title: Multiple accessory pathways in the young: the impact of structural heart disease.
abstract: BACKGROUND
  The presence of multiple accessory pathways (MultAP) is described in structural heart disease (SHD) such as Ebstein's anomaly and cardiomyopathies. Structural defects can impact the tolerability of tachyarrhythmia and can complicate both medical management and ablation. In a large cohort of pediatric patients with and without SHD undergoing invasive electrophysiology study, we examined the prevalence of MultAP and the effect of both MultAP and SHD on ablation outcomes.
  
  
  METHODS
  Accessory pathway number and location, presence of SHD, ablation success, and recurrence were analyzed in consecutive patients from our center over a 16-year period.
  
  
  RESULTS
  In 1088 patients, 1228 pathways (36% retrograde only) were mapped to the right side (TV) in 18%, septum (S) in 39%, and left side (MV) in 43%. MultAP were present in 111 pts (10%), involving 250 distinct pathways. SHD tripled the risk of MultAP (26% SHD vs 8% no SHD, P < .001). Multivariable adjusted risk factors for MultAP included Ebstein's (OR 8.7[4.4-17.5], P < .001) and cardiomyopathy (OR 13.3[5.1-34.5], P < .001). Of 1306 ablation attempts, 94% were acutely successful with an 8% recurrence rate. Ablation success was affected by SHD (85% vs 95% for no SHD, P < .01) but not by MultAP (91% vs 94% for single, P = .24). Recurrence rate was higher for SHD (17% SHD vs 8% no SHD, P < .05) and MultAP (19% MultAP vs 8% single, P < .001).
  
  
  CONCLUSIONS
  MultAP are found in 10% of pediatric patients, and are more common in SHD compared to those with normal hearts. Both the presence of MultAP and SHD negatively influence ablation outcomes.
authors.affiliation: Department of Cardiology, Boston Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, MA, USA. justin.zachariah@childrens.harvard.edu
authors.forename: Justin P
authors.initials: JP
authors.lastname: Zachariah
authors.forename: Edward P
authors.initials: EP
authors.lastname: Walsh
authors.forename: John K
authors.initials: JK
authors.lastname: Triedman
authors.forename: Charles I
authors.initials: CI
authors.lastname: Berul
authors.forename: Frank
authors.initials: F
authors.lastname: Cecchin
authors.forename: Mark E
authors.initials: ME
authors.lastname: Alexander
authors.forename: Laura M
authors.initials: LM
authors.lastname: Bevilacqua
mesh_terms: D058606:Accessory Atrioventricular Bundle / Q000150:complications / Q000453:epidemiology*; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D002648:Child; D004594:Electrophysiology; D005260:Female; D006331:Heart Diseases / Q000150:complications* / Q000209:etiology / Q000601:surgery; D006801:Humans; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D016896:Treatment Outcome