jp273676] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/12/2016] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS [Ca2+ ]i enhanced rabbit ventricular slowly activating delayed rectifier K+ current (IKs ) by negatively shifting the voltage dependence of activation and slowing deactivation, similar to perfusion of isoproterenol. Rabbit ventricular rapidly activating delayed rectifier K+ current (IKr ) amplitude and voltage dependence were unaffected by high [Ca2+ ]i . When measuring or simulating IKs during an action potential, IKs was not different during a physiological Ca2+ transient or when [Ca2+ ]i was buffered to 500 nm. ABSTRACT The slowly activating delayed rectifier K+ current (IKs ) contributes to repolarization of the cardiac action potential (AP). Intracellular Ca2+ ([Ca2+ ]i ) and β-adrenergic receptor (β-AR) stimulation modulate IKs amplitude and kinetics, but details of these important IKs regulators and their interaction are limited. We assessed the [Ca2+ ]i dependence of IKs in steady-state conditions and with dynamically changing membrane potential and [Ca2+ ]i during an AP. IKs was recorded from freshly isolated rabbit ventricular myocytes using whole-cell patch clamp. With intracellular pipette solutions that controlled free [Ca2+ ]i , we found that raising [Ca2+ ]i from 100 to 600 nm produced similar increases in IKs as did β-AR activation, and the effects appeared additive. Both β-AR activation and high [Ca2+ ]i increased maximally activated tail IKs , negatively shifted the voltage dependence of activation, and slowed deactivation kinetics. These data informed changes in our well-established mathematical model of the rabbit myocyte. In both AP-clamp experiments and simulations, IKs recorded during a normal physiological Ca2+ transient was similar to IKs measured with [Ca2+ ]i clamped at 500-600 nm. Thus, our study provides novel quantitative data as to how physiological [Ca2+ ]i regulates IKs amplitude and kinetics during the normal rabbit AP. Our results suggest that micromolar [Ca2+ ]i , in the submembrane or junctional cleft space, is not required to maximize [Ca2+ ]i -dependent IKs activation during normal Ca2+ transients.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Kenneth S Ginsburg
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
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17
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Bohnen MS, Peng G, Robey SH, Terrenoire C, Iyer V, Sampson KJ, Kass RS. Molecular Pathophysiology of Congenital Long QT Syndrome. Physiol Rev 2017; 97:89-134. [PMID: 27807201 PMCID: PMC5539372 DOI: 10.1152/physrev.00008.2016] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.
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Affiliation(s)
- M S Bohnen
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - G Peng
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - S H Robey
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - C Terrenoire
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - V Iyer
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - K J Sampson
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
| | - R S Kass
- Department of Pharmacology, Columbia University Medical Center, New York, New York; and The New York Stem Cell Foundation Research Institute, New York, New York
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18
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The evolution of sports participation guidelines and the influence of genotype–phenotype correlation in long QT syndrome. Trends Cardiovasc Med 2016; 26:690-697. [DOI: 10.1016/j.tcm.2016.04.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 04/29/2016] [Accepted: 04/29/2016] [Indexed: 01/02/2023]
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19
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Cho Y. Management of Patients with Long QT Syndrome. Korean Circ J 2016; 46:747-752. [PMID: 27826330 PMCID: PMC5099327 DOI: 10.4070/kcj.2016.46.6.747] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/19/2016] [Accepted: 03/22/2016] [Indexed: 01/02/2023] Open
Abstract
Long QT syndrome (LQTS) is a rare cardiac channelopathy associated with syncope and sudden death due to torsades de pointes and ventricular fibrillation. Syncope and sudden death are frequently associated with physical and emotional stress. Management of patients with LQTS consists of life-style modification, β-blockers, left cardiac sympathetic denervation (LCSD), and implantable cardioverter-defibrillator (ICD) implantation. Prohibition of competitive exercise and avoidance of QT-prolonging drugs are important issues in life-style modification. Although β-blockers are the primary treatment modality for patients with LQTS, these drugs are not completely effective in some patients. Lifelong ICD implantation in young and active patients is associated with significant complications. LCSD is a relatively simple and highly effective surgical procedure. However, LCSD is rarely used.
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Affiliation(s)
- Yongkeun Cho
- Department of Internal Medicine, Kyungpook National Univeristy Hospital, Daegu, Korea
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20
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Cheung CC, Laksman ZWM, Mellor G, Sanatani S, Krahn AD. Exercise and Inherited Arrhythmias. Can J Cardiol 2016; 32:452-8. [PMID: 26927864 DOI: 10.1016/j.cjca.2016.01.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 12/29/2015] [Accepted: 01/06/2016] [Indexed: 01/11/2023] Open
Abstract
Sudden cardiac death (SCD) in an apparently healthy individual is a tragedy that prompts a series of investigations to identify the cause of death and to prevent SCD in potentially at-risk family members. Several inherited channelopathies and cardiomyopathies, including long QT syndrome (LQTS), catecholaminergic polymorphic ventricular cardiomyopathy (CPVT), hypertrophic cardiomyopathy (HCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC) are associated with exercise-related SCD. Exercise restriction has been a historical mainstay of therapy for these conditions. Syncope and cardiac arrest occur during exercise in LQTS and CPVT because of ventricular arrhythmias, which are managed with β-blockade and exercise restriction. Exercise may provoke hemodynamic or ischemic changes in HCM, leading to ventricular arrhythmias. ARVC is a disease of the desmosome, whose underlying disease process is accelerated by exercise. On this basis, expert consensus has erred on the side of caution, recommending rigorous exercise restriction for all inherited arrhythmias. With time, as familiarity with inherited arrhythmia conditions has increased and patients with milder forms of disease are diagnosed, practitioners have questioned the historical rigorous restrictions advocated for all. This change has been driven by the fact that these are often children and young adults who wish to lead active lives. Recent evidence suggests a lower risk of exercise-related arrhythmias in treated patients than was previously assumed, including those with previous symptoms managed with an implantable cardioverter-defibrillator. In this review, we emphasize shared decision making, monitored medical therapy, individual and team awareness of precautions and emergency response measures, and a more permissive approach to recreational and competitive exercise.
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Affiliation(s)
- Christopher C Cheung
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Zachary W M Laksman
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gregory Mellor
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shubhayan Sanatani
- Children's Heart Centre, BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Andrew D Krahn
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada.
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21
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Itoh H, Berthet M, Fressart V, Denjoy I, Maugenre S, Klug D, Mizusawa Y, Makiyama T, Hofman N, Stallmeyer B, Zumhagen S, Shimizu W, Wilde AAM, Schulze-Bahr E, Horie M, Tezenas du Montcel S, Guicheney P. Asymmetry of parental origin in long QT syndrome: preferential maternal transmission of KCNQ1 variants linked to channel dysfunction. Eur J Hum Genet 2015; 24:1160-6. [PMID: 26669661 DOI: 10.1038/ejhg.2015.257] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 10/30/2015] [Accepted: 11/15/2015] [Indexed: 11/09/2022] Open
Abstract
Transmission distortion of disease-causing alleles in long QT syndrome (LQTS) has been reported, suggesting a potential role of KCNQ1 and KCNH2 in reproduction. This study sought to investigate parental transmission in LQTS families according to ethnicity, gene loci (LQT1-3: KCNQ1, KCNH2, and SCN5A) or severity of channel dysfunction. We studied 3782 genotyped members from 679 European and Japanese LQTS families (2748 carriers). We determined grandparental and parental origins of variant alleles in 1903 children and 624 grandchildren, and the grandparental origin of normal alleles in healthy children from 44 three-generation control families. LQTS alleles were more of maternal than paternal origin (61 vs 39%, P<0.001). The ratio of maternally transmitted alleles in LQT1 (66%) was higher than in LQT2 (56%, P<0.001) and LQT3 (57%, P=0.03). Unlike the Mendelian distribution of grandparental alleles seen in control families, variant grandparental LQT1 and LQT2 alleles in grandchildren showed an excess of maternally transmitted grandmother alleles. For LQT1, maternal transmission differs according to the variant level of dysfunction with 68% of maternal transmission for dominant negative or unknown functional consequence variants vs 58% for non-dominant negative and variants leading to haploinsufficiency, P<0.01; however, for LQT2 or LQT3 this association was not significant. An excess of disease-causing alleles of maternal origin, most pronounced in LQT1, was consistently found across ethnic groups. This observation does not seem to be linked to an imbalance in transmission of the LQTS subtype-specific grandparental allele, but to the potential degree of potassium channel dysfunction.
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Affiliation(s)
- Hideki Itoh
- INSERM, UMR S1166, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR S1166, Paris, France.,Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Myriam Berthet
- INSERM, UMR S1166, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR S1166, Paris, France.,Institute of Cardiometabolism and Nutrition, ICAN, Pitié-Salpêtrière Hospital, Paris, France
| | - Véronique Fressart
- INSERM, UMR S1166, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR S1166, Paris, France.,Institute of Cardiometabolism and Nutrition, ICAN, Pitié-Salpêtrière Hospital, Paris, France.,AP-HP, Groupe Hospitalier Pitié-Salpétrière, Service de Biochimie Métabolique, UF Cardiogénétique et Myogénétique Moléculaire et Cellulaire, Paris, France
| | - Isabelle Denjoy
- INSERM, UMR S1166, Paris, France.,Cardiology Department, AP-HP, Hôpital Bichat, Paris, France
| | - Svetlana Maugenre
- INSERM, UMR S1166, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR S1166, Paris, France.,Institute of Cardiometabolism and Nutrition, ICAN, Pitié-Salpêtrière Hospital, Paris, France
| | - Didier Klug
- Hôpital Cardiologique de Lille, CHRU, Service de cardiologie A, Lille, France
| | - Yuka Mizusawa
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Nynke Hofman
- Department of Clinical Genetics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Birgit Stallmeyer
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Sven Zumhagen
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Wataru Shimizu
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan.,Division of Cardiology, Department of Internal Medicine, Nippon Medical School, Tokyo, Japan
| | - Arthur A M Wilde
- AMC Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany.,Interdisciplinary Centre for Clinical Research (IZKF) of the University of Münster, Münster, Germany
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Sophie Tezenas du Montcel
- Biostatistics Unit, AP-HP, Groupe Hospitalier Pitié-Salpêtrière Charles-Foix, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, INSERM, Institut Pierre Louis d'Epidémiologie et de Santé Publique (IPLESP UMRS 1136), Paris, France
| | - Pascale Guicheney
- INSERM, UMR S1166, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR S1166, Paris, France.,Institute of Cardiometabolism and Nutrition, ICAN, Pitié-Salpêtrière Hospital, Paris, France
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22
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Koponen M, Marjamaa A, Hiippala A, Happonen JM, Havulinna AS, Salomaa V, Lahtinen AM, Hintsa T, Viitasalo M, Toivonen L, Kontula K, Swan H. Follow-up of 316 molecularly defined pediatric long-QT syndrome patients: clinical course, treatments, and side effects. Circ Arrhythm Electrophysiol 2015; 8:815-23. [PMID: 26063740 DOI: 10.1161/circep.114.002654] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 05/26/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Inherited long-QT syndrome (LQTS) is associated with risk of sudden death. We assessed the clinical course and the fulfillment of current treatment strategies in molecularly defined pediatric LQTS type 1 and (LQT1) and type 2 (LQT2) patients. METHODS AND RESULTS Follow-up data covering a mean of 12 years were collected for 316 genotyped LQT1 and LQT2 patients aged 0 to 18 years. No arrhythmic deaths occurred during the follow-up. Finnish KCNQ1 and KCNH2 founder mutations were associated with fewer cardiac events than other KCNQ1 and KCNH2 mutations (hazard ratio [HR], 0.33; P=0.03 and HR, 0.16; P=0.01, respectively). QTc interval ≥500 ms increased the risk of cardiac events compared with QTc <470 ms (HR, 3.32; P=0.001). Treatment with β-blocker medication was associated with reduced risk of first cardiac event (HR, 0.23; P=0.001). Noncompliant LQT2 patients were more often symptomatic than compliant LQT2 patients (18% and 0%, respectively; P=0.03). Treatment with implantable cardioverter defibrillator was rare (3%) and resulted in reinterventions in 44% of cases. CONCLUSIONS Severe cardiac events are uncommon in molecularly defined and appropriately treated pediatric LQTS mutation carriers. β-Blocker medication reduces the risk of cardiac events and is generally well tolerated in this age group of LQTS patients.
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Affiliation(s)
- Mikael Koponen
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.).
| | - Annukka Marjamaa
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Anita Hiippala
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Juha-Matti Happonen
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Aki S Havulinna
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Veikko Salomaa
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Annukka M Lahtinen
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Taina Hintsa
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Matti Viitasalo
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Lauri Toivonen
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Kimmo Kontula
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
| | - Heikki Swan
- From the Heart and Lung Center, Helsinki University Central Hospital (M.K., A.M., M.V., L.T., H.S.), Children's Hospital, Helsinki University Central Hospital (A.H., J.-M.H.), Department of Medicine, Helsinki University Central Hospital (A.M.L., K.K.), and Institute of Behavioural Sciences, Psychology (T.H.), University of Helsinki, Helsinki, Finland; and Department of Health, National Institute for Health and Welfare, Helsinki, Finland (A.S.H., V.S.)
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23
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Fukuda K, Kanazawa H, Aizawa Y, Ardell JL, Shivkumar K. Cardiac innervation and sudden cardiac death. Circ Res 2015; 116:2005-19. [PMID: 26044253 PMCID: PMC4465108 DOI: 10.1161/circresaha.116.304679] [Citation(s) in RCA: 255] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/11/2014] [Indexed: 12/14/2022]
Abstract
Afferent and efferent cardiac neurotransmission via the cardiac nerves intricately modulates nearly all physiological functions of the heart (chronotropy, dromotropy, lusitropy, and inotropy). Afferent information from the heart is transmitted to higher levels of the nervous system for processing (intrinsic cardiac nervous system, extracardiac-intrathoracic ganglia, spinal cord, brain stem, and higher centers), which ultimately results in efferent cardiomotor neural impulses (via the sympathetic and parasympathetic nerves). This system forms interacting feedback loops that provide physiological stability for maintaining normal rhythm and life-sustaining circulation. This system also ensures that there is fine-tuned regulation of sympathetic-parasympathetic balance in the heart under normal and stressed states in the short (beat to beat), intermediate (minutes to hours), and long term (days to years). This important neurovisceral/autonomic nervous system also plays a major role in the pathophysiology and progression of heart disease, including heart failure and arrhythmias leading to sudden cardiac death. Transdifferentiation of neurons in heart failure, functional denervation, cardiac and extracardiac neural remodeling has also been identified and characterized during the progression of disease. Recent advances in understanding the cellular and molecular processes governing innervation and the functional control of the myocardium in health and disease provide a rational mechanistic basis for the development of neuraxial therapies for preventing sudden cardiac death and other arrhythmias. Advances in cellular, molecular, and bioengineering realms have underscored the emergence of this area as an important avenue of scientific inquiry and therapeutic intervention.
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Affiliation(s)
- Keiichi Fukuda
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.).
| | - Hideaki Kanazawa
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.)
| | - Yoshiyasu Aizawa
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.)
| | - Jeffrey L Ardell
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.)
| | - Kalyanam Shivkumar
- From the Department of Cardiology, Keio University School of Medicine, Tokyo, Japan (K.F., H.K., Y.A.); and UCLA Cardiac Arrhythmia Center, Neurocardiology Research Center of Excellence (J.L.A., K.S.).
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24
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Tadros R, Cadrin-Tourigny J, Abadir S, Rivard L, Nattel S, Talajic M, Khairy P. Pharmacotherapy for inherited arrhythmia syndromes: mechanistic basis, clinical trial evidence and practical application. Expert Rev Cardiovasc Ther 2015; 13:769-82. [DOI: 10.1586/14779072.2015.1049156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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25
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Abstract
Long QT syndrome is the most commonly recognised cause of sudden cardiac death in children. With a prevalence of 1 in 2000, family screening is identifying large numbers of hitherto asymptomatic gene carriers in the community, about a third of whom have a normal QT interval. The mainstay of treatment is long term uninterrupted beta blocker therapy, a treatment with many potential side effects. This article reviews the evidence and suggests a cohort who may, after assessment in a specialised cardiac-genetic clinic, be spared this treatment because of very low baseline risk. These are asymptomatic boys and prepubertal girls with a heart rate corrected QT interval persistently less than 470 ms who do not indulge in high risk activities (especially swimming) and do not have a missense mutation in the c-loop region of the KCNQ1 (long QT 1) gene.
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Affiliation(s)
- Kathryn E Waddell-Smith
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand Department of Cardiology, University of Auckland, Auckland, New Zealand Department of Child Health, University of Auckland, Auckland, New Zealand
| | - Nikki Earle
- Department of Cardiology, University of Auckland, Auckland, New Zealand Department of Child Health, University of Auckland, Auckland, New Zealand
| | - Jonathan R Skinner
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand Department of Cardiology, University of Auckland, Auckland, New Zealand Department of Child Health, University of Auckland, Auckland, New Zealand Cardiac Inherited Disease Group, Auckland City Hospital, Auckland, New Zealand
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26
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O-Uchi J, Rice JJ, Ruwald MH, Parks XX, Ronzier E, Moss AJ, Zareba W, Lopes CM. Impaired IKs channel activation by Ca(2+)-dependent PKC shows correlation with emotion/arousal-triggered events in LQT1. J Mol Cell Cardiol 2014; 79:203-11. [PMID: 25479336 DOI: 10.1016/j.yjmcc.2014.11.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 10/23/2014] [Accepted: 11/12/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND The most common inherited cardiac arrhythmia, LQT1, is due to IKs potassium channel mutations and is linked to high risk of adrenergic-triggered cardiac events. We recently showed that although exercise-triggered events are very well treated by ß-blockers for these patients, acute arousal-triggered event rate were not significantly reduced after beta-blocker treatment, suggesting that the mechanisms underlying arousal-triggered arrhythmias may be different from those during exercise. IKs is strongly regulated by β-adrenergic receptor (β-AR) signaling, but little is known about the role of α1-AR-mediated regulation. METHODS AND RESULTS Here we show, using a combination of cellular electrophysiology and computational modeling, that IKs phosphorylation and α1-AR regulation via activation of calcium-dependent PKC isoforms (cPKC) may be a key mechanism to control channel voltage-dependent activation and consequently action potential duration (APD) in response to adrenergic-stimulus. We show that simulated mutation-specific combined adrenergic effects (β+α) on APD were strongly correlated to acute stress-triggered cardiac event rate for patients while β-AR effects alone were not. CONCLUSION We were able to show that calcium-dependent PKC signaling is key to normal QT shortening during acute arousal and when impaired, correlates with increased rate of sudden arousal-triggered cardiac events. Our study suggests that the acute α1-AR-cPKC regulation of IKs is important for QT shortening in "fight-or-flight" response and is linked to decreased risk of sudden emotion/arousal-triggered cardiac events in LQT1 patients.
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Affiliation(s)
- Jin O-Uchi
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA
| | - J Jeremy Rice
- Functional Genomics and Systems Biology Group, IBM T.J. Watson Research Center, New York, USA
| | - Martin H Ruwald
- Cardiology Division, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA
| | - Xiaorong Xu Parks
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA
| | - Elsa Ronzier
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA
| | - Arthur J Moss
- Cardiology Division, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA
| | - Wojciech Zareba
- Cardiology Division, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA
| | - Coeli M Lopes
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, New York, USA.
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27
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Barsheshet A, Dotsenko O, Goldenberg I. Congenital long QT syndromes: prevalence, pathophysiology and management. Paediatr Drugs 2014; 16:447-56. [PMID: 25288402 DOI: 10.1007/s40272-014-0090-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Long QT syndrome is a genetic disorder associated with life threatening ventricular arrhythmias and sudden death. This inherited arrhythmic disorder exhibits genetic heterogeneity, incomplete penetrance, and variable expressivity. During the past two decades there have been major advancements in understanding the genotype-phenotype correlations in LQTS. This genotype-phenotype relationship can lead to improved management of LQTS. However, development of genotype-specific or mutation-specific management strategies is very challenging. This review describes the pathophysiology of LQTS, genotype-phenotype correlations, and focuses on the management of LQTS. In general, the treatment of LQTS consists of lifestyle modifications, medical therapy with beta-blockers, device and surgical therapy. We further summarize current data on the efficacy of pharmacological treatment options for the three most prevalent LQTS variants including beta-blockers in LQT1, LQT2 and LQT3, sodium channel blockers and ranolazine for LQT3, potassium supplementation and spironolactone for LQT2, and possibly sex hormone-based therapy for LQT2.
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Affiliation(s)
- Alon Barsheshet
- Cardiology Department, Rabin Medical Center, Petach Tikva, Israel
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28
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Vickers Saarel E, Etheridge SP. Congenital long QT syndrome: The race to refine risk. Heart Rhythm 2014; 11:83-4. [DOI: 10.1016/j.hrthm.2013.10.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Indexed: 11/25/2022]
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29
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Barsheshet A, Dotsenko O, Goldenberg I. Genotype-specific risk stratification and management of patients with long QT syndrome. Ann Noninvasive Electrocardiol 2013; 18:499-509. [PMID: 24206565 DOI: 10.1111/anec.12117] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Long QT syndrome (LQTS) is an inherited disorder associated with life-threatening ventricular arrhythmias. An understanding of the relationship between the genotype and phenotype characteristics of LQTS can lead to improved risk stratification and management of this hereditary arrhythmogenic disorder. Risk stratification in LQTS relies on combined assessment of clinical, electrocardiographic, and mutations-specific factors. Studies have shown that there are genotype-specific risk factors for arrhythmic events including age, gender, resting heart rate, QT corrected for heart rate, prior syncope, the postpartum period, menopause, mutation location, type of mutation, the biophysical function of the mutation, and response to beta-blockers. Importantly, genotype-specific therapeutic options have been suggested. Lifestyle changes are recommended according to the prevalent trigger for cardiac events. Beta-blockers confer greater benefit among patients with LQT1 with the greatest benefit among those with cytoplasmic loops mutations; specific beta-blocker agents may provide greater protection than other agents in specific LQTS genotypes. Potassium supplementation and sex hormone-based therapy may protect patients with LQT2. Sodium channel blockers such as mexiletine, flecainide, and ranolazine could be treatment options in LQT3.
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Affiliation(s)
- Alon Barsheshet
- Cardiology Department, Rabin Medical Center, Petah Tikva, and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Cardiology Division, University of Rochester Medical Center, Rochester, NY
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30
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John RM, Tedrow UB, Koplan BA, Albert CM, Epstein LM, Sweeney MO, Miller AL, Michaud GF, Stevenson WG. Ventricular arrhythmias and sudden cardiac death. Lancet 2012; 380:1520-9. [PMID: 23101719 DOI: 10.1016/s0140-6736(12)61413-5] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Management strategies for ventricular arrhythmias are guided by the risk of sudden death and severity of symptoms. Patients with a substantial risk of sudden death usually need an implantable cardioverter defibrillator (ICD). Although ICDs effectively end most episodes of ventricular tachycardia or ventricular fibrillation and decrease mortality in specific populations of patients, they have inherent risks and limitations. Generally, antiarrhythmic drugs do not provide sufficient protection from sudden death, but do have a role in reducing arrhythmias that cause symptoms. Catheter ablation is likewise important for reducing the frequency of spontaneous arrhythmias and is curative for some patients, usually those with idiopathic arrhythmias and no heart disease. Arrhythmia surgery is now infrequent, offered by only a few specialised centres for refractory arrhythmias. Advances in understanding of genetic arrhythmia syndromes and in technology for mapping and ablation of ventricular arrhythmias, and enhanced algorithms in implantable devices for rhythm management, have contributed to improved outcomes.
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Affiliation(s)
- Roy M John
- Department of Medicine, Division of Cardiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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31
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Perrin MJ, Gollob MH. Genetics of cardiac electrical disease. Can J Cardiol 2012; 29:89-99. [PMID: 23062665 DOI: 10.1016/j.cjca.2012.07.847] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 07/27/2012] [Accepted: 07/30/2012] [Indexed: 10/27/2022] Open
Abstract
Few tragedies compare to the sudden death of a family member. Sadly, this may represent the first sign of a familial vulnerability to such events. One common cause is an inherited cardiac arrhythmia syndrome. Sufferers are prone to premature sudden cardiac death due to altered ion channel function in the heart. Typical causes include Brugada syndrome, long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and the newly recognized early repolarization syndrome. Our knowledge of the genetic underpinnings of each of these disorders has increased markedly in recent years. Genetic screening is now a routine part of clinical care and promises more accurate diagnosis and efficient family screening. This review summarizes the diagnosis and management of each of the listed syndromes in the context of currently available genetic testing.
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Affiliation(s)
- Mark J Perrin
- Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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32
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Zumhagen S, Stallmeyer B, Friedrich C, Eckardt L, Seebohm G, Schulze-Bahr E. Inherited long QT syndrome: clinical manifestation, genetic diagnostics, and therapy. Herzschrittmacherther Elektrophysiol 2012; 23:211-219. [PMID: 22996910 DOI: 10.1007/s00399-012-0232-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 07/20/2012] [Indexed: 06/01/2023]
Abstract
Inherited long QT syndrome (LQTS) is characterized by a prolonged ventricular repolarization (QTc interval) and symptoms (syncope, sudden cardiac arrest) due to polymorphic ventricular arrhythmias. As of today, 13 different cardiac ion channel genes have been associated with congenital LQTS. The most common ones are due to KCNQ1 (LQT-1), KCNH2 (LQT-2), and SCN5A (LQT-3) gene mutations and account for up to 75 % of cases. Typical clinical findings are an increased QT interval on the surface electrocardiogram, specifically altered T wave morphologies, polymorphic ventricular arrhythmias, or an indicative family history. Recently, in the HRS/EHRA expert consensus statement, comprehensive genetic testing of major LQTS genes was recommended for index patients for whom there is a strong clinical suspicion of LQTS. Overall, antiadrenergic therapy, in particular β-receptor blockers, has been the mainstay of therapy and has significantly reduced cardiac events. For high-risk patients, an implantable cardioverter defibrillator (ICD) is recommended. Importantly, lifestyle modification and avoidance of arrhythmia triggers are additional important approaches.
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Affiliation(s)
- Sven Zumhagen
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, Gebäude D3, 48149, Münster, Germany.
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Abstract
PURPOSE OF REVIEW In this article, we summarize the main features of the most common inherited channelopathies, focusing on the findings that advanced the field in the last few years. RECENT FINDINGS The progress in genetics prompted the discovery of several new genes associated with ion-channel disorders, elucidating new molecular pathways and new arrhythmogenic mechanisms. The diffusion and availability of genetic screening gave a new relevance to the application of genetics not only for diagnosis, but also for risk assessment and therapeutic decisions. As a consequence, the present challenge in the field is represented by the need to use genetic data to develop personalized clinical approaches. SUMMARY Over a few years, the field of inherited arrhythmogenic diseases has rapidly expanded, thus reshaping clinical management for these conditions. It is now clear that to handle these patients a specialized expertise is needed, able to translate the discoveries derived from basic science studies into the clinical care of the patients.
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34
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Brenyo AJ, Huang DT, Aktas MK. Congenital long and short QT syndromes. Cardiology 2012; 122:237-47. [PMID: 22906875 DOI: 10.1159/000339537] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 05/08/2012] [Indexed: 11/19/2022]
Abstract
Congenital long and short QT syndromes are familial arrhythmias characterized by derangement of repolarization and a high risk of sudden cardiac death due to ventricular tachyarrhythmias. With growing understanding of these syndromes in both the medical and lay communities, diagnostic and therapeutic difficulties are increasingly faced by health care providers. Modern genomics has determined the mechanism of arrhythmia induction in these patients, resulting in specific medical therapies and improved risk stratification. This paper reviews the common presentations, genetic etiology, basic evaluation, risk stratification, and therapeutic approach for both syndromes. Particular attention is paid to the effect of the individual syndrome on the cardiac action potential and its correlate the surface 12 lead ECG. In conclusion, patients with long and short QT syndromes are at risk for sudden death, with accurate diagnosis, risk stratification, and resulting appropriate therapy favorably altering their outcome.
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Affiliation(s)
- Andrew J Brenyo
- Department of Cardiovascular Diseases, University of Rochester Medical Center, Strong Memorial Hospital, Rochester, NY 14642, USA.
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35
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Wu CT, Nattel S. Triggering of cardiac arrhythmic events in long QT syndrome: lessons from funny bunnies. J Physiol 2012; 590:1311-2. [PMID: 22422115 DOI: 10.1113/jphysiol.2012.229344] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Chia Tung Wu
- Department of Medicine and Research Centre, Montreal Heart Institute and Université de Montréal, Canada
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36
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Perrin MJ, Gollob MH. The genetics of cardiac disease associated with sudden cardiac death: a paper from the 2011 William Beaumont Hospital Symposium on molecular pathology. J Mol Diagn 2012; 14:424-36. [PMID: 22749884 DOI: 10.1016/j.jmoldx.2012.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/03/2012] [Accepted: 04/13/2012] [Indexed: 11/17/2022] Open
Abstract
Sudden cardiac death due to ventricular arrhythmia most commonly occurs in the setting of coronary artery disease. However, a number of inherited syndromes have now been identified that carry a significant risk of sudden cardiac death and that are disproportionately represented in the young. Arrhythmia in such conditions may result from genetically mediated structural heart disease (eg, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy) or from altered function of cardiac ion channels in the absence of overt structural disease (eg, Brugada syndrome and long QT syndrome). The past 15 years have seen considerable progress in our understanding of the genetic underpinnings of these disorders. With the advent of clinical genetic testing as a routine part of clinical care, a new knowledge base is required of practicing cardiologists and genetic testing facilities, particularly related to the rational ordering of genetic testing and the interpretation of results. This review addresses the latest findings in regard to the genetic causes of inherited syndromes associated with sudden cardiac death and summarizes recently published guidelines for the genetic testing of affected individuals and their families.
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Affiliation(s)
- Mark J Perrin
- Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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37
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Napolitano C, Bloise R, Monteforte N, Priori SG. Sudden cardiac death and genetic ion channelopathies: long QT, Brugada, short QT, catecholaminergic polymorphic ventricular tachycardia, and idiopathic ventricular fibrillation. Circulation 2012; 125:2027-34. [PMID: 22529064 DOI: 10.1161/circulationaha.111.055947] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Carlo Napolitano
- Molecular Cardiology, IRCCS Salvatore Maugeri Foundation, Pavia, Italy
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38
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Risk indicators in long QT syndrome: Does location matter? Heart Rhythm 2012; 9:899-900. [DOI: 10.1016/j.hrthm.2012.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Indexed: 11/17/2022]
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