Standard length of peroral endoscopic myotomy (POEM) for achalasia: a systematic review and meta-analysis

Peroral endoscopic myotomy (POEM) is an established treatment for achalasia, yet there is still a lack of technical standardization. No clear definition of 'long', 'standard', or 'short' POEM exists to date. We conducted a systematic review with meta-analysis to analyze current POEM length standards. We included studies reporting technical details of POEM, in which no definite or comparative myotomy length was intentionally adopted (standard myotomy). The primary outcome was the pooled mean total myotomy length. Sub-group analyses were performed to explore heterogeneity across studies. From the initial 7172 records, 31 studies with 3023 patients were included. Pooled mean of total myotomy length was 10.39 cm (95% CI 10.06-10.71; I2 99.3%). 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. On 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 it was 14.02 cm (95% CI 10.59-17.44; I2 98.9%). Pooled mean myotomy length for studies conducted between 2014-2020 was 10.53 cm (95% CI, 10.22-10.84; I2 99.1%) and 9.74 cm (95% CI, 7.95-11.54; I2 99.7%) in 2021-2022. Myotomy length during a 'standard' POEM is 10.4 cm, remaining over 10 cm in non-spastic achalasia. The high heterogeneity across studies confirms that the POEM technique needs further standardization. We found no significant time trend towards adopting short POEM, despite recent evidence supporting its use.