The Use of Body Surface Gastric Mapping in Assessing the Clinical Success of G-POEM

The aim of this protocol is to build on the investigators currently approved study to evaluate the outcomes and predictors of success of Gastric peroral endoscopic myotomy (G-POEM). The investigators plan to incorporate BSGM in determining the treatment success after G-POEM in patients with refractory gastroparesis and potentially identify a phenotype of gastroparesis patients who may respond more favorably to G-POEM based on their baseline BSGM profile. The currently approved G-POEM study (IRB #1708840627 and ClinicalTrials.gov ID NCT04434781) at our center tracks patients' symptoms and quality of life at baseline and post G-POEM. the investigators plan to supplement the existing study by adding BSGM variables. Although the investigators have specific outcomes identified, the investigators would like to stress that this is a pilot study that will serve to identify patterns and trends that could be studied further in the future using larger cohorts of patients.

The investigators' primary objective is to evaluate the safety and feasibility BSGM in refractory gastroparesis patients undergoing G-POEM.

the investigators will also investigate whether changes in BSGM measures correlate with changes in symptoms and quality of life.

Additionally, the investigators' aim to compare the diagnostic performance of BSGM, and gastric emptying scans as depicted on scintigraphy.

The investigators' primary aim is to assess the feasibility and safety of in gastroparesis patients undergoing G-POEM. Clinical success is defined as improvement in GCSI by 1 point or more compared to baseline.

The investigators will report four spectral metrics, each profiling distinct features of gastric function:

• Body Surface Gastric Mapping Rhythm IndexTM (GA-RI) - a measure of gastric rhythm stability.
• Principal Gastric Frequency - the frequency associated with stable, persistent gastric activity as defined by GA-RI.
• BMI-adjusted amplitude.
• Fed: Fasted Amplitude Ratio (ff-AR).

Although not directly related to this outcome, the investigators will continue our symptom analysis (as has been previously done under the existing G-POEM protocol) that includes both the pattern and severity of individual symptoms, such as vomiting, reflux, and belching. The investigators will continue to assess patient quality of life using standardized questionnaires (SF-36) at baseline and 3 months post-G-POEM as is currently done with the existing protocol.

This is an addition to an existing study protocol. The study will involve patients with refractory gastroparesis (proven on a 4-hour solid-phase gastric emptying scan, along with limited or no response (or intolerance) to at least 3 months of lifestyle adjustments, dietary modifications, and medications) who will undergo G-POEM. BSGM will be used to assess gastric motility before and after the procedure. This design allows for the collection of data at multiple time points to assess changes in BSGM phenotypes, gastroparesis symptoms, and other relevant variables over time.

The study team will enroll 20 participants who will undergo BSGM at baseline prior to G-POEM procedure and then again 3-6 months after G-POEM. The study team plan to contact participants prior to their standard of care clinic visit to ensure participants meet eligibility criteria. The study team will also explain the study over the phone using the telephone script that has been approved (Appendix 1). If they are interested in the study, the study team will schedule them for BSGM and go over prep instructions. Once the participant arrives in clinic, teh study team will consent in-person.

Inclusion criteria

• • Patients clinically eligible for G-Poem at our center.

Exclusion criteria

• • Pregnant or breast-feeding

• Patients with gastroparesis due to spinal cord injuries due to difficulties in conducting the BSGM. Of note, we rarely see gastroparesis in this context.
• Inability to perform BSGM: history of severe skin allergies or sensitivity to cosmetics or lotions; chronically damaged or vulnerable epigastric skin (fragile skin, wounds, inflammation); patients unable to remain in a relaxed reclined position for the test duration.
• Patients with abdominal drains or tubes