Abstract
Long QT syndrome (LQTS) is an inherited arrhythmic disorder associated with sudden cardiac death (SCD). This study aimed to identify the clinical and molecular genetic risk factors that contribute to major arrhythmic events (MAEs) in patients with genetically confirmed childhood onset LQTS 1–3. This study was a retrospective double-center study. An MAE was defined as the occurrence of SCD, aborted SCD, appropriate implantable cardioverter defibrillator discharge, or sustained ventricular tachycardia. During a median follow-up of 4.6 years (range 0.1–24.3 years), MAEs occurred in 18 (17.8%) of 101 patients diagnosed with LQTS at a median of 7.7 years (range 0.0–18.0 years) despite the use of beta-blockers in 91.6% of patients at the last follow-up. A multivariate analysis identified a genetic diagnosis of LQTS2 and LQTS3 and variants within the KCNH2 S5-loop-S6 pore region as independent risk factors for MAEs, independent of the QTc value or a history of syncope detected from a univariate analysis. MAEs occur frequently in childhood onset LQTS despite beta-blocker treatment. A detailed molecular genetic diagnosis can contribute to the arrhythmia risk stratification and optimize the use of preventive measures in this vulnerable patient population.
Highlights
Long QT syndrome (LQTS) is an inherited arrhythmogenic disorder caused by variants in the genes encoding cardiac ion channels [1]
A total of 54 patients were affected by LQTS1 (53.5%), 40 by LQTS2 (39.6%), and 7 by LQTS3 (6.9%)
LQTS2 and LQTS3 as well as variants in the KCNH2 S5-loop-S6 region were identified as independent risk factors for an major arrhythmic event (MAE), irrespective of the QTc value and the occurrence of syncope
Summary
Long QT syndrome (LQTS) is an inherited arrhythmogenic disorder caused by variants in the genes encoding cardiac ion channels [1]. These ion channels generate the cardiac action potential by regulating the flux of ions across the membrane such as the influx of sodium and calcium or the outflow of potassium [2]. In LQTS, an increase in the sodium and calcium currents or a decrease in the potassium outflow can prolong the action potential duration, leading to the eponymous phenotype of a prolonged QT interval [3].
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