Esophageal Cooling For Protection During Left Atrial Ablation: A Systematic Review And Meta- Analysis

Background Thermal damage to the esophagus is a risk from radiofrequency (RF) ablation of the left atrium for the treatment of atrial fibrillation (AF), with the most extreme type of thermal injury resulting in atrio-esophageal fistula (AEF), with a correspondingly high mortality rate. Various approaches have been developed to reduce esophageal injury, including power reduction, avoidance of greater contact-force, esophageal deviation, and esophageal cooling. One method of esophageal cooling involves direct instillation of cold water or saline into the esophagus during RF ablation. Although this method provides limited heat-extraction capacity, studies of it have suggested potential benefit. Objective We sought to perform a meta-analysis of existing studies evaluating esophageal cooling via direct liquid instillation for the reduction of thermal injury. Methods We reviewed Medline for existing studies involving esophageal cooling for protection of thermal injury during RF ablation. A meta-analysis was then performed using random effects model to calculate estimated effect size with 95% confidence intervals, with outcome of esophageal lesions, stratified by severity, as determined by post-procedure endoscopy. Results A total of 9 studies were identified and reviewed. After excluding pre-clinical and mathematical model studies, 3 were included in the meta-analysis, totaling 494 patients. Esophageal cooling showed a tendency to shift lesion severity downward, such that total lesions did not show a statistically significant change (OR 0.6, 95% CI 0.15 to 2.38). For high grade lesions, a significant OR of 0.39 (95% CI 0.17 to 0.89) in favor of esophageal cooling was found, suggesting that esophageal cooling, even utilizing a low-capacity thermal extraction technique, reduces lesion severity from RF ablation. Conclusions Esophageal cooling reduces lesion severity encountered during RF ablation, even when using relatively low heat extraction methods such as direct instillation of cold liquid. Further investigation of this approach is warranted.