The relationship between cardiac muscularis propria and clinical outcomes of peroral endoscopic myotomy in achalasia.

Background and Aim: Achalasia patients usually present lower esophageal sphincter thickening, which can impact the expansibility of cardia. We aimed to investigate the effect of cardiac muscularis propria (MP) on perioperative adverse events (AEs) and treatment outcomes of patients treated with peroral endoscopic myotomy (POEM).
Methods: We retrospectively reviewed 114 patients with achalasia undergoing pre-POEM endoscopic ultrasonography (EUS) between May 2013 and November 2019. Cardiac MP thickness was measured using EUS. POEM failure was defined as Eckardt score >3. Risk factors for perioperative AEs and POEM failure were identified.
Results: Patients were divided into the thin (n = 52) and the thick group (n = 62) based on the median of cardiac MP thickness (3.0 mm). Perioperative AEs rate of the thin group seemed to be slightly higher than that of the thick group (11.5% vs. 4.8%, P = 0.30). During a median follow-up of 30 months (range 1-77), 100 patients completed follow-up, 16 (16%) of which occurred clinical failure. The clinical outcomes of patients in the thin group were significantly poorer than those patients in the thick group (P = 0.006). Cardiac MP thickness was an independent risk factor for POEM failure (hazard ratio 3.9, P = 0.02; Cox regression), but not the risk factor for perioperative AEs (odds ratio 2.6, P = 0.2; logistic regression).
Conclusion: Cardiac MP thickness could be a novel predictive factor for POEM failure in patients with achalasia.
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