101
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Havakuk O, Viskin S. A Tale of 2 Diseases: The History of Long-QT Syndrome and Brugada Syndrome. J Am Coll Cardiol 2016; 67:100-8. [PMID: 26764071 DOI: 10.1016/j.jacc.2015.10.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/18/2015] [Accepted: 10/06/2015] [Indexed: 12/21/2022]
Abstract
The Brugada syndrome (BrS) and long-QT syndrome (LQTS) present as congenital or acquired disorders with diagnostic electrocardiograms (ST-segment elevation and prolonged QT interval, respectively) and increased risk for malignant arrhythmias. Our understanding of the 2 disease forms (congenital vs. acquired) differs. A female patient on quinidine for atrial fibrillation who develops ventricular fibrillation is diagnosed with "acquired LQTS" and is discharged with no therapy other than instructions to avoid QT-prolonging medications. In contrast, an asymptomatic male patient who develops a Brugada electrocardiogram on flecainide is diagnosed with "asymptomatic BrS" and could be referred for an electrophysiological evaluation that could result in defibrillator implantation. The typical patient undergoing defibrillator implantation for BrS is asymptomatic but has a Brugada electrocardiogram provoked by a drug. The authors describe how the histories of LQTS and BrS went through the same stages, but in different sequences, leading to different conclusions.
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Affiliation(s)
- Ofer Havakuk
- Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sami Viskin
- Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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102
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Clinical evaluation of unselected cardiac arrest survivors in a tertiary center over a 1-year period (the LAZARUZ study). J Electrocardiol 2016; 49:707-13. [PMID: 27237785 DOI: 10.1016/j.jelectrocard.2016.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Indexed: 12/16/2022]
Abstract
OBJECTIVES When the cause of an aborted cardiac arrest is unclear the initiation of therapy, counseling and family screening is challenging. METHODS We included 43 unselected, prospectively identified cardiac arrest survivors with or without a diagnosis. Family history for cardiac disease and supplemental electrocardiograms were evaluated for additional diagnostic information. RESULTS 43 cardiac arrest survivors were included, 34 (79%) were male and the average age was 48years (range 23-64, SD 13.0). The most common etiologies identified in cardiac arrest survivors were ischemic heart disease (33%), cardiomyopathies (14%), miscellaneous (e.g. drug induced arrhythmias, coronary spasms) (12%) and channelopathies (5%). Family history of cardiac disease - even inheritable conditions - was not indicative of etiology in cardiac arrest survivors. Supplemental ECGs were abnormal in 10 of 43 patients; in the majority of these patients (7) no conclusive diagnosis was reached. CONCLUSIONS In this study 16/43 (37%) of unselected, prospectively included cardiac arrest survivors remained without a diagnosis despite exhaustive investigations. We may extract additional diagnostic information from simple maneuvers during the recording of the electrocardiogram. We suggest that these ECG derived clues be investigated in future studies including genetic test results and data from relatives.
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103
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Waddell-Smith KE, Skinner JR. Update on the Diagnosis and Management of Familial Long QT Syndrome. Heart Lung Circ 2016; 25:769-76. [PMID: 27262388 DOI: 10.1016/j.hlc.2016.01.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/20/2016] [Indexed: 01/16/2023]
Abstract
This update was reviewed by the CSANZ Continuing Education and Recertification Committee and ratified by the CSANZ board in August 2015. Since the CSANZ 2011 guidelines, adjunctive clinical tests have proven useful in the diagnosis of LQTS and are discussed in this update. Understanding of the diagnostic and risk stratifying role of LQTS genetics is also discussed. At least 14 LQTS genes are now thought to be responsible for the disease. High-risk individuals may have multiple mutations, large gene rearrangements, C-loop mutations in KCNQ1, transmembrane mutations in KCNH2, or have certain gene modifiers present, particularly NOS1AP polymorphisms. In regards to treatment, nadolol is preferred, particularly for long QT type 2, and short acting metoprolol should not be used. Thoracoscopic left cardiac sympathectomy is valuable in those who cannot adhere to beta blocker therapy, particularly in long QT type 1. Indications for ICD therapies have been refined; and a primary indication for ICD in post-pubertal females with long QT type 2 and a very long QT interval is emerging.
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Affiliation(s)
- Kathryn E Waddell-Smith
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland New Zealand; The University of Auckland, Department of Child Health, Auckland, New Zealand
| | - Jonathan R Skinner
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland New Zealand; The University of Auckland, Department of Child Health, Auckland, New Zealand.
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104
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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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105
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Márquez MF. Sudden cardiac death syndromes: Changing the paradigm of diagnosis from ECG to molecular genetics. Trends Cardiovasc Med 2015; 25:749-50. [DOI: 10.1016/j.tcm.2015.03.011] [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: 03/24/2015] [Accepted: 03/24/2015] [Indexed: 10/23/2022]
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106
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Osadchii OE. Flecainide attenuates rate adaptation of ventricular repolarization in guinea-pig heart. SCAND CARDIOVASC J 2015; 50:28-35. [DOI: 10.3109/14017431.2015.1099721] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Oleg E. Osadchii
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
- Department of Health Science and Technology, University of Aalborg, Aalborg, Denmark
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107
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Page A, Aktas MK, Soyata T, Zareba W, Couderc JP. "QT clock" to improve detection of QT prolongation in long QT syndrome patients. Heart Rhythm 2015; 13:190-8. [PMID: 26334569 DOI: 10.1016/j.hrthm.2015.08.037] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND The QT interval is a risk marker for cardiac events such as torsades de pointes. However, QT measurements obtained from a 12-lead ECG during clinic hours may not capture the full extent of a patient's daily QT range. OBJECTIVE The purpose of this study was to evaluate the utility of 24-hour Holter ECG recording in patients with long QT syndrome (LQTS) to identify dynamic changes in the heart rate-corrected QT interval and to investigate methods of visualizing the resulting datasets. METHODS Beat-to-beat QTc (Bazett) intervals were automatically measured across 24-hour Holter recordings from 202 LQTS type 1, 89 type 2, and 14 type 3 genotyped patients and a reference group of 200 healthy individuals. We measured the percentage of beats with QTc greater than the gender-specific threshold (QTc ≥470 ms in women and QTc ≥450 ms in men). The percentage of beats with QTc prolongation was determined across the 24-hour recordings. RESULTS Based on the median percentage of heartbeats per patient with QTc prolongation, LQTS type 1 patients showed more frequent QTc prolongation during the day (~3 PM) than they did at night (~3 AM): 97% vs 48%, P ~10(-4) for men, and 68% vs 30%, P ~10(-5) for women. LQTS type 2 patients showed less frequent QTc prolongation during the day compared to nighttime: 87% vs 100%, P ~10(-4) for men, and 62% vs 100%, P ~10(-3) for women. CONCLUSION In patients with genotype-positive LQTS, significant differences exist in the degree of daytime and nocturnal QTc prolongation. Holter monitoring using the "QT clock" concept may provide an easy, fast, and accurate method for assessing the true personalized burden of QTc prolongation.
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Affiliation(s)
- Alex Page
- Electrical and Computer Engineering Department, University of Rochester, Rochester, New York
| | - Mehmet K Aktas
- Cardiology Department, University of Rochester Medical Center, Rochester, New York
| | - Tolga Soyata
- Electrical and Computer Engineering Department, University of Rochester, Rochester, New York
| | | | - Jean-Philippe Couderc
- Electrical and Computer Engineering Department, University of Rochester, Rochester, New York; Heart Research Follow Up Program, Rochester, New York.
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108
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Chorin E, Havakuk O, Adler A, Steinvil A, Rozovski U, van der Werf C, Postema PG, Topaz G, Wilde AAM, Viskin S, Rosso R. Diagnostic value of T-wave morphology changes during "QT stretching" in patients with long QT syndrome. Heart Rhythm 2015; 12:2263-71. [PMID: 26142298 DOI: 10.1016/j.hrthm.2015.06.040] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND Specific T-wave patterns on the resting electrocardiogram (ECG) aid in diagnosing long QT syndrome (LQTS) and identifying the specific genotype. However, provocation tests often are required to establish a diagnosis when the QT interval is borderline at rest. OBJECTIVE The purpose of this study was to determine whether T-wave morphology changes provoked by standing aid in the diagnosis of LQTS and determination of the genotype. METHODS The quick-standing test was performed by 100 LQTS patients (40 type 1 [LQT1], 42 type 2 [LQT2], 18 type 3 [LQT3]) and 100 controls. Logistic regression was used to determine whether T-wave morphology changes provoked by standing added to the already established diagnostic value of QTc stretching in identifying LQTS. RESULTS During maximal QT stretching, the T-wave morphologies that best discriminated LQTS from controls included "notched," "late-onset," and "biphasic" T waves. These 3 categories were grouped into a category named "abnormal T-wave response to standing." During quick standing, a QTc stretched ≥490 ms increased the odds of correctly identifying LQTS. T-wave morphology changes provoked by standing were most helpful for identifying LQT2, less helpful for LQT1, and least helpful for LQT3. CONCLUSION The sudden heart rate acceleration produced by abrupt standing not only increases the QTc but also exposes abnormal T waves that are valuable for diagnosing LQTS.
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Affiliation(s)
- Ehud Chorin
- Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ofer Havakuk
- Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Arnon Adler
- Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Arie Steinvil
- Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Uri Rozovski
- Department of Internal Medicine, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Christian van der Werf
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Pieter G Postema
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Guy Topaz
- Department of Internal Medicine, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Arthur A M Wilde
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Sami Viskin
- Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Raphael Rosso
- Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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109
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Adler A, Viskin S. Syncope in Hereditary Arrhythmogenic Syndromes. Cardiol Clin 2015; 33:433-40. [PMID: 26115829 DOI: 10.1016/j.ccl.2015.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Since the discovery of the first mutation causing long QT syndrome (LQTS) in 1995, the field of hereditary arrhythmogenic syndromes has expanded greatly. Today, these syndromes include LQTS, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, and short QT syndrome. There is also evidence suggesting that the newly described malignant early repolarization syndrome also has a genetic cause.
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Affiliation(s)
- Arnon Adler
- Sackler School of Medicine, Tel Aviv Medical Center, Tel Aviv University, Israel
| | - Sami Viskin
- Sackler School of Medicine, Tel Aviv Medical Center, Tel Aviv University, Israel.
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110
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Meijborg VM, Chauveau S, Janse MJ, Anyukhovsky EP, Danilo PR, Rosen MR, Opthof T, Coronel R. Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome. Heart Rhythm 2015; 12:1343-51. [DOI: 10.1016/j.hrthm.2015.02.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 11/27/2022]
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111
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Abstract
Molecular genetic studies in the last 2 decades have revealed a link between several inherited cardiac arrhythmias and genes encoding for ion channels or other membrane components. Two recent international expert consensus statements endorsed by 3 continental electrophysiology societies have updated the clinical and genetic diagnoses and management in patients with inherited arrhythmia syndromes, including congenital long QT syndrome (LQTS) and Brugada syndrome. Thirteen genotypes have been identified in 50% to 80% of clinically affected patients with congenital LQTS. Therefore, genotype-phenotype correlations have been investigated, especially, in the 3 major genotypes--LQT1, LQT2 and LQT3 syndromes--enabling genotype-specific management and therapy. On the other hand, less than half of patients with Brugada syndrome can be genotyped, and mainly for the sodium channel gene, SCN5A. However, recent advances in molecular genetic testing include genome-wide association studies using gene arrays and targeted, whole-exome and whole-genome next-generation sequencing techniques. In this article, I will review the clinical and genetic diagnoses in congenital LQTS and Brugada syndrome.
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Affiliation(s)
- Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School
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112
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Giustetto C, Scrocco C, Schimpf R, Maury P, Mazzanti A, Levetto M, Anttonen O, Dalmasso P, Cerrato N, Gribaudo E, Wolpert C, Giachino D, Antzelevitch C, Borggrefe M, Gaita F. Usefulness of exercise test in the diagnosis of short QT syndrome. Europace 2015; 17:628-34. [DOI: 10.1093/europace/euu351] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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113
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Chockalingam P, Mizusawa Y, Wilde AA. Channelopathies - emerging trends in the management of inherited arrhythmias. Indian Pacing Electrophysiol J 2015; 15:43-54. [PMID: 25852242 PMCID: PMC4380694 DOI: 10.1016/s0972-6292(16)30841-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In spite of their relative rarity, inheritable arrhythmias have come to the forefront as a group of potentially fatal but preventable cause of sudden cardiac death in children and (young) adults. Comprehensive management of inherited arrhythmias includes diagnosing and treating the proband and identifying and protecting affected family members. This has been made possible by the vast advances in the field of molecular biology enabling better understanding of the genetic underpinnings of some of these disease groups, namely congenital long QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. The ensuing knowledge of the genotype-phenotype correlations enables us to risk-stratify, prognosticate and treat based on the genetic test results. The various diagnostic modalities currently available to us, including clinical tools and genetic technologies, have to be applied judiciously in order to promptly identify those affected and to spare the emotional burden of a potentially lethal disease in the unaffected individuals. The therapeutic armamentarium of inherited arrhythmias includes pharmacological agents, device therapies and surgical interventions. A treatment strategy keeping in mind the risk profile of the patients, the local availability of drugs and the expertise of the treating personnel is proving effective. While opportunities for research are numerous in this expanding field of medicine, there is also tremendous scope for incorporating the emerging trends in managing patients and families with inherited arrhythmias in the Indian subcontinent.
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Affiliation(s)
| | | | - Arthur A.M. Wilde
- Academic Medical Center, Amsterdam, The Netherlands
- Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, Jeddah, Kingdom of Saudi Arabia
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114
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Ng J, Barbhaiya C, Reichlin T, Nagashima K, John R. Never Out of the Woods: Onset of Events in Long QT Syndrome Late in Life Provoked by Atrial Arrhythmias. Indian Pacing Electrophysiol J 2014; 14:263-7. [PMID: 25408567 PMCID: PMC4217303 DOI: 10.1016/s0972-6292(16)30798-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The assessment of risk in the asymptomatic patient with long QT syndrome can often be a challenging task, particularly when the available evidence is limited to relatively small retrospective registries, not to mention the need to consider the effect of individual patient factors which are often difficult to quantitate. We describe the relatively uncommon case of a man with a long-standing diagnosis of Long QT 2 syndrome who suffered his first cardiac event in his late 60's, likely precipitated by the development of paroxysmal atrial tachycardia. A brief review of the available literature on risk assessment in adults with genetically confirmed long QT syndrome who have remained asymptomatic late into adulthood will follow the case.
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Affiliation(s)
- Justin Ng
- Brigham and Women's Hospital, United States
| | | | | | | | - Roy John
- Brigham and Women's Hospital, United States
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115
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Postema PG, Wilde AAM. The measurement of the QT interval. Curr Cardiol Rev 2014; 10:287-94. [PMID: 24827793 PMCID: PMC4040880 DOI: 10.2174/1573403x10666140514103612] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 06/10/2013] [Accepted: 01/28/2014] [Indexed: 12/14/2022] Open
Abstract
The evaluation of every electrocardiogram should also include an effort to interpret the QT interval to assess the risk of malignant arrhythmias and sudden death associated with an aberrant QT interval. The QT interval is measured from the beginning of the QRS complex to the end of the T-wave, and should be corrected for heart rate to enable comparison with reference values. However, the correct determination of the QT interval, and its value, appears to be a daunting task. Although computerized analysis and interpretation of the QT interval are widely available, these might well over- or underestimate the QT interval and may thus either result in unnecessary treatment or preclude appropriate measures to be taken. This is particularly evident with difficult T-wave morphologies and technically suboptimal ECGs. Similarly, also accurate manual assessment of the QT interval appears to be difficult for many physicians worldwide. In this review we delineate the history of the measurement of the QT interval, its underlying pathophysiological mechanisms and the current standards of the measurement of the QT interval, we provide a glimpse into the future and we discuss several issues troubling accurate measurement of the QT interval. These issues include the lead choice, U-waves, determination of the end of the T-wave, different heart rate correction formulas, arrhythmias and the definition of normal and aberrant QT intervals. Furthermore, we provide recommendations that may serve as guidance to address these complexities and which support accurate assessment of the QT interval and its interpretation.
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Affiliation(s)
| | - Arthur A M Wilde
- Department of Cardiology, Academic Medical Center, P.O. box 22660, 1100 DD Amsterdam, The Netherlands.
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116
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Choudhuri I, Pinninti M, Marwali MR, Sra J, Akhtar M. Polymorphic ventricular tachycardia--part II: the channelopathies. Curr Probl Cardiol 2014; 38:503-48. [PMID: 24262155 DOI: 10.1016/j.cpcardiol.2013.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this article, we explore the clinical and cellular phenomena of primary electrical diseases of the heart, that is, conditions purely related to ion channel dysfunction and not structural heart disease or reversible acquired causes. This growing classification of conditions, once considered together as "idiopathic ventricular fibrillation," continues to evolve and segregate into diseases that are phenotypically, molecularly, and genetically unique.
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117
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Herman A, Bennett MT, Chakrabarti S, Chakrabarti S, Krahn AD. Life threatening causes of syncope: channelopathies and cardiomyopathies. Auton Neurosci 2014; 184:53-9. [PMID: 24795161 DOI: 10.1016/j.autneu.2014.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 04/04/2014] [Accepted: 04/14/2014] [Indexed: 01/08/2023]
Abstract
Syncope is common, has a high recurrence rate and carries a risk of morbidity and, dependent on the cause, mortality. Although the majority of patients with syncope have a benign prognosis, syncope as a result of cardiomyopathy or channelopathy carries a poor prognosis. In addition, the identification of these disorders allows for the institution of treatments, which are effective at reducing the risk of both syncope and mortality. It is for these reasons that the identification of a cardiomyopathy or channelopathy in patients with syncope is crucial. This review article will describe the characteristics of common cardiomyopathies and channelopathies and their investigation.
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Affiliation(s)
- Adam Herman
- Division of Cardiology, University of British Columbia, Vancouver, BC, Canada
| | - Matthew T Bennett
- Division of Cardiology, University of British Columbia, Vancouver, BC, Canada
| | | | | | - Andrew D Krahn
- Division of Cardiology, University of British Columbia, Vancouver, BC, Canada.
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118
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Koenig T, Duncker D, Hohmann S, Schroeder C, Oswald H, Veltmann C. Clinical evaluation and risk stratification in patients with syncope. Herz 2014; 39:429-36. [PMID: 24743921 DOI: 10.1007/s00059-014-4099-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Syncope accounts for approximately 1 % of visits to emergency departments. The first diagnostic step is to rule out nonsyncopal conditions as a cause of the transient loss of consciousness. Next, the basic clinical evaluation should identify patients at high risk for potentially life-threatening events. These patients should be admitted and monitored until a diagnosis is made and definitive treatment can be offered. Guided by the basic evaluation findings, specific tests should be performed to prove or rule out the suspected diagnosis. In low-risk patients, this should preferably be done in an outpatient setting. To date, there is no consensus on a structured algorithm for the evaluation of patients with syncope. Therefore, it seems beneficial to formulate an algorithm based on the current guidelines for the management of syncope for use in the clinical setting.
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Affiliation(s)
- T Koenig
- Rhythmologie und klinische Elektrophysiologie, Klinik für Kardiologie und Angiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
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119
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HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. J Arrhythm 2014. [DOI: 10.1016/j.joa.2013.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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120
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Affiliation(s)
- Yuka Mizusawa
- The Heart Failure Research Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science
| | - Arthur AM Wilde
- The Heart Failure Research Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam
- Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, King Abdulaziz University
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121
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Inherited arrhythmia syndromes leading to sudden cardiac death in the young: a global update and an Indian perspective. Indian Heart J 2013; 66 Suppl 1:S49-57. [PMID: 24568830 DOI: 10.1016/j.ihj.2013.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 11/07/2013] [Indexed: 12/15/2022] Open
Abstract
Inherited primary arrhythmias, namely congenital long QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia, account for a significant proportion of sudden cardiac deaths in young and apparently healthy individuals. Genetic testing plays an integral role in the diagnosis, risk-stratification and treatment of probands and family members. It is increasingly obvious that collaborative efforts are required to understand and manage these relatively rare but potentially lethal diseases. This article aims to update readers on the recent developments in our knowledge of inherited arrhythmias and to lay the foundation for a national synergistic effort to characterize them in the Indian population.
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Priori SG, Wilde AA, Horie M, Cho Y, Behr ER, Berul C, Blom N, Brugada J, Chiang CE, Huikuri H, Kannankeril P, Krahn A, Leenhardt A, Moss A, Schwartz PJ, Shimizu W, Tomaselli G, Tracy C. HRS/EHRA/APHRS Expert Consensus Statement on the Diagnosis and Management of Patients with Inherited Primary Arrhythmia Syndromes. Heart Rhythm 2013; 10:1932-63. [DOI: 10.1016/j.hrthm.2013.05.014] [Citation(s) in RCA: 1341] [Impact Index Per Article: 121.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 12/15/2022]
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123
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Ben Bassat OK, Peles E, Schreiber S, Adelson M, Zeltser D, Viskin S, Adler A. Response of QT interval in methadone maintenance treated patients to the rapid changes in heart rate provoked by brisk standing: Comparison to healthy controls and patients with long QT syndrome. J Electrocardiol 2013; 46:519-23. [DOI: 10.1016/j.jelectrocard.2013.08.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Indexed: 10/26/2022]
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124
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Schwartz PJ, Volders PGA. Sudden death by stress: how far under the nerves should we dig to find out why LQT1 patients die? J Am Coll Cardiol 2013; 63:828-30. [PMID: 24184246 DOI: 10.1016/j.jacc.2013.09.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 09/25/2013] [Indexed: 12/29/2022]
Affiliation(s)
- Peter J Schwartz
- Research Hospital Istituto Auxologico Italiano, Center for Cardiac Arrhythmias of Genetic Origin, Milan, Italy; Department of Molecular Medicine, University of Pavia, Pavia, Italy; Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, University of Cape Town, Cape Town, South Africa; Department of Medicine, University of Stellenbosch, Stellenbosch, Western Cape, South Africa; Department of Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, the Netherlands
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125
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Sensoy B, Ozeke O, Canpolat U, Cay S, Oksuz F, Topaloglu S, Aras D, Aydogdu S. Postexercise recovery phase T-wave notching in concealed long QT syndrome. Herz 2013; 40:153-6. [PMID: 24154883 DOI: 10.1007/s00059-013-3968-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/22/2013] [Accepted: 08/23/2013] [Indexed: 10/26/2022]
Affiliation(s)
- B Sensoy
- Department of Cardiology, Turkiye Yuksek Ihtisas Training and Research Hospital, Kardiyoloji Klinigi , 06100, Ankara, Turkey
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Fossa AA, Zhou M, Brennan N, Round P, Ford J. Use of continuous ECG for improvements in assessing the standing response as a positive control for QT prolongation. Ann Noninvasive Electrocardiol 2013; 19:82-9. [PMID: 24460808 DOI: 10.1111/anec.12079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Standing invoked change in QT interval has been identified as a promising autonomic maneuver for the assessment of QT/QTc prolongation in patients with underlying heart abnormalities or as a positive control in healthy volunteers for drug studies. Criticism for its more widespread use is the high variability in reported results and the need for a more standardized methodology with defined normal ranges. METHODS Forty healthy male subjects underwent continuous ECG collection on the day before dosing in a double-blind, placebo-controlled, randomized, single ascending dose trial. A brisk supine to standing (3 minutes) response was conducted at three time points. Results were grouped by treatment cohort or assessed as a pooled group at each time point. Maximum time and median change from baseline (ΔTmax QTcF, ΔQTcF) were calculated for each individual over sequential 30-second periods staggered by 5 seconds. RESULTS Maximum ΔQTcF at all time points and in all groups was significant (i.e., the lower bound of 90% CI was > 5 milliseconds) which is the ICH E14 regulatory requirement for a positive control. Variability of the time to maximum response was also reduced 9-fold by the third time period. CONCLUSIONS Standing invoked ΔQTcF can be utilized to validate the sensitivity of a study for assessment of the QT interval effect of drugs in early development. The methodology may be used to further improve its diagnostic use of long QT syndromes by reducing the variability and allowing adequate definition of normal limits.
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127
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Schwartz PJ, Ackerman MJ. The long QT syndrome: a transatlantic clinical approach to diagnosis and therapy. Eur Heart J 2013; 34:3109-16. [PMID: 23509228 DOI: 10.1093/eurheartj/eht089] [Citation(s) in RCA: 230] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The mind-boggling progress in the understanding of the molecular mechanisms underlying the long QT syndrome (LQTS) has been the subject of many articles and reviews. Still, when it comes to the management of the patients affected by this life-threatening disorder, too many errors still take place, both in the diagnostic process and in the therapeutic choices. The price of these errors is paid by the patients and their families. This review is not directed to the relatively small number of LQTS experts who know what to do. It does not deal with genetics, with epidemiology, or with the well-known clinical manifestations. We have focused solely on the approach to diagnosis and therapy and we have directed this review to the average clinical cardiologist who, in his/her practice, sees occasionally patients affected or suspected to be affected by LQTS; the cardiologist who may know enough to manage them but not enough to be completely confident on his/her most critical choices. We have provided our personal views without making any attempt to blend differences whenever present. On most issues we agree fully but where we do not, we make it clear to the reader by indicating who is thinking what. The result may be unconventional, but it mirrors the challenges, often severe, that we all face in managing and protecting these patients from sudden death while also helping them live and thrive despite their diagnosis. We trust that this unabashed presentation of our clinical approach will be useful for both cardiologists and patients.
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Affiliation(s)
- Peter J Schwartz
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
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128
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[ECG diagnostics in competitive athletes. Current implications for preparticipation screening]. Herz 2013; 37:474-84. [PMID: 22695724 DOI: 10.1007/s00059-012-3636-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In young competitive athletes sudden cardiac death frequently occurs as a tragic first manifestation of clinically inapparent underlying structural or electrical cardiac disorders. An increased risk may be reflected by typical electrocardiogram (ECG) alterations preceding symptoms but a correct interpretation is often challenging due to a high prevalence of training-related ECG alterations in competitive athletes mimicking such disorders. Misinterpretation may thus result in either unnecessary disqualification from competitive sports or continuation despite an increased risk or extensive diagnostic work-ups yielding additional equivocal findings. However, as observed in large athlete cohorts in recent years a variety of ECG alterations, such as isolated increased QRS voltage, early repolarization, sinus bradycardia, first degree AV block or incomplete right bundle branch block, represent common variants of ECGs of athletes reflecting physiological and training-related cardiac adaptations. These alterations do not usually require further diagnostic evaluation. In contrast, alterations such as repolarization abnormalities, complete bundle branch block, prolonged QT intervals or pathological Q waves, are strongly suggestive of underlying disorders and require further evaluation even in asymptomatic athletes. Thus, the ECG plays a pivotal role in the prevention of sudden cardiac death in competitive athletes. The present article summarizes current recommendations for the interpretation of athlete ECGs regarding the differentiation between physiological or pathological cardiac adaptation.
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129
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Abstract
Unexplained cardiac arrest is defined as a cardiac arrest in the absence of coronary artery disease and overt structural heart disease, present in 5%-10% of cardiac arrest survivors. A genetic contribution to cardiac arrest is more common in this population, most commonly attributed to an inherited ion channel abnormality leading to familial syncope and sudden death. The common causes are Long QT and Brugada syndrome, catecholaminergic ventricular tachycardia, idiopathic ventricular fibrillation, and early repolarization syndrome. Latent structural causes include inherited cardiomyopathy such as arrhythmogenic right ventricular cardiomyopathy. We review these causes in detail and a structured approach to the investigation of these patients, which provides a diagnosis in approximately half of these patients. This allows for the initiation of disease-specific treatments and enables family screening.
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130
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Abrahamsson C, Dota C, Skallefell B, Carlsson L, Frison L, Berggren A, Edvardsson N, Duker G. Assessment of ventricular repolarization variability with the DeltaT50 method improves identification of patients with congenital long QT syndromes. Ann Noninvasive Electrocardiol 2012; 18:240-50. [PMID: 23714082 DOI: 10.1111/anec.12016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
BACKGROUND We analyzed ventricular repolarization variability in genotyped long QT syndrome (LQTS) patients and in healthy volunteers (HV). METHOD The deltaT50, that is, the temporal variability of ventricular repolarization at 50% of the T-wave downslope, was analyzed every 15th minute on 175 and 390 Holter electrocardiogram (ECG) recordings from HV and genotyped LQTS patients, respectively. The average deltaT50 and QTcF were calculated in each subject. RESULTS DeltaT50 was 2.26 ± 0.71 ms (mean ± SD) in the HV and 5.74 ± 2.30 ms in the LQTS population (P < 0.0001). The sensitivity and specificity of QTcF (cutoff value 450 ms) to discriminate between the LQTS patients and the HV were 51.5% and 98.9%, and for deltaT50 (cutoff value 3 ms) 93.9% and 88.6%, respectively. The combination of both variables improved the diagnosis of the LQTS patients even further. Subgroups of LQTS patients at higher risk of cardiac events (with LQTS3, JLN, QTc > 500 ms or symptoms) had higher deltaT50 than subgroups at lower risk (with LQTS1, QTc < 450 ms or without symptoms). The variation in deltaT50 between day and night was concordant with the risk of symptoms; patients with LQTS1 had higher deltaT50 in the daytime and patients with LQTS3 had higher deltaT50 during the night. CONCLUSION DeltaT50 more accurately distinguished between LQTS patients and HV than QTcF and was higher in LQTS patients with a higher risk of cardiac events. DeltaT50 can be used together with QTcF to improve the diagnosis in patients with the LQTS phenotype and tentatively also be of value for risk assessment in such patients.
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131
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Crotti L, Spazzolini C, Porretta AP, Dagradi F, Taravelli E, Petracci B, Vicentini A, Pedrazzini M, La Rovere MT, Vanoli E, Goosen A, Heradien M, George AL, Brink PA, Schwartz PJ. Vagal reflexes following an exercise stress test: a simple clinical tool for gene-specific risk stratification in the long QT syndrome. J Am Coll Cardiol 2012; 60:2515-24. [PMID: 23158531 DOI: 10.1016/j.jacc.2012.08.1009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 07/06/2012] [Accepted: 08/07/2012] [Indexed: 12/16/2022]
Abstract
OBJECTIVES The study assessed whether heart rate (HR) reduction following an exercise stress test (ExStrT), an easily quantifiable marker of vagal reflexes, might identify high- and low-risk long QT syndrome (LQTS) type 1 (LQT1) patients. BACKGROUND Identification of LQTS patients more likely to be symptomatic remains elusive. We have previously shown that depressed baroreflex sensitivity, an established marker of reduced vagal reflexes, predicts low probability of symptoms among LQT1. METHODS We studied 169 LQTS genotype-positive patients < 50 years of age who performed an ExStrT with the same protocol, on and off β-blockers including 47 South African LQT1 patients all harboring the KCNQ1-A341V mutation and 122 Italian LQTS patients with impaired (I(Ks)-, 66 LQT1) or normal (I(Ks)+, 50 LQT2 and 6 LQT3) I(Ks) current. RESULTS Despite similar maximal HR and workload, by the first minute after cessation of exercise the symptomatic patients in both I(Ks)- groups had a greater HR reduction compared with the asymptomatic (19 ± 7 beats/min vs. 13 ± 5 beats/min and 27 ± 10 beats/min vs. 20 ± 8 beats/min, both p = 0.009). By contrast, there was no difference between the I(Ks)+ symptomatic and asymptomatic patients (23 ± 9 beats/min vs. 26 ± 9 beats/min, p = 0.47). LQT1 patients in the upper tertile for HR reduction had a higher risk of being symptomatic (odds ratio: 3.28, 95% confidence interval: 1.3 to 8.3, p = 0.012). CONCLUSIONS HR reduction following exercise identifies LQT1 patients at high or low arrhythmic risk, independently of β-blocker therapy, and contributes to risk stratification. Intense exercise training, which potentiates vagal reflexes, should probably be avoided by LQT1 patients.
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Affiliation(s)
- Lia Crotti
- Department of Molecular Medicine, Section of Cardiology, University of Pavia, Pavia, Italy
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Junttila MJ, Castellanos A, Huikuri HV, Myerburg RJ. Risk markers of sudden cardiac death in standard 12-lead electrocardiograms. Ann Med 2012; 44:717-32. [PMID: 21745092 DOI: 10.3109/07853890.2011.594807] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The annual incidence of sudden cardiac death (SCD) is estimated at 1 per 1,000 for adults over the age of 35 years, and 1 per 100,000 for adolescents and young adults. Although the overall incidence of unexpected SCD among previously healthy persons is small, the emotional impact of these events is devastating. The 12-lead electrocardiogram (ECG) has been used as a risk assessment tool from healthy occupational applicants and athletes to patients with cardiovascular disorders. The ECG is also routinely recorded in the majority of patients hospitalized for non-cardiovascular causes. Thus, it is a widely used tool intended for identification of unsuspected heart disease generally, as well as for diagnosing specific disorders predisposing to fatal arrhythmias in subjects who have not experienced such events but who are at increased risk. Recognition of specific ECG features is of importance for prevention of SCD in asymptomatic persons. The purpose of this review is to catalog the disorders associated with SCD that may be reflected in 12-lead ECGs seen in office or hospital practices and to discuss their prevalence and the magnitude of risks. The focus is on ECG findings suggesting increased SCD risk among the asymptomatic subjects without previously diagnosed cardiac disease.
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Affiliation(s)
- M Juhani Junttila
- Division of Cardiology, University of Miami Miller School of Medicine, Miami, FL, USA.
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133
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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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134
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Halamek J, Couderc JP, Jurak P, Vondra V, Zareba W, Viscor I, Leinveber P. Measure of the QT-RR dynamic coupling in patients with the long QT syndrome. Ann Noninvasive Electrocardiol 2012; 17:323-30. [PMID: 23094878 DOI: 10.1111/j.1542-474x.2012.00526.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The patients with the long QT syndrome type-1 (LQT-1) have an impaired adaptation of the QT interval to heart rate changes. Yet, the description of the dynamic QT-RR coupling in genotyped LQT-1 has never been thoroughly investigated. METHOD We propose a method to model the dynamic QT-RR coupling by defining a transfer function characterizing the relationship between a QT interval and its previous RR intervals measured from ambulatory Holter recordings. Three parameters are used to characterize the QT-RR coupling: a fast gain (Gain(F) ), a slow gain (Gain(L) ), and a time constant (τ). We investigated the values of these parameters across genders, and in genotyped LQT-1 patients with normal QTc interval duration (QTc < 470 ms). RESULTS The QT-RR dynamic profiles are significantly different between LQT-1 patients (97) and controls (154): LQT-1 have longer QTc interval (453 ± 35 vs. 384 ± 26 ms, P < 0.0001), and an increased dependency of the QT interval to previous RR changes revealed by a larger Gain(L) (0.22 ± 0.06 vs. 0.18 ± 0.07, P < 0.0001) and Gain(F) (0.05 ± 0.02 vs. 0.03 ± 0.01, P < 0.0001). Importantly, LQT-1 patients have a faster QT dynamic response to previous RR changes described by τ: 122 ± 44 vs. 172 ± 92 beats (P < 0.0001). This faster QT dynamic response of the QT-RR dynamic coupling remained in LQT-1 patients with QTc in a normal range (<430 ms). CONCLUSIONS The measurement of QT-RR dynamic coupling could be used in patients suspected to carry a concealed form of the LQT-1 syndrome, or to provide insights into the types of arrhythmogenic triggers a patient may be prone to.
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Affiliation(s)
- Josef Halamek
- Institute of Scientific Instruments, AS CR, Brno, Czech Republic.
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135
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Vandenberg JI, Perry MD, Perrin MJ, Mann SA, Ke Y, Hill AP. hERG K+ Channels: Structure, Function, and Clinical Significance. Physiol Rev 2012; 92:1393-478. [DOI: 10.1152/physrev.00036.2011] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the rapid component of the delayed rectifier K+ channel, Kv11.1, which are expressed in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. However, it is the role that Kv11.1 channels play in the heart that has been best characterized, for two main reasons. First, it is the gene product involved in chromosome 7-associated long QT syndrome (LQTS), an inherited disorder associated with a markedly increased risk of ventricular arrhythmias and sudden cardiac death. Second, blockade of Kv11.1, by a wide range of prescription medications, causes drug-induced QT prolongation with an increase in risk of sudden cardiac arrest. In the first part of this review, the properties of Kv11.1 channels, including biogenesis, trafficking, gating, and pharmacology are discussed, while the second part focuses on the pathophysiology of Kv11.1 channels.
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Affiliation(s)
- Jamie I. Vandenberg
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Matthew D. Perry
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Mark J. Perrin
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Stefan A. Mann
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Ying Ke
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Adam P. Hill
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
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136
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El síndrome de QT largo: una breve revisión del diagnóstico electrocardiográfico incluyendo la prueba de Viskin. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2012; 82:243-7. [DOI: 10.1016/j.acmx.2012.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 06/08/2012] [Indexed: 11/22/2022] Open
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137
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Obeyesekere MN, Leong-Sit P, Gula LJ, Yee R, Skanes AC, Klein GJ, Krahn AD. The Evaluation of a Borderline Long QT Interval in an Asymptomatic Patient. Card Electrophysiol Clin 2012; 4:227-238. [PMID: 26939820 DOI: 10.1016/j.ccep.2012.02.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
QT prolongation on resting electrocardiography (ECG) is common, and the clinician is often challenged by the dilemma of excluding acquired causes and recognizing potential congenital long QT syndrome (LQTS). The hallmark of LQTS is an abnormally long QT interval. However, a normal or borderline long QT interval may be observed in up to 50% of patients with LQTS because of the intermittent nature of QT prolongation. This review presents an approach to evaluating the asymptomatic patient with a borderline long QT interval, which incorporates a comprehensive clinical assessment, rest and provocative ECG testing, and genetic testing when appropriate.
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Affiliation(s)
- Manoj N Obeyesekere
- Division of Cardiology, The University of Western Ontario, 339 Windermere Road, London, Ontario N6A 5A5, Canada
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138
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Couderc JP, Xia X, Denjoy I, Extramiana F, Maison-Blanche P, Moss AJ, Zareba W, Lopes CM. Genotype- and Sex-Specific QT-RR Relationship in the Type-1 Long-QT Syndrome. J Am Heart Assoc 2012; 1:e000570. [PMID: 23130128 PMCID: PMC3487370 DOI: 10.1161/jaha.112.000570] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/21/2012] [Indexed: 12/28/2022]
Abstract
BACKGROUND Genotype-phenotype investigations have revealed significantly larger risk for cardiac events in patients with type 1 long-QT syndrome (LQT-1), particularly in adult females, with missense mutation in the cytoplasmic loop (C-loop) regions of the α subunit of the KCNQ1 gene associated with an impaired ion channel activation by adrenergic stimulus. We hypothesize that the impaired response to increases in heart rate leads to abnormal QT-RR dynamic profiles and is responsible for the increased cardiac risk for these patients. METHODS AND RESULTS We measured the QT-RR slope in 24-hour Holter ECGs from LQT-1 patients with the mutations associated with impaired adrenergic stimulus (C-loop, n=18) and compared to LQT-1 patients with other mutations (non-C-loop, n=48), and to a healthy control group (n=195). The diurnal QT-RR slope was less steep in C-loop mutation patients (0.10±0.05) than in the ECGs from non-C-loop mutation patients (0.17±0.09, P=0.002). For female patients, slower heart rates were associated with prolonged QT and increased QT-RR slope. Male patients with C-loop mutations showed an impaired repolarization for shorter range of heart rates than in females, which is consistent with gender differences in triggers for events in this syndrome. CONCLUSIONS Our observations suggest that the C-loop LQT-1 patients have specific impaired adrenergic regulation of the ventricular repolarization. This response to heart rate increases may be useful in identification of high-risk patients with inherited prolonged QT and may help select an optimal antiarrhythmic therapeutic strategy. (J Am Heart Assoc. 2012;1:e000570 doi: 10.1161/JAHA.112.000570.).
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Affiliation(s)
- Jean-Philippe Couderc
- Center for Quantitative Electrocardiography and Cardiac Safety, Heart Research Follow-Up Program, University of Rochester Medical Center, NY (J.-P.C., X.X., A.J.M., W.Z.)
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139
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Rodday AM, Triedman JK, Alexander ME, Cohen JT, Ip S, Newburger JW, Parsons SK, Trikalinos TA, Wong JB, Leslie LK. Electrocardiogram screening for disorders that cause sudden cardiac death in asymptomatic children: a meta-analysis. Pediatrics 2012; 129:e999-1010. [PMID: 22392183 PMCID: PMC3313631 DOI: 10.1542/peds.2011-0643] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Pediatric sudden cardiac death (SCD) occurs in an estimated 0.8 to 6.2 per 100 000 children annually. Screening for cardiac disorders causing SCD in asymptomatic children has public appeal because of its apparent potential to avert tragedy; however, performance of the electrocardiogram (ECG) as a screening tool is unknown. We estimated (1) phenotypic (ECG- or echocardiogram [ECHO]-based) prevalence of selected pediatric disorders associated with SCD, and (2) sensitivity, specificity, and predictive value of ECG, alone or with ECHO. METHODS We systematically reviewed literature on hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), and Wolff-Parkinson-White syndrome, the 3 most common disorders associated with SCD and detectable by ECG. RESULTS We identified and screened 6954 abstracts, yielding 396 articles, and extracted data from 30. Summary phenotypic prevalences per 100 000 asymptomatic children were 45 (95% confidence interval [CI]: 10-79) for HCM, 7 (95% CI: 0-14) for LQTS, and 136 (95% CI: 55-218) for Wolff-Parkinson-White. The areas under the receiver operating characteristic curves for ECG were 0.91 for detecting HCM and 0.92 for LQTS. The negative predictive value of detecting either HCM or LQTS by using ECG was high; however, the positive predictive value varied by different sensitivity and specificity cut-points and the true prevalence of the conditions. CONCLUSIONS Results provide an evidence base for evaluating pediatric screening for these disorders. ECG, alone or with ECHO, was a sensitive test for mass screening and negative predictive value was high, but positive predictive value and false-positive rates varied.
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Affiliation(s)
| | - John K. Triedman
- Children’s Hospital Boston, Boston, Massachusetts;,Harvard Medical School, Boston, Massachusetts; and
| | - Mark E. Alexander
- Children’s Hospital Boston, Boston, Massachusetts;,Harvard Medical School, Boston, Massachusetts; and
| | - Joshua T. Cohen
- Tufts Medical Center, Boston, Massachusetts;,Tufts University School of Medicine, Boston, Massachusetts
| | - Stanley Ip
- Tufts Medical Center, Boston, Massachusetts;,Tufts University School of Medicine, Boston, Massachusetts
| | - Jane W. Newburger
- Children’s Hospital Boston, Boston, Massachusetts;,Harvard Medical School, Boston, Massachusetts; and
| | - Susan K. Parsons
- Tufts Medical Center, Boston, Massachusetts;,Tufts University School of Medicine, Boston, Massachusetts
| | - Thomas A. Trikalinos
- Tufts Medical Center, Boston, Massachusetts;,Tufts University School of Medicine, Boston, Massachusetts
| | - John B. Wong
- Tufts Medical Center, Boston, Massachusetts;,Tufts University School of Medicine, Boston, Massachusetts
| | - Laurel K. Leslie
- Tufts Medical Center, Boston, Massachusetts;,Tufts University School of Medicine, Boston, Massachusetts
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Abstract
Transgenic rabbits expressing pore mutants of K(V)7.1 display a long QT syndrome 1 (LQT1) phenotype. Recently, NS1643 has been described to increase I(Kr).We hypothesized that NS1643 would shorten the action potential duration (APD(90)) in LQT1 rabbits. Transgenic LQT1 rabbits were compared with littermate control (LMC) rabbits. In vivo electrocardiogram studies in sedated animals were performed at baseline and during 45 minutes of intravenous infusion of NS1643 or vehicle in a crossover design. Ex vivo monophasic action potentials were recorded from Langendorff-perfused hearts at baseline and during 45-minute perfusion with NS1643. Left ventricular refractory periods were assessed before and after NS1643 infusion. Genotype differences in APD accommodation were also addressed. In vivo NS1643 shortened the QTc significantly in LQT1 compared with vehicle. In Langendorff experiments, NS1643 significantly shortened the APD(90) in LQT1 and LMC [32.0 ± 4.3 milliseconds (ms); 21.0 ± 5.0 ms] and left ventricular refractory periods (23.7 ± 8.3; 22.6 ± 9.9 ms). NS1643 significantly decreased dp/dt (LQT1: 49% ± 3%; LMC: 63% ± 4%) and increased the incidence of arrhythmia. The time course of APD adaptation was impaired in LQT1 rabbits and unaffected by I(Kr) augmentation. In conclusion, K(V)11.1 channel activation shortens the cardiac APD in a rabbit model of inherited LQT1, but it comes with the risk of excessive shortening of APD.
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142
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Torsades de pointes following acute myocardial infarction: evidence for a deadly link with a common genetic variant. Heart Rhythm 2012; 9:1104-12. [PMID: 22338672 DOI: 10.1016/j.hrthm.2012.02.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Indexed: 01/26/2023]
Abstract
BACKGROUND Although QT prolongation following myocardial infarction (MI) is generally moderate, cases with marked QT prolongation leading to life-threatening torsades de pointes (TdP) have been described. OBJECTIVE To investigate the genetic substrate of this phenomenon. METHODS We studied 13 patients who developed TdP in the subacute phase of MI (2-11 days) and a group of 133 ethnically matched controls with uncomplicated MI. Long QT syndrome genes and the KCNH2-K897T polymorphism were screened by using denaturing high-performance liquid chromatography plus direct sequencing and a specific TaqMan assay, respectively. RESULTS Two of the 13 patients (15%) who presented with QT prolongation and TdP were found to carry long QT syndrome mutations (KCNH2-R744X and SCN5A-E446K). Nine of the remaining 11 patients (82%) carried the KCNH2-K897T polymorphism, which was present in 35% of the controls (P = .0035). Thus, patients with an acute MI carrying the KCNH2-K897T polymorphism had an 8-fold greater risk of experiencing TdP compared with controls (95% confidence interval = 2-40). CONCLUSIONS Our data suggest that the common K897T polymorphism is associated with an increased risk of TdP developing in the subacute phase of MI. Our findings support the concept that the electrical remodeling associated with this healing phase of MI may unmask a genetic substrate predisposing to a time-limited development of life-threatening arrhythmias. They also provide the first line of evidence in support of the hypothesis that a common polymorphism, previously described as a modifier of the severity of LQTS, may increase the risk of life-threatening arrhythmias in a much more prevalent cardiac disease such as myocardial infarction.
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143
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Adler A, van der Werf C, Postema PG, Rosso R, Bhuiyan ZA, Kalman JM, Vohra JK, Guevara-Valdivia ME, Marquez MF, Halkin A, Benhorin J, Antzelevitch C, Wilde AAM, Viskin S. The phenomenon of "QT stunning": the abnormal QT prolongation provoked by standing persists even as the heart rate returns to normal in patients with long QT syndrome. Heart Rhythm 2012; 9:901-8. [PMID: 22300664 DOI: 10.1016/j.hrthm.2012.01.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Indexed: 01/08/2023]
Abstract
BACKGROUND Patients with long QT syndrome (LQTS) have inadequate shortening of the QT interval in response to the sudden heart rate accelerations provoked by standing-a phenomenon of diagnostic value. We now validate our original observations in a cohort twice as large. We also describe that this abnormal QT-interval response persists as the heart rate acceleration returns to baseline. OBJECTIVES To describe a novel observation, termed "QT stunning" and to validate previous observations regarding the "QT-stretching" phenomenon in patients with LQTS by using our recently described "standing test." METHODS The electrocardiograms of 108 patients with LQTS and 112 healthy subjects were recorded in the supine position. Subjects were then instructed to stand up quickly and remain standing for 5 minutes during continuous electrocardiographic recording. The corrected QT interval was measured at baseline (QTc(base)), when heart rate acceleration without appropriate QT-interval shortening leads to maximal QT stretching (QTc(stretch)) and upon return of heart rate to baseline (QTc(return)). RESULTS QTc(stretch) lengthened significantly more in patients with LQTS (103 ± 80 ms vs 66 ± 40 ms in controls; P <.001) and so did QTc(return) (28 ± 48 ms for patients with LQTS vs -3 ± 32 ms for controls; P <.001). Using a sensitivity cutoff of 90%, the specificity for diagnosing LQTS was 74% for QTc(base), 84% for QTc(return), and 87% for QTc(stretch). CONCLUSIONS The present study extends our previous findings on the abnormal response of the QT interval in response to standing in patients with LQTS. Our study also shows that this abnormal response persists even after the heart rate slows back to baseline.
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Affiliation(s)
- Arnon Adler
- Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Ackerman MJ, Priori SG, Willems S, Berul C, Brugada R, Calkins H, Camm AJ, Ellinor PT, Gollob M, Hamilton R, Hershberger RE, Judge DP, Le Marec H, McKenna WJ, Schulze-Bahr E, Semsarian C, Towbin JA, Watkins H, Wilde A, Wolpert C, Zipes DP. HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies this document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA). Heart Rhythm 2012; 8:1308-39. [PMID: 21787999 DOI: 10.1016/j.hrthm.2011.05.020] [Citation(s) in RCA: 729] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Indexed: 10/18/2022]
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145
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Ackerman MJ, Priori SG, Willems S, Berul C, Brugada R, Calkins H, Camm AJ, Ellinor PT, Gollob M, Hamilton R, Hershberger RE, Judge DP, Le Marec H, McKenna WJ, Schulze-Bahr E, Semsarian C, Towbin JA, Watkins H, Wilde A, Wolpert C, Zipes DP. HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies: this document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA). Europace 2011; 13:1077-109. [PMID: 21810866 DOI: 10.1093/europace/eur245] [Citation(s) in RCA: 560] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Vahedi F, Haney MF, Jensen SM, Näslund U, Bergfeldt L. Effect of heart rate on ventricular repolarization in healthy individuals applying vectorcardiographic T vector and T vector loop analysis. Ann Noninvasive Electrocardiol 2011; 16:287-94. [PMID: 21762257 DOI: 10.1111/j.1542-474x.2011.00444.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Ventricular repolarization (VR) is strongly influenced by heart rate (HR) and autonomic nervous activity, both of which also are important for arrhythmogenesis. Their relative influence on VR is difficult to separate, but might be crucial for understanding while some but not other individuals are at risk for life-threatening arrhythmias at a certain HR. This study was therefore designed to assess the "pure" effect of HR increase by atrial pacing on the ventricular gradient (VG) and other vectorcardiographically (VCG) derived VR parameters during an otherwise unchanged condition. METHODS In 19 patients with structurally normal hearts, a protocol with stepwise increased atrial pacing was performed after successful arrhythmia ablation. Conduction intervals were measured on averaged three-dimensional (3D) QRST complexes. In addition, various VCG parameters were measured from the QRS and T vectors as well as from the T loop. All measurements were performed after at least 3 minutes of rate adaptation of VR. RESULTS VR changes at HR from 80 to 120 bpm were assessed. The QRS and QT intervals, VG, QRSarea, Tarea, and Tamplitude were markedly rate dependent. In contrast, the Tp-e/QT ratio was rate independent as well as the T-loop morphology parameters Tavplan and Teigenvalue describing the bulginess and circularity of the loop. CONCLUSIONS In healthy individuals, the response to increased HR within the specified range suggests a decreased heterogeneity of depolarization instants, action potential morphology, and consequently of the global VR.
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Affiliation(s)
- Farzad Vahedi
- Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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147
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Obeyesekere MN, Klein GJ, Modi S, Leong-Sit P, Gula LJ, Yee R, Skanes AC, Krahn AD. How to Perform and Interpret Provocative Testing for the Diagnosis of Brugada Syndrome, Long-QT Syndrome, and Catecholaminergic Polymorphic Ventricular Tachycardia. Circ Arrhythm Electrophysiol 2011; 4:958-64. [DOI: 10.1161/circep.111.965947] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Manoj N. Obeyesekere
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - George J. Klein
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - Simon Modi
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - Peter Leong-Sit
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - Lorne J. Gula
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - Raymond Yee
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - Allan C. Skanes
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
| | - Andrew D. Krahn
- From the University of Western Ontario, Division of Cardiology, London, Ontario, Canada
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148
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Sy RW, van der Werf C, Chattha IS, Chockalingam P, Adler A, Healey JS, Perrin M, Gollob MH, Skanes AC, Yee R, Gula LJ, Leong-Sit P, Viskin S, Klein GJ, Wilde AA, Krahn AD. Derivation and Validation of a Simple Exercise-Based Algorithm for Prediction of Genetic Testing in Relatives of LQTS Probands. Circulation 2011; 124:2187-94. [DOI: 10.1161/circulationaha.111.028258] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Genetic testing can diagnose long-QT syndrome (LQTS) in asymptomatic relatives of patients with an identified mutation; however, it is costly and subject to availability. The accuracy of a simple algorithm that incorporates resting and exercise ECG parameters for screening LQTS in asymptomatic relatives was evaluated, with genetic testing as the gold standard.
Methods and Results—
Asymptomatic first-degree relatives of genetically characterized probands were recruited from 5 centers. QT intervals were measured at rest, during exercise, and during recovery. Receiver operating characteristics were used to establish optimal cutoffs. An algorithm for identifying LQTS carriers was developed in a derivation cohort and validated in an independent cohort. The derivation cohort consisted of 69 relatives (28 with LQT1, 20 with LQT2, and 21 noncarriers). Mean age was 35±18 years, and resting corrected QT interval (QTc) was 466±39 ms. Abnormal resting QTc (females ≥480 ms; males ≥470 ms) was 100% specific for gene carrier status, but was observed in only 48% of patients; however, mutations were observed in 68% and 42% of patients with a borderline or normal resting QTc, respectively. Among these patients, 4-minute recovery QTc ≥445 ms correctly restratified 22 of 25 patients as having LQTS and 19 of 21 patients as being noncarriers. The combination of resting and 4-minute recovery QTc in a screening algorithm yielded a sensitivity of 0.94 and specificity of 0.90 for detecting LQTS carriers. When applied to the validation cohort (n=152; 58 with LQT1, 61 with LQT2, and 33 noncarriers; QTc=443±47 ms), sensitivity was 0.92 and specificity was 0.82.
Conclusions—
A simple algorithm that incorporates resting and exercise-recovery QTc is useful in identifying LQTS in asymptomatic relatives.
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Affiliation(s)
- Raymond W. Sy
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Christian van der Werf
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Ishvinder S. Chattha
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Priya Chockalingam
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Arnon Adler
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Jeffrey S. Healey
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Mark Perrin
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Michael H. Gollob
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Allan C. Skanes
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Raymond Yee
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Lorne J. Gula
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Peter Leong-Sit
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Sami Viskin
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - George J. Klein
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Arthur A. Wilde
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
| | - Andrew D. Krahn
- From the University of Western Ontario, London, ON, Canada (R.W.S., I.S.C., A.C.S., R.Y., L.J.G., P.L.-S., G.J.K., A.D.K.); Academic Medical Center, Amsterdam, Netherlands (C.V.d.W., P.C., A.A.W.); Tel Aviv University, Tel Aviv, Israel (A.A., S.V.); McMaster University, Hamilton, ON, Canada (J.S.H.); and University of Ottawa, Ottawa, ON, Canada (M.P., M.H.G.)
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Pressler A, Vogel A, Scherr J, Wolfarth B, Halle M. Applying the "Viskin test": QT interval in response to standing in elite athletes. Int J Cardiol 2011; 154:93-4. [PMID: 22056043 DOI: 10.1016/j.ijcard.2011.10.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 10/18/2011] [Indexed: 11/17/2022]
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150
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Abstract
Sudden cardiac death is the leading cause of nontraumatic mortality in young athletes. The estimated incidence varies; however, recent studies have provided more accurate data. Most cases are attributed to silent hereditary or congenital cardiac disorders, many of which may be detected through preparticipation screening programs. This article provides a comprehensive review of the incidence and etiology of sudden cardiac death in young athletes, with practical advice regarding evaluation and management in light of a large number of recent advances. A brief outline of current perspectives on preparticipation screening programs and prevention is included.
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Affiliation(s)
- Nabeel Sheikh
- Department of Cardiovascular Sciences, St. George's University of London, London, UK
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