title: Atrial tachycardia ablation in patients with a functional single ventricle after the Fontan surgery.
abstract: BACKGROUND
  Atrial tachyarrhythmias are a leading source of morbidity and mortality after Fontan-type procedures and antiarrhythmic drug therapy is often ineffective in these patients.
  
  
  OBJECTIVE
  To evaluate short- and long-term outcomes of radiofrequency current ablation for atrial tachycardia (AT) in patients after the Fontan procedure, and to report clinical, electrophysiological and electroanatomical characteristics of these arrhythmias.
  
  
  METHODS
  We retrospectively analysed data obtained in 8 patients (5 males, 3 females) after the Fontan procedure who underwent ablation for AT between 2002 and 2013. In order to compare the clinical impact of arrhythmia before and after ablation, we used the modified arrhythmia score, ranging from 0 (no arrhythmia activity) to 12 (very severe arrhythmia). In all patients, electroanatomical mapping using the CARTO system was performed, allowing semiquantification of low-voltage (< 0.5 mV) areas and scars.
  
  
  RESULTS
  Seven patients had an atriopulmonary connection and 1 patient had an extracardiac conduit. The mean patient age was 9.4 ± 3.1 years at the time of the Fontan procedure and 26.2 ± 4.6 years at the time of the first ablation. A total of 18 ablations were performed with no complications, 1 to 4 (median 2.5) procedures per patient. In patients who had more than 1 ablation, the mean time from the first to the last procedure was 34.8 months (range 1-64 months). In individual patients, 1 to 4 (median 2.5) different ATs were observed, with the mean tachycardia cycle length of 334 ± 95 ms. In 6 patients, low-voltage area (< 0.5 mV) comprised 25-50% of the right atrium, and in two others it comprised 10-25% and < 10% of the right atrium, respectively. Seven procedures were fully successful (ablation of all ATs), 7 were partially successful (ablation of only some AT, including clinical arrhythmia, but not of all ATs) and 4 were unsuccessful (failed ablation of clinical AT). The mean procedural, fluoroscopy and ablation times were 176 ± 54.6, 13.7 ± 5.7 and 21.7 ± 11.9 min, respectively. Freedom from arrhythmia during the mean follow-up of 58.6 ± 46 months (range 11-127 months) since the last procedure was obtained in 4 patients. The median arrhythmia score after the last ablation was significantly reduced compared to baseline (4.5 vs. 8; p < 0.05).
  
  
  CONCLUSIONS
  Catheter ablation of AT in patients after the Fontan procedure is safe but its acute and long-term efficacy is limited. Due to complex and extensive substrate, along with complex anatomy, recurrences are frequent and patients may require repeat ablation procedures. Suppression of arrhythmia is associated with an improved clinical status of the patients.
authors.affiliation: Department of Cardiac Arrhythmias, Institute of Cardiology, Warsaw, Poland. pderejko@yahoo.com.
authors.forename: Paweł
authors.initials: P
authors.lastname: Derejko
authors.forename: Justyna
authors.initials: J
authors.lastname: Rybicka
authors.forename: Elżbieta Katarzyna
authors.initials: EK
authors.lastname: Biernacka
authors.forename: Franciszek
authors.initials: F
authors.lastname: Walczak
authors.forename: Mirosław
authors.initials: M
authors.lastname: Kowalski
authors.forename: Piotr
authors.initials: P
authors.lastname: Urbanek
authors.forename: Robert
authors.initials: R
authors.lastname: Bodalski
authors.forename: Michał
authors.initials: M
authors.lastname: Orczykowski
authors.forename: Artur
authors.initials: A
authors.lastname: Oręziak
authors.forename: Joanna
authors.initials: J
authors.lastname: Duliban
authors.forename: Piotr
authors.initials: P
authors.lastname: Hoffman
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Szumowski
mesh_terms: D000328:Adult; D017115:Catheter Ablation; D002648:Child; D002675:Child, Preschool; D005260:Female; D018729:Fontan Procedure / Q000009:adverse effects*; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery*; D006352:Heart Ventricles / Q000601:surgery; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D013610:Tachycardia / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Fontan procedure; ablation; atrial tachycardia