POEM for achalasia: Looking good, but the final verses are yet to be penned

Choice of therapy will be determined by the compromises and uncertainties most acceptable for the patient and their clinician

Achalasia is an uncommon oesophageal motor disorder (annual incidence in North America: 1.6 per 100 000 population1) of unknown aetiology. Its hallmarks are failure of peristalsis and failed deglutitive relaxation of the lower oesophageal sphincter, the result of the loss of inhibitory neurons in the oesophagus. Treatment for achalasia focuses on mechanical disruption of the integrity of the lower oesophageal sphincter, usually by laparoscopic Heller myotomy (LHM) or endoscopic pneumatic dilatation (PD).2,3 The short term response rates for a third, novel option, per‐oral endoscopic myotomy (POEM), have been impressive since its introduction ten years ago.4 However, as achalasia is a chronic relapsing condition, treatment decisions must be based on long term outcomes (5‒10 years). The long term durability of POEM is unknown; more importantly, how the long term symptom relapse rate compares with the substantial rates following PD or LHM has not yet been established.

In this issue of the MJA, Gupta and colleagues report a large, multicentre, longitudinal study of POEM in Australia (142 patients during 2014‒2019) with symptomatic outcome follow‐up at six, 12 and 24 months (median follow‐up: 12 months).5 The authors report a 6‐month clinical success rate of 89%, consistent with other reports.4,6,7 Chicago subtype classification did not predict outcome. The median hospital stay was two days. Five patients (4%) experienced serious adverse events: one case each of intramural oesophageal leak that required stenting, empyema and para‐oesophageal haematoma that required chest drain insertion, and bleeding that required transfusion, and two of pneumonia. As only 61 patients (43%) had been followed to two years at the time of analysis, the longer term symptom relapse rate could not be robustly estimated.

The study by Gupta and his colleagues5 confirms that experienced Australian endoscopists can achieve results comparable with those of their overseas colleagues. Unfortunately, it does not provide data on post‐procedure erosive oesophagitis, nor did it address the key question of the long term symptom relapse rate.

The choice of first line therapy for people with achalasia is difficult, both because of uncertainty about long term outcomes following POEM and the fact that each of the three options has their own specific strengths and shortcomings; to some extent, we are comparing apples with oranges. There are three primary considerations: short term success and procedural risks; long term remission rates; and long term risks.

The probability of clinical benefit one to two years after the initial intervention is similar for all three options (85‒90%).2,6 The risks of serious complications (including death) are similar for POEM and LHM (3‒7%),6,8 and higher than the risk of perforation during PD (2%).9

We do not know how many patients will still be in remission five years after POEM, but 85% of patients undergoing PD or LHM will be in remission at this point.3,9,10 However, the symptom relapse rate is higher for PD than for LHM; 25‒30% of patients will need at least one further PD within five years of the initial intervention.3,9 By ten years post‐procedure, symptoms recur in one‐third of patients treated by LHM and in one‐half treated by PD.9

As POEM is not combined with an anti‐reflux procedure, the risk of erosive oesophagitis is higher (41‒57%)4,6,7 than after LHM (20%)6 or PD (7%).7,9 The incidence of serious long term reflux‐related complications after POEM, such as fibrotic strictures or Barrett oesophagus, is unknown, as is whether proton pump inhibitor therapy mitigates the risk.

Additional considerations include centre‐specific feasibility and expertise, cost, and convenience. The ability of POEM to extend proximally the length of myotomy to match the spastic segment length in type 3 achalasia may be an advantage for patients with this subtype. However, the evidence regarding this question was deemed inconclusive by a recent meta‐analysis,11 and was unsupported by the findings of the study by Gupta and colleagues.5

In light of these uncertainties, best practice remains to be established, but the following might form the basis of discussions with your patient:

PD is a day procedure and the least invasive option. One in four patients will require at least two dilatations to achieve initial success. The long term relapse rate is greater for PD than for LHM; by 10 years, one in two patients will need repeat PD. However, if they are willing to accept this possibility, the benefit will be sustained long term in at least 90% of patients. Clinically significant reflux is infrequent.

LHM requires a median two‐day admission. Complications are more frequent than after PD. Longer term, one‐third of patients will require salvage PD (or POEM) following symptom relapse, as repeat LHM outcomes are poor.12 At least 90% of patients will experience long term remission, with periodic on‐demand PD as required. Reflux is somewhat more common following LHM than after PD.

POEM also requires a median two‐day admission, and the complication rate is similar to that for LHM. The clinical benefit at two years is comparable with that of PD and LHM, but the longer term relapse rate is unknown, as is the best salvage strategy in case of relapse. Reflux is more common than after PD or LHM, and its long term impact is unknown.

The final choice of therapy will be driven by the compromises and uncertainties that the patient and their clinician find most acceptable.