BACKGROUND AND AIMS: Peroral endoscopic myotomy (POEM) may be associated with 
higher rates of gastroesophageal reflux disease (GERD) than laparoscopic 
Heller's myotomy with fundoplication (LHM), since POEM is not combined with a 
fundoplication. However, peri-esophageal anti-reflux barriers are preserved in 
POEM, which might prevent GERD. Hence, we sought to compare the objective 
esophageal pH study findings in achalasia patients after POEM and LHM.
METHODS: Achalasia patients undergoing POEM from 2014 to 2015 at our institution 
were matched 1:3 with LHM patients using propensity score matching. 
Demographics, prior interventions, pre-treatment and 2-month post-treatment 
timed barium esophagram (TBE), high-resolution esophageal manometry (HREM) and 
24-h esophageal pH study findings were compared between the two groups.
RESULTS: Thirty-one patients in the POEM group and 88 patients in the LHM group 
were included. Larger proportion of POEM patients had prior interventions for 
achalasia as compared to LHM patients (overall: 71% vs. 44.3%; p = 0.012). 
Esophageal acid exposure was significantly higher in POEM as compared to LHM 
patients (abnormal total acid exposure: 48.4% vs. 13.6%; p < 0.001, abnormal 
DeMeester score 54.8% vs. 17.4%; p = 0.005 respectively). In sub-group analysis, 
similar results were noted on 24-h pH study after exclusion of the POEM patients 
with prior LHM and corresponding matches. There was no significant difference in 
the rate of GERD symptoms between POEM and LHM. There was no significant 
correlation between the post-treatment basal lower esophageal sphincter pressure 
and integrated relaxation pressure with abnormal acid exposure in either POEM or 
LHM.
CONCLUSIONS: In patients with achalasia, POEM leads to significantly higher 
rates of abnormal esophageal acid exposure, without an increase in the rate of 
GERD symptoms, when compared to LHM with fundoplication. Interestingly, prior 
LHM has no impact on post-POEM pH study findings. Potential of increased 
esophageal acid exposure and possible consequences should be discussed with all 
patients prior to POEM. Further studies are needed to determine the long-term 
effects of increased acid exposure after POEM.