title: Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: implications for disease progression and response to catheter ablation.
abstract: BACKGROUND
  Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease.
  
  
  OBJECTIVE
  This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities.
  
  
  METHODS
  Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (≤5% LA wall enhancement), Utah II (>5% to ≤20%), Utah III (>20% to ≤35%), or Utah IV (>35%).
  
  
  RESULTS
  Distribution in Utah I to IV was comparable in patients with lone AF and non-lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 ± 8.94 vs. 16.94 ± 11.37) was not significantly different between the 2 groups (P = .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non-lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P < .001).
  
  
  CONCLUSIONS
  The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.
authors.affiliation: Comprehensive Arrhythmia and Research Management (CARMA) Center, University of Utah School of Medicine, Salt Lake City, Utah, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Mahnkopf
authors.forename: Troy J
authors.initials: TJ
authors.lastname: Badger
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Burgon
authors.forename: Marcos
authors.initials: M
authors.lastname: Daccarett
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Haslam
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Badger
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: McGann
authors.forename: Nazem
authors.initials: N
authors.lastname: Akoum
authors.forename: Eugene
authors.initials: E
authors.lastname: Kholmovski
authors.forename: Rob S
authors.initials: RS
authors.lastname: Macleod
authors.forename: Nassir F
authors.initials: NF
authors.lastname: Marrouche
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000473:pathology* / Q000601:surgery; D017115:Catheter Ablation; D003287:Contrast Media; D018450:Disease Progression; D005260:Female; D006325:Heart Atria / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged
chemical_list: D003287:Contrast Media