title: Ablation index, a novel marker of ablation lesion quality: prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values.
abstract: OBJECTIVE
  Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonary vein isolation (PVI), but does not incorporate power. Ablation Index (AI) is a novel lesion quality marker that utilizes contact force, time, and power in a weighted formula. Furthermore, only a single FTI target value has been suggested despite regional variation in left atrial wall thickness. We aimed to study AI's and FTI's relationships with PV reconnection at repeat electrophysiology study, and regional threshold values that predicted no reconnection.
  
  
  RESULTS
  Forty paroxysmal atrial fibrillation patients underwent contact force-guided PVI, and the minimum and mean AI and FTI values for each segment were identified according to a 12-segment model. All patients underwent repeat electrophysiology study at 2 months, regardless of symptoms, to identify sites of PV reconnection. Late PV reconnection was seen in 53 (11%) segments in 25 (62%) patients. Reconnected segments had significantly lower minimum AI [308 (252-336) vs. 373 (323-423), P < 0.0001] and FTI [137 (92-182) vs. 228 (157-334), P < 0.0001] compared with non-reconnected segments. Minimum AI and FTI were both independently predictive, but AI had a smaller P value. Higher minimum AI and FTI values were required to avoid reconnection in anterior/roof segments than for posterior/inferior segments (P < 0.0001). No reconnection was seen where the minimum AI value was ≥370 for posterior/inferior segments and ≥480 for anterior/roof segments.
  
  
  CONCLUSIONS
  The minimum AI value in a PVI segment is independently predictive of reconnection of that segment at repeat electrophysiology study. Higher AI and FTI values are required for anterior/roof segments than for posterior/inferior segments to prevent reconnection.
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.|Department of Cardiology, Freeman Hospital, Freeman Road, Newcastle upon Tyne NE7 7DN, UK.
authors.forename: Moloy
authors.initials: M
authors.lastname: Das
authors.affiliation: University of Liverpool, Liverpool L69 3BX, UK.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Loveday
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Wynn
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Sean
authors.initials: S
authors.lastname: Gomes
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Yawer
authors.initials: Y
authors.lastname: Saeed
authors.affiliation: University of Liverpool, Liverpool L69 3BX, UK.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Bonnett
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Johan E P
authors.initials: JEP
authors.lastname: Waktare
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Derick M
authors.initials: DM
authors.lastname: Todd
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Mark C S
authors.initials: MCS
authors.lastname: Hall
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Snowdon
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Modi
authors.affiliation: Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, UK.
authors.forename: Dhiraj
authors.initials: D
authors.lastname: Gupta
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D018780:Body Surface Potential Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011667:Pulmonary Veins / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: Atrial fibrillation; Catheter ablation; Impedance drop; Lesion quality; Pulmonary vein isolation