Abstract Body (Do not enter title and authors here): Introduction: Atrioesophageal fistulas (AEF) are severe life-threatening complications that can occur after left atrial ablation for the treatment of atrial fibrillation (AF). Although new ablation modalities promote a non-thermal mechanism of action, uncertainty remains surrounding their ability to reduce AEFs when implemented at scale. The international POTTER-AF survey found that AEFs continue to occur despite traditional preventative efforts, but trends in the U.S. are less clear. However, data from the Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience (MAUDE) database can provide insight.

Research Question: What are the recent trends in AEF reporting following left atrial ablation?

Aim: To determine the number of AEFs and patient outcomes reported using the FDA’s MAUDE database over the last 5 years.

Methods: Reports were reviewed from the FDA’s MAUDE database for entries filed from January 1st, 2019 through January 1st, 2024. Product codes LPB, OAE, and OAD, representing cardiac ablation catheters and radiofrequency generators, were reviewed for reports of AEFs. Each report was reviewed to remove duplicate reports and to verify patient outcomes.

Results: A total of 202 reports of AEF were identified, with 128 non-fatal fistulas, and 74 reported deaths. Of the 202 reports, 110 were reported under the code LPB, 66 under OAE, and 26 under OAD. Reports generally increased over the analysis time frame, with 30 reports in 2019, 28 in 2020, 45 in 2021, 45 in 2022, and 54 in 2023 (Figure 1). Esophageal protective methods were reported to be luminal esophageal temperature (LET) monitoring in 61 cases, esophageal deviation in 3 cases, no protective method in 10 cases, and not mentioned in the remaining 128 cases.

Conclusion: Despite widespread AEF awareness and adoption of traditional preventive efforts the annual rate of reported AEFs in the United States continues to grow, and fatality rates remain high, suggesting the need for improved preventative efforts.