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Over the last few decades, we have seen the further advancement and progress of the field of interventional and therapeutic endoscopy, bringing us to undiscovered areas of the gut's lumen. The development of peroral endoscopic myotomy (POEM) created a breakthrough in the field of therapeutic endoscopy by bringing us to the so-called "third space," which is an artificially created space in the submucosal layer. The rise of third space endoscopy brought us novel and fundamental aspects into therapeutic endoscopy by paving the way to interventions throughout the gastrointestinal (GI) tract. With the success of POEM, the same third space principles have become the foundation for the development of other third space endoscopic techniques for the management of motility disorders of the GI tract, giving rise to a number of POEM offshoots. Since motility disorders of the GI tract are commonly encountered in clinical practice, the development of third space endoscopic interventions to address these disorders was seemingly timely, providing patients optimal care. In this chapter, we would like to offer a closer look and provide the readers a general overview of POEM and other POEM-based techniques which have been developed for the management of motility disorders of the GI tract.

Background and Aims: Peroral endoscopic myotomy (POEM) is conducted for patients with esophageal motility disorders based on high-resolution manometry (HRM) findings. However, the impact of POEM on HRM findings and the associations between post-POEM HRM and outcomes have not been clarified., Methods: In a multicenter, observational, cohort study, patients with achalasia treated by POEM received follow-up HRM. Associations between patient characteristics, POEM procedures, and post-POEM HRM findings, including integrated relaxation pressure (IRP) and distal contractile integral (DCI), were investigated. Furthermore, POEM procedure outcomes were compared with post-POEM HRM findings., Results: Of 2171 patients, 151 (7.0%) showed residual high post-POEM IRP (≥26 mm Hg; Starlet [Starmedical Ltd, Tokyo, Japan]). In a multivariate analysis, high pre-POEM IRPs (odds ratio [OR], 24.3) and gastric myotomy >2 cm (OR, .22) were found to be positive and negative predictive factors of high post-POEM IRPs, respectively. Peristalsis recovery (DCI ≥500 mm Hg/cm/s, at least 1 swallow; Starlet) was visible in 121 of 618 patients (19.6%) who had type II to III achalasia. High pre-POEM IRP (OR, 2.65) and DCI ≥500 (OR, 2.98) predicted peristalsis recovery, whereas esophageal dilation (OR, .42) predicted a risk of no recovery. Extended myotomy did not reveal a significant impact on peristalsis recovery. High or low post-POEM IRP and DCI did not increase the incidence of clinical failure, reflux esophagitis, or symptomatic GERD., Conclusions: Extended gastric myotomy decreased IRP values, whereas peristalsis recovery depended on the characteristics of achalasia. A residual high post-POEM IRP does not necessarily mean clinical failure. Routine HRM follow-up is not recommended after POEM., (Copyright © 2023 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

Background: Peroral endoscopic myotomy (POEM) is effective for the management of achalasia and its variants; however, it can be ineffective in some patients. We aimed to develop and validate a risk scoring system to predict the clinical failure of POEM preoperatively., Methods: Consecutive patients who underwent POEM in 14 high volume centers between 2010 and 2020 were enrolled in this study. Clinical failure was defined as an Eckardt score of ≥ 4 or retreatment. A risk scoring system to predict the short-term clinical failure of POEM was developed using multivariable logistic regression and internally validated using bootstrapping and decision curve analysis., Results: Of the 2740 study patients, 112 (4.1 %) experienced clinical failure 6 months after POEM. Risk scores were assigned for three preoperative factors as follows: preoperative Eckardt score (1 point), manometric diagnosis (-4 points for type II achalasia), and a history of prior treatments (1 point for pneumatic dilation or 12 points for surgical/endoscopic myotomy). The discriminative capacity (concordance statistics 0.68, 95 %CI 0.62-0.72) and calibration (slope 1.15, 95 %CI 0.87-1.40) were shown. Decision curve analysis demonstrated its clinical usefulness. Patients were categorized into low (0-8 points; estimated risk of clinical failure < 5 %) and high risk (9-22 points; ≥ 5 %) groups. The proportions of clinical failure for the categories were stratified according to the mid-term outcomes (log-rank test, P  < 0.001)., Conclusions: This risk scoring system can predict the clinical failure of POEM preoperatively and provide useful information when making treatment decisions., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objectives: Reports on learning curve for peroral endoscopic myotomy (POEM) in therapeutic endoscopy nonexperts are limited. We aimed to assess the number of cases required to achieve POEM proficiency for endoscopic submucosal dissection (ESD) experts and nonexperts., Methods: This is a retrospective study at the largest POEM referral center in Japan. POEM between April 2014 and December 2020 were included. Nonexperts and ESD experts were divided by training phases: A, 1-20; B, 21-40; C, 41-60; D, 61-80; and E, 81-100 cases. Primary outcome was operation time, and the phase to reach target time (83 min) was investigated. Secondary outcomes were clinical success rate, adverse events, and post-POEM gastroesophageal reflux disease (GERD)., Results: Five hundred and sixty-six cases were performed by 14 nonexperts, and 555 cases by 15 ESD experts. As the primary outcome, operation time in nonexperts was: A, 95 (79-115.8); B, 86.5 (71-105); C, 80 (70-100); D, 73 (64.5-100.5); and E, 73.5 (57.8-88.8) min, while in ESD experts: A, 90 (74-128); B, 77 (70-92); and C, 77 (70-93.5) min (median [interquartile range]). Operation time decreased significantly as experience increased in both groups (P < 0.001), and nonexperts required 41-60 cases to achieve proficiency, while experts required 21-40 cases. As secondary outcomes, in nonexperts, clinical success was 96.9-100%, adverse events were 5.0-9.2%, symptomatic GERD was 11.8-26.5%, and proton pump inhibitor (PPI) intake was 11.5-18.7% in each phase. While in experts, clinical success was 96.2-100%, adverse events were 3.0-5.8%, symptomatic GERD was 14.6-22.0%, and PPI intake was 12.6-17.9%. There were no significant differences among training phases., Conclusions: Non-ESD experts require more cases to achieve proficiency in POEM. These results are useful for establishing POEM training programs and institutional implementation of the procedure., (© 2022 Japan Gastroenterological Endoscopy Society.)

Third-space endoscopy, also known as submucosal endoscopy, allows for a wide range of therapeutic interventions within the submucosal layer and even into the muscular or subserosal layers of the gastrointestinal lumen. The technical development of peroral endoscopic myotomy (POEM) for achalasia has revolutionized the field of therapeutic endoscopy and the method has been continuously refined and modified. Although POEM has been applied to treat primary achalasia, it shows a favorable clinical response in other esophageal motility disorders and as a salvage treatment after previously failed intervention. Gastroesophageal reflux after POEM has drawn considerable attention and there have been major advancements in its prevention and management. POEM has led to advantageous derivatives such as peroral endoscopic tumor resection or submucosal tunneling endoscopic resection for resection of subepithelial lesions, Zenker POEM for hypopharyngeal diverticula, diverticular POEM for epiphrenic esophageal diverticula, and gastric POEM for refractory gastroparesis. These techniques have a similar concept, which constitutes submucosal tunneling with a mucosal flap valve and secure mucosal incision closure. The submucosal tunneling technique is widely accepted and continues to evolve. This study aimed to review in detail the indications, outcomes, and technical variations in POEM and explore several emerging submucosal tunneling procedures. This review will benefit future studies by providing a summary of recent developments in this field., (© 2022 Japan Gastroenterological Endoscopy Society.)

Objectives: Patients with esophageal motility disorders (EMDs) including achalasia after gastric surgery have not been thoroughly characterized. Furthermore, the efficacy of peroral endoscopic myotomy (POEM) in this population should be clarified., Methods: In this retrospective multicenter study of 3707 patients with EMDs, 31 patients (0.8%) had a history of gastric surgery. Patient characteristics and POEM efficacy were compared between patients with and without previous gastric surgery., Results: In patients with EMD after gastric surgery, age at EMD diagnosis was higher (72.0 years), male sex was predominant (90.3%), and the American Society of Anesthesiologists physical status score was higher (≥II, 48.4%). High-resolution manometry (HRM) findings did not reveal significant differences. In patients who underwent gastric surgery, atrophic gastritis was common (80.6%), and gastric cancer was the primary surgical indication (32.3%). Distal gastrectomy was performed in 28 patients (90.3%). POEM was effective (3.3% adverse events; 100% treatment success). The incidence rates of reflux esophagitis (RE) and symptomatic gastroesophageal reflux disease (GERD) were 60.0% and 16.7%, respectively, without significant intergroup differences, and severe RE was not observed in the long-term follow-up. Extended gastric myotomy was a risk factor for RE., Conclusion: Patients with gastric surgery often present severe disease manifestations; the surgical indication is mainly gastric cancer. HRM findings can be similarly used for diagnosis in patients with and without gastric surgery. POEM maintains safety and efficacy with acceptable RE and symptomatic GERD rates. To prevent RE, extended myotomy should be avoided., (© 2022 Japan Gastroenterological Endoscopy Society.)

Background and Aims: The etiology of chest pain in achalasia-related esophageal motility disorders and the frequency and risk factors of persistent chest pain after peroral endoscopic myotomy (POEM) remain unclear., Methods: A multicenter cohort study including 14 hospitals was conducted to elucidate the characteristics of patients with chest pain and the efficacy of POEM., Results: Consecutive cases of achalasia-related esophageal motility disorders included 2294 (64.2%) and 1280 (35.8%) patients with and without chest pain, respectively. Among the 2107 patients with chest pain who underwent POEM, we observed complete remission in 1464 patients (69.5%) and nonremission in 643 patients (30.5%), including a partial response in 619 patients (29.4%) and resistance in 24 patients (1.1%). Multivariate analysis revealed that advanced age (odds ratio [OR], .28), male sex (OR, .70), prior treatment (OR, 1.39), and sigmoid type (OR, .65) were related to the prevalence of chest pain. Long disease duration (OR, .69) and esophageal dilation (OR, .79) were related to decreased severity. POEM improved patients' quality of life that was hindered by chest pain. Early onset (OR, 1.45), advanced age (OR, .58), male sex (OR, .79), prior treatment (OR, 1.37), and posterior myotomy (OR, 1.42) were associated with nonremission after POEM; high-resolution manometry (HRM) findings and myotomy length showed no statistical significance on pain etiology and persistence after POEM., Conclusions: The prevalence and severity of chest pain were dependent on age, sex, disease duration, prior treatment, and esophageal morphology rather than HRM findings. The efficacy of POEM is satisfactory; however, residual pain was often observed. Excessively long myotomy can be avoided, and anterior myotomy may be recommended., (Copyright © 2022 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

BACKGROUND : Gastroesophageal reflux disease (GERD) and reflux esophagitis remain problems after peroral endoscopic myotomy (POEM). This study aimed to elucidate the risk factors and long-term course of reflux esophagitis and symptomatic GERD after POEM. METHODS : This multicenter cohort study involved 14 high volume centers. Overall, 2905 patients with achalasia-related esophageal motility disorders treated with POEM were analyzed for reflux esophagitis, severe reflux esophagitis (Los Angeles classification C or D), and symptomatic GERD. RESULTS : Reflux esophagitis was diagnosed in 1886 patients (64.9 %). Age ≥ 65 years (risk ratio [RR] 0.85), male sex (RR 1.11), posterior myotomy (RR 1.12), esophageal myotomy > 10 cm (RR 1.12), and gastric myotomy > 2 cm (RR 1.17) were independently associated with reflux esophagitis. Severe reflux esophagitis was diagnosed in 219 patients (7.5 %). Age ≥ 65 years (RR 1.72), previous treatments (RR 2.21), Eckardt score ≥ 7 (RR 0.68), sigmoid-type achalasia (RR 1.40), and esophageal myotomy > 10 cm (RR 1.59) were factors associated with severe reflux esophagitis. Proton pump inhibitors (PPIs) were more effective for reflux esophagitis at 5-year follow-up ( P  = 0.03) than after 1 year ( P  = 0.08). Symptomatic GERD was present in 458 patients (15.9 %). Symptom duration ≥ 10 years (RR 1.28), achalasia diagnosis (RR 0.68), integrated relaxation pressure ≥ 26 (RR 0.60), and posterior myotomy (RR 0.80) were associated with symptomatic GERD. The incidence of symptomatic GERD was lower at 5-year follow-up compared with that after 1 year ( P  = 0.04), particularly in PPI users ( P  < 0.001). CONCLUSIONS : The incidence of severe reflux esophagitis was low after POEM, but excessive myotomy for older patients with previous treatments should be avoided. Early phase symptomatic GERD is non-acid reflux dependent and the natural course is favorable, basically supporting conservative treatment., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objectives: Indications for peroral endoscopic myotomy (POEM) and endoscopic submucosal dissection (ESD) in patients with achalasia concomitant with esophageal carcinoma (EC) are unclear. This study aimed to clarify the role of POEM in cases of achalasia concomitant with EC and to elucidate the indications for ESD and efficient surveillance for EC., Methods: We conducted a multicenter cohort study at 14 hospitals in Japan, including 3707 cases of achalasia-related esophageal motility disorders (EMDs). Factors contributing to EC risk, the characteristics of EC, and clinical outcomes of POEM/ESD were analyzed., Results: In patients undergoing POEM, screening and surveillance endoscopy throughout a 1-year period resulted in diagnosis of 72.1% new EC cases. Of 62 patients with 123 ECs, 40.3% had multiple or metachronous lesions within 37.5 months. EC was predominantly observed in the middle thoracic esophagus (58.5%) and posteriorly (73.2%). POEM had comparable safety and efficacy in cases of concomitant EC even after ESD. Endoscopic en bloc resection was performed in 95.8% and 89.3% of ECs diagnosed before and after POEM, respectively (P = 0.351); however, ESD on the POEM-line was impaired by fibrosis. Multivariate analysis revealed risk factors for EC, including regular alcohol consumption, a history of smoking, advanced age, and extended disease duration. Alcohol intake and smoking had a synergistic effect on EC development., Conclusions: Screening and surveillance of POEM help in detecting EC. ESD is feasible in achalasia, although on the POEM-line is challenging. Surveillance endoscopy for EC is recommended for cases with specific risks and a history of ECs., (© 2021 Japan Gastroenterological Endoscopy Society.)

Geriatric patients with existing studies on the safety and efficacy of peroral endoscopic myotomy (POEM) for achalasia involve small sample sizes and single institutions. However, multi-center, large-scale data analyses are lacking. The study aimed to clarify the characteristics of geriatric patients with esophageal motility disorders (EMDs) and determine the procedure-related outcomes and clinical course following POEM. This cohort study included 2,735 patients with EMDs who were treated at seven Japanese facilities between 2010 and 2019. The patients' characteristics and post-POEM clinical courses were compared between the geriatric (age ≥ 75 years; n = 321) and non-geriatric (age < 75 years; n = 2,414) groups. Compared with the non-geriatric group, the geriatric group had higher American Society of Anesthesiologists physical status scores; more recurrent cases; lower incidence of chest pain; and higher incidence of type III achalasia, distal esophageal spasm, and Jackhammer esophagus. Furthermore, the incidence of sigmoid esophagus was higher, although esophageal dilation was not severe in this group. POEM was safe and effective for geriatric patients with treatment-naïve and recurrent EMDs. Furthermore, compared with the non-geriatric group, the geriatric group had lower post-POEM Eckardt scores, fewer complaints of refractory chest pain, and a lower incidence rate of post-POEM reflux esophagitis. Geriatric patients are characterized by worse clinical conditions, more spastic disorders, and greater disease progression of EMDs, which are also the indications for minimally invasive POEM. POEM is more beneficial in geriatric patients as it has lowering symptom scores and incidence rates of reflux esophagitis., (© The Author(s) 2021. Published by Oxford University Press on behalf of International Society for Diseases of the Esophagus. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Peroral endoscopic myotomy (POEM) is standard treatment for achalasia. Gastroesophageal reflux disease (GERD) after POEM has been an important challenge since the early days of POEM implementation. The esophagogastric junction anti-reflux barrier consists of internal lower esophageal sphincter (LES) (i.e., intrinsic muscles of distal esophagus with sling fibers) and external LES (crural diaphragm and phrenoesophageal ligament anchors the distal esophagus to the crural diaphragm). During conventional POEM, the entire internal LES is unintentionally dissected. Preservation of the sling fiber may reduce post-POEM GERD, but its safety and effectiveness have been unclear. In this study, we investigated the safety and effectiveness of sling fiber preservation POEM (SP-POEM) for reducing severe post-procedural erosive esophagitis., Methods: We analyzed data of 236 patients who underwent POEM; of these, 203 patients underwent posterior myotomy without (Group 1) or with attempted (Group 2) sling fiber preservation. Group 1 (N = 79; sling fiber excision, N = 68) and Group 2 (N = 90; sling fiber preservation, N = 81) were compared. Post-procedural erosive esophagitis (Los Angeles classification) were assessed and the area (direction and length) of mucosal break was also investigated. The gastroesophageal flap valve was evaluated by Hill's classification., Results: Severe erosive esophagitis exceeding grade C (Los Angeles classification) occurred in 44.1% of patients (30/68) in Group 1 and in 18.5% of patients (15/81) in Group 2. In mapping of erosive esophagitis, mucosal breaks appeared widely in all directions in Group 1; they tended to be limited in Group 2 (especially in the 2 o'clock direction). Assessment using the Hill's classification showed that the gastroesophageal flap valve was preserved after SP-POEM., Conclusion: SP-POEM is safe and effective, with a success rate of 90%. The rate of severe erosive esophagitis can be decreased by preserving sling fibers., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Aim: To elucidate the impact of the coronavirus disease 2019 (COVID-19) on the practice of high-resolution manometry (HRM) and peroral endoscopic myotomy (POEM) in Japan., Methods: We utilized a large-scale database involving 14 high-volume centers in Japan to investigate changes in the numbers of HRM and POEM procedures performed and outcomes of POEM between 2019 and 2020. A questionnaire survey was also conducted to analyze pandemic-associated changes in the HRM and POEM protocols., Results: Compared to that in 2019, the number of HRM and POEM procedures decreased by 17.2% (1587-1314) and 20.9% (630-498), respectively. These declines were prominent during the state of emergency from April to May 2020, particularly in pandemic areas. HRM and POEM in nonpandemic areas were relatively unaffected. From 2019 to 2020, there was a 0.4% (254-248) decrease in POEM cases within the prefecture, but the number outside the prefecture decreased by 33.6% (372-247). During the pandemic, the safety and efficacy of POEM were maintained. The implementation of personal protective equipment (PPE) measures varied among facilities, and PPE for POEM was relatively insufficient compared to that for HRM., Conclusion: The COVID-19 pandemic influenced HRM and POEM practices in Japan. It is necessary to establish a sufficient system for HRM and POEM in each hospital as well as countrywide to overcome the effects of the pandemic., (© 2021 Japan Gastroenterological Endoscopy Society.)

Background and Aim: The perioperative management and clinical course of per-oral endoscopic myotomy for patients receiving antithrombotic therapy remains unknown. This study aimed to clarify the status of antithrombotic therapy in per-oral endoscopic myotomy and to determine its safety and efficacy., Methods: Patients treated with per-oral endoscopic myotomy from 2010 to 2019 in seven high-volume centers in Japan were retrospectively investigated. The patients' characteristics and antithrombotic agent management were analyzed; clinical outcomes were compared with those without antithrombotic agents., Results: Of 2752 patients who underwent per-oral endoscopic myotomy, 120 patients on antithrombotic therapy (mean age 71.0 years, American Society of Anesthesiologists class II-IV [67.5%]) were identified. Antiplatelet, anticoagulant, and a combination of antithrombotic agents were used in 82, 30, and 8 patients, respectively. The perioperative management adhered to the therapeutic endoscopy guidelines published by the Japanese Society of Gastroenterological Endoscopy in most patients (88.3%). A poorer clinical baseline status (American Society of Anesthesiologists class II-IV; 67.0% vs 24.3%) and the sigmoid type (40.7% vs 22.3%) were more frequently observed in patients with achalasia on antithrombotic therapy. However, the clinical success (Eckardt score ≤ 3; 97.6% vs 94.6) and adverse event rates, such as bleeding and thromboembolic events (5.5% vs 4.7%), did not show inferiority., Conclusions: Per-oral endoscopic myotomy on antithrombotic therapy is safe and effective. However, caution is required as patients on antithrombotic therapy tend to have poorer baseline health and achalasia statuses. Our experience should help establish perioperative management with antithrombotic therapy., (© 2021 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Background: Artificial intelligence (AI) and computer vision (CV) have revolutionized image analysis. In surgery, CV applications have focused on surgical phase identification in laparoscopic videos. We proposed to apply CV techniques to identify phases in an endoscopic procedure, peroral endoscopic myotomy (POEM)., Methods: POEM videos were collected from Massachusetts General and Showa University Koto Toyosu Hospitals. Videos were labeled by surgeons with the following ground truth phases: (1) Submucosal injection, (2) Mucosotomy, (3) Submucosal tunnel, (4) Myotomy, and (5) Mucosotomy closure. The deep-learning CV model-Convolutional Neural Network (CNN) plus Long Short-Term Memory (LSTM)-was trained on 30 videos to create POEMNet. We then used POEMNet to identify operative phases in the remaining 20 videos. The model's performance was compared to surgeon annotated ground truth., Results: POEMNet's overall phase identification accuracy was 87.6% (95% CI 87.4-87.9%). When evaluated on a per-phase basis, the model performed well, with mean unweighted and prevalence-weighted F1 scores of 0.766 and 0.875, respectively. The model performed best with longer phases, with 70.6% accuracy for phases that had a duration under 5 min and 88.3% accuracy for longer phases., Discussion: A deep-learning-based approach to CV, previously successful in laparoscopic video phase identification, translates well to endoscopic procedures. With continued refinements, AI could contribute to intra-operative decision-support systems and post-operative risk prediction.

Background and Aims: The risk of bleeding and thromboembolic events in patients undergoing peroral endoscopic myotomy (POEM) who are receiving antithrombotic therapy is unknown. Our primary aim was to assess the safety of POEM in this patient subset. Secondary outcomes were rates of clinical success, GERD, and procedure-related outcomes., Methods: This was an international, 1:1, case-control study performed at 10 centers using prospectively maintained databases. All consecutive patients who underwent POEM before November 2019 were considered for inclusion. Cases were patients on antiplatelet and/or anticoagulant therapy. Controls not receiving antithrombotics were matched for age and esophageal motility disorder. Primary outcomes were major bleeding and thromboembolic events on postprocedural day 30., Results: Of 2895 patients who underwent POEM, 126 cases (103 on antiplatelets, 35 anticoagulants, 12 both) and 126 controls were enrolled. The rate of major bleeding was higher for the antithrombotics users (5.6% vs 0.8%, P = .03). Anticoagulants and clopidogrel were temporarily interrupted in all cases. Aspirin was continued in 40.5% of users without increasing the bleeding risk. One thromboembolic event occurred in each group (0.79%; P = 1.00). No POEM-related deaths were noted. Rates of clinical success (91.7% vs 96% in controls, P = .20), postprocedural GERD, and technical-related outcomes were similar in both groups. Antithrombotic management was heterogeneous, and guidelines were not adhered to in 23.8% of cases., Conclusions: POEM is safe and effective in patients receiving antithrombotic therapy although it is associated with a greater risk of major bleeding., (Copyright © 2021 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

Objectives: Per-oral endoscopic myotomy (POEM) is a safe and effective treatment for achalasia and esophageal motility disorders. The role of second-look endoscopy (SE) on postoperative day 1 has not been examined. This study aimed to evaluate the findings and need of SE after POEM., Methods: This is a single-center, retrospective study. All consecutive patients who underwent POEM and SE on postoperative day 1 between December 2017 and September 2019 were included. The primary endpoint was the rate of newly-detected adverse events (nAE) during SE that required endoscopic intervention or deviation from the normal postoperative course. Multivariate logistic regression was used to identify predictors of nAE., Results: Four-hundred-ninety-seven patients (mean age, 50.3 years; female, 49.9%) were included. SE identified abnormal findings in a total of 71 patients (14.3%). nAE which required endoscopic intervention or deviation from the normal postoperative course were identified in 12 patients (2.4%): eight (1.6%) entry site dehiscence; two (0.4%) submucosal hemorrhage or hematoma; and two (0.4%) dehiscence of an intraoperative perforation site after endoclip closure. Other findings such as mucosal thermal damage without perforation and small submucosal hematoma were found in 54 patients (10.9%) and five patients (1.0%), respectively. Multivariate analysis showed that longer operation time and intraoperative adverse events (AE) were associated with clinically significant nAE during SE., Conclusions: Second-look endoscopy can detect and treat nAE that may lead to severe AE. Thus, SE should be highly considered before starting oral ingestion in all cases, and especially in those who present an intraoperative AE and longer operation time., (© 2020 Japan Gastroenterological Endoscopy Society.)

Backgrounds and Aims: Per oral endoscopic myotomy (POEM) has been reported as an effective and safe salvage therapy for achalasia but there is limited composite data. We performed a systematic review and meta-analysis of studies that reported the rates of clinical success and adverse events among patients who underwent POEM after failed conventional endoscopic or surgical therapy., Methods: Electronic literature search was conducted from inception through December 2018 for articles reporting the efficacy and safety of POEM in patients with achalasia who failed endoscopic or surgical therapy. Primary outcome was the pooled estimated rates of clinical success, defined as Eckardt score ≤ 3 after POEM. Secondary outcomes were procedural time, the rates of POEM-related gastroesophageal reflux disease (GERD) and procedure-related adverse events., Results: Seven studies reporting outcomes on 487 patients met our criteria. Pooled estimated rate of clinical success of POEM was 88% (95% confidence interval (CI) 79-94%). Mean procedural time was 64 minutes (95% CI 44-85 minutes). POEM-related GERD was found in 20% (95% CI 16-24%) of patients. Estimated incidence of overall adverse events was 10% (95% CI 5-18%) with individual risk of bleeding, mucosotomy, pneumothorax, pneumoperitoneum hydrothorax/mediastinitis, and subcutaneous emphysema ranging from 1 to 4%., Conclusions: Per oral endoscopic myotomy after failed endoscopic or surgical therapy in patients with achalasia is an effective and safe treatment. Further long-term follow-up studies in a larger number of patients are warranted to validate the sustainable efficacy of POEM for achalasia., (© 2020 Japan Gastroenterological Endoscopy Society.)

Background: Since Inoue performed the first POEM in 2008, safety and efficacy have been well-established. Early studies focused on refining the technique and avoiding incomplete myotomy. Following the discovery that many patients with abnormal acid exposure are asymptomatic, the focus shifted to post-POEM reflux, but no studies have identified any associated procedural factors. In this study, we examined the intermediate-term results of our previous randomized controlled trial, with particular attention to post-POEM reflux., Methods: Previously, 100 consecutive patients were randomized to either double- or single-scope POEM. Endoscopy was conducted 2 months post-POEM and annually thereafter. Patients were included in the present study if they completed endoscopy ≥ 6 months post-POEM, and the clinical results of both groups were analyzed with particular attention to clinical efficacy and post-POEM reflux., Results: Median follow-up was 3 years, and most myotomies were performed in the posterior location. The final gastric myotomy length was longer in the double-scope group (3.3 vs. 2.6 cm). Clinical efficacy (≥ 80%) and rates of post-POEM reflux (~ 60%) were similar; however, there was a higher incidence of moderate esophagitis (Los Angeles Grade B) in the double-scope group (25% vs. 4%). There were no cases of severe esophagitis (Los Angeles Grade C/D). Among patients with normal endoscopy at 2 months, > 40% developed erosive esophagitis on intermediate-term follow-up., Conclusions: This is the first study to demonstrate a procedural factor that increases post-POEM esophagitis. Gastric myotomy > 2.5 cm results in increased rates of moderate esophagitis without improving clinical efficacy. Some patients developed esophagitis in a delayed fashion, emphasizing the importance of ongoing surveillance. We also believe that preserving the gastric sling fibers may help to reduce reflux rates. The double-scope method may help to control myotomy length (2.0-2.5 cm) and direction (lesser curve to avoid the gastric sling) to help maximize clinical efficacy while minimizing post-POEM reflux.

Background and Aims: Peroral endoscopic myotomy (POEM) is an available treatment modalities for achalasia. The reported efficacy of POEM in the only prospective multicenter study was 82%; however, a retrospective multicenter study in Japan reported a higher efficacy rate of 95%. The aim of this study was to prospectively verify treatment outcomes after POEM at multiple facilities in Japan., Methods: This was a prospective single-arm trial of POEM for achalasia at 8 facilities in Japan between April 2016 and March 2018 to evaluate its safety and efficacy. Patients were re-evaluated at 3 months and up to 1 year after POEM., Results: Among the 233 patients with achalasia who underwent POEM, procedure-related adverse events occurred in 24 patients (10.3%), none of whom required surgical intervention. In the 207 patients satisfying the inclusion criteria, the efficacy rate of POEM, defined by an Eckardt score ≤3 at 1 year, was 97.4% (95% CI, 95.3%-99.7%). The Eckardt score decreased significantly from 6.6 ± 2.0 preoperatively to 1.1 ± 1.1, 1 year after POEM. Postoperative reflux esophagitis, severe reflux esophagitis, and symptomatic GERD were reported in 54.2%, 5.6%, and 14.7%, respectively, and proton pump inhibitors were administered in 21.1%., Conclusions: Our prospective multicenter study in Japan showed greater efficacy of POEM for achalasia compared with the results of a previous prospective multicenter study. POEM is safe and highly effective for at least 1 year. (Clinical trial registration number: UMIN 000021550.)., (Copyright © 2020 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

It has been 10 years since peroral endoscopic myotomy (POEM) was reported for the first time, and POEM has currently become the standard treatment for achalasia and related disorders globally because it is less invasive and has a higher curative effect than conventional therapeutic methods. However, there are limited studies comparing the long-term outcomes of POEM with those of conventional therapeutic methods, particularly in the occurrence of gastroesophageal reflux disease (GERD) after therapy. With this background, we held a consensus meeting to discuss the pathophysiology and management of GERD after POEM based on published papers and experiences of each expert and to discuss the prevention of GERD and dealing with anti-acid drug refractory GERD. This meeting was held on April 27, 2018 in Tokyo to establish statements and finalize the recommendations using the modified Delphi method. This manuscript presents eight statements regarding GERD after POEM.

Objectives: Per-oral endoscopic myotomy (POEM) is a recommended treatment modality for achalasia, but there is little published data for its use in children. The objective of the present study was to evaluate whether POEM is clinically effective and safe for children., Methods: International multicenter retrospective study conducted in 14 tertiary centers that included consecutive children who underwent POEM between January 2012 and August 2018. Outcomes, such as clinical response were assessed whenever available. Adverse events and factors associated with clinical failure were also investigated., Results: A total of 117 patients (mean ± SD age: 14.2 ± 3.7 years) underwent POEM for achalasia (type I, n = 36; type II n=66; type III, n=8). Among these, 30 (26%) were pretreated (botulinum injection and/or pneumatic dilatation). Mean ± SD baseline Eckardt score was 7.5 ± 2.0. Clinical success was achieved in 90.6% of cases (95%CI [83.8%;95.2%]) in the intention-to-treat analysis. The mean ± SD Eckardt score post-POEM was 0.9 ± 1.2 (P < 0.001). The mean duration of follow-up time 545 days (range: 100-1612). A total of 7 adverse events occurred (4 mucosotomies, 2 subcutaneous emphysema, 1 esopleural fistula). Gastroesophageal reflux symptoms were seen in 17 patients (15%); missing data for 10 patients (9%). There was a trend towards more frequent clinical failure in achalasia associated with genetic disorders (40% vs 8%, P = 0.069)., Conclusions: POEM in pediatric patients appears to be effective and safe, although there was a trend towards more frequent clinical failure achalasia associated with genetic disorders. Further studies are needed to assess the long-term outcomes, especially the consequences of GERD.

Competing Interests: None

Background: Peroral endoscopic myotomy (POEM) for achalasia is technically challenging to carry out in patients with type III, multiple prior treatments, prior myotomy, and sigmoid type. Herein, we present a series of consecutive patients with complex achalasia and introduce the POEM difficulty score (PDS)., Aim: To demonstrate the application and discuss the utility of PDS and present the feasibility, safety, and efficacy of POEM in complex achalasia patients., Methods: Forty consecutive POEM were carried out with 28 meeting the criteria for complex achalasia. Primary outcome was clinical success (Eckardt score ≤3) at a minimum of 3 months follow-up. Secondary outcomes included adverse events, procedural velocity and PDS., Results: Twenty-eight complex and 12 non-complex POEM procedures were carried out with 100% and 92% clinical success, respectively, without any major adverse events with a median follow up of 15 months (complex) and 8 months (non-complex). Mean velocities for non-complex, type III, prior myotomy, ≥4 procedures and sigmoid type were as follows: 4.4 ± 1.6, 4.8 ± 1.5, 5.9 ± 2.2, 6.9 ± 2.2 and 8.2 ± 3.2 min/cm, respectively. Median PDS for non-complex, type III, prior myotomy, ≥4 treatments and sigmoid type were 1 (0-3), 2 (0-4), 2.5 (1-6), 3 (2-6) and 3.5 (1-6), respectively. PDS was shown to correlate well with procedural velocity with a correlation coefficient of 0.772 (Spearman's P < 0.001)., Conclusions: PDS identifies the factors that contribute to challenging POEM procedures and correlates well with procedural velocity. The order of increasing difficulty of POEM in complex achalasia appears to be type III, prior myotomy, ≥4 treatments and sigmoid type., (© 2018 Japan Gastroenterological Endoscopy Society.)

Background: Peroral endoscopic myotomy (POEM) has become the minimally invasive endoscopic treatment for achalasia; however, gastroesophageal reflux (GER) post-POEM has been reported. A pilot study was conducted in which an endoscopic fundoplication was added to the standard POEM (POEM + F) procedure to overcome this issue. We report the technical details of POEM + F and short-term safety results., Methods: POEM + F was performed in 21 patients. After completing myotomy, the endoscope was advanced from the submucosal tunnel into the peritoneal cavity. A partial mechanical barrier was created by retracting the anterior gastric wall at the esophagogastric junction with the use of endoclips and an endoloop., Results: POEM + F was technically feasible in all cases and created a visually recognizable fundoplication. The clinical course after POEM + F was uneventful. No immediate or delayed complications occurred., Conclusion: POEM + F may help mitigate the post-POEM incidence of GER and serve as a minimally invasive endoscopic alternative to a laparoscopic Heller-Dor procedure. This is the largest case series of peroral natural orifice transluminal endoscopic surgery without laparoscopic assistance in the human foregut., Competing Interests: Dr. Inoue is an advisor for Olympus Corporation and Top Corporation. He has also received educational grants from Olympus Corp. and Takeda Pharmaceutical Co., (© Georg Thieme Verlag KG Stuttgart · New York.)

Peroral endoscopic myotomy (POEM) is a groundbreaking procedure for treating esophageal achalasia, and many reports from various facilities have described its safety and efficacy. However, there have been few reports on adverse events. Here, we report a case of a patient with mediastinitis caused by delayed mucosal damage after POEM. This case was the most severe among all POEM cases at our hospital. A 58-year-old man had experienced dysphagia and chest tightness since he was around 50 years old. At a previous hospital, he had been diagnosed with nonerosive reflux disease and had undergone fundoplication. As his symptoms did not improve, he was referred to our department. POEM was able to be finished but a stable visual field could not be maintained throughout procedure because of strong esophageal contractions. From findings of endoscopy and esophagography after POEM, the patient was diagnosed mediastinitis caused by delayed esophageal perforation. In this case, conservative treatment (fasting, antibiotic therapy, and enteral feeding) was successful. However, the option to administer surgical treatment, such as drainage, must not be overlooked., (© 2018 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and John Wiley & Sons Australia, Ltd.)

Peroral endoscopic myotomy (POEM) is a novel clinical technique developed in Japan used to treat esophageal achalasia and esophageal motility disorders. This technique has been rapidly accepted and widely disseminated throughout our clinical practice because of its low invasiveness, technical novelty, and high efficacy. Since the advent of POEM, there have been no clinical guidelines that clearly indicated its standard of care, and these guidelines have been anticipated both nationally and internationally by clinicians who engage in POEM practice. In 2017, to meet these needs, the Japan Gastroenterological Endoscopy Society (JGES) launched the guideline committee for POEM. Based on the guideline development process proposed by the Medical Information Network Distribution Service (MINDS), the guideline committee initially created research questions on POEM and conducted a systematic review and meta-analysis on each topic. The clinical research extracted from databases for these clinical questions and the systematic review mainly comprised a few retrospective studies with a small number of participants and short trial periods; hence, the strength of the evidence and recommendations derived from these results was low. Throughout this process, the guideline committee met thrice: once on May 13, 2017, and again on September 17, 2017, to formulate the draft. A consensus meeting was then held on January 14, 2018, in Tokyo to establish the guideline statements and finalize the recommendations using the modified Delphi method. This manuscript presents clinical guidelines regarding current standards of practice and recommendations in terms of the nine chief topics in POEM., (© 2018 Japan Gastroenterological Endoscopy Society.)

Allgrove syndrome, also known as Triple A syndrome, is a rare autosomal recessive genetic disease characterized by three signs: esophageal achalasia, adrenocorticotropic hormone refractoriness, and alacrima. A 31-year-old male presented to our hospital for treatment of difficulty swallowing caused by esophageal achalasia. Because he had complicating alacrima, a neurologic disease, and a family history of consanguineous marriage, a genetic neurologic disease was suspected. Then, a mutation in the achalasia-addisonianism-alacrima syndrome gene was identified. With the diagnosis of Allgrove syndrome, a per-oral endoscopic myotomy (POEM) was performed for esophageal achalasia. After the POEM, the symptoms and the esophageal pressure findings ameliorated quickly, with no recurrence noted throughout a follow-up of more than 1 year. Here, we report the first case of POEM performed for esophageal achalasia in Allgrove syndrome.

Achalasia cardia (AC) is a frequently encountered motility disorder of the esophagus resulting from an irreversible degeneration of neurons. Treatment modalities are palliative in nature, and there is no curative treatment available for AC as of now. Significant advancements have been made in the management of AC over last decade. The introduction of high resolution manometry and per-oral endoscopic myotomy (POEM) has strengthened the diagnostic and therapeutic armamentarium of AC. High resolution manometry allows for the characterization of the type of achalasia, which in turn has important therapeutic implications. The endoscopic management of AC has been reinforced with the introduction of POEM that has been found to be highly effective and safe in palliating the symptoms in short-term to mid-term follow-up studies. POEM is less invasive than Heller's myotomy and provides the endoscopist with the opportunity of adjusting the length and orientation of esophageal myotomy according to the type of AC. The management of achalasia needs to be tailored for each patient, and the role of pneumatic balloon dilatation, POEM, or Heller's myotomy needs to be revisited. In this review, we discuss the important aspects of diagnosis as well as management of AC. The statements presented in the manuscript reflect the cumulative efforts of an expert consensus group., (© 2018 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

Competing Interests: None

Background and Aims: Per-oral endoscopic myotomy (POEM) for achalasia is particularly appealing in the elderly because it is minimally invasive. However, data in patients aged ≥80 years are scarce. The aim of this study was to assess the clinical outcome of POEM in octogenarians., Methods: This was a multicenter retrospective study at 8 centers. Consecutive octogenarians with achalasia who underwent POEM between 2010 and 2016 were included. Rates of technical success (completion of myotomy), clinical response (Eckardt score ≤3), and adverse events (severity graded as per American Society for Gastrointestinal Endoscopy lexicon) were assessed., Results: A total of 76 patients (47.4% female, mean age 84 years) underwent POEM for treatment of achalasia: type I, 17.1%; type II, 35.5%; type III, 17.1%; and unspecified, 30.3%. Overall, 41.1% were treatment naïve, whereas others had previous botulinum toxin injection and/or pneumatic dilation. The mean (± standard deviation [SD]) age-adjusted Charlson comorbidity index score was 6.2 ± 2.4, with the majority of patients having American Society of Anesthesiologists Physical Status Classification System (ASA) scores of II/III. Technical success was 93.4%, with a median follow-up of 256 days. Fourteen adverse events occurred in 11 patients (14.5%). There were 3 inadvertent mucosotomies, 6 cases of symptomatic capnoperitoneum and/or capnomediastinum, 2 esophageal leaks, 1 cardiac arrhythmia, and 2 other). The severities of these adverse events were mild (78.6%), moderate (14.3%), and severe (7.1%). Clinical success was achieved in 90.8% of patients, with a mean (± SD) Eckardt score reduction from 7.0 ± 2.3 to 0.8 ± 0.1 (P < .001), a median follow-up of 256 days, and interquartile range of 66 to 547., Conclusion: Although the rate of technical success may be somewhat lower and the rate of adverse events slightly higher than previously reported, our data suggest that POEM in octogenarians is safe and effective, supporting its role as a primary modality for achalasia in this patient population., (Copyright © 2018 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

Background and Aim: One of the challenges during peroral endoscopic myotomy (POEM) is ensuring the appropriate length of myotomy on the gastric side. To determine the appropriate distal end of the gastric myotomy, we focused on the two penetrating vessels (TPVs) found in the gastric cardia during POEM. In the present study, we evaluated whether the TPVs could serve as an accurate indicator of the appropriate distal end of the gastric myotomy., Methods: All patients who underwent POEM between March and August 2016 were included for this study. When making the submucosal tunnel in the 5 o'clock direction into the stomach, two vessels penetrating through the circular muscle along the edge of oblique muscle in the cardia can be exposed. We designated these two vessels as TPVs. The myotomy was extended until the second TPVs was exposed. The anal end of the submucosal tunnel was confirmed by the double-scope POEM technique, and the length from the gastroesophageal junction to the anal side end of the myotomy was measured by the scale on the endoscope., Results: Among 37 patients who underwent myotomy in the 5 o'clock position, TPVs were found in 34 patients (91.2%). Sufficient submucosal tunneling on the gastric side was confirmed by the double-scope POEM technique in these 34 patients. Median length of the gastric myotomy was 3.0 cm (range 2-4 cm)., Conclusion: TPVs appears to be a simple and reliable indicator to determine the appropriate distal end of myotomy., (© 2017 Japan Gastroenterological Endoscopy Society.)

Background: Treatment for achalasia has traditionally been Heller myotomy (HM). Despite its excellent efficacy rate, a number of patients remain symptomatic post-procedure. Limited data exist as to the best management for recurrence of symptoms post-HM. We present an international, multicenter experience evaluating the efficacy and safety of post-HM peroral endoscopic myotomy (POEM)., Methods: Patients who underwent POEM post-HM from 13 centers from January 2012 to January 2017 were included as part of a prospective registry. Technical success was defined as successful completion of the myotomy. Clinical success was defined as an Eckardt score of ≤3 on 12-month follow up. Adverse events (AE) including anesthesia-related, operative, and postoperative complications were recorded., Results: Fifty-one patients were included in the study (mean age 54.2, 47% male). Technical success was achieved in 100% of patients. Clinical success on long-term follow up was achieved in 48 patients (94%), with a mean change in Eckardt score of 6.25. Seven patients (13%) had AE: six experienced periprocedural mucosal defect treated endoscopically and two patients developed mediastinitis treated conservatively., Conclusion: For patients with persistent symptoms after HM, POEM is a safe salvation technique with good short-term efficacy. As a result of the challenge associated with repeat HM, POEM might become the preferred technique in this patient population. Further studies with longer follow up are needed., (© 2017 Japan Gastroenterological Endoscopy Society.)

Background & Aims: In patients with persistent symptoms after Heller myotomy (HM), treatment options include repeat HM, pneumatic dilation, or peroral endoscopic myotomy (POEM). We evaluated the efficacy and safety of POEM in patients with achalasia with prior HM vs without prior HM., Methods: We conducted a retrospective cohort study of 180 patients with achalasia who underwent POEM at 13 tertiary centers worldwide, from December 2009 through September 2015. Patients were divided into 2 groups: those with prior HM (HM group, exposure; n = 90) and those without prior HM (non-HM group; n = 90). Clinical response was defined by a decrease in Eckardt scores to 3 or less. Adverse events were graded according to criteria set by the American Society for Gastrointestinal Endoscopy. Technical success, clinical success, and rates of adverse events were compared between groups. Patients were followed up for a median of 8.5 months., Results: POEM was technically successful in 98% of patients in the HM group and in 100% of patients in the non-HM group (P = .49). A significantly lower proportion of patients in the HM group had a clinical response to POEM (81%) than in the non-HM group (94%; P = .01). There were no significant differences in rates of adverse events between the groups (8% in the HM group vs 13% in the non-HM group; P = .23). Symptomatic reflux and reflux esophagitis after POEM were comparable between groups., Conclusions: POEM is safe and effective for patients with achalasia who were not treated successfully by prior HM. Although the rate of clinical success in patients with prior HM is lower than in those without prior HM, the safety profile of POEM is comparable between groups., (Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background and Aims: Per-oral endoscopic myotomy (POEM) has become an accepted treatment for patients with achalasia. Despite its excellent efficacy rate of greater than 80%, a small percentage of patients remain symptomatic after the procedure. Limited data exist as to the best management for recurrence of symptoms after POEM. We present the first international, multicenter experience on the efficacy and safety of a repeat POEM in the management of achalasia., Methods: Patients who underwent a redo POEM from 15 centers in 9 countries were included in a dedicated registry. Technical success was defined as successful completion of a second myotomy. Clinical success was defined as an Eckardt score of less than or equal to 3 after the second myotomy. Adverse events including anesthesia-related, operative, and postoperative adverse events were recorded., Results: Forty-six patients were included in the study. The average age was 49.3 ± 16.78 years. Twenty (45%) patients were male. The mean pre-redo-POEM Eckardt score was 4.3 ± 2.48. Technical success was achieved in 46 (100%) patients. Clinical success was achieved in 41 patients (85%). The average post-POEM Eckardt score was 1.64 ± 1.67, with a significant difference of 2.58 (P < .00001). Eight patients (17%) had adverse events consisting of procedural bleeding, all managed endoscopically. There were no deaths. No POEMs were aborted or required surgical conversion or assistance., Discussion: For patients with persistent symptoms after POEM, repeat POEM appears to be an efficacious and safe technique. Further randomized trials comparing redo POEM versus Heller should be considered. (Clinical trial registration number: NCT02162589.)., (Copyright © 2017 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

Objectives: High‐resolution manometry (HRM) and esophagography are used for achalasia diagnosis; however, achalasia phenotypes combining esophageal motility and morphology are unknown. Moreover, predicting treatment outcomes of peroral endoscopic myotomy (POEM) in treatment‐naïve patients remains an unmet need. Methods: In this multicenter cohort study, we included 1824 treatment‐naïve patients diagnosed with achalasia. In total, 1778 patients underwent POEM. Clustering by machine learning was conducted to identify achalasia phenotypes using patients' demographic data, including age, sex, disease duration, body mass index, and HRM/esophagography findings. Machine learning models were developed to predict persistent symptoms (Eckardt score ≥3) and reflux esophagitis (RE) (Los Angeles grades A–D) after POEM. Results: Machine learning identified three achalasia phenotypes: phenotype 1, type I achalasia with a dilated esophagus (n = 676; 37.0%); phenotype 2, type II achalasia with a dilated esophagus (n = 203; 11.1%); and phenotype 3, late‐onset type I–III achalasia with a nondilated esophagus (n = 619, 33.9%). Types I and II achalasia in phenotypes 1 and 2 exhibited different clinical characteristics from those in phenotype 3, implying different pathophysiologies within the same HRM diagnosis. A predictive model for persistent symptoms exhibited an area under the curve of 0.70. Pre‐POEM Eckardt score ≥6 was the greatest contributing factor for persistent symptoms. The area under the curve for post‐POEM RE was 0.61. Conclusion: Achalasia phenotypes combining esophageal motility and morphology indicated multiple disease pathophysiologies. Machine learning helped develop an optimal risk stratification model for persistent symptoms with novel insights into treatment resistance factors. [ABSTRACT FROM AUTHOR]