Introduction:
Left atrial (LA) ablation using radiofrequency (RF) is a well established treatment for patients with atrial fibrillation (AF). The aim of the study was to compare ablation data and procedural safety with a special focus on esophageal safety between contact force only guided ablation (CFG), ablation index guided low power ablation (AIG) and AI guided high power short duration ablation (AI-HPSD) for a voltage guided strategy.

Methods:
Clinical data from 76 consecutive patients undergoing ablation with 50 W AI-HPSD in whom both pulmonary vein isolation (PVI) and voltage-guided ablation were performed was compared with AIG (n=100) and CFG (n=100). AI targets were >500 anteriorly and > 350 to 400 posteriorly. Periprocedural parameters including posterior ablation characteristics and complications were analyzed. Upper endoscopy was performed one to three days after ablation.

Results:
Baseline characteristics were comparable in all three groups (see table 1). Procedure duration (including waiting time) was significantly shorter for AI-HPSD (AI-HPSD 138±39 min vs. 193±59min in AIG; p<0.001 and 205±60 min in CFG; p<0.001). Fluoroscopy time was also significanly shorter for HPSD group (AI-HPSD 7.7±5.3 min vs. 9.8±5.2min in AIG; p=0.01 vs. CFG 9.6±2.9 min; p=0.009).

Posterior ablation data showed that AI Max and AI Min values were less extreme in AI-HPSD and AIG versus CFG ablation. AI Max were 508±41 and 496±54 vs. 530±61; p<0.008 (CFG vs. AI-HPSD) and p=0.001 (CFG vs. AIG). AI Min were 392±49 (AI-HPSD) and 276±69 (AIG) vs. 226±58 (CFG); p<0.01 (CFG vs. AI-HPSD) and p<0.01 (CFG vs. AIG). Total posterior RF time was 4.5±1.6min for AI-HPSD and 11.9±5min for AIG vs. 15.1±5.5 min for CFG; p<0.001 (CFG vs. AI-HPSD); p<0.001 (CFG vs. AIG). Mean posterior impedance drop was significantly higher in AI-HPSD group with 8.5±2.1 vs. 7.6±2.4; p 0.02 in CFG and 7.8±2.5; p 0.05 in AIG.

Major complications occurred in 4% in each of the groups. Endoscopically detected thermal esophageal lesions (EDEL) occurred in 2.6% and 5% versus 6% (n.s.) in AI-HPSD and AIG versus CFG.

Conclusions:
AI-HPSD and AIG ablation resulted in more homogeneous lesion application at posterior wall. Although mean posterior impedance drop was higher in AI-HPSD ablation, EDEL rate was numerically lowest. Altogether, all three ablation methods showed comparable safety.



Table 1: Baseline and procedural characteristics