S969 Prospective Comparison of Functional Lumen Imaging Probe and High Resolution Esophageal Manometry to Assess Clinical Response After Per-Oral Endoscopic Myotomy

Abstract

Introduction: Per oral endoscopic myotomy (POEM) has become the standard of care for management of achalasia and esophagogastric junction (EGJ) outlet obstruction (EGJOO). Post-POEM outcomes may be assessed clinically by the Eckardt score (ES) or objectively high-resolution manometry (HRM) and functional lumen imaging probe (FLIP). There are limited data comparing HRM with FLIP to evaluate clinical response (CR) after POEM. Methods: Patients between 2015 and 12/2019 who underwent POEM for achalasia or EGJOO and at least 6 months follow up were identified. Exclusion criteria: Baseline ES < 3 or IRP< 15mmHg and follow-up >6 months but no HRM, FLIP or ES assessment made. Baseline evaluation: EGD, HRM and (beginning in 2016) FLIP of the EGJ to measure EGJ distensibility index (EGJ-DI). POEM included myotomy with extension 2-3 cm into the cardia. Esophageal width was measured from a post-POEM esophagram by a radiologist. Patients returned 6 months post-POEM for repeat EGD, FLIP and HRM. ES was calculated at baseline and 6 months after POEM. CR was defined by three independent metrics: a) ES ≤3; b) EGJ-DI >2.8 mm2/mmHg at any distention 20-50mls and; c) IRP< 15mmHg. ROC curves were constructed and AUC was used to compare the relative performance of the 3 metrics. Results: 118 consecutive patients (60% male, mean 54±17 yrs.) were included. Mean ES and IRP were 8±1.8 and 31.9±13.1 mmHg respectively. Type 2 achalasia was present in 70.3% and previous EGJ therapy was performed in 47.5%. Type 1 had a shorter mean LES length (p=0.003), wider esophagus (p< 0.001) and higher EGJ-DI at 20ml (p=0.04) and 30ml (p=0.042). Type 3 patients had a longer myotomy (p< 0.001). The groups were otherwise similar. Overall CR by ES, IRP and EGJ-DI were 94.9%, 86.4%, and 94.9%, respectively. A normal post-POEM IRP and EGJ-DI had a sensitivity and specificity of 87.5% and 33.3% and 94.6% and 0%, respectively to predict a post-POEM ES≤ 3 (p=0.472 comparing AUCs). In 23 patients with post-POEM ES< 3, EGJ-DI alone (n=5), IRP alone (n=11) or both (n=7) incorrectly predicted no clinical response by ES. A normal post-POEM EGJ-DI had a sensitivity and specificity of 97.1% and 18.8% to predict a normal post-POEM IRP. Conclusion: For patients with achalasia or EGJOO, a normal IRP and EGJ-DI at least 6 months after POEM show excellent sensitivity, poor specificity but are equivalent to evaluate for a normal post-POEM ES. FLIP is an acceptable alternative to HRM to evaluate the LES after POEM in these patients.Table 1.: Comparison of Normalized Integrated Relaxation Pressure (IRP) and Functional Lumen Imaging Probe (FLIP) Distensibility Index to Predict Eckardt Score Response at least 6 months after POEM in 118 Consecutive Patients with Achalasia and EGJOO