INTRODUCTION: Anti-reflux mucosectomy (ARMS) and anti-reflux mucosal ablation (ARMA) are novel endoscopic treatments for proton pump inhibitor or potassium-competitive acid blocker-refractory gastroesophageal reflux disease. These procedures induce scarring of the artificial ulcer at the gastric cardia, which tightens the enlarged cardiac opening. However, we encountered patients with unresolved symptoms due to insufficient cardiac shrinkage despite multiple ARMS/ARMA treatments. This study analyzed the frequency and characteristics of the refractory cases. METHODS: We retrospectively reviewed patients who underwent ARMS/ARMA treatments at our institution from January 2014 to October 2022. Refractory cases were defined as those undergoing multiple ARMS/ARMA treatments but with insufficient cardiac shrinkage and also persistence of reflux symptoms. RESULTS: Out of 131 ARMS/ARMA patients, seven (5.3%) cases were categorized as refractory cases. The male-to-female ratio was 5:2, with a mean age of 70 (58-73) years, and a mean BMI of 20.4 (20.0-24.0). Gastroesophageal reflux disease grades were grade ( = 2), M ( = 2), B ( = 2), and C ( = 1). All had NERD diagnosis confirmed by pH monitoring. One patient underwent ARMS twice, two underwent ARMA after ARMS, and four had ARMA more than twice, but none achieved sufficient cardia shrinkage. Finally, three cases were managed with medication, while four required surgical fundoplication, which improved their symptoms. CONCLUSION: Approximately 5% of ARMS/ARMA cases could not achieve sufficient cardiac shrinkage. However, the surgical treatment performed as a final step was effective, which may suggest that ARMS/ARMA treatment serves as a treatment option between medical therapy and surgical treatment.