title: Inverse relationship between fractionated electrograms and atrial fibrosis in persistent atrial fibrillation: combined magnetic resonance imaging and high-density mapping.
abstract: OBJECTIVE
  This study sought to evaluate the relationship between fibrosis imaged by delayed-enhancement (DE) magnetic resonance imaging (MRI) and atrial electrograms (Egms) in persistent atrial fibrillation (AF).
  
  
  BACKGROUND
  Atrial fractionated Egms are strongly related to slow anisotropic conduction. Their relationship to atrial fibrosis has not yet been investigated.
  
  
  METHODS
  Atrial high-resolution MRI of 18 patients with persistent AF (11 long-lasting persistent AF) was registered with mapping geometry (NavX electro-anatomical system (version 8.0, St. Jude Medical, St. Paul, Minnesota)). DE areas were categorized as dense or patchy, depending on their DE content. Left atrial Egms during AF were acquired using a high-density, 20-pole catheter (514 ± 77 sites/map). Fractionation, organization/regularity, local mean cycle length (CL), and voltage were analyzed with regard to DE.
  
  
  RESULTS
  Patients with long-lasting persistent versus persistent AF had larger left atrial (LA) surface area (134 ± 38 cm(2) vs. 98 ± 9 cm(2), p = 0.02), a higher amount of atrial DE (70 ± 16 cm(2) vs. 49 ± 10 cm(2), p = 0.01), more complex fractionated atrial Egm (CFAE) extent (54 ± 16 cm(2) vs. 28 ± 15 cm(2), p = 0.02), and a shorter baseline AF CL (147 ± 10 ms vs. 182 ± 14 ms, p = 0.01). Continuous CFAE (CFEmean [NavX algorithm that quantifies Egm fractionation] <80 ms) occupied 38 ± 19% of total LA surface area. Dense DE was detected at the left posterior left atrium. In contrast, the right posterior left atrium contained predominantly patchy DE. Most CFAE (48 ± 14%) occurred at non-DE LA sites, followed by 41 ± 12% CFAE at patchy DE and 11 ± 6% at dense DE regions (p = 0.005 and p = 0.008, respectively); 19 ± 6% CFAE sites occurred at border zones of dense DE. Egms were less fractionated, with longer CL and lower voltage at dense DE versus non-DE regions: CFEmean: 97 ms versus 76 ms, p < 0.0001; local CL: 153 ms versus 143 ms, p < 0.0001; mean voltage: 0.63 mV versus 0.86 mV, p < 0.0001.
  
  
  CONCLUSIONS
  Atrial fibrosis as defined by DE MRI is associated with slower and more organized electrical activity but with lower voltage than healthy atrial areas. Ninety percent of continuous CFAE sites occur at non-DE and patchy DE LA sites. These findings are important when choosing the ablation strategy in persistent AF.
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque and the Université Victor Segalen Bordeaux II, Bordeaux, France. amir.s.jadidi@gmail.com
authors.forename: Amir S
authors.initials: AS
authors.lastname: Jadidi
authors.forename: Hubert
authors.initials: H
authors.lastname: Cochet
authors.forename: Ashok J
authors.initials: AJ
authors.lastname: Shah
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kim
authors.forename: Edward
authors.initials: E
authors.lastname: Duncan
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Maxime
authors.initials: M
authors.lastname: Sermesant
authors.forename: Heiko
authors.initials: H
authors.lastname: Lehrmann
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lederlin
authors.forename: Nick
authors.initials: N
authors.lastname: Linton
authors.forename: Andrei
authors.initials: A
authors.lastname: Forclaz
authors.forename: Isabelle
authors.initials: I
authors.lastname: Nault
authors.forename: Lena
authors.initials: L
authors.lastname: Rivard
authors.forename: Matthew
authors.initials: M
authors.lastname: Wright
authors.forename: Xingpeng
authors.initials: X
authors.lastname: Liu
authors.forename: Daniel
authors.initials: D
authors.lastname: Scherr
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Wilton
authors.forename: Laurent
authors.initials: L
authors.lastname: Roten
authors.forename: Patrizio
authors.initials: P
authors.lastname: Pascale
authors.forename: Nicolas
authors.initials: N
authors.lastname: Derval
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sacher
authors.forename: Sebastien
authors.initials: S
authors.lastname: Knecht
authors.forename: Cornelius
authors.initials: C
authors.lastname: Keyl
authors.forename: Mélèze
authors.initials: M
authors.lastname: Hocini
authors.forename: Michel
authors.initials: M
authors.lastname: Montaudon
authors.forename: Francois
authors.initials: F
authors.lastname: Laurent
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
authors.forename: Pierre
authors.initials: P
authors.lastname: Jaïs
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005355:Fibrosis; D006325:Heart Atria / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
keywords: AF; CFAE; CFEmean; CL; CS; DE; Egm; LA; MRI; NavX algorithm that quantifies electrogram fractionation; PV; PVI; aDE; ablation; atrial delayed enhancement; atrial fibrillation; atrial fibrosis; complex fractionated atrial electrogram; coronary sinus; cycle length; delayed enhancement; electrogram; left atrial; magnetic resonance imaging; pulmonary vein; pulmonary vein isolation