title: Recovery of mitral isthmus conduction leads to the development of macro-reentrant tachycardia after left atrial linear ablation for atrial fibrillation.
abstract: BACKGROUND
  Left atrial linear ablation for atrial fibrillation (AF) may be proarrhythmic, leading to left atrial macro-reentrant tachycardia (LAT). Whether due to failure to achieve block initially or to recovery of conduction after ablation is unknown. This study was designed to evaluate the frequency of recovery of mitral isthmus (MI) conduction compared with cavo-tricuspid isthmus (CTI) conduction, and the relationship between recovery of MI conduction and postablation LAT.
  
  
  RESULTS
  Of 163 patients with AF who underwent circumferential pulmonary vein ablation plus left atrial linear ablation, in whom MI and CTI ablation produced bidirectional conduction block, 52 underwent repeat ablation for recurrent atrial arrhythmias (AF or LAT). Of these 52 patients, coronary sinus ablation was required in 48 to achieve bidirectional MI block at the index ablation. During repeat ablation, MI and CTI conduction was assessed in sinus rhythm. At repeat ablation, MI conduction had recovered in 38 of 52 patients, as compared with CTI conduction which recovered in only 12 of 52 patients (P=0.001). At repeat ablation, the recurrent clinical arrhythmia in 12 patients was MI-dependent LAT. Recovery of MI conduction was associated with development of MI-dependent LAT (P=0.01).
  
  
  CONCLUSIONS
  Despite using bidirectional conduction block as a procedural end point, recovery of MI conduction is common and may lead to LAT after left atrial linear ablation for AF. The reason for greater recovery of MI versus CTI conduction is unknown but could be due to differences in isthmus anatomy or lower power used for ablation in the left versus right atrium.
authors.affiliation: Division of Cardiology, and Cardiac Electrophysiology Program, University of California, San Diego, School of Medicine, San Diego, CA 92103-8649, USA. navinsawhney@gmail.com
authors.forename: Navinder
authors.initials: N
authors.lastname: Sawhney
authors.forename: Kislay
authors.initials: K
authors.lastname: Anand
authors.forename: Clare E
authors.initials: CE
authors.lastname: Robertson
authors.forename: Taylor
authors.initials: T
authors.lastname: Wurdeman
authors.forename: Ramtin
authors.initials: R
authors.lastname: Anousheh
authors.forename: Gregory K
authors.initials: GK
authors.lastname: Feld
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D002140:California; D017115:Catheter Ablation / Q000009:adverse effects*; D016009:Chi-Square Distribution; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000503:physiopathology / Q000601:surgery; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000503:physiopathology / Q000601:surgery*; D020127:Recovery of Function; D012008:Recurrence; D012086:Reoperation; D012189:Retrospective Studies; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome