title: CMR-guided approach to localize and ablate gaps in repeat AF ablation procedure.
abstract: OBJECTIVE
  The aim of this study was to test the feasibility and usefulness of a new delayed-enhancement cardiac magnetic resonance (DE-CMR)-guided approach to ablate gaps in redo procedures.
  
  
  BACKGROUND
  Recurrences of atrial fibrillation (AF) after pulmonary vein isolation (PVI) may be related to gaps at the ablation lines. DE-CMR allows identification of radiofrequency lesions and gaps (CMR gaps).
  
  
  METHODS
  Fifteen patients undergoing repeated AF ablations were included (prior procedure was PVI in all patients and roof-line ablation in 8 patients). Pre-procedure 3-dimensional (3D) DE-CMR was performed with a respiratory-navigated (free-breathing) and electrocardiographically gated inversion-recovery gradient-echo sequence (voxel size 1.25 × 1.25 × 2.5 mm). Endocardium and epicardium were manually segmented to create a 3D reconstruction (DE-CMR model). A pixel signal intensity map was projected on the DE-CMR model and color-coded (thresholds 40 ± 5% and 60 ± 5% of maximum intensity). The DE-CMR model was imported into the navigation system to guide the ablation of CMR gaps, with the operator blinded to electrical data. Fifteen conventional procedures were used as controls to compare procedural duration, radiofrequency, and fluoroscopy times.
  
  
  RESULTS
  Fifteen patients (56 pulmonary veins [PVs]; 57 ± 8 years of age; 9 with paroxysmal AF) were analyzed. In total, 67 CMR gaps were identified around PVs (mean 4.47 gaps/patient; median length 13.33 mm/gap) and 9 at roof line. All of the electrically reconnected PVs (87.5%) had CMR gaps. The site of electrical PV reconnection (assessed by circular mapping catheter) matched with a CMR gap in 79% of PVs. CMR-guided ablation led to reisolation of 95.6% of reconnected PVs (median radiofrequency time of 13.3 [interquartile range: 7.5 to 21.7] min/patient) and conduction block through the roof line in all patients (1.4 [interquartile range: 0.7 to 3.1] min/patient). Compared with controls, the CMR-guided approach shortened radiofrequency time (1,441 ± 915 s vs. 930 ± 662 s; p = 0.026) but not the procedural duration or fluoroscopy time.
  
  
  CONCLUSIONS
  DE-CMR can successfully guide repeated PVI procedures by accurately identifying and localizing gaps and may reduce procedural duration and radiofrequency application time.
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Bisbal
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Guiu
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Cabanas-Grandío
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain. Electronic address: berruezo@clinic.ub.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Berruezo
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Prat-Gonzalez
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Bárbara
authors.initials: B
authors.lastname: Vidal
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Cesar
authors.initials: C
authors.lastname: Garrido
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Andreu
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Fernandez-Armenta
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Jose María
authors.initials: JM
authors.lastname: Tolosana
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Arbelo
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Teresa M
authors.initials: TM
authors.lastname: de Caralt
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Rosario J
authors.initials: RJ
authors.lastname: Perea
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Brugada
authors.affiliation: Unitat de Fibrilació Auricular, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Mont
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012086:Reoperation
keywords: atrial fibrillation; catheter ablation; delayed-enhancement; gaps; magnetic resonance imaging