title: Risk factors for recurrent syncope and subsequent fatal or near-fatal events in children and adolescents with long QT syndrome.
abstract: OBJECTIVE
  We aimed to identify risk factors for recurrent syncope in children and adolescents with congenital long QT syndrome (LQTS).
  
  
  BACKGROUND
  Data regarding risk assessment in LQTS after the occurrence of the first syncope episode are limited.
  
  
  METHODS
  The Prentice-Williams-Peterson conditional gap time model was used to identify risk factors for recurrent syncope from birth through age 20 years among 1,648 patients from the International Long QT Syndrome Registry.
  
  
  RESULTS
  Multivariate analysis demonstrated that corrected QT interval (QTc) duration (≥500 ms) was a significant predictor of a first syncope episode (hazard ratio: 2.16), whereas QTc effect was attenuated when the end points of the second, third, and fourth syncope episodes were evaluated (hazard ratios: 1.29, 0.99, 0.90, respectively; p < 0.001 for the null hypothesis that all 4 hazard ratios are identical). A genotype-specific subanalysis showed that during childhood (0 to 12 years), males with LQTS type 1 had the highest rate of a first syncope episode (p = 0.001) but exhibited similar rates of subsequent events as other genotype-sex subsets (p = 0.63). In contrast, in the age range of 13 to 20 years, long QT syndrome type 2 females experienced the highest rate of both first and subsequent syncope events (p < 0.001 and p = 0.01, respectively). Patients who experienced ≥1 episodes of syncope had a 6- to 12-fold (p < 0.001 for all) increase in the risk of subsequent fatal/near-fatal events independently of QTc duration. Beta-blocker therapy was associated with a significant reduction in the risk of recurrent syncope and subsequent fatal/near-fatal events.
  
  
  CONCLUSIONS
  Children and adolescents who present after an episode of syncope should be considered to be at a high risk of the development of subsequent syncope episodes and fatal/near-fatal events regardless of QTc duration.
authors.affiliation: Heart Research Follow-up Program, Cardiology Division, Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Judy F
authors.initials: JF
authors.lastname: Liu
authors.forename: Christian
authors.initials: C
authors.lastname: Jons
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Moss
authors.forename: Scott
authors.initials: S
authors.lastname: McNitt
authors.forename: Derick R
authors.initials: DR
authors.lastname: Peterson
authors.forename: Ming
authors.initials: M
authors.lastname: Qi
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Robinson
authors.forename: Alon
authors.initials: A
authors.lastname: Barsheshet
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ackerman
authors.forename: Jesaia
authors.initials: J
authors.lastname: Benhorin
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Kaufman
authors.forename: Emanuela H
authors.initials: EH
authors.lastname: Locati
authors.forename: Carlo
authors.initials: C
authors.lastname: Napolitano
authors.forename: Silvia G
authors.initials: SG
authors.lastname: Priori
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schwartz
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Towbin
authors.forename: Michael
authors.initials: M
authors.lastname: Vincent
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Ilan
authors.initials: I
authors.lastname: Goldenberg
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002423:Cause of Death; D002648:Child; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000209:etiology; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008133:Long QT Syndrome / Q000150:complications / Q000151:congenital / Q000175:diagnosis* / Q000401:mortality*; D008297:Male; D015999:Multivariate Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D012008:Recurrence; D012042:Registries; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D013575:Syncope / Q000150:complications / Q000175:diagnosis* / Q000401:mortality*