title: Atrial fibrillation ablation outcome is predicted by left atrial remodeling on MRI.
abstract: BACKGROUND
  Although catheter ablation therapy for atrial fibrillation (AF) is becoming more common, results vary widely, and patient selection criteria remain poorly defined. We hypothesized that late gadolinium enhancement MRI (LGE-MRI) can identify left atrial (LA) wall structural remodeling (SRM) and stratify patients who are likely or not to benefit from ablation therapy.
  
  
  RESULTS
  LGE-MRI was performed on 426 consecutive patients with AF without contraindications to MRI before undergoing their first ablation procedure and on 21 non-AF control subjects. Patients were categorized by SRM stage (I-IV) based on the percentage of LA wall enhancement for correlation with procedure outcomes. Histological validation of SRM was performed comparing LGE-MRI with surgical biopsy. A total of 386 patients (91%) with adequate LGE-MRI scans were included in the study. After ablation, 123 patients (31.9%) experienced recurrent atrial arrhythmias during the 1-year follow-up. Recurrent arrhythmias (failed ablations) occurred at higher SRM stages with 28 of 133 (21.0%) in stage I, 40 of 140 (29.3%) in stage II, 24 of 71 (33.8%) in stage III, and 30 of 42 (71.4%) in stage IV. In multivariate analysis, ablation outcome was best predicted by advanced SRM stage (hazard ratio, 4.89; P<0.0001) and diabetes mellitus (hazard ratio, 1.64; P=0.036), whereas increased LA volume and persistent AF were not significant predictors. LA wall enhancement was significantly greater in patients with AF versus non-AF controls (16.6±11.2% versus 3.1±1.9%; P<0.0001). Histological evidence of remodeling from surgical biopsy specimens correlated with SRM on LGE-MRI.
  
  
  CONCLUSIONS
  Atrial SRM is identified on LGE-MRI, and extensive LGE (≥30% LA wall enhancement) predicts poor response to catheter ablation therapy for AF.
authors.affiliation: Comprehensive Arrhythmia Research and Management Center, Division of Cardiology, Department of Surgery, Department of Radiology, Scientific Computing and Imaging Institute, Bioengineering, Department of Pathology, and Division of Epidemiology, University of Utah Health Sciences Center, Salt Lake City.
authors.forename: Christopher
authors.initials: C
authors.lastname: McGann
authors.forename: Nazem
authors.initials: N
authors.lastname: Akoum
authors.forename: Amit
authors.initials: A
authors.lastname: Patel
authors.forename: Eugene
authors.initials: E
authors.lastname: Kholmovski
authors.forename: Patricia
authors.initials: P
authors.lastname: Revelo
authors.forename: Kavitha
authors.initials: K
authors.lastname: Damal
authors.forename: Brent
authors.initials: B
authors.lastname: Wilson
authors.forename: Josh
authors.initials: J
authors.lastname: Cates
authors.forename: Alexis
authors.initials: A
authors.lastname: Harrison
authors.forename: Ravi
authors.initials: R
authors.lastname: Ranjan
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Burgon
authors.forename: Tom
authors.initials: T
authors.lastname: Greene
authors.forename: Dan
authors.initials: D
authors.lastname: Kim
authors.forename: Edward V R
authors.initials: EV
authors.lastname: Dibella
authors.forename: Dennis
authors.initials: D
authors.lastname: Parker
authors.forename: Rob S
authors.initials: RS
authors.lastname: Macleod
authors.forename: Nassir F
authors.initials: NF
authors.lastname: Marrouche
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D016279:Atrial Function, Left; D064752:Atrial Remodeling; D001706:Biopsy; D016022:Case-Control Studies; D017115:Catheter Ablation / Q000009:adverse effects; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D005355:Fibrosis; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives; D008875:Middle Aged; D015999:Multivariate Analysis; D009942:Organometallic Compounds; D018579:Patient Selection; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012008:Recurrence; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine
keywords: atrial remodeling; catheter ablation; magnetic resonance imaging