Peroral endoscopic myotomy is expanding its indications: (j am coll surg 2013;217:598-605).

Summary

Peroral endoscopic myotomy (POEM) is a novel non-surgical endoscopic procedure for treatment of achalasia, and has been performed as a primary therapy for achalasia with good short-term outcomes. Heller myotomy is a surgical therapy for treatment of achalasia and has a good long-term prognosis. However, symptoms of achalasia after Heller myotomy persist or recur with the rate of 3.5% to 15%.1

Recently, Onimaru et al2 have tested the feasibility of POEM as a rescue therapy in achalasia patients with persistent or recurrent symptoms after undergoing surgical myotomy. Of 315 patients receiving POEM in Showa University Northern Yokohama Hospital, 11 (3.5%) patients had been treated with surgical myotomy as a primary therapy. They had complained persistent or recurrent symptoms of achalasia. Of these 11 patients, 10 patients underwent POEM as a rescue therapy. In 10 patients at 3 months after POEM, lower esophageal sphincter resting pressure (22.1 ± 6.6 mmHg vs. 10.9 ± 4.5 mmHg) was significantly reduced, and Eckardt symptom scores (6.5 ± 1.3 vs. 1.1 ± 1.3) were also significantly improved. Adverse events related to POEM procedure in these patients were not reported.

Comments

The conventional modalities for treatment of achalasia include pharmacologic agents, pneumatic balloon dilatation, botulinum toxin injection and surgical myotomy. POEM is a newly-developed minimally-invasive modality, and it intends a permanent cure for achalasia.3 It is opening up a new chapter in treatment of achalasia, although the history of POEM is very short. The first pre-clinical experiments of endoscopic esophageal myotomy were performed in an animal model by Pasricha et al4 in the early 2000s. Doctor Inoue firstly has applied POEM to human patients with achalasia, and his pioneering work has been proved effective until now, although follow-up periods are short.3,5 Around the same time, Doctor Zhou also has independently reported his own experience of POEM in patients.6 His results are consistent with those of Inoue et al Since then, POEM has been performed in several institutes of the world, and the short-term outcomes of POEM are very promising. The first prospective multicenter study performed at 5 centers in Europe and North America has shown that the treatment success rates at 6 months and 12 months were 88.5% and 82.4%, respectively, during the mean follow-up period of 10.1 months.7 However long-term outcomes remain uncertain, and further investigation is needed.

Recently, two comparative studies between POEM and Heller myotomy have been published. The one study has shown that treatment results of POEM were compatible to those of Heller myotomy, but POEM had the benefit of a shorter hospitalization than Heller myotomy (mean, 1.1 days vs. 2.2 days).8 In this study, 64 patients received Heller myotomy, and 37 patients received POEM, and both groups had similar improvements in Eckardt scores (mean, 1.7 vs. 1.2, respectively) at 6 months after treatment. Another small study composed of 17 patients undergoing Heller myotomy and 12 patients undergoing POEM has reported similar findings.9 Heller myotomy may be destined to be substituted with POEM as a first-line modality for treatment of achalasia.

The appropriate therapy for recurrence or persistent achalasia after Heller myotomy remains undetermined. Additional treatments such as pneumatic dilatation, redo Heller myotomy and esophagectomy have been tried, but the outcomes are controversial. One review article has reported a good response of redo Heller myotomy for failed Heller myotomy (approximately 86%), compared with pneumatic dilatation, and another study has reported a substantial efficacy (approximately 80%) of redo Heller myotomy.10,11

The current study by Inoue et al2 has suggested that POEM is an effective rescue therapy in patients who have persistent or recurrent symptoms of achalasia after Heller myotomy. During a mean period of 18.3 months (range, 3–31 months), all patients had improved clinical parameters. Coincidentally, these findings are compatible with those of another study by Zhou et al12 having reported that 11 patients of 12 patients with failed relief of symptom after Heller myotomy had successful outcome from POEM during a mean follow-up period of 10.4 months (range, 5–15 months). These 2 independent studies have shown the similar results favoring POEM as a secondary therapy after Heller myotomy. In addition, POEM is minimally-invasive, although the technique is somewhat difficult, and reduces hospitalization days. However, these two studies have common limitations: the small sample size and single-armed design. Considering the low prevalence of achalasia, the small sample size is not an obstacle to introducing the innovative treatment, and this problem will be resolved over time.

In addition, POEM is making progress, and even applied to the stomach. Recently, so-called gastric peroral myotomy is attempted to treat refractory gastroparesis in a human patient.13 The gastric peroral myotomy is an endoscopic pyloromytomy to improve gastroparesis symptoms.

In summary, POEM is an innovative therapeutic modality of achalasia, and it may become a substitute of Heller myotomy as a primary therapy and a rescue therapy of failed Heller myotomy in achalasia.