title: Impact of stepwise ablation on the biatrial substrate in patients with persistent atrial fibrillation and heart failure.
abstract: BACKGROUND
  Ablation of persistent atrial fibrillation can be challenging, often involving not only pulmonary vein isolation (PVI) but also additional linear lesions and ablation of complex fractionated electrograms (CFE). We examined the impact of stepwise ablation on a human model of advanced atrial substrate of persistent atrial fibrillation in heart failure.
  
  
  RESULTS
  In 30 patients with persistent atrial fibrillation and left ventricular ejection fraction ≤35%, high-density CFE maps were recorded biatrially at baseline, in the left atrium (LA) after PVI and linear lesions (roof and mitral isthmus), and biatrially after LA CFE ablation. Surface area of CFE (mean cycle length ≤120 ms) remote to PVI and linear lesions, defined as CFE area, was reduced after PVI (18.3±12.03 to 10.2±7.1 cm(2); P<0.001) and again after linear lesions (7.7±6.5 cm(2); P=0.006). Complete mitral isthmus block predicted greater CFE reduction (P=0.02). Right atrial CFE area was reduced by LA ablation, from 25.9±14.1 to 12.9±11.8 cm(2) (P<0.001). Estimated 1-year arrhythmia-free survival was 72% after a single procedure. Incomplete linear lesion block was an independent predictor of arrhythmia recurrence (hazard ratio, 4.69; 95% confidence interval, 1.05-21.06; P=0.04).
  
  
  CONCLUSIONS
  Remote LA CFE area was progressively reduced following PVI and linear lesions, and LA ablation reduced right atrial CFE area. Reduction of CFE area at sites remote from ablation would suggest either regression of the advanced atrial substrate or that these CFE were functional phenomena. Nevertheless, in an advanced atrial fibrillation substrate, linear lesions after PVI diminished the target area for CFE ablation, and complete lesions resulted in a favorable clinical outcome.
authors.affiliation: Heart Rhythm Centre and NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, Imperial College London, United Kingdom.
authors.forename: David G
authors.initials: DG
authors.lastname: Jones
authors.forename: Shouvik K
authors.initials: SK
authors.lastname: Haldar
authors.forename: Julian W E
authors.initials: JW
authors.lastname: Jarman
authors.forename: Sofian
authors.initials: S
authors.lastname: Johar
authors.forename: Wajid
authors.initials: W
authors.lastname: Hussain
authors.forename: Vias
authors.initials: V
authors.lastname: Markides
authors.forename: Tom
authors.initials: T
authors.lastname: Wong
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D018572:Disease-Free Survival; D015716:Electrocardiography, Ambulatory; D022062:Electrophysiologic Techniques, Cardiac; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D016015:Logistic Models; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011667:Pulmonary Veins / Q000503:physiopathology / Q000601:surgery; D012008:Recurrence; D012307:Risk Factors; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left
keywords: ablation; atrial fibrillation; complex fractionated electrograms; heart failure; mapping