PREcision MEDicine In Achalasia (PREMEDIA)

The goal of this clinical trial is to learn if shorter Per-Oral Endoscopic Myotomy (POEM) works as well as a longer POEM in patients with trouble swallowing due to certain conditions. The main question\[s\] it aims to answer \[is/are\]: * Does making a smaller cut in the muscle at the bottom of the esophagus work just as well as making the standard bigger cut in relieving symptoms? * Does making the smaller cut reduce the side effects of the procedure compared to the standard bigger cut? Researchers will compare the symptoms and side effects of making a shorter cut to the symptoms and side effects of a longer cut. Participants will allow researchers to access their standard of care information in their medical record, complete questionnaires at up to 6 times over a 2-year period.

Inclusion Criteria 1. Age ≥ 18 2. Type I achalasia or type II achalasia or cEGJOO 3. Eckardt score \> 3 Exclusion Criteria The following exclusion criteria are for the RCT, but 1-13 below also pertain to the observational study: 1. Prior POEM 2. Prior surgical treatment for achalasia 3. Endoscopic pneumatic dilation or lower esophageal sphincter botulinum toxin (botox) injection within 6 months 4. Prior unrelated esophageal or upper gastric surgery, including Roux-en-Y gastric bypass and sleeve gastrectomy 5. Prior endoscopic gastroesophageal intervention for obesity or GERD, such endoscopic sleeve gastroplasty or transoral incisionless fundoplication 6. Known secondary achalasia related to malignancy (pseudoachalasia) 7. Known eosinophilic esophagitis 8. Diverticulum (\> 2 cm) in distal esophagus 9. Megaesophagus 10. Fibroinflammatory stricture of the esophagus due to any etiology (e.g., peptic, radiation, eosinophilic) 11. Pregnancy 12. Standard contraindications to general anesthesia 13. Standard contraindications to endoscopic myotomy in the esophagus (e.g. untreated varices) 14. Unwillingness or inability to consent for the study 15. Anticipated inability to follow protocol 16. Weekly (or more frequent) opioid medication use in the last 2 years