title: The association of pre-existing left atrial fibrosis with clinical variables in patients referred for catheter ablation of atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) recurrence after ablation is associated with left atrial (LA) fibrosis on late gadolinium enhanced (LGE) magnetic resonance imaging (MRI). We sought to determine pre-ablation, clinical characteristics that associate with the extent of LA fibrosis in patients undergoing catheter ablation for AF.
  
  
  RESULTS
  Consecutive patients presenting for catheter ablation of AF were enrolled and underwent LGE-MRI prior to initial AF ablation. The extent of fibrosis as a percentage of total LA myocardium was calculated in all patients prior to ablation. The cohort was divided into quartiles based on the percentage of fibrosis. Of 60 patients enrolled in the cohort, 13 had <5% fibrosis (Group 1), 15 had 5-7% fibrosis (Group 2), 17 had 8-13% fibrosis (Group 3), and 15 had 14-36% fibrosis (Group 4). The extent of LA fibrosis was positively associated with time in continuous AF, and the presence of persistent or longstanding persistent AF. However, no statistically significant difference was observed in the presence of comorbid conditions, age, BMI, LA volume, or family history of AF among the four groups. After adjusting for diabetes and hypertension in a multivariable linear regression model, paroxysmal AF remained independently and negatively associated with the extent of fibrosis (-4.0 ± 1.8, P = 0.034).
  
  
  CONCLUSIONS
  The extent of LA fibrosis in patients undergoing AF ablation is associated with AF type and time in continuous AF. Our results suggest that the presence and duration of AF are primary determinants of increased atrial LGE.
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Jane
authors.initials: J
authors.lastname: Dewire
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Irfan M
authors.initials: IM
authors.lastname: Khurram
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD.
authors.forename: Farhad
authors.initials: F
authors.lastname: Pashakhanloo
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: David
authors.initials: D
authors.lastname: Spragg
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Marine
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ashikaga
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: John
authors.initials: J
authors.lastname: Rickard
authors.affiliation: Department of Radiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Stefan L
authors.initials: SL
authors.lastname: Zimmerman
authors.affiliation: Department of Biostatistics, Johns Hopkins University, Baltimore, MD.
authors.forename: Vadim
authors.initials: V
authors.lastname: Zipunnikov
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.affiliation: Division of Cardiology, Johns Hopkins University, Baltimore, MD. ; Department of Epidemiology, Johns Hopkins University, Baltimore, MD.
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
keywords: MRI; atrial fibrillation; fibrosis