Gastroesophageal reflux disease after peroral endoscopic myotomy: lest we forget what we already know

After the performance of the first peroral endoscopic myotomy (POEM) in 2008, POEM has now spread worldwide and has arguably become a first-line treatment option for achalasia. Recently, there is increasing debate regarding post-POEM gastroesophageal reflux (GER) and gastroesophageal reflux disease (GERD). The reported incidences of GERD vary widely, owing to the variability in the definitions used. The literature regarding GERD and achalasia patients with a focus on 24-hour pH testing, esophageal acid exposure, and fermentation and the definitions of GERD used in the POEM literature are examined. 24-hour pH testing in achalasia patients may be abnormal due to fermentation both pre- and post-treatment. It is vital that POEM operators ensure that fermentation is recognized during 24-hour pH testing and excluded in the analysis of acid exposure time (AET) used in the diagnosis of GERD. In untreated achalasia, 24-hour pH testing may suggest abnormal AET in over a third of patients. However, most abnormal AETs in untreated achalasia patients are due to fermentation rather than GER. In treated achalasia, up to half of the patients with abnormal AET may be attributable to fermentation. To have a candid discussion and appropriately address the questions surrounding post-POEM GERD, consistent definitions need to be applied. We suggest the recent definition of GERD from the Lyon Consensus to be utilized when diagnosing GERD in post-POEM patients. Further studies are required in establishing ideal parameters for 24-hour pH testing in achalasia patients.