title: Pulmonary veins branching pattern, assessed by magnetic resonance, does not affect transcatheter atrial fibrillation ablation outcome.
abstract: OBJECTIVE
  The aim of the present study is to provide, in a large cohort of patients, a description of the left atrium (LA) and pulmonary veins (PV) anatomy in relation to ablation outcome.
  
  
  BACKGROUND
  The role of LA imaging, assessed before transcatheter ablation of atrial fibrillation (AF), is unknown.
  
  
  METHODS
  330 patients referred for transcatheter ablation of AF (paroxysmal 62.7%; persistent 25.5%; long-standing 11.8%) underwent contrast-enhanced magnetic resonance imaging (MRI) before the procedure. Transcatheter ablation was performed aiming to AF interruption and/or absence of inducibility. Patients were followed clinically, by ECG, and 24-hour Holter ECG at 1-3-6-12-18-24 months.
  
  
  RESULTS
  The MRI preceding the procedure depicted a typical PV branching pattern, two left and two right, in 130 (39.4%) patients; 117 (35.4%) presented common left trunk (short and long) and 75 (22.7%) at least one accessory PV. Mean atrial volume was 142.0 +/- 48.5 ml. The ablation procedure resulted successful, after 15.6 +/- 7.2 months follow-up, in 174 (52.7%) patients. PV branching pattern did not relate (P = 0.304) to ablation outcome. A multiple Cox proportional hazard model, adjusted for potential confounders, proved that only LA volume was independently related to ablation outcome (HR 1.007, 95% CI 1.003-1.011; P = 0.001). A LA cut-off volume of 135 ml emerged as a significant predictor of ablation failure (ROC curve area 0.651, 95% CI 0.591-0.710; P < 0.001).
  
  
  CONCLUSIONS
  Less than half of the patients referred for transcatheter AF ablation present a typical PV branching pattern; the PV branching pattern, however, does not affect ablation outcome. LA volume strongly predicts AF ablation outcome.
authors.affiliation: Cardiology Division, Department of Internal Medicine, University of Turin, Asti, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Anselmino
authors.forename: Marco
authors.initials: M
authors.lastname: Scaglione
authors.forename: Alessandro
authors.initials: A
authors.lastname: Blandino
authors.forename: Serena
authors.initials: S
authors.lastname: Beninati
authors.forename: Domenico
authors.initials: D
authors.lastname: Caponi
authors.forename: Carlo
authors.initials: C
authors.lastname: Boffano
authors.forename: Antonio
authors.initials: A
authors.lastname: Montefusco
authors.forename: Federico
authors.initials: F
authors.lastname: Cesarani
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Gaita
mesh_terms: D001281:Atrial Fibrillation / Q000628:therapy*; D017115:Catheter Ablation; D005260:Female; D006325:Heart Atria / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011667:Pulmonary Veins / Q000033:anatomy & histology*; D016896:Treatment Outcome