Introduction
Per-oral endoscopic myotomy (POEM) has revolutionised achalasia treatment, nevertheless there is still a lack of technical standardization. No clear definition of “long”, “standard” or “short” POEM exists to date. With the exception of type III achalasia, there is evidence that myotomy limited to the lower esophageal sphincter (<6 cm) may be highly effective, time-saving and associated with less post-postoperative gastroesophageal reflux, yet it is common practice to use long myotomy in these patients.
Aims & Methods
We conducted a systematic review with meta-analysis to define current myotomy length standards during POEM. A literature search was performed on MEDLINE-Pubmed, Embase, Scopus, and Cochrane Library (from inception to December 2022). We included prospective, retrospective clinical studies and randomized controlled trials reporting technical details of POEM, in which no definite or comparative myotomy length was intentionally adopted thus representing a “standard” myotomy for the operator. The primary outcome was the pooled mean total myotomy length. Secondary outcomes included clinical success and reflux symptoms. Main exclusion criteria were: patient age < 18 years; studies providing achalasia diagnosis without high-resolution manometry, studies including patients with non-achalasia esophageal motility disorders, studies comparing different myotomy lengths or adopting pre-specified myotomy lengths, studies including type III achalasia patients only. Sub-group analyses were performed to explore heterogeneity across studies and to assess the impact of different subtypes, geography and time trends on the primary outcome.
Results
From initial 7,172 records, after exclusion criteria were applied, a total of 25 articles were included. Of those, 6 provided results on the primary outcome in separate subgroups and were therefore included as separate studies. Overall, 31 studies with a total 3023 patients were evaluated. The pooled mean of total myotomy length was 10.39 cm (95% CI 10.06-10.71; I2 99.3%). The pooled mean of esophageal and gastric myotomy length, provided by 17 studies, was 7.11 cm (95% CI 6.51-7.71; I2 99.8%) and 2.81 cm (95% CI 2.41-3-22; I2 99.8%) respectively. At the subgroup analysis for achalasia subtypes, pooled mean length in non-spastic achalasia (type I and II) was 10.17 cm (95% CI 9.91-10.43; I2 94.2%), while in type III attested at 14.02 cm (95% CI 10.59-17.44; I2 98.9%). Pooled mean myotomy length for studies conducted between 2014-2018 was 10.56 cm (95% CI 9.51-11.61; I2 99.0%) while studies between 2019-2022 showed a mean length of 10.3 cm (95% CI 9.99-10.61; I2 99.6%). No geographical difference was observed: in eastern countries mean length was 10.2 cm (95% CI 9.12-10.92; I2 98.9%), while in western countries was 10.95 cm (95% CI 9.83-12.07; I2 99.5%). At a median follow-up of 29 months, the pooled clinical success rate was 91% (95% CI 88.9%-93.2%; I2 67.2%), while the pooled rate of post-POEM clinical reflux was 26% (95% CI 21.0%-31.3%; I2 89.5%).
Conclusion
Our meta-analysis found that the pooled mean myotomy length during a "standard” POEM is 10.4 cm, remaining over 10 cm in non-spastic (type I and II) achalasia. The high heterogeneity across studies confirms that POEM technique needs further standardization. We found no time trend towards adopting short POEM, despite recent evidence supporting efficacy and safety of this approach.
