P60 The risk of pathological acid reflux following per-oral endoscopic myotomy for the treatment of achalasia

Introduction Per-oral endoscopic myotomy (POEM) is a proven, effective treatment for patients with achalasia, but there are concerns regarding the risk of developing post procedure acid reflux with published studies reporting conflicting results. This study aims to determine the risk of acid reflux and related complications following POEM and influencing factors. Methods This was a single centre, retrospective study. As part of the routine patient pathway, all patients following POEM were offered oesophageal pH testing at 3 months, symptom screening at each follow-up appointment (validated GORD HRQL questionnaire) and surveillance gastroscopy 2–3 years post POEM. Outcomes of interest included abnormal acid exposure time (AET>4.2%), DeMeester Score (>14.72), GORD-HRQL scores and endoscopic findings at surveillance gastroscopy (reflux oesophagitis, Barrett’s oesophagus and malignancy) indicating acid reflux related complications. Results 130 POEM procedures were included in analysis (mean age: 47.4 years, 55 female and median disease duration = 3.0 years). Oesophageal pH results were available for 47 patients; 13/47 (27.7%) had an abnormal AET and 12/47 (25.5%) had a positive DeMeester score. Mean GORD-HRQL symptom scores were lower in patients with abnormal AET (3.1 vs 5.8) but was not statistically significant (p=0.15). Comparing patients with abnormal and normal AET there was no significant difference for history of prior therapy (p=0.79), prior myotomy (p=0.80), disease duration (p=0.49) and total myotomy length (p=0.14). 4/20 (20.0%) of surveillance gastroscopies demonstrated evidence of reflux oesophagitis; there were no cases of Barrett’s oesophagus or malignancy. Conclusions This study demonstrated a prevalence of 27.7% for abnormal acid exposure following POEM based on pH studies, this is at the lower limit of published research. No factors influencing the development of abnormal AET were identified. Symptom scores were lower in patients with abnormal AET but not statistically significant. Although, it is reassuring that acid reflux may be lower following POEM than previously thought, clinicians must remain vigilant and continue to offer routine pH testing and surveillance gastroscopy. Especially, as symptoms of acid reflux are a poor correlate with abnormal AET. Long-term surveillance should continue in this patient group to truly determine the long-term risks of post POEM acid reflux and associated sequalae.