S825 Evaluation of Distensibility Index to Determine Procedural Success After Peroral Endoscopic Myotomy (POEM) for Non-Spastic Achalasia

Introduction: Per-oral endoscopic myotomy (POEM) is a highly effective treatment for achalasia. Functional luminal imaging probe (FLIP) offers real-time measurement of esophagogastric junction (EGJ) opening parameters, allowing for an objective method to assess myotomy adequacy, a measure of how easily the esophagus can expand and contract, calculated by dividing the area of the esophagus by the pressure it's under during a controlled distension. The aim of this study was to assess if the change in pre-POEM to post-POEM distensibility index (DI) was more predictive of symptomatic outcome compared to an absolute threshold. Methods: Thirty-one patients with type I and type II achalasia who received POEM between November 2022 and August 2024 were included. Based on previous literature, an EGJ DI 2.8 mm2/mmHg was considered a complete myotomy. Clinical success of POEM was defined as Eckardt score <4. Concordance was defined by symptom improvement and a normal post-POEM DI, or no symptom improvement and an abnormal post-POEM DI. Discordance was defined by symptom improvement and an abnormal post-POEM DI, or no symptom improvement and a normal post-POEM DI. Results: Thirty-one patients with achalasia who underwent POEM had pre-POEM and post-POEM DI data. A proposed cut-off using the change in pre-POEM to post-POEM DI change of 0.8 mm2/mmHg (delta-DI) was evaluated. Most of the discordance was driven by patients with symptomatic improvement, but abnormal DI. The accuracy of delta-DI versus an absolute cutoff for assessing treatment response was evaluated using the receiver operating curve analysis. The difference in percentage of concordance between patients with pre-POEM and post-POEM DI using the absolute cut-off and the proposed delta-DI was significant (P = 0.014). There was a 68% concordance with the absolute DI cut-off vs 90% concordance with the delta-DI cut-off. Conclusion: DI is a useful diagnostic tool in patients with achalasia. However, discrepant symptomatic and DI outcomes have been difficult to reconcile post-POEM. Using a traditional cut-off of an absolute post-POEM DI of 2.8 may result in more discordance than using the delta-DI described in this study. This study highlights the importance of updates regarding DI as a metric of procedural success and the need to redefine its parameters in this setting.