FISTULA-RFA Trial (Fistula Inactivation by Segmental Thermal Uniform Lesion Ablation-Radiofrequency Ablation): A Prospective, Multicenter, Single-Arm Pilot Study in Patients With Perianal Fistula

Perianal fistula is a chronic inflammatory tract that can cause persistent discharge, pain, recurrent abscess formation, and substantial impairment in daily activities and quality of life. While definitive surgical management aims to eradicate the fistula while preserving sphincter function, conventional approaches may be limited by variable healing rates, risk of recurrence, and concerns regarding sphincter injury and subsequent continence disturbance-particularly in complex fistulas or in patients at higher risk of incontinence. As a result, sphincter-preserving, minimally invasive techniques have been actively explored to improve clinical outcomes while minimizing functional compromise.

Radiofrequency ablation (RFA) is a thermal energy-based modality that can induce controlled tissue coagulation and remodeling. For perianal fistula treatment, RFA has the potential to ablate the fistula tract internally and promote tract closure without dividing sphincter muscles. However, a key challenge in energy-based fistula treatments is achieving consistent and uniform ablation along the entire tract length, because uneven energy delivery may lead to insufficient ablation in certain segments and treatment failure or recurrence. To address this limitation, a novel, dedicated RFA fistula device has been developed to deliver thermal energy in a standardized manner along the tract, with the intent of achieving more uniform ablation across tract segments (ie, segment-by-segment energy delivery rather than focal "dot" ablation). Prior preclinical work using a porcine perianal fistula model was performed to establish feasible operating parameters and to support translation to a first-in-human clinical pilot study.

Objectives The primary objective of this prospective multicenter single-arm pilot study is to evaluate the clinical efficacy of a novel RFA device for the treatment of perianal fistula in adult participants, with clinical fistula closure assessed at 6 months after the procedure. Secondary objectives are to evaluate safety (procedure- and device-related adverse events), recurrence patterns during follow-up, and changes in symptom burden and functional outcomes over time. In addition, this pilot study aims to assess procedural feasibility and to generate data that will inform the design of larger confirmatory studies, including refinement of outcome definitions, follow-up strategy, and operational standardization across sites.

Methods This is a prospective, multicenter, single-arm pilot interventional study enrolling adult participants with perianal fistula who are considered appropriate for a sphincter-preserving approach. All enrolled participants will receive RFA treatment using the dedicated fistula RFA device under a standardized procedural framework across participating sites.

Intervention (RFA procedure):