Achalasia is an idiopathic motility disorder, primarily identified by the absence of esophageal peristalsis and the inability of the lower esophageal sphincter (LES) to relax properly. Although it is usually misdiagnosed and treated as gastroesophageal reflux disease (GERD), the main symptom is progressive dysphagia, accompanied by additional symptoms like nocturnal cough, heartburn, weight loss, regurgitation of undigested food and aspiration.

The severity of achalasia and the effectiveness of treatments are commonly assessed using the Eckardt Symptom Score (ESS), which evaluates symptoms like weight loss, regurgitation, dysphagia, and retrosternal pain.

Diagnosis of achalasia is often delayed, affecting up to 50% of patients. It typically involves a combination of diagnostic tools, such as time barium esophagram (TBE) study, which assesses the movement and clearance of barium in the esophagus; esophagogastroduodenoscopy (EGD), which allows visual examination of the esophagus, stomach, and duodenum; and high-resolution esophageal manometry (HREM), considered the gold standard for achalasia. HREM can also help stratify the condition into different types, influencing treatment choices. Furthermore, the endoluminal functional lumen imaging probe (Endoflip, Crospon Corp, Dangan Galaway, Ireland), which measures baseline parameters of LES, aiding in both diagnosis and treatment evolution.

While there is no cure for achalasia, treatments aim to reduce LES pressure. The include pharmacological treatments, such as calcium channel blockers or nitrates; endoscopic treatment, including injection of botulinum toxin in the LES, pneumatic dilation, or per-oral endoscopic myotomy (POEM); and surgical therapies (laparoscopic Heller myotomy). POEM has emerged as a first-line treatment for achalasia due to its minimally invasive nature and high success rates (80%-90%). This technique involves creating a submucosal tunnel and performing myotomy, and it can be performed anteriorly (at 2 o'clock) or posteriorly (at 5 o'clock).

The choice between anterior and posterior approaches to POEM often depends on the endoscopist's experience and preference. While current data is inconclusive regarding the superiority of either approach, some suggest that the posterior approach might be technically easier due to procedural characteristics (i.e., alignment between endoscopic accessories and mucosal incision). The introduction to novel technologies with smaller diameters can improve this minimally invasive approach making the procedure more efficient and safer for patients with achalasia. Thus, we aim to evaluate the safety and effectiveness of a novel radiofrequency and microwave ablation flexible bipolar (SpydrBlade Flex, CREO Medical, UK) for per-oral endoscopic myotomy in patients with achalasia.

Inclusion Criteria:

• Patients with 18 years of age or older.
• Patients referred to the participating center with a clinical indication for POEM. This includes conditions such as: achalasia, native or failed Heller myotomy, balloon dilation, and EGJ outflow obstruction.
• Patients who provide informed consent.

Exclusion Criteria:

• Patients who have contraindications for EGD.
• Patients with an Eckardt score < 3 before POEM.
• Positive diagnosis of Chagas disease.
• Patients unable to withstand general anesthesia.