Severe submucosal fibrosis – the “Achilles’ heel” of peroral endoscopic myotomy

We read with great interest the article by Zhou et al. entitled “Submucosal fibrosis in achalasia patients is a rare cause of aborted peroral endoscopic myotomy procedures” [1]. This was a retrospective analysis of a large cohort of patients (n = 1693) in which the authors assessed the factors responsible for premature termination of peroral endoscopic myotomy (POEM) procedures. The authors concluded that severe submucosal fibrosis was the major factor leading to technical failure. We applaud the authors for their efforts in extracting enlightening information with regard to the prediction of submucosal fibrosis.

In this study, submucosal fibrosis was not uncommon (111/1693). However, severe submucosal fibrosis leading to termination of the procedure was rare (12/1693). Out of the 12 technical failures due to submucosal fibrosis, four patients were treatment naïve, while eight had a history of prior treatment. Although, prolonged disease duration (≥ 6 years) and a history of prior treatment were present in the majority of patients, mucosal edema (n = 3) and sigmoid esophagus (n = 2) were found in fewer patients. Therefore, dilated esophagus or mucosal edema may not predict severe submucosal fibrosis as they were absent in the majority of patients with severe submucosal fibrosis that led to the abortion of POEM.

We have previously described the reasons for technical failure in 408 patients with achalasia cardia [2]. Overall, POEM procedures were prematurely terminated in 12 patients (2.9 %). Severe submucosal fibrosis was responsible for technical failure in the majority of our patients (9/12; 75 %). The other reason we identified was inadvertent enlargement of the mucosal incision, which was responsible for abortion of three POEM procedures (25 %). Of the nine patients with severe submucosal fibrosis, four were treatment naïve and five had a history of prior treatment (pneumatic balloon dilation [n = 3], laparoscopic Heller’s myotomy [n = 2]). Therefore, submucosal fibrosis is not exclusively limited to previously treated patients and other factors including long duration of disease, sigmoid esophagus, and unhealthy esophageal mucosa possibly contribute to submucosal fibrosis, as concluded by the authors.

The authors attempted POEM via a second tunnel in two patients but were not successful. In the remaining 10 patients, a second tunneling procedure was not performed based on the operator’s clinical judgement, occurrence of adverse events, or the assumption that the fibrosis might be diffuse rather than localized. However, it would be premature to conclude that a second tunnel should not be attempted in these patients. In patients who have localized submucosal fibrosis, we may still be able to finish the job by choosing a different location. Endoscopically, it may be difficult to predict whether the submucosal fibrosis is localized or diffuse. In our study, we attempted POEM via a double-tunnel technique in two patients with submucosal fibrosis and, in both of these patients, the technical and clinical outcomes were satisfactory [2].

In addition to a difficult tunneling procedure, a friable and edematous esophageal mucosa can easily lead to inadvertent extension of the incision. In such cases, prior balloon dilation to provide relief and prevent stasis, at least transiently, can buy some time for the mucosa to improve. The impact of such an approach on mucosal healing, submucosal fibrosis, and technical failure needs to be evaluated.

To conclude, severe submucosal fibrosis is the “Achilles’ heel” of POEM and leads to the majority of technical failures. Whether these patients should undergo POEM via a different location, receive alternative treatment (Heller’s myotomy or pneumatic balloon dilation), or undergo a further attempt at POEM after an interval remains to be seen.

• References

• 1 Wu QN, Xu XY, Zhang XC. et al. Submucosal fibrosis in achalasia patients is a rare cause of aborted peroral endoscopic myotomy procedures. Endoscopy 2017; 49: 736-744
• 2 Nabi Z, Ramchandani M, Chavan R. et al. Per-oral endoscopic myotomy for achalasia cardia: outcomes in over 400 consecutive patients. Endosc Int Open 2017; 5: E331-E339