Selective inner muscle layer myotomy is associated with lower pain and same clinical efficacy that full-thickness myotomy in patients treated by POEM for achalasia: A multicenter retrospective comparative analysis of 158 patients.

Introduction: The aim of this study was to compare the impact of the depth of myotomy (selective inner layer myotomy (SIM) vs. full-thickness myotomy (FTM)) on the outcome of patients treated with POEM for achalasia.

Methods: This was a retrospective, observational, conducted in two tertiary centers between October 2018 and September 2022. Patients were divided into two groups: SIM and FTM. The primary endpoint was clinical efficacy at 6 months, while secondary endpoints were postoperative criteria (such as pain, length of hospital stay, complications) and occurrence of gastroesophageal reflux disease (GERD) (esophagitis at 6 months, heartburn, and pH-metry).

Results: 158 patients were included in the study (33 in the FTM group and 125 in the SIM group). The success rates at 6 and 12 months were similar in both groups, with 84 % and 70 % in the SIM group versus 90 % and 80 % in the FTM group, respectively (p = 0.57 and p = 0.74). However, more opioid analgesics were consumed in the FTM group compared to the SIM group (41% vs 21 %, p < 0.01). The length of hospitalization was longer in the FTM group than in the SIM group (2.17 ± 2.62 vs 2.94 ± 2.33, p < 0.001). The rate of esophagitis at 6 months was comparable (16 % in the SIM group vs 12 % in the FTM group, p = 0.73). There was no significant difference in terms of heartburn at 6 or 12 months between the SIM and FTM groups (18.5% vs 3.8 %, p = 0.07 and 27% vs 12.5 %, p = 0.35, respectively).

Conclusion: There was no significant difference in terms of clinical efficacy and GERD occurrence between FTM and SIM. However, full-thickness myotomy was associated with more postoperative pain and a longer length of hospital stay. Therefore, selective internal myotomy should be preferred over full-thickness myotomy.