title: The incidence and characteristics of supraventricular tachycardia in left atrial isomerism: a high incidence of atrial fibrillation in young patients.
abstract: BACKGROUND
  In left atrial isomerism (LAI), both atria show left atrial morphology. Although bradyarrhythmias are frequent and highly complex in LAI patients, previous studies have reported a low incidence of supraventricular tachycardia (SVT).
  
  
  METHODS
  To evaluate the incidence and characteristics of SVT in LAI, we retrospectively evaluated the clinical characteristics of SVTs in 83 patients with LAI (age at last follow-up, 15.3±10.5 years).
  
  
  RESULTS
  There were 27 SVTs in 19 patients (23%), including nine episodes of atrial fibrillation (AF) and eight non-reentrant SVTs. Sixteen of the 19 patients with SVT had histories of atriotomy, but the three patients with AF or non-reentrant tachycardia had no history of atriotomy. The rates of freedom from SVT were 66% and 59% at ages of 20 and 30 years, respectively; the corresponding rates for freedom from AF were 89% and 74%. In multivariate analysis, the predictors of SVT were age (OR, 1.14; 95% CI, 1.06-1.26; p=0.003) and sinus node dysfunction (SND) (OR, 3.88; 95% CI, 1.57-13.34; p=0.01).
  
  
  CONCLUSIONS
  In patients with LAI, SVTs are common, and AF and non-reentrant SVTs are the major type of SVTs. The incidence of AF was high in young patients with LAI. The lack of anatomical barriers in the atria that allow the formation of macro-reentrant circuits may account for the higher incidence of AF and non-reentrant SVT than macro-reentrant tachycardia. Moreover, the increasing prevalence of SND with age should contribute to a higher incidence of SVT.
authors.affiliation: Department of Pediatric Cardiology, National Cerebral and Cardiovascular Center, Osaka, Japan. ayamiya@hsp.ncvc.go.jp
authors.forename: Aya
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Heima
authors.initials: H
authors.lastname: Sakaguchi
authors.forename: Hideo
authors.initials: H
authors.lastname: Ohuchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Takehiro
authors.initials: T
authors.lastname: Igarashi
authors.forename: Jun
authors.initials: J
authors.lastname: Negishi
authors.forename: Naoki
authors.initials: N
authors.lastname: Toyota
authors.forename: Koji
authors.initials: K
authors.lastname: Kagisaki
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Yagihara
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamada
mesh_terms: D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D059446:Heterotaxy Syndrome / Q000175:diagnosis* / Q000453:epidemiology* / Q000532:radiotherapy; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D055815:Young Adult