S2308 Predictive Value of Gastric Myoelectrical Activity in Patient Satisfaction after Gastric Per-Oral Myotomy

Introduction: Gastric per-oral endoscopic myotomy (G-POEM) has emerged as a promising approach for managing refractory gastroparesis. Factors predicting its success remain uncertain. Our study aims to investigate whether features of electrogastrography (EGG) can serve as predictive markers for patient outcomes following G-POEM. By analyzing the relationship between specific gastric myoelectrical activity (GMA) subgroups and patient symptoms post-G-POEM, we seek to understand factors influencing the therapeutic efficacy of G-POEM in treating gastroparesis. Methods: This study included patients with medically refractory gastroparesis diagnosed via gastric scintigraphy and who underwent a G-POEM between May 2022 and December 2023. Each patient completed an EGG and was classified into 1 of 5 groups based on their results: tachygastria, bradygastria, mixed dysrhythmia, normal, and hypernormal. GMA threshold (GMAT) and water load satiety test (WLST) scores were collected. Symptoms were assessed before and after G-POEM using the Gastroparesis Cardinal Symptom Index (GCSI), which include subscores for nausea/vomiting (N/V), postprandial fullness/early satiety, and bloating. We included demographic information and other potential predictors of G-POEM response. Clinical success following G-POEM was defined as a GCSI improvement of ≥1. Results: We analyzed 130 patients: 85.4% female; 36% diabetic; mean age 43.7 (SD= 14.8); 64.6% had idiopathic gastroparesis, 23.1% had diabetic gastroparesis, the rest had other etiologies; 24.6% had normal EGG results. EGG subgroup and GMAT score were not predictive of clinical success after G-POEM. Univariate analysis indicated that greater intake in the WLST (P= 0.049), greater water load tolerance ( > 300mL) (P= 0.028), higher total GCSI score (P= 0.006), and higher GCSI N/V subscore (P= 0.003) were predictive of clinical success. Backward stepwise multivariate analysis indicated that patients with the ability to tolerate more water in WLST (odds ratio (OR) 1.004, P= 0.019), less time between G-POEM and the follow-up GCSI (OR 0.993, P= 0.038), and worse baseline GCSI N/V (OR 1.880, P< 0.001) had higher odds of clinical success following G-POEM. Conclusion: In this retrospective analysis, EGG features were not predictive of clinical success after G-POEM. However, water load tolerance, GCSI N/V subscores, and time between G-POEM and GCSI were predictive. Larger randomized trials are needed to evaluate the predictive value of EGG in treating medical refractory gastroparesis (Table 1). Table 1. - Summary of univariate and multivariate analysis on clinical success outcome (ΔGCSI ≧ 1) Variables Univariate Analysis Multivariate Analysis Frequency(%) P-value Adjusted Odds Ratio P-value Gastroparesis etiology 0.861 Idiopathic 64.6 Diabetic 23.1 Post-surgical 5.4 Autoimmune 3.1 Post-viral 3.1 Ehler-Danlos Syndrome 0.8 Female 85.4 0.066 Diabetes 36.2 0.379 Cholecystectomy 47.7 0.948 Major psychiatric disease 46.2 0.413 Marijuana 24.6 0.672 Narcotics 12.3 0.370 GLP-1 agonists 19.3 0.532 Dentures 8.5 0.167 Uncontrolled constipation (< 1BM/week) 21.5 0.756 EGG subgroup: 0.190 Tachygastria 16.9 Bradygastria 15.4 Normal 3CPM 24.6 Mixed dysrhythmia 40.8 Hypernormal 2.3 GMAT ≧ 0.59 14.6 0.506 WLST >300mL 70.8 0.028* GCSI > 2.6 80.0 0.052 Gastric emptying study >20% retention 73.5 0.464 Mean (SD) for ΔGCSI ≧ 1 Mean (SD) for ΔGCSI <1 P-value Time from symptom onset to G-POEM (years) 4.66 (5.71) 4.96 (6.39) 0.788 BMI (kg/m2) 30.08 (6.69) 28.76 (7.58) 0.299 Age (years) 45.39 (14.87) 42.37 (14.84) 0.253 GMAT score -2.86 (3.23) -1.65 (4.47) 0.089 WLST (mL) 382.02 (126.31) 338.29 (122.76) 0.049* 1.004 0.019* GCSI total score 3.60 (0.78) 3.17 (0.95) 0.006* GCSI nausea/vomiting subscore 3.07 (1.03) 2.45 (1.22) 0.003* 1.880 < 0.001* GCSI postprandial fullness/early satiety subscore 4.14 (0.99) 3.97 (0.90) 0.283 GCSI bloating subscore 3.59 (1.52) 3.08 (1.63) 0.069 Time between G-POEM and follow-up GCSI (days) 68.07 (60.59) 96.21 (97.44) 0.058 0.993 0.038* This table presents the results from the univariate and multivariate analysis on the primary outcome (ΔGCSI ≧ 1). Frequency and P-value from chi-squared tests are presented for categorical variables. Mean, standard deviation, and P-value from 2-sided t-test (assuming equal variance) are presented for continuous variables. A backward stepwise approach was used for the multivariate regression, resulting in a model with 3 significant variables. Note: * indicates P-value < 0.005 Gastric per-oral endoscopic myotomy (G-POEM), Gastric myoelectrical activity (GMA), GMA threshold (GMAT), Electrogastrography (EGG), Gastroparesis cardinal symptom index (GCSI), Water load satiety test (WLST), Body mass index (BMI), cycle per minute (cpm).