title: Correlation between AF substrate ablation difficulty and left atrial fibrosis quantified by delayed-enhancement cardiac magnetic resonance.
abstract: BACKGROUND
  Studies have shown that the presence of left atrial (LA) fibrosis can be assessed by LA delayed-enhancement cardiac magnetic resonance (LA DE-CMR) and may be predictive of outcome after ablation for atrial fibrillation (AF). We sought to test the hypothesis that the amount of LA fibrosis evaluated by DE-CMR correlates with the difficulty of complex fractionated atrial electrograms (CFAE) ablation.
  
  
  METHODS
  Twenty-two consecutive patients (86.4% nonparoxysmal AF) underwent substrate CFAE radiofrequency (RF) ablation (±Pulmonary veins isolation) with AF termination as the endpoint. LA DE-CMR was performed prior to ablation. A global index of DE was defined by an average of six LA segmental scores based on a four-grade scale (no enhancement to maximum enhancement). Time between first RF application and AF termination, and RF duration until AF termination, was recorded. CFAE area/total LA surface was also measured on CARTO maps (Biosense Webster, Diamond Bar, CA, USA). These measures served to evaluate ablation difficulty, and were correlated with CMR images by double-blinded analysis.
  
  
  RESULTS
  Ablation restored sinus rhythm in 20 of 22 patients (91%), with a time to terminate AF of 140 ± 91 minutes. There was a significant correlation between the global averaged DE-CMR fibrosis grade and the electrophysiological substrate indexes such as "time to terminate AF" (Rho = 0.70, P = 0.0003), "RF duration until AF termination" (Rho = 0.65, P = 0.001), and a trend toward correlation with "CFAE area/LA surface" (Rho = 0.47, P = 0.03).
  
  
  CONCLUSIONS
  LA DE-CMR can predict increased difficulty of CFAE ablation in AF. This tool may be beneficial in both selection of patients and ablation strategy.
authors.affiliation: Institut Cardiovasculaire Paris Sud, Hôpital Privé Jacques Cartier, Massy, France. j.seitz@gsante.net
authors.forename: Julien
authors.initials: J
authors.lastname: Seitz
authors.forename: Jérôme
authors.initials: J
authors.lastname: Horvilleur
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lacotte
authors.forename: Darach
authors.initials: D
authors.lastname: O H-Ici
authors.forename: Yamina
authors.initials: Y
authors.lastname: Mouhoub
authors.forename: Alice
authors.initials: A
authors.lastname: Maltret
authors.forename: Fiorella
authors.initials: F
authors.lastname: Salerno
authors.forename: Darren
authors.initials: D
authors.lastname: Mylotte
authors.forename: Mehran
authors.initials: M
authors.lastname: Monchi
authors.forename: Jérôme
authors.initials: J
authors.lastname: Garot
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005355:Fibrosis; D006325:Heart Atria / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents