POEM is a minimally invasive endoscopic therapy that is highly efficacy in the treatment of achalasia of any type. POEM has an increased risk of GERD. Systematic PPI therapy has never been studied for the prevention of post-POEM GERD.

The investigators wish to retrospectively compare patients who have received routine PPI therapy vs. patients who don't.

Inclusion criteria:

• > 18 years old
• Consent given
• Achalasia all types with eckhardt score > 3

Exclusion criteria:

• Patient who is a minor or under judicial protection
• Pregnant or breastfeeding woman
• Contraindication to PPIs
• Carrier of mediastinal and exogastric neoplasia
• Patient on PPIs prior to the procedure for indication that does not allow for their discontinuation
• Peptic esophagitis (Grade B, C or D) before or at the time of the procedure
• Previous treatment with Heller myotomy

Patients will be included from several French university hospitals that have POEM as a treatment for esophageal achalasia and which routinely perform an endoscopic evaluation of esophagitis between 6 to 9 months after the POEM.

Data collection will be retrospective from patient records at each center.

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