# Utility of Esophageal Cooling Therapy for the Prevention of Thermal Injury During Atrial Fibrillation

> **NIH NIH R44** · ADVANCED COOLING THERAPY, LLC · 2023 · $1,300,000

## Abstract

ABSTRACT
Atrial fibrillation (AF) is the most common type of heart arrhythmia; an estimated 2.7 to 6.1 million people in the
United States have been diagnosed with AF and this number is expected to increase. Cardiac catheter ablation
is an effective AF treatment and is performed up to a quarter million times per year in the US; however, safety
concerns exist. Endoscopically detected esophageal lesions (EDELs) occur in 15-40% of cases and can
progress into serious injuries, including atrioesophageal fistula (AEF), which is fatal in most cases. Current
prevention strategies include reducing ablation energy applied to the left atrium, monitoring esophageal
temperature, and mechanically displacing the esophagus. None of these methods have demonstrated
reproducible clinical effectiveness in preventing or reducing severe EDELs or AEF. Previous studies have
shown that active cooling reduces thermal esophageal injury but challenges in clinical implementation limited
commercialization of this approach. The ensoETM, originally designed and successfully commercialized for
whole-body temperature modulation by Attune Medical using SBIR seed funding provides the first scalable
solution for active esophageal cooling during cardiac ablation. The ensoETM device is a novel device FDA-
cleared for core temperature modulation using a multi-lumen silicone tube placed in the esophagus to cool or
warm a patient. During radiofrequency (RF) ablation procedures, the ensoETM device acts as a heat sink for
RF energy inadvertently delivered to the esophagus, thus minimizing unwanted tissue damage. Pilot
randomized, controlled studies show a large and consistent effect size, and suggest benefits in efficiency and
fluoroscopy reduction as well, warranting larger, multi-site investigation. The Specific Aims of this project are:
1) Determine the occurrence rate of esophageal thermal injury and compare the severity of esophageal injury
between groups with and without ensoETM; 2) Measure the impact of ensoETM on procedural efficiency and
fluoroscopy use; 3) Determine specific ensoETM design changes and cooling protocol changes necessary for
optimization. Demonstration of these aims will pave the way for commercialization of this innovative approach
to esophageal protection, and support an expanded FDA label claim, making catheter ablation safer for the
hundreds of thousands of people who currently undergo AF ablation per year, and expanding an alternative to
expensive and life-long pharmaceutical treatment.

## Key facts

- **NIH application ID:** 10693273
- **Project number:** 5R44HL158375-03
- **Recipient organization:** ADVANCED COOLING THERAPY, LLC
- **Principal Investigator:** DAVID J CALLANS
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $1,300,000
- **Award type:** 5
- **Project period:** 2021-09-15 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10693273

## Citation

> US National Institutes of Health, RePORTER application 10693273, Utility of Esophageal Cooling Therapy for the Prevention of Thermal Injury During Atrial Fibrillation (5R44HL158375-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10693273. Licensed CC0.

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