Tu1158 ESOPHAGOGASTRIC JUNCTION DISTENSIBILITY MEASUREMENT MAY OFFER VALUABLE INFORMATION ON ETIOLOGY OF ACHALASIA SYMPTOMS AND CORRELATES WITH OUTCOMES OF PERORAL ENDOSCOPIC MYOTOMY Xiaocen Zhang* 4 , Rani J. Modayil 1 , Dmitriy O. Khodorskiy 1 , Sharon I. Taylor 2 , Maria M. Kollarus 1 , Collin E. Brathwaite 3 , sivaram Neppala 1 , Shahidul Islam 1 , David Friedel 1 , Stavros N. Stavropoulos 1 1 Gastroenterology, NYU Winthrop Hospital, Mineola, NY; 2 Radiology, NYU Winthrop Hospital, Mineola, NY; 3 Surgery, NYU Winthrop Hospital, Mineola, NY; 4 Internal Meidicine, Mount Sinai St Luke’s-West Hospital, New York, NY Background: The functional lumen probe (FLIP) is a new tool to measure esophago- gastric junction (EGJ) distensibility and potentially offers valuable information on the etiology, physiology and treatment of esophageal motility disorders. Methods: 247 patients received FLIP (EndoFLIP; Crospon Ltd., Galway, Ireland) measurement pre and post peroral endoscopic myotomy (POEM) in a single US center between 2012.9 and 2016.11. Pressure, minimal diameter, cross-sectional area (CSA), distensibility index (DI) and compliance were recorded at 30ml and 50 ml. The correlation be- tween these parameters and patient characteristics/treatment responses (Eckardt score, gastroesophageal reflux symptoms, endoscopic sign of reflux and BravoÒ pH study) was analyzed with the logistic regression model, analysis or variance (AN- OVA), student’s t test or Wilcoxon rank sum test as appropriate. Result: Under the logistic regression model, high pre-POEM DI 30 was found to be related to young age, sigmoid esophagus, prior treatment (especially Heller myotomy), type I acha- lasia, and high achalasia stage. High post-POEM DI 30 was found to be related to only sigmoid esophagus. After POEM, there was a significant increase of DI (median 2.33 vs. 9.30cm 2 /mmHg, p<0.01). Paradoxically, high post-POEM DI 30 was found to be related to both poor symptom resolution (Eckardt score>1/failure) and endo- scopic sign of reflux (Table 1). Forty-three patients had repeat Endoflip after a median follow up of 25 months (range 5-59). There was a significant decrease of DI during the follow up period (median 9.30 vs. 5.50cm 2 /mmHg, p<0.01) (Figure 1). Patients with low DI at follow up seem to have more residual symptoms (33.3% vs. 15.8% patients with Eckardt score>1, pZ0.20) and less overall reflux (66.7% vs. 89.5% patient with GERD score>1 or objective reflux, pZ0.07). Conclusion: EGJ distensibility significantly increases in achalasia patients after treatment. High DI immediately after POEM is related to both high Eckardt score and reflux, while high DI after a median follow up of 25 months seems to be related to low Eckardt score but more reflux. DI measurements after healing of the myotomy and submucosal tunnel and any edema or scarring caused by residual food stasis/impaction or acid reflux may be more physiologically relevant than DI measurements immediately post POEM. Therefore, EGJ distensibility at follow up, rather than immediately after POEM might be a better prognostic factor for recurrent dysphagia or significant GERD. Figure 1. Distensibility Index (DI) before POEM, immediately after POEM and at follow up. Tu1159 MULTICENTER EVALUATION OF THE PERFORMANCE OF PARTIALLY VERSUS FULLY COVERED SELF-EXPANDING METAL STENTS (SEMS) AND IMPACT ON NUTRITIONAL STATUS IN PATIENTS WITH MALIGNANT ESOPHAGEAL OBSTRUCTION Koushik K. Das* 1 , Sherif Elhanafi 2 , Jeffrey A. Elsner 1 , Michael Ansstas 1 , Thomas Hollander 1 , Kimberly A. Forde 2 , Gregory G. Ginsberg 2 , Nuzhat A. Ahmad 2 , Michael Rajala 2 , Gabriel Lang 1 , Vladimir Kushnir 1 , Daniel Mullady 1 , Michael L. Kochman 2 , Vinay Chandrasekhara 3 1 Division of Gastroenterology, Department of Medicine, Washington University, Saint Louis, MO; 2 Division of Gastroenterology, Departmernt of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA; 3 Division of Gastroenterology, Department of Medicine, Mayo Clinic, Rochester, MN Background: Self-expanding metal stents (SEMS) are effective in the palliation of ma- lignant dysphagia; however, the performance of partially covered (pc) vs fully covered (fc) SEMS vs fcSEMS with antimigration fins (AF) with regard to the rates of stent migration and stent overgrowth remain unclear. In addition, the effect of esophageal SEMS placement on nutritional outcomes is unknown. Aim: To examine the performance characteristics and factors predicting migration in patients who underwent palliative esophageal SEMS placement for malignant esophageal obstruction and the effect of SEMS on nutritional outcomes. Methods: A multicenter retrospective review of the electronic medical records at Washington University in St Louis and the University of Pennsylvania from 2000 to 2017 of patients who un- derwent SEMS placement for malignant esophageal obstruction was performed. Results: The cohort consisted of 210 patients: mean age of 66.1 (SD 13.5), 168 (80%) had Stage IV disease, and 59 (28%) were female. A total of 158 esophageal ca, 13 GE junction ca, and 39 other extrinsic malignancies were palliated. Adverse events including migration (42/210), epithelial hyperplasia (31/210), and food impaction (18/210) occurred in 43% of patients. Stent removal was performed in 7 patients. Migration occurred in 20/118 (17%) pcSEMS,16/61 (26%) fcSEMS, and 6/31 (19%) of fcSEMS with AF cases. Interestingly, epithelial hyperplasia occurred in 18/118 (15%) pcSEMS, 6/61 (10%) fcSEMS, and 7/31 (23%) of fcSEMS with AF cases. Traversability of the stricture with a diagnostic endoscope (OD9.8mm) was associated with increased risk of migration in univariable and multivariable logistic regression models (Univariable - OR 2.56, pZ0.012, Multivariable OR 3.09, p<0.004). Factors that were not associated with an increased risk of migration included stent place- ment across the GE Junction, stricture length >3 cm, dilation pre-placement, intrinsic vs extrinsic stricture. There was an 18% and 49% non-procedure related mortality noted at 30 and 90 days, with a median survival of 79 days post-procedure (IQR 41, 199). At 30 and 60 days, weight (0.29% and 0.59%) and albumin (0.107g/dL and -0.067g/dL) were stable. However, in the subset of patients who underwent PEG placement before or after SEMS and were alive at 30 days (nZ54), weight was significantly improved vs those patients without PEG (3.0% vs -1.1%, p<0.020). Conclusion: 1. SEMS placement for malignant dysphagia stabilized nutritional out- comes of weight loss, however the placement of a PEG significantly improved this outcome. 2. Migration was significantly more likely in cases with a traversable stricture. 3. fcSEMS were more likely to migrate as compared to pcSEMS, which was partly mitigated by AF. 4. While overall rates of epithelial hyperplasia were low, this was increased with both pcSEMS and fcSEMS with AF. www.giejournal.org Volume 87, No. 6S : 2018 GASTROINTESTINAL ENDOSCOPY AB547 Abstracts