title: Comparison of preexisting and ablation-induced late gadolinium enhancement on left atrial magnetic resonance imaging.
abstract: BACKGROUND
  Postablation atrial fibrillation recurrence is positively associated with the extent of preexisting left atrial (LA) late gadolinium enhancement (LGE) on magnetic resonance imaging (MRI), but negatively associated with the extent of postablation LGE regardless of proximity to the pulmonary vein antra. The characteristics of pre- vs postablation LA LGE may provide insight into this seeming paradox and inform future strategies for ablation.
  
  
  OBJECTIVE
  The purpose of this study was to define the characteristics of preexisting vs ablation-induced LA LGE.
  
  
  METHODS
  LGE-MRI was prospectively performed before and ≥3 months after initial ablation in 20 patients. The intracardiac locations of ablation points were coregistered with the corresponding sites on axial planes of postablation LGE-MRI. The image intensity ratio (IIR), defined as the LA myocardial MRI signal intensity divided by the mean LA blood pool intensity, and LA myocardial wall thickness were calculated on pre- and postablation images.
  
  
  RESULTS
  Imaging data from 409 pairs of pre- and postablation axial LGE-MRI planes and 6961 pairs of pre- and postablation image sectors were analyzed. Ablation-induced LGE revealed a higher IIR, suggesting greater contrast uptake and denser fibrosis, than did preexisting LGE (1.25 ± 0.25 vs 1.14 ± 0.15; P < .001). In addition, ablation-induced LGE regions had thinner LA myocardium (2.10 ± 0.67 mm vs 2.37 ± 0.74 mm; P < .001).
  
  
  CONCLUSIONS
  Regions with ablation-induced LGE exhibit increased contrast uptake, likely signifying higher scar density, and thinner myocardium as compared with regions with preexisting LGE. Future studies examining the association of postablation LGE intensity and nonuniformity with ablation success are warranted and may inform strategies to optimize ablation outcome.
authors.affiliation: Division of Cardiology.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fukumoto
authors.affiliation: Division of Cardiology.
authors.forename: Mohammadali
authors.initials: M
authors.lastname: Habibi
authors.affiliation: Division of Cardiology.
authors.forename: Esra
authors.initials: E
authors.lastname: Gucuk Ipek
authors.affiliation: Division of Cardiology.
authors.forename: Irfan M
authors.initials: IM
authors.lastname: Khurram
authors.affiliation: Department of Radiology.
authors.forename: Stefan L
authors.initials: SL
authors.lastname: Zimmerman
authors.affiliation: Department of Biostatistics.
authors.forename: Vadim
authors.initials: V
authors.lastname: Zipunnikov
authors.affiliation: Division of Cardiology.
authors.forename: David D
authors.initials: DD
authors.lastname: Spragg
authors.affiliation: Division of Cardiology.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ashikaga
authors.affiliation: Division of Cardiology.
authors.forename: John
authors.initials: J
authors.lastname: Rickard
authors.affiliation: Division of Cardiology.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Marine
authors.affiliation: Division of Cardiology.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
authors.affiliation: Division of Cardiology.
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.affiliation: Division of Cardiology; Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland. Electronic address: snazarian@jhmi.edu.
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000601:surgery; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D002921:Cicatrix / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005682:Gadolinium / Q000494:pharmacology*; D006325:Heart Atria / Q000473:pathology*; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000494:pharmacology; D012008:Recurrence; D015203:Reproducibility of Results
chemical_list: D019275:Radiopharmaceuticals; D005682:Gadolinium
keywords: Atrial fibrillation; Catheter ablation; Fibrosis; Late gadolinium enhancement; MRI