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Paediatric long QT syndrome: clinical outcomes and therapy in the Spanish National Registry
Francesca Perin1,2, Antonio J Cartón3,4, Francisco Jose Bermúdez-Jiménez2,5
1Pediatric Cardiology Department, Virgen de las Nieves University Hospital, Avenida de las Fuerzas Armadas 2, Granada 18014, Spain.
Insights
Major arrhythmic events (MAEs) are uncommon in children with congenital long QT syndrome (LQTS), primarily affecting those with high-risk genotypes or very early presentation. Management strategies guided by genotype and QTc duration are supported by these findings.
Area of Science:
- Cardiology
- Genetics
- Pediatrics
Background:
- Congenital long QT syndrome (LQTS) is a heterogeneous genetic disorder.
- Genotype and QTc duration influence the risk of major arrhythmic events (MAEs).
- Limited contemporary data exist on pediatric LQTS outcomes.
Purpose of the Study:
- To characterize clinical features in a nationwide pediatric LQTS cohort.
- To identify management strategies for pediatric LQTS.
- To determine predictors of MAEs in children with LQTS.
Main Methods:
- Retrospective multicenter study of children (<18 years) diagnosed with LQTS.
- Utilized 2022 European Society of Cardiology criteria.
- Defined MAEs as sudden cardiac death, aborted cardiac arrest, or appropriate ICD therapy.
Main Results:
- 86.5% of 371 children had pathogenic variants; 5.7% had high-risk genotypes.
- MAEs occurred in 3.8% during median 6-year follow-up, predominantly in high-risk groups.
- Beta-blockers were used in 92.4%; ICDs in 8.9%; LcSd in 8.9%.
Conclusions:
- MAEs in pediatric LQTS are uncommon, clustering in those with malignant genotypes, prolonged QTc, and early presentation.
- Current genotype and QTc-guided management, with beta-blockers as first-line therapy, is supported.
- Selective use of LcSd and ICDs is recommended for high-risk pediatric LQTS patients.
Background And Aims:
Congenital long QT syndrome (LQTS) is a heterogeneous disorder in which genotype and QTc duration modulate the risk of major arrhythmic events (MAEs), but contemporary paediatric outcome data remain limited. This study aimed to characterize clinical features, management strategies, and predictors of MAEs in a nationwide paediatric LQTS cohort.
Methods:
This retrospective multicentre study analysed children (<18 years) diagnosed with LQTS across 30 tertiary centres (2004-24) using 2022 European Society of Cardiology criteria. MAEs were defined as sudden cardiac death, aborted cardiac arrest, or appropriate implantable cardioverter-defibrillator (ICD) therapy.
Results:
The cohort included 371 children (58% male; median diagnosis age 6.0 years; interquartile range .25-11 years). Pathogenic/likely pathogenic variants were identified in 86.5%, mainly in KCNQ1, KCNH2, or SCN5A, while 5.7% harboured high-risk genotypes (Jervell-Lange-Nielsen, calmodulinopathies, CACNA1C/Timothy). Beta-blockers were prescribed in 92.4%. Over a median 6-year follow-up, 14 children (3.8%) experienced MAEs, which occurred predominantly in those with high-risk genotypes, QTc ≥550 ms or very early presentation. MAEs were rare in LQT1-3 with QTc <500 ms. Foetal/neonatal bradycardia (5.1%) correlated with high-risk genotypes and adverse outcomes. ICDs were implanted in 33 children (8.9%); 10 (30%) received appropriate therapies, and 8 (24%) experienced complications. Left cardiac sympathetic denervation was performed in 33 (8.9%), mainly high-risk patients, and was associated with >80% arrhythmia-free survival without major complications.
Conclusions:
In this nationwide paediatric LQTS cohort, MAEs were uncommon and clustered in children with malignant genotypes, markedly prolonged QTc and very early presentation, particularly foetal or neonatal bradycardia. These data support the current genotype and QTc-guided management strategy, with beta-blockers as the cornerstone therapy and selective use of left cardiac sympathetic denervation and ICDs in high-risk profiles.
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