Achalasia is a disorder of the esophagus that makes it difficult for food and
liquid to pass into the stomach. Achalasia results from the degeneration of
ganglion cells in the myenteric plexus in the wall of the esophagus. This
degeneration leads to failure of relaxation of the lower esophageal sphincter
(LES) together with loss of peristalsis in the distal esophagus. The most
common symptoms in patients with achalasia are dysphagia for solids and
liquids as well as regurgitation of undigested foods or saliva. Additional
symptoms include chest pain, heartburn, and difficulty belching. Complications
of achalasia may include progressive dilation of the esophagus (megaesophagus)
possibly leading to esophagectomy. Patients with achalasia are also at
increased risk of developing esophageal cancer. Achalasia can be treated with
pneumatic dilatation (PD), botulinum toxin injection, and surgical myotomy.
Laparoscopic Heller Myotomy (LHM) is the most common surgical myotomy
procedure for treatment of achalasia.

Peroral Endoscopic Myotomy (POEM) is the endoscopic complement of surgical
myotomy and is a newer, less invasive procedure for the management of
achalasia. POEM is an endoscopic procedure, which creates a tunnel in the
submucosal layer of the esophagus and proximal stomach. Through this
submucosal tunnel, an esophageal and gastric myotomy are made using a flexible
endoscope.1 The POEM procedure is performed in 4 steps: 1) mucosal
incision/entry into the submucosa, 2) creation of a submucosal tunnel, 3)
myotomy, and 4) closure of the mucosal incision.6,7,8,12,21,23,24,31

POEM is a form of natural orifice transluminal endoscopic surgery (NOTES). The
procedure is performed perorally, without any incisions in the chest or
abdomen. The advantage of this approach is to reduce procedure-related pain
and return patients to regular activities sooner than surgeries requiring
external incisions.

POEM may be considered medically necessary for treatment of symptomatic,
monometrically proven primary idiopathic achalasia, types I, II, or III. Prior
to performing a POEM procedure, it is crucial to confirm that patients have
the correct diagnosis of achalasia and the following documentation must be
included in the clinician's preoperative evaluation:

  * **History and physical exam** - including a standardized, validated symptom assessment form completed by all patients (i.e., Eckardt score 3);
  * **High-resolution esophageal manometry (HRM)** - achalasia is subclassified according to the Chicago Classification of esophageal motility disorders, which is based upon the result of a high-resolution esophageal manometry test;
  * **Contrast esophagram** - findings on contrast esophagram that are suggestive of achalasia include a narrowed esophagogastric junction (EGJ) with a "bird-beak" appearance and esophageal aperistalsis. Late or end-stage achalasia may give the appearance that the esophagus is significantly dilated, angulated, and tortuous, giving it a sigmoid shape35;
  * **E sophagogastroduodenoscopy (EGD)** - EGD sometimes reveals a dilated esophagus that contains residual material with normal appearing esophageal mucosa.

**Contraindications** -- if 1 of the following conditions is present, the
patient should not undergo POEM:

  * Severe erosive esophagitis
  * Significant coagulation disorders
  * Liver cirrhosis with portal hypertension
  * Severe pulmonary disease
  * Esophageal malignancy
  * Prior therapy that may compromise the integrity of the esophageal mucosa or lead to submucosal fibrosis, including recent esophageal surgery, radiation, endoscopic mucosal resection, or radiofrequency ablation

Previous therapies for achalasia, such as PD, botulinum toxin injection, or
LHM, are **not** contraindications to POEM.

Prior to treatment with POEM, patients should be educated on the risk of
gastroesophageal reflux disease (GERD). Also, follow-up acid suppression
treatment should be considered after POEM. Patients should be counseled that
treatments exist with a lower incidence of post-procedure GERD, such as LHM
and PD.

POEM is considered a safe but complex procedure. POEM will be considered
medically reasonable and necessary only if it is performed by adequately
trained, experienced physicians in high-volume centers. These centers must
have the available staff to address any potential adverse events from POEM
immediately, including but not limited to gastrointestinal or cardio-thoracic
complications.

POEM appears to be highly beneficial in the short-term management of
achalasia. According to a 2014 (Stavropoulos, et al.) Natural Orifice Surgery
Consortium for Assessment and Research (NOSCAR) POEM White Paper Committee,
clinical success, defined as a post-treatment Eckardt score of 3 and/or a
>50% decrease in the LES pressure, was achieved in 82% to 100% of patients.22

Additional studies documented similar patient improvements after POEM using
either a timed barium esophagram or quality of life (QOL) assessment:

Sharata, et al. (2015) reported on a consecutive patient cohort with clinical
and objective outcomes.21 Comprehensive data was collected prospectively on
all subjects undergoing POEM from October 2010 to November 2013 at a single
institution. Subjects were classified based on HRM results. Operative data and
immediate outcomes were reviewed. Symptom scores, HRM, and timed barium
swallow (TBS) were performed prior to the procedure. Subjects were asked to
undergo routine postoperative testing 6-12 months following surgery with the
addition of standard 24-hour pH to the preoperative protocol. Morbidity was
defined as requiring additional procedures or prolonged hospital stay >2 days.
100 POEM patients were included in the final analysis. The mean age was 58
years (18-83 years). Results demonstrated that the primary presenting symptoms
included dysphagia 81, chest pain 10, and regurgitation 9. The mean follow-up
was 16 months. HRM diagnoses were 75 achalasia (30 type I, 43 type II, 2 type
III), 12 nutcracker esophagus, 5 diffuse esophageal spasm (DES), and 8
isolated hypertensive non-relaxing LES. The mean operative time was 128
minutes. The median hospital length of stay (LOS) was 1 day. The overall
morbidity was 6%; all these patients were treated endoscopically or with
conservative management without further sequelae. The average LES
resting/residual pressure significantly decreased (44.3/22.2 to 19.6/11.7 in
millimeters of mercury). Esophageal emptying improved from 40% to 90% on TBS
with 93% patients demonstrating >90% emptying at 1 minute. Of the achalasia
patients, 36% (17/47) showed some return of normal peristalsis (70%
peristalsis) on post-op HRM. Abnormal acid exposure was present on
postoperative testing in 38% of patients (26/68). Of these, 14 patients were
asymptomatic. No reflux patient required any additional antireflux procedure.
Eckardt scores decreased from 6 to 1. Dysphagia was improved or eliminated in
97% of patients with a complete resolution accomplished in 89%. Complete
dysphagia relief was better for achalasia patients (46/47 patients; 97.8%) vs.
non-achalasia patients (17/24; 70.8%). Of those with preoperative chest pain,
91.5% reported complete relief. 4 patients have refractory dysphagia. 2 non-
achalasia patients underwent subsequent LHM and 2 are improved following
serial endoscopic dilatations. Sharata, et al. were able to conclude that
despite reflux in 1 out of 3 of patients, POEM provides excellent relief of
dysphagia (97%) and chest pain (91.5%) for patients with esophageal spastic
disorders with acceptable procedural morbidity.

Teitelbaum, et al. (2013) looked at the effect on anatomic and functional
outcomes regarding the differences in POEM vs. LHM since an antireflux
procedure is not performed in POEM with mobilization of the hiatus.26 This
study looked at patients who underwent LHM or POEM and had both a pre- and
postoperative timed barium esophagogram (TBE). TBEs were performed with 200 mL
of contrast, with radiographs taken at 1, 2, and 5 minutes. Results
demonstrated that a total of 17 LHM and 12 POEM patients had undergone pre-
and postoperative TBEs. Both groups had decreased column heights
postoperatively at 1, 2, and 5 minutes (LHM: pre, 15.6, 12.7, 11.3 cm vs.
post, 3.6, 2.5, 1.8 cm; P<.001 and POEM: pre, 14.7, 11, 9.4 cm vs. post, 4.4,
2.5, 1.2 cm; P<.001). There was no difference between procedures in changes
from baseline column height. Both operations resulted in decreased esophageal
width and less angulation between the esophageal body and EGJ. The authors
concluded that POEM and LHM produce a similar short-term anatomic and
functional result at the EGJ. POEM results in a similar narrowing and
straightening of the esophagus despite the fact that POEM does not include
hiatal mobilization.

Verlaan, et al. (2013) published a prospective trial to evaluate the effect of
POEM on esophagogastric function.28 The study included patients aged >17 years
with achalasia and an Eckardt score of 3\. Before and 3 months post-POEM, 10
consecutive patients underwent esophageal manometry, TBEs, and EndoFLIP as
well as an EGD. Patient symptom scores were found to be significantly reduced
post-POEM (1, interquartile range [IQR 0-1] vs. 8 [IQR 4-8]; P = .005). LES
pressure decreased significantly (6.0 mmHg [IQR 2.6-7.4] vs. 19.0 mmHg [IQR
13.0-28.0]; P = .008). Esophageal emptying increased significantly, and a
5-minute barium column measured 2.3 cm (IQR 0-3.2 cm) vs. 10.1 cm (IQR
5.7-10.8 cm; P = .005). EGJ distensibility increased significantly (6.7
mm2/mmHg [IQR 3.8-16.6] vs. 1.0 mm2/mmHg [IQR 0.4-2.3]; P = .02) at 50 mL. 6
of 10 patients had signs of reflux esophagitis. Of these patients, 3 were
symptomatic. The authors concluded that POEM improves esophagogastric function
and suggests improved long-term clinical results.

Vigneswaran, et al. (2015) evaluated the QOL following POEM.29 All patients
who presented to their institution for surgical management of achalasia after
2011 were asked to complete QOL (SF-36), dysphagia, reflux severity index, and
GERD questionnaires while in the clinic preoperatively and at 3 weeks, 6
months, and 1 year postoperatively. Patients who underwent a POEM procedure (n
= 37), demonstrated a significant improvement in dysphagia scores, reflux
severity scores, and GERD scores (p<0.05) at each time point. SF-36
questionnaires specifically demonstrated a significant improvement in several
concepts. At 3 weeks, emotional well-being scores were significantly higher (p
= 0.006). At 6 months, emotional well-being (p = 0.039), social functioning (p
= 0.038), and general health (p = 0.029) were all significantly higher. At 1
year, role limitations due to physical health (p = 0.001) and social
functioning (p = 0.002) were significantly higher. The investigators concluded
that there is a significant improvement in several measures of QOL after POEM,
which is comparable to that seen after LHM.

Additional studies provided an assessment of the intermediate to long-term
efficacy of POEM:

Li, et al. (2018) conducted a large cohort study of 564 patients post-POEM for
achalasia.9 After a median follow-up of 49 months, the Eckardt score (median
score, 8 vs. 2 [P < 0.05]) and LES pressure (29.7 mmHg vs. 11.9 mmHg [P <
0.05]) were both improved post-POEM. The clinical success rates, estimated by
the Kaplan-Meier survival function, at 1, 2, 3, 4, and 5 years were 94.2%,
92.2%, 91.1%, 88.6%, and 87.1% respectively. Clinical reflux occurred in 37.3%
of participants post-POEM. The study concluded that POEM was a safe and
effective long-term treatment for achalasia.

Werner, et al. (2016) published a retrospective study of 80 patients who were
followed for a minimum of 2 years.32 The main outcome was the rate of POEM
failures, defined by an Eckardt score of >3, related to follow-up time. 80
patients (mean age 44.9 years, 54% men) were followed clinically for 29 months
(range 24-41). 77 patients (96.3%) achieved initial clinical response. Of
those patients, clinical recurrences (later failures) were seen in a further
14 cases (17.7%), accounting for a total failure rate of 21.5%, making an
overall success rate of POEM of 78% at 24 to 49 months. In a multivariate
analysis, age and endoscopic reflux signs were independent predictors of
treatment success. Endoscopic evidence of reflux esophagitis, mostly Los
Angeles grade A/B, were seen in 37.5% (37/72) at the 2-year control.
Conclusions from this published retrospective analysis, show a high initial
success rate of POEM, which is followed by a mid-term recurrence rate of 18%.
Reflux esophagitis, although mild, is frequent and should likely be treated by
regular low-dose proton pump inhibitor (PPI) therapy.

Inoue, et al. (2015) conducted a retrospective study of 500 consecutive
achalasia patients.4 POEM was successfully completed in all patients, with
adverse events observed in 3.2%. 2 months following POEM, reductions in
symptom scores (Eckardt score 6.03.0 vs. 1.02.0, p<0.0001) and LES pressures
(25.417.1 vs. 13.45.9 mmHg, p<0.0001) were achieved, and this persisted at 3
years post-POEM. 61 patients were followed for 3 years or longer. 91% of the
patients achieved clinical success at 1 to 2 years post-POEM. This number
decreased to 88% at 3 years. Gastroesophageal reflux was seen in 16.8% of
patients at 2 months and 21.3% at 3-year follow-up. The authors were able to
conclude that POEM was successfully completed in all cases, even when extended
indications, such as extremes of age, previous interventions, or sigmoid
esophagus were present. Adverse events were rare (3.2%) with no mortalities.
POEM appears to be a safe and effective treatment for achalasia; there are
relatively few contraindications, and the procedure may be used as either
first or second-line therapy.

A retrospective study conducted by Hungness, et al. (2016) looked at 115
consecutive patients who underwent POEM at a single, high-volume center.3
Treatment success was defined as an Eckardt score 3 without reintervention.
Gastroesophageal reflux was defined by abnormal pH-testing or reflux
esophagitis >Los Angeles grade A. Results showed that for the 115 patients,
operative time was 10129 minutes, with 95% (109/115) of patients discharged
on postoperative day 1. Clavien-Dindo grade III complications occurred in
2.7%, 1 of which required diagnostic laparoscopy to rule out Veress needle
injury to the gallbladder. The rate of grade I complications was 15.2%. The
overall success rate was 92% at an average of 28 months post-POEM (range 12-52
months). The success rate was slightly higher for nonspastic achalasia (94%)
than for type III achalasia or spastic motility disorders (90%). Objective
evidence of reflux was found in 40% of all patients and 33% for patients with
a body mass index <35 kg/m2 and no hiatal hernia. Conclusions from this study
showed that POEM, performed by experienced surgeons, provided long-lasting
symptomatic relief in 94% of patients with nonspastic achalasia and 90% of
patients with type III achalasia/spastic esophageal motility disorders, with a
low rate of complications. The rate of gastroesophageal reflux was similar to
previous studies of both POEM and LHM.

In a single-center retrospective study of 23 patients with achalasia,
Teitelbaum, et al. (2018) evaluated patients that underwent POEM and were
greater than 5 years removed from their operation.25 The mean Eckardt score
improved at 6 months (0.6) post-POEM compared with the baseline (6.4). This
improvement was maintained at 2 years post-POEM. Eckardt scores worsened
between 2 and 5 years (mean current 1.7 vs. preoperative 6.4, p < 0.001). 19
patients (83%) with achalasia remained asymptomatic (Eckardt 3) and none
required retreatment for symptoms at a median follow-up of 65 months. POEM
resulted in a successful alleviation of symptoms in the majority of patients
after 5 years.

The efficacy and safety of POEM has been compared to LHM:

Marano, et al. (2016) conducted a meta-analysis to investigate the efficacy
and safety of POEM compared with LHM for the treatment of achalasia.11 The
databases of PubMed, Medline, Cochrane, and Ovid were systematically
searched between January 1, 2005 and January 31, 2015, with the medical
subject headings (MeSH) and keywords "achalasia," "POEM," "per oral endoscopic
myotomy," "peroral endoscopic myotomy," "laparoscopic Heller myotomy" (LHM),
and "Heller myotomy." All types of study designs including adult patients with
diagnosis of achalasia were selected. The total number of included patients
was 486 (196 in POEM group and 290 in LHM group). No differences existed
between POEM and LHM in reduction in Eckardt score (MD=-0.659, 95% CI: -1.70
to 0.38, P=0.217), operative time (MD=-0.354, 95% CI: -1.12 to 0.41, P=0.36),
postoperative pain scores (MD=-1.86, 95% CI: -5.17 to 1.44, P=0.268),
analgesic requirements (MD=-0.74, 95% CI: -2.65 to 1.16, P=0.445), and
complications (OR=1.11, 95% CI: 0.5-2.44, P=0.796). Length of hospital stay
was significantly lower for POEM (MD=-0.629, 95% CI: -1.256 to -0.002,
P=0.049). Significant reduction in symptomatic gastroesophageal reflux rate
showed greater improvement with LHM compared to POEM (OR=1.81, 95% CI:
1.11-2.95, P=0.017). All included studied were not randomized. Also, all
selected studies did not report the results of follow-up longer than 1 year.
POEM appeared to represent a safe and efficacious procedure that is comparable
to the safety profile and efficacy of LHM for achalasia at a short-term
follow-up.

Park, et al. (2019) conducted a meta-analysis to compare the efficacy between
POEM and Heller myotomy.16 15 studies were evaluated with 1213 total patients.
Follow-up ranged from 2-46.2 months in the POEM group and 2-54.2 months in the
Heller myotomy group. Eckardt scores were lower in the post-POEM group
compared to the post Heller myotomy group (pooled standard mean difference
[SMD], -0.58; 95% CI, -1.03 to -0.13). Length of myotomy was greater in the
POEM group (pooled SMD, 0.63; 95% CI, 0.42-0.84). No difference between the
groups was seen in reflux symptoms (pooled risk ratio [RR], 1.03; 95% CI,
0.61-1.73) and pathologic reflux on pH monitoring (pooled RR, 1.22; 95% CI,
0.67-2.25). Erosive esophagitis, evaluated by endoscopy, appeared to be less
common in the Heller myotomy group (pooled RR, 1.88; 95% CI, 0.98-3.62).

Werner, et al. (2019) conducted a multicenter, randomized trial to compare
POEM with LHM plus Dor's fundoplication in patients with symptomatic
achalasia.33 The primary end point was clinical success, which was defined as
an Eckardt symptom score of <3 (range, 0 to 12, with higher scores indicating
more severe symptoms of achalasia) without the use of additional treatments,
at the 2-years post-POEM. A noninferiority margin of -12.5 percentage points
was used in the primary analysis. Secondary end points included adverse
events, esophageal function, Gastrointestinal Quality of Life Index score
(GIQLI) (range, 0 to 144, with higher scores indicating better function), and
gastroesophageal reflux. A total of 221 patients were randomly assigned to
undergo either POEM (112 patients) or LHM plus Dor's fundoplication (109
patients). Each randomly assigned group showed equal clinical success at
2-years, 83.0% of patients in the POEM group and 81.7% of patients in the LHM
group (difference, 1.4 percentage points; 95% confidence interval [CI], -8.7
to 11.4; P = 0.007 for noninferiority). Compared with LHM, POEM was associated
with a lower rate of serious adverse events (2.7% of patients in the POEM
group vs. 7.3% of patients in the LHM group). Improvement in esophageal
function from baseline to 24 months did not differ significantly between the
treatment groups (difference, -0.75 mmHg; 95% CI, -2.26 to 0.76), nor did
improvement in the score on the QOL (difference, 0.14 points; 95% CI, -4.01 to
4.28). POEM was associated with a higher rate of reflux esophagitis (57% of
patients in the POEM group and 20% of patients in the LHM group at 3 months;
44% vs. 29% at 2 years). POEM was considered to be equally effective to LHM
plus Dor's fundoplication in controlling symptoms of achalasia at 2 years.
Gastroesophageal reflux was more common among patients who underwent POEM than
among those who underwent LHM.

In a meta-analysis of >7000 patients in over 70 cohort studies, Schlottmann,
et al. (2018) compared the outcome of POEM and LHM for the treatment of
esophageal achalasia.19 A Medline literature search of articles on LHM and
POEM for the treatment of achalasia was performed. The main outcomes measured
were improvement of dysphagia and posttreatment GERD. Linear regression was
used to model the effect of each procedure on the different outcomes. Mean
follow-up was significantly longer for LHM (41.5 vs. 16.2 mo, P<0.0001).
Predicted probabilities for improvement in dysphagia at 12 months were 93.5%
for POEM and 91.0% for LHM (P = 0.01), and at 24 months were 92.7% for POEM
and 90.0% for LHM (P = 0.01). POEM resulted in higher incidences of GERD
symptoms (OR 1.69, 95% CI 1.33-2.14, P<0.0001), as evidenced by erosive
esophagitis (OR 9.31, 95% CI 4.71-18.85, P<0.0001), and as evidenced by pH
monitoring (OR 4.30, 95% CI 2.96-6.27, P<0.0001). POEM also was associated
with a slightly longer hospital stay by 1 day (P = 0.04). Short-term results
showed that POEM is more effective than LHM in relieving dysphagia. However,
it is also associated with a high incidence of pathologic reflux.

POEM in comparison with PD:

Ponds, et al. (2019) compared the effects of POEM vs. PD as initial treatment
of treatment-naive patients with achalasia in a randomized multicenter
clinical trial.17 133 randomized adult patients with newly diagnosed achalasia
and an Eckardt score >3 who had not undergone previous intervention were
included. The duration of follow-up was 2 years after the initial treatment.
Patients were randomized to receive POEM (n = 67) or PD with a 30-mm and a
35-mm balloon (n = 66), with stratification according to hospital. The primary
outcome was treatment success (defined as an Eckardt score 3 and the absence
of severe complications or re-treatment) at the 2-year follow-up. Of the 133
randomized patients, 130 (mean age, 48.6 years; 73 [56%] men) underwent
treatment (64 in the POEM group and 66 in the PD group) and 126 (95%)
completed the study. POEM resulted in a higher rate of treatment success than
PD at 2 years (92% in the POEM group vs. 54% in the PD group), a difference of
38% ([95% CI, 22%-52%]; P < .001). 0 cm in the PD group; difference, 2.3 cm
[95% CI, 1.0-3.6]; P = .05. No serious procedure related events occurred after
POEM, while 2 serious adverse events, including 1 perforation, occurred after
PD. Reflux esophagitis developed more often in the POEM group compared to PD
(41% vs. 7%); difference, 34% [95% CI, 12%-49%]; P = .002). This study showed
that among treatment-naive patients with achalasia, POEM compared with PD
resulted in a significantly higher treatment success rate at 2 years. The
results help support consideration of POEM as the primary endoscopic therapy
for patients with achalasia.

POEM has been shown to be safe and effective for the treatment of patients
with achalasia who have failed prior endoscopic or surgical treatment10,15,20:

According to the International Per Oral Endoscopic Myotomy Survey (IPOEMS),
40% of POEM procedures were performed in patients who previously underwent
endoscopic treatment for achalasia.23 Submucosal fibrosis resulting from
previous botulinum toxin injection or PD may make the dissection more
difficult; however, the consensus among those performing POEM was the efficacy
of the procedure was not jeopardized.

Studies have shown that POEM is a valid option of rescue treatment for those
who develop recurrent symptoms or receive no relief from their current
symptoms post-Heller myotomy:

Zhou, et al. (2013) observed that approximately 20% of patients post-LHM for
achalasia either had persistence or recurrence of their symptoms.36 The
authors prospectively included 12 patients with recurrent or persistent
symptoms (defined by established methods and an Eckardt score of 4) 2 to 38
years (mean of 12 years) after previous Heller myotomy. After undergoing a
successful POEM procedure, at a mean follow-up of 10.4 months, treatment
success (defined as an Eckardt score of 3) was achieved in 11 of 12 patients
with a significant reduction in the Eckardt score (91.7 %; mean score pre- vs.
post-treatment 9.2 vs. 1.3; P<0.001). Further outcome measures demonstrated a
lower LES pressure following POEM. Mean LES pressure was 29.4 mmHg pre-
treatment and 13.5 mmHg post-treatment (P<0.001). 1 patient developed mild
reflux symptoms and required intermittent treatment with PPIs. No serious
complications related to POEM occurred. Conclusions from this study showed
that previous Heller myotomy does not prevent successful POEM. POEM may be a
potential treatment for failed Heller myotomy with treatment success in >90%
of cases.

In an additional study by Onimaru, et al. (2013), 10 patients underwent
successful POEM procedures, without complications, after failed surgical
myotomy.14 All patients in whom surgical myotomy failed received PD as the
first line "rescue" treatment, and only if PD failed were patients considered
for rescue POEM. 3 months post-POEM, a significant reduction in both mean LES
resting pressures (22.16.6 mmHg vs. 10.94.5 mmHg, p<0.01) and Eckardt scores
(6.51.3 vs. 1.11.3, p<0.001) were observed. Short-term results of POEM for
failed surgical myotomy were considered excellent.

A study by Vigneswaran, et al. (2014) looked at 5 patients who underwent redo
myotomy with POEM after failed LHM.30 POEM patients were able to achieve a
significant reduction in Eckardt scores 6.8 vs. 0.6; p <0.05) after
approximately 5 months. The authors concluded that POEM can be safely
performed using a similar technique as for primary myotomy apart from creating
the myotomy laterally along the right side of the esophagus and lesser
curvature, thus avoiding the prior anterior myotomy.

In a multicenter study by Ngamruengphong, et al. (2017), the authors conducted
a retrospective cohort study of 180 patients with achalasia who underwent
POEM.13 The patients were divided into 2 groups, 90 patients with prior LHM
and 90 patients without prior LHM. Clinical response was defined by a decrease
in Eckardt scores to 3\. Adverse events were graded according to criteria set
by the American Society for Gastrointestinal Endoscopy (ASGE). Technical
success, clinical success, and rates of adverse events were compared between
groups after a median of 8.5 months. The technical success rates (98% of
patients in the LHM group vs. 100% of patients in the non-LHM group (P = .49))
and the adverse event rates (8% in the LHM group vs. 13% in the non-LHM group;
P = .23) were comparable between the groups. The clinical success rate was
lower in the group of patients who underwent prior LHM (81% vs. 94%; P = .01).
Symptomatic reflux and reflux esophagitis after POEM were similar between
groups. Conclusions from this study showed that POEM is safe and effective for
patients with achalasia who underwent prior failed LHM. The rate of clinical
success in patients with prior LHM was lower than in those without prior LHM;
however, the safety profile of POEM is comparable between the 2 groups.

Tyberg, et al. (2017) conducted a multicenter retrospective study of 46
patients with failed POEM for achalasia.27 Redo POEM was technically
successful in 100% and clinically successful in 85%. The mean Eckardt score
decreased from pre-redo-POEM of 4.32.48 to post-POEM of 1.641.67,
significant difference of 2.58 (P <.00001). Repeat POEM appears to be an
effective and safe technique in patients with persistent or recurrent symptoms
following a previous POEM procedure. Typically, the redo-POEM procedure is
performed on the opposite side of the esophagus.

POEM is considered a safe procedure that has a low rate of post-procedure
complications when performed by experienced operators.34 Most adverse events
that occur with POEM can be managed expectantly, medically, or endoscopically.
An international multicenter study by Haito-Chavez, et al. (2017) included
1862 patients who underwent POEM.2 137 patients experienced 1 or more
complications with a prevalence of 7.5%. Of the 156 total complications, 116
were mild, 31 moderate, and 9 severe. 51 inadvertent mucosotomies were
reported in 2.8% of patients.

GERD is the most common late adverse event with POEM. Depending on the study,
the prevalence of GERD following POEM ranges between 20-57%.22

A meta-analysis by Repici, et al. (2018) found that the prevalence of GERD was
higher post-POEM than post-LHM with fundoplication.18 The rate of
postprocedural symptoms was 19.0% (95% confidence interval [CI], 15.7%-22.8%)
post-POEM and 8.8% (95% CI, 5.3%-14.1%) post-LHM. The rate of abnormal pH
study was 39.0% (95% CI, 24.5%-55.8%) post-POEM and 16.8% (95% CI,
10.2%-26.4%) post-LHM, respectively. The rate of esophagitis after POEM was
29.4% (95% CI, 18.5%-43.3%) post-POEM and 7.6% (95% CI, 4.1%-13.7%) post-LHM.
The study concluded that the incidence of GERD appears to be more frequent
after POEM when compared to after LHM with fundoplication. In order to prevent
long-term complications from reflux, clinicians should ensure appropriate
treatment for GERD following POEM.

**American Gastroenterological Association (AGA)**

The American Gastroenterological Association's (AGA, 2017) Clinical Practice
Updates Committee proposed the following recommendations regarding POEM based
on expert opinion and relevant publications5: 1) patient-specific parameters
(Chicago Classification subtype, comorbidities, early vs. late disease,
primary or secondary causes) should be reviewed along with published efficacy
data when evaluating the need for achalasia treatment; 2) POEM should be
performed by experienced physicians in high-volume centers because an
estimated 20-40 procedures are needed to achieve competence; 3) POEM should be
considered as primary therapy for type III achalasia when the expertise is
available; 4) POEM should be considered as a treatment option comparable with
LHM for any of the achalasia syndromes when expertise is available; and 5)
post-POEM patients should be considered high risk to develop reflux
esophagitis and educated pre-POEM on the management of this potential
complication (potential indefinite PPI therapy and/or surveillance endoscopy).

**International Society for Diseases of the Esophagus (ISDE)**

The International Society for Diseases of the Esophagus (ISDE): achalasia
guidelines (2018) proposed and endorsed the Esophageal Achalasia Guidelines
(I-GOAL) from a systematic literature review.35 51 experts from 11 countries
and 3 representatives from patient support associations participated in the
drafting of the guidelines. Regarding the treatment of achalasia with POEM,
the ISDE recommended POEM as an effective treatment both in short- and medium-
term follow-up with results comparable to LHM and PD for symptom improvement.
They also recommended that POEM is an effective and feasible treatment for
achalasia patients who were previously treated with endoscopic therapies as
well as those who experience recurrence of symptoms following LHM. Further
recommendations included that pre-POEM patients are educated on the risk of
GERD and follow-up acid suppression therapy considered; patients who desire a
treatment with a lower incidence of post-procedure GERD, such as PD or LHM,
should be counseled that these options are available; appropriate training
with in vivo/in vitro animal models and adequate supervision should be
considered prior to performing POEM independently.

The available evidence suggests that POEM is generally safe and may achieve at
least similar results as PD and LHM for most efficacy and harms outcomes
regarding treatment of achalasia. Evidence also suggests that a select group
of patients with achalasia would benefit from POEM. Some of these patients are
not appropriate surgical candidates or do not desire to undergo surgery if
there is a less invasive option available for treatment. These patients could
potentially benefit from a non-invasive procedure such as POEM.