Background: The IMPACT study established the role of esophageal temperature control in preventing esophageal injury during radiofrequency (RF) ablation for atrial fibrillation (AF). The procedures were performed using Ablation Index (AI) technology.
Objective: To determine the effect of esophageal cooling on the formation of RF lesions and the characteristics of RF lesions associated with esophageal injury.
Methods: Participants in the IMPACT trial underwent AF ablation guided by AI (30W at 350-400 AI posteriorly, 40W at ≥450 AI anteriorly). A blinded 1:1 randomisation assigned patients to the use of the ensoETM® device to keep esophageal temperature at 4°C during ablation or standard practice using a single-sensor temperature probe. Endoscopic evaluation occurred 7 days post ablation. Ablation parameters and short-term outcomes were analysed.
Results: We recruited 188 patients. Procedure and fluoroscopy times were similar, and all pulmonary veins were isolated. First pass pulmonary vein isolation and reconnection at the end of the waiting period were similar in both randomized groups (51/64 vs 51/68; p=0.54 and 5/64 vs 7/68; p=0.76, respectively). Posterior wall isolation was also similar: 24/33 vs 27/38; p=0.88. Ablation effect on tissue, measured in impedance drop, was no different between the 2 randomized groups: 8.6Ω (IQR: 6-11.8) vs 8.76Ω (IQR: 6-12.2) p=0.25. Thermal injury was significantly less common in the randomized group receiving oesophageal protection (p<0.008). Ablation characteristics of cases with thermal injury were similar to those without thermal injury, with no difference in RF duration, maximum power or impedance drop (p=0.08-0.69). A smaller proportion of ablation index values >500 was located at posterior left atrial sites compared to cases with no thermal injury (32.3% vs 78.4%; p<0.001). Arrhythmia recurrence was similar at the 6-month follow up (4.5% vs 6.1%; p=0.75).
Conclusions: Esophageal cooling has been shown to be effective in reducing ablation-related thermal injury during RF ablation. AI data confirm that this protection does not make it any more difficult to achieve standard procedural endpoints, or to obtain clinical success in the short term.