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Impact pilot study: improving oesophageal protection during catheter ablation for AF. A double-blind randomized controlled trial.


Can a cooling device protect the oesophagus from ablation-related injury?

Yes! That is the key finding of a trial led by Doctor Mark Gallagher (St. George's University of London, UK).

Thermal damage to the oesophagus is a serious complication of atrial fibrillation (AF) ablation. As Dr. Gallagher explains, “Atrio-oesophageal fistula accounts for about 50% of the mortality associated with AF ablation. The risk of oesophageal injury is a real impediment to our ability to perform the procedure with maximum success. Previous methods for avoidance of injury have included reduced wattage and reduced contact force, which limit procedural effectiveness, and other methods such as proton pump inhibitors, displacement of the oesophagus and cooling with injections of small amounts of cold water, which are not satisfactory. EnsoETM® is a temperature-regulating device that is used to control a patient’s whole-body temperature in the operating room, emergency room, intensive care unit. etc. We investigated whether this device could be used to specifically modulate local oesophageal temperature and so protect it from thermal damage.”

The single-centre, prospective double-blind IMPACT PILOT study included 188 patients undergoing catheter ablation for AF or left atrial ablation for atrial tachycardia. They were randomised to either standard care (temperature monitoring probe only) or to the ensoETM device where temperature control was set to counteract any transmitted ablation energy (the oesophageal lumen was cooled to 4⁰C for radiofrequency ablation). During a follow-up endoscopy within 7 days of the ablation, assessments were made for thermal injury (epithelial damage or peri-oesophageal vagal plexus injury graded 0–6) and for gastroparesis (the presence of significant food residue despite >6 hours of fasting), and patient symptoms were recorded.

[Call out: Among the 120 patients who underwent endoscopy, thermal injury was significantly more common in the control group than in those protected by the ensoETM device (12/60 vs. 2/60; p=0.008), with a trend towards a reduction in gastroparesis (6/60 vs. 2/60; p=0.27).]

There was no difference between groups in radiofrequency duration, force, power and combined ablation index (p-value range, 0.2–0.9), or in the procedure duration or fluoroscopy duration (p=0.97 and p=0.91, respectively).

Dr. Gallagher is so impressed with these findings that he is now using the device for all routine AF ablation procedures where possible. He says, “I think this is a really major breakthrough for AF ablation because if we can eliminate thermal injury as a complication, it makes ablation overwhelmingly safer than pharmacological treatment for AF. We are now planning a larger multi-centre trial, which will have a similar design as the pilot study, to establish if the thermal-protection effect can be replicated at other centres.”