Retraction notice to 'Long-term outcomes of per-oral endoscopic myotomy in patients with achalasia with a minimum follow-up of 2 years: an international multicenter study': [YMGE 85 (2017) 927-933]

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted due to overlapping/duplicate material. Data from some patients from this study have previously been published in other journals without cross-referencing. Twenty patients overlap with a paper by Kumbhari et al.