title: Initial experience with magnetic resonance imaging of atrial scar and co-registration with electroanatomic voltage mapping during atrial fibrillation: success and limitations.
abstract: BACKGROUND
  Ablation for atrial fibrillation (AF) frequently requires multiple procedures to achieve durable restoration of sinus rhythm. Early studies have suggested that delayed enhancement magnetic resonance imaging (DE-MRI) of the left atrium (LA) can assist in performing repeat ablation procedures.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the utility of DE-MRI in delineating regions of LA low voltage and PV reconnection sites in patients undergoing repeat PV isolation for recurrent AF.
  
  
  METHODS
  We enrolled 10 patients undergoing repeat ablation for AF recurrence to undergo preprocedural DE-MRI of the LA in conjunction with high-density voltage mapping (>100 sites) of the LA during the ablation procedure. LA wall regions with hyperenhancement were segmented from DE-MRI images and retrospectively co-registered with the electroanatomic LA map. The association between scar on DE-MRI images and low-voltage regions of the LA was assessed, as was the association between scar gaps and electrogram-determined PV reconnection sites.
  
  
  RESULTS
  Ten patients underwent successful DE-MRI imaging and repeat AF ablation without complication. In all 10 patients, the majority of PVs were found to have regained electrical continuity with the LA (30/37 PVs electrically active); all patients underwent successful reisolation of all PVs using standard ablation techniques. There was a significant association between scar identified by DE-MRI and low-voltage regions of the LA (-0.7±0.1 mV in scar regions; generalized estimating equations model clustered by patient, P<.001). However, there was no association between scar gaps and PV reconnection sites.
  
  
  CONCLUSIONS
  We demonstrate the co-registration of DE-MRI scar imaging and electroanatomic LA mapping, with agreement between regions of scar on DE-MRI and low voltage by mapping. However, at our center, this technique did not provide accurate information on the location of PV reconnection sites in patients undergoing repeat ablation for AF.
authors.affiliation: Division of Cardiology, Johns Hopkins Hospital, Baltimore, Maryland, USA. dspragg1@jhmi.edu
authors.forename: David D
authors.initials: DD
authors.lastname: Spragg
authors.forename: Irfan
authors.initials: I
authors.lastname: Khurram
authors.forename: Stefan L
authors.initials: SL
authors.lastname: Zimmerman
authors.forename: Hirad
authors.initials: H
authors.lastname: Yarmohammadi
authors.forename: Bernie
authors.initials: B
authors.lastname: Barcelon
authors.forename: Matthew
authors.initials: M
authors.lastname: Needleman
authors.forename: David
authors.initials: D
authors.lastname: Edwards
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Marine
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation; D002921:Cicatrix / Q000209:etiology / Q000473:pathology*; D005260:Female; D006325:Heart Atria / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome