NATIONAL HARBOR, MD. – Thermal injury of a patient’s esophagus during radiofrequency catheter ablation of atrial fibrillation is notorious as a relatively common and problematic complication of the procedure, but two new approaches showed promise for substantially cutting the risk of esophageal thermal injury and the potential for the most severe damage: perforation.
One of these innovations is intensive esophageal cooling with a commercially marketed, fluid-chilled catheter placed in a patient’s esophagus during radiofrequency catheter ablation that keeps the inner surface of the esophagus at 4°C. This approach cut the incidence of periprocedural episodes of endoscopically detected esophageal thermal injury from 20% among controls to 3% in patients who had esophageal cooling in a randomized study with 120 patients, Mark M. Gallagher, MD, said at the annual International AF Symposium. The same device can also maintain a temperature on the inner surface of the esophagus of 42 ° C in patients undergoing cryoablation of atrial fibrillation, noted Dr. Gallagher, a cardiac electrophysiologist at St. George’s University Hospitals in London.
A second approach to cutting esophageal damage focuses on modifying the energy delivery with a radiofrequency ablation method known as high-power short-duration (HPSD). As the name says, this strategy uses a relatively high level of radiofrequency energy, 50 watts in the reported experience, for the brief interval of about 7 seconds, ideally delivering an overall Ablation Index of at least 350 but below 360, said Thomas Deneke, MD, an electrophysiologist, professor, and cochief of cardiology at the Heart Center in Bad Neustadt, Germany.
Dr. Deneke and his associates in Bad Neustadt began using this HPSD approach in mid-2019, and by early 2020 they had data from 179 patients who underwent first-time catheter ablation of atrial fibrillation (AFib), all of whom had undergone routine esophageal endoscopy 1-3 days after their treatment. Eight patients (4%) showed evidence of endoscopically detected esophageal lesions (EDEL), including three patients (2%) with an actual esophageal ulcer, and one (0.6%) who developed a perforation that healed after 52 days, Dr. Deneke reported. An additional 55 patients underwent a redo catheter ablation procedure using the HPSD method during this period, and in that group follow-up endoscopy in all patients showed EDEL in two patients (4%). In contrast, during Jan. 2012–May 2019, the same German center treated 2,102 patients who had a first radiofrequency catheter ablation using convention energy levels and treatment times, which resulted in 291 patients having an EDEL (14%), including 94 (4%) with an ulcer, and six patients (0.3%) with an esophageal perforation, he said.
His center’s recent safety experience with HPSD radiofrequncy ablation, compared with the historical controls, suggests that this technique can produce a substantial reduction in esophageal thermal injury, but HPSD has not completely eliminated the risk and hence there is need for continued alertness for this potential complication Dr. Deneke concluded. The HPSD method is also limited by having “a very narrow window” between efficacy at an Ablation Index of 350 and safety when the index remains below 360, he added.
The randomized study that Dr. Gallagher ran at St. George’s followed an analysis he and his associates recently published that suggested efficacy using esophageal cooling in prior reports when the data combined in a meta-analysis (J Interv Card Electrophysiol. 2019 Nov 22. doi: 10.1007/s10840-019-00661-5). They also concluded that the clinical setting required a temperature control device with an enhanced capacity for rapid cooling, which prior studies had lacked. So they turned to a Food and Drug Administration–approved catheter designed for placement in the esophagus for the purpose of either whole-body cooling or warming.
The study randomized a total of 187 patients, but collected follow-up endoscopy at 5-7 days after the ablation procedure on 120 patients, of whom 60 received esophageal cooling and 60 did not. The types of ablations performed on patients in the two study arms were similar, and use of esophageal cooling had no impact on treatment duration or efficacy, either acute and longer term, Dr. Gallagher reported.
Cooling had a marked and statistically significant impact on endoscopically detected thermal injury. Although two patients in the group that underwent cooling had injuries, in one of these cases the injury involved a protocol violation: Radiofrequency ablation mistakenly occurred after the cooling device shut off, and it was during this period when the injury happened. In the second case of thermal injury, blinded scoring judged the injury as grade 2 in severity – an erosion of less than 5 mm – on a nine-item scale that ranged from zero to grade 6, the most severe level denoting a fistula. By contrast, among the 12 patients with thermal injury in the nonprotected subgroup, one patient had a grade 5a lesion denoting a deep ulcer, one had a 4b denoting a superficial ulcer with a clot, and four had a 4a lesion defined as a clean superficial ulcer.
“This is really effective. It’s the first study to show reduced damage without affecting ablation efficacy,” Dr. Gallagher said. He plans to now use this method of esophageal protection routinely for his AFib ablation patients who pay privately, and for patients insured under the national U.K. system once this coverage is approved. Dr. Deneke expressed his interest in also using this approach to esophageal protection, but noted that currently he did not have access to the cooling catheter that Dr. Gallagher used because of regulatory constraints.
The esophageal cooling study was sponsored by Attune Medical, which markets the cooling device. Dr. Gallagher has received research funding from Attune Medical, and has received honoraria as a speaker on behalf of Biosense Webster and Medtronic. Dr. Deneke has been a speaker on behalf of Abbott, Biosense Webster, Biotronik, and Boston Scientific, and his institution has received research funding from Biosense Webster and Securus/Boston Scientific.