Low incidence of cardiac events with ?-blocking therapy in children with long QT syndrome

Villain, Elisabeth; Denjoy, Isabelle; Lupoglazoff, Jean‐Marc; Guicheney, Pascale; Hainque, Bernard; Lucet, V.; Bonnet, D

doi:10.1016/j.ehj.2004.06.016

Cited by 100 publications

(45 citation statements)

References 19 publications

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“…Increasingly, evidence suggests those who are asymptomatic at diagnosis remain so once started on appropriate β‐blockers3, 20. The increasing recognition of LQTS in the medical community and the implementation of familial screening means that many are diagnosed prior to the onset of symptoms, compared with prior eras when more than half of patients were diagnosed following a symptomatic event 3, 18, 19, 21. Secondly, and closely associated with the above, the overall QTc intervals reported here are shorter than prior studies, whose average QTc range up to 520 ms.…”

Section: Discussionmentioning

confidence: 99%

Cardiac Events During Competitive, Recreational, and Daily Activities in Children and Adolescents With Long QT Syndrome

Chambers

Ladouceur

Alexander

et al. 2017

JAHA

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BackgroundThe 2005 Bethesda Conference Guidelines advise patients with long QT syndrome against competitive sports. We assessed cardiac event rates during competitive and recreational sports, and daily activities among treated long QT syndrome patients.Methods and ResultsLong QT syndrome patients aged ≥4 years treated with anti‐adrenergic therapy were included. Demographics included mechanism of presentation, corrected QT interval pretreatment, symptom history, medication compliance, and administration of QT‐prolonging medications. Corrected QT interval ≥550 ms or prior cardiac arrest defined high risk. Sports were categorized by cardiovascular demand per the 2005 Bethesda Conference Guidelines. Each was classified as recreational or competitive. One hundred seventy‐two patients (90; 52% female) with median age 15.2 years (interquartile range 11.4, 19.4) were included. Evaluation was performed for family history (102; 59%), incidental finding (34; 20%), and symptoms (36; 21%). Median corrected QT interval was 474 ms (interquartile range 446, 496) and 14 patients (8%) were deemed high risk. Treatment included β‐blockers (171; 99%), implantable cardioverter‐defibrillator (27; 16%), left cardiac sympathetic denervation (7; 4%), and pacemaker (3; 2%). Sports participation was recreational (66; 38%) or competitive (106; 62%), with 92 (53%) exercising against the Bethesda Conference Guidelines. There were no cardiac events in competitive athletes and no deaths. There were 13 cardiac events in 9 previously symptomatic patients during either recreational exercise or activities of daily life.ConclusionsIn this cohort of appropriately managed children with long QT syndrome, cardiac event rates were low and occurred during recreational but not competitive activities. This study further supports the need for increased assessment of arrhythmia risk during exercise in this patient population.

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Section: Discussionmentioning

confidence: 99%

Cardiac Events During Competitive, Recreational, and Daily Activities in Children and Adolescents With Long QT Syndrome

Chambers

Ladouceur

Alexander

et al. 2017

JAHA

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“…Beta blockers are extremely protective in lQt1 patients but are only moderately protective in lQt2 and lQt3. 12,13 female lQt2 patients may not be as fully protected with beta blockers as male lQt2 patients. Given the electrophysiological consequence of an lQt3-causing sCn5a mutation, late sodium current blockers including mexiletine, flecainide, or ranolazine may represent gene-specific therapeutic options for lQt3.…”

Section: The Major Lqts Genotypesmentioning

confidence: 99%

Genetics of Long QT Syndrome

Tester¹,

Ackerman

2014

Methodist DeBakey Cardiovascular Journal

168

112

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Long QT syndrome (LQTS) is a potentially life-threatening cardiac arrhythmia characterized by delayed myocardial repolarization that produces QT prolongation and increased risk for torsades des pointes (TdP)-triggered syncope, seizures, and sudden cardiac death (SCD) in an otherwise healthy young individual with a structurally normal heart. Currently, there are three major LQTS genes (KCNQ1, KCNH2, and SCN5A) that account for approximately 75% of the disorder. For the major LQTS genotypes, genotype-phenotype correlations have yielded gene-specific arrhythmogenic triggers, electrocardiogram (ECG) patterns, response to therapies, and intragenic and increasingly mutation-specific risk stratification. The 10 minor LQTS-susceptibility genes collectively account for less than 5% of LQTS cases. In addition, three atypical LQTS or multisystem syndromic disorders that have been associated with QT prolongation have been described, including ankyrin-B syndrome, Anderson-Tawil syndrome (ATS), and Timothy syndrome (TS). Genetic testing for LQTS is recommended in patients with either a strong clinical index of suspicion or persistent QT prolongation despite their asymptomatic state. However, genetic test results must be interpreted carefully.

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“…[11][12][13][14][15] Indeed, in LQT1 study populations with a percentage of symptomatic patients between 50% and 70%, the combined incidence of CA and SCD during rather long follow-up periods is only 1%. 13,15 We were therefore surprised by observing what appears to be a rather incomplete protection for patients with A341V.…”

Section: Response To ␤-Blocker Therapymentioning

confidence: 99%

The Common Long-QT Syndrome Mutation KCNQ1/A341V Causes Unusually Severe Clinical Manifestations in Patients With Different Ethnic Backgrounds

et al. 2007

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Background-The impressive clinical heterogeneity of the long-QT syndrome (LQTS) remains partially unexplained. In a South African (SA) founder population, we identified a common LQTS type 1 (LQT1)-causing mutation (KCNQ1-A341V) associated with high clinical severity. We tested whether the arrhythmic risk was caused directly by A341V or by its presence in the specific ethnic setting of the SA families. Methods and Results-Seventy-eight patients, all with a single KCNQ1-A341V mutation, from 21 families and 8 countries were compared with 166 SA patients with A341V and with 205 non-A341V LQT1 patients. In the 2 A341V populations (SA and non-SA), the probability of a first event through 40 years of age was similar (76% and 82%), and the QTc was 484Ϯ42 versus 485Ϯ45 ms (PϭNS). Compared with the 205 non-A341V patients with the same median follow-up (30 versus 32 years), the 244 A341V patients were more likely to have cardiac events (75% versus 24%), were younger at first event (6 versus 11 years), and had a longer QTc (485Ϯ43 versus 465Ϯ38 ms) (all PϽ0.001). Arrhythmic risk remained higher (PϽ0.0001) even when the A341V patients were compared with non-A341V patients with mutations either localized to transmembrane domains or exhibiting a dominant-negative effect. A341V patients had more events despite ␤-blocker therapy. Conclusions-The hot spot KCNQ1-A341V predicts high clinical severity independently of the ethnic origin of the families. This higher risk of cardiac events also persists when compared with LQT1 patients with either transmembrane or dominant-negative mutations. The identification of this high-risk mutation and possibly others may improve the risk stratification and management of LQTS.

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Low incidence of cardiac events with ?-blocking therapy in children with long QT syndrome

Abstract: The outcome of children with LQTS under effective beta-blockers is favourable. Persisting arrhythmia or symptoms despite beta-blockers should aim at identifying other genotypes than KCNQ1.

Cited by 100 publications

References 19 publications

Cardiac Events During Competitive, Recreational, and Daily Activities in Children and Adolescents With Long QT Syndrome

Cardiac Events During Competitive, Recreational, and Daily Activities in Children and Adolescents With Long QT Syndrome

Genetics of Long QT Syndrome

The Common Long-QT Syndrome Mutation KCNQ1/A341V Causes Unusually Severe Clinical Manifestations in Patients With Different Ethnic Backgrounds

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