title: Atrial fibrosis quantified using late gadolinium enhancement MRI is associated with sinus node dysfunction requiring pacemaker implant.
abstract: BACKGROUND
  Sinus node dysfunction (SND) commonly manifests with atrial arrhythmias alternating with sinus pauses and sinus bradycardia. The underlying process is thought to be because of atrial fibrosis. We assessed the value of atrial fibrosis, quantified using late gadolinium enhanced-MRI (LGE-MRI), in predicting significant SND requiring pacemaker implant.
  
  
  METHODS
  Three hundred forty-four patients with atrial fibrillation (AF) presenting for catheter ablation underwent LGE-MRI. Left atrial (LA) fibrosis was quantified in all patients and right atrial (RA) fibrosis in 134 patients. All patients underwent catheter ablation with pulmonary vein isolation with posterior wall and septal debulking. Patients were followed prospectively for 329 ± 245 days. Ambulatory monitoring was instituted every 3 months. Symptomatic pauses and bradycardia were treated with pacemaker implantation per published guidelines.
  
  
  RESULTS
  The average patient age was 65 ± 12 years. The average wall fibrosis was 16.7 ± 11.1% in the LA, and 5.3 ± 6.4% in the RA. RA fibrosis was correlated with LA fibrosis (R(2) = 0.26; P < 0.01). Patients were divided into 4 stages of LA fibrosis (Utah I: <5%, Utah II: 5-20%, Utah III: 20-35%, Utah IV: >35%). Twenty-two patients (mean atrial fibrosis, 23.9%) required pacemaker implantation during follow-up. Univariate and multivariate analysis identified LA fibrosis stage (OR, 2.2) as a significant predictor for pacemaker implantation with an area under the curve of 0.704.
  
  
  CONCLUSIONS
  In patients with AF presenting for catheter ablation, LGE-MRI quantification of atrial fibrosis demonstrates preferential LA involvement. Significant atrial fibrosis is associated with clinically significant SND requiring pacemaker implantation.
authors.affiliation: Comprehensive Arrhythmia Research and Management (CARMA) Center, University of Utah, Salt Lake City, Utah, USA. nazem.akoum@hsc.utah.edu
authors.forename: Nazem
authors.initials: N
authors.lastname: Akoum
authors.forename: Christopher
authors.initials: C
authors.lastname: McGann
authors.forename: Gaston
authors.initials: G
authors.lastname: Vergara
authors.forename: Troy
authors.initials: T
authors.lastname: Badger
authors.forename: Ravi
authors.initials: R
authors.lastname: Ranjan
authors.forename: Christian
authors.initials: C
authors.lastname: Mahnkopf
authors.forename: Eugene
authors.initials: E
authors.lastname: Kholmovski
authors.forename: Rob
authors.initials: R
authors.lastname: Macleod
authors.forename: Nassir
authors.initials: N
authors.lastname: Marrouche
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000150:complications* / Q000473:pathology / Q000601:surgery; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D005355:Fibrosis; D006325:Heart Atria / Q000473:pathology* / Q000601:surgery; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives*; D008875:Middle Aged; D016017:Odds Ratio; D009942:Organometallic Compounds; D010138:Pacemaker, Artificial; D011237:Predictive Value of Tests; D012008:Recurrence; D018570:Risk Assessment; D012307:Risk Factors; D012804:Sick Sinus Syndrome / Q000209:etiology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D014589:Utah
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine