title: Energy titration strategies with the endoscopic ablation system: lessons from the high-dose vs. low-dose laser ablation study.
abstract: OBJECTIVE
  To assess the effects of low-dose (LD) and high-dose (HD) ablation on acute and chronic success in patients with atrial fibrillation (AF). While the concept of visually guided pulmonary vein isolation (PVI) has been established little is known on energy titration using laser ablation.
  
  
  RESULTS
  In 60 patients with AF, PVI using the endoscopic ablation system (EAS) was performed in two groups. Visually guided ablation was carried out after obtaining optimal tissue contact with 5.5-8.5 W in the LD group and with >8.5 W in the HD group. Acute PVI after a single visually guided circular lesion set was achieved in 89% (HD) and 69% (LD), respectively, (P = 0.0004). In 70 and 39% of patients all PVs were isolated after a single ablation circle in the HD and LD group, respectively, (P = 0.009). After gap ablation all PVs were isolated with the EAS. More energy was deployed (6483 ± 1834 vs. 5306 ± 2258 Ws; P ≤ 0.0001) with less applications (31.6 ± 8 vs. 35.2 ± 15 applications per PV; P = 0.03) leading to shorter procedure times (128 ± 17 vs. 154 ± 38 min; P = 0.001). During median follow-up of 311 days (261-346) recurrence rate was 17 and 40% in the HD and LD group, respectively. In both groups one phrenic nerve palsy was observed.
  
  
  CONCLUSIONS
  For the first time, it was demonstrated that high ablation power affects acute and chronic outcomes. High-dose laser balloon ablation allows for an acute PVI rate of 89% solely by visually guided circular ablation and is associated with a chronic success rate of 83% after a single procedure.
authors.affiliation: Cardioangiologisches Centrum Bethanien, Markus-Krankenhaus, Wilhelm-Epstein Str. 4, Frankfurt/M., Germany.
authors.forename: Stefano
authors.initials: S
authors.lastname: Bordignon
authors.forename: Kyoung-Ryul Julian
authors.initials: KR
authors.lastname: Chun
authors.forename: Melanie
authors.initials: M
authors.lastname: Gunawardene
authors.forename: Verena
authors.initials: V
authors.lastname: Urban
authors.forename: Mehmet
authors.initials: M
authors.lastname: Kulikoglu
authors.forename: Kristin
authors.initials: K
authors.lastname: Miehm
authors.forename: Beate
authors.initials: B
authors.lastname: Brzank
authors.forename: Britta
authors.initials: B
authors.lastname: Schulte-Hahn
authors.forename: Bernd
authors.initials: B
authors.lastname: Nowak
authors.forename: Boris
authors.initials: B
authors.lastname: Schmidt
mesh_terms: D001281:Atrial Fibrillation / Q000473:pathology* / Q000601:surgery*; D006328:Cardiac Catheterization / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D004724:Endoscopy / Q000379:methods*; D004735:Energy Transfer; D005260:Female; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D016896:Treatment Outcome