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A study of endoscopic closure using the MANTIS Clip to prevent bleeding after gastric endoscopic submucosal dissection in patients undergoing antithrombotic therapy (AT-MANTIS study)

Basic Information

Recruitment status	Recruiting
Health condition(s) or Problem(s) studied	Bleeding after gastric endoscopic submucosal dissection in patient taking antithrombotic drugs.
Date of first enrollment	22/12/2025
Target sample size	160
Countries of recruitment
Study type	Interventional
Intervention(s)	Endoscopic closure using the MANTIS Clip to prevent bleeding after gastric endoscopic submucosal dissection in patient taking antithrombotic drugs.

Outcome(s)

Primary Outcome	Proportion of postoperative bleeding.
Secondary Outcome	(1)Closure time (a major secondary outcome). (2)Success rate of closure. (3)Percentage of patients with closure retention 7 days after treatment. (4)Number of MANTIS Clips used. (5)Adverse events (intraoperative perforation, delayed perforation, aspiration pneumonia). (6)Proportion of medical device defects.

Key inclusion & exclusion criteria

Age minimum	>= 18age old
Age maximum	Not applicable
Gender	Both
Include criteria	(1)Patients who are taking antithrombotic drugs (or are taking them off) and are scheduled to have a BEST-J score of 3 or more at the time of protocol treatment. (2)Diagnosed with early gastric cancer, gastric adenoma, or suspected of having such cancer. (3)The lesion is scheduled to be removed by ESD. (4)Even if multiple lesions are found, only one will be resected. However, if multiple lesions are close to each other and will be resected in one section, this is acceptable. (5)The mucosal defect after ESD can be closed or is unlikely to cause stenosis due to closure. In other words, all of A) to D) below are met. A)Regardless of the location of the tumor, the extent of resection by ESD is judged to be less than 2/3 circumferential. B)Regardless of the location of the tumor, the length of the resected specimen after ESD is judged to be 5 cm or less. C)The oral margin of the tumor does not extend beyond the esophagogastric junction, unless it does extend beyond the esophagogastric junction if the extent of ESD resection is deemed to be less than 1/2 circumference. D)The anal margin of the tumor does not touch the pylorus ring. However, if the extent of ESD resection is deemed to be less than 1/2 circumference, the tumor may touch the pylorus ring. (6)Age 18 or older at the time of consent acquisition. (7)Patients who have received sufficient information about participating in the study and have given their voluntary written consent.
Exclude criteria	(1) Patients with a tendency to bleed: - Platelet count less than 50,000/uL or PT-INR 3.0 or higher while on antithrombotic therapy. (2) Patients with nickel sensitivity. (3) Patients with a history of gastrectomy (including gastric tube patients). (4) Patients who are deemed inappropriate by the investigator.