Energy titration strategies with the endoscopic ablation system: lessons from the high-dose vs. low-dose laser ablation study.
AIMS
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.


METHODS AND 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.


CONCLUSION
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.