Distensibility measurement in the selection of patients for endoscopic pyloromyotomy: promising and logical, but still not ready for prime time

Gastroparesis is a serious condition with complex pathophysiology. Treatment of gastroparesis might be a real challenge because there is no universal therapy suitable for all patients. Invasive approaches should never be applied as first-line treatments, and management of patients with gastroparesis should start with dietary measures, pharmacotherapy (a wide range of medications such as prokinetics, neuromodulators, and antiemetics are available) and alternative approaches such as hypnotherapy.

“It is obvious that gastroparesis is not only about the pylorus, and endoscopists should keep this in mind.”

Pylorospasm – or more accurately, pyloric muscle that does not function correctly during digestion – is considered an important pathophysiological factor responsible for the development of gastroparesis. As a result, increasing attention is being paid to therapies targeting the pylorus, which aim to relieve its presumed spasm. Endoscopic pyloromyotomy (G-POEM) is currently the most studied pylorus-targeted therapy, achieving clinical success in about 50%–75% of cases. It means that about two-thirds of patients experience symptomatic relief (however, no cure) but approximately one-third of patients remain without adequate clinical improvement. G-POEM (in contrast to gastric electrical stimulation) also accelerates gastric emptying. However, there is no correlation between clinical effect and improvement in gastric emptying. Two randomized trials showed superiority of G-POEM over sham procedure or botulinum toxin injection [1] [2]. These studies proved that pylorospasm is partially responsible for symptoms in about two-thirds of patients with gastroparesis.

In this issue of Endoscopy, Farooq et al. report on a large prospective study on whether assessment of pyloric function using functional intraluminal imaging probe (FLIP) may predict symptomatic response to G-POEM [3]. Overall treatment success was achieved in 71.1% of the patients at 6 months. The authors obtained FLIP values prior to and immediately after G-POEM and then at 6 months. Responders had significantly lower baseline distensibility index (DI, at 40 mL filling volume) compared with non-responders (7.10 [SD 2.75] vs. 9.24 [3.14] mm²/mmHg; P = 0.002), and a baseline DI value below 7.35 mm²/mmHg predicted clinical success with 81% specificity. DI increased in all patients immediately after the procedure, but at 6 months, increased DI value remained only in responders while in non-responders, DI decreased to values measured at baseline. The authors suggest that “recurrent” pylorospasm due to less compliant pylorus – maybe because of fibrosis – may be responsible. However, when looking at absolute DI values at 6 months, they were very similar between responders and non-responders (10.44 [SD 4.4] vs. 9.68 [SD 4.7]). Finally, the authors found that clinical success after G-POEM and FLIP values were in no way influenced by previous botulinum toxin injection. Botulotoxin toxin injection has been used in several centers to select patients with gastroparesis for G-POEM. However, the recent study is in line with the recommendation of several societies (European Society of Gastrointestinal Endoscopy, American Society for Gastrointestinal Endoscopy, and American Gastroenterological Association) not to recommend botulinum toxin as a selection tool for G-POEM [4].

Other studies have also analyzed impedance planimetry in patients undergoing G-POEM, but the results are conflicting and inconsistent. The problem is that several cutoff values of DI or cross-sectional area have been suggested to predict clinical success or failure. The studies are only consistent in terms of increased values of both DI and cross-sectional area after G-POEM. For example, Vosoughi et al. found a cutoff post-G-POEM cross-sectional area of >154 mm² to predict 1-year clinical success [5]. In a randomized study, post G-POEM DI values >13 mm²/mmHg were associated with clinical success [1]. These results are consistent with the logical assumption that the more the pylorus is relaxed, the greater is the therapeutic success. However, a real predictor should be available before, not after the procedure. In terms of impedance planimetry, two studies reported such a predictor. Jacques et al. identified a distensibility threshold of 9.2 mm²/mmHg before the G-POEM that predicted a clinical response with 100% specificity and 72.2% sensitivity [6]. In the present study, which is more robust in terms of patient number and the inclusion of three systematic planimetry measurements, the authors identified a pre-G-POEM distensibility threshold of 7.35 mm²/mmHg as a predictor of clinical success [3]. However, due to low sensitivity (60.6%) and negative predictive value (46.7%), it is obvious that should these thresholds be used in clinical practice, many potential responders would be missed.

Should impedance planimetry (FLIP) be performed systematically before and after G-POEM? The measurement before G-POEM should be a standard part of the preoperative assessment, as well as distensibility measurement after the procedure, especially in non-responders. Patients should be provided with information about the possible probability of treatment success based on the measured values. If performed during the procedure, it may also help to guide sufficient myotomy even if most endoscopists recognize it without the measurement. Post-procedure impedance planimetry measurement may identify those with a recurrent/residual pylorospasm who might benefit from repeat G-POEM. But should FLIP be used for patient selection? At present, patients not fulfilling the present cutoff planimetry values (e.g. high baseline DI) should not be denied G-POEM. Therefore, FLIP itself should not be used for patient selection because the predictive values are not accurate enough.

The fundamental question is whether we really need predictors of clinical success/failure of endoscopic pyloromyotomy. If predictors are reliable enough, their usefulness would not be in doubt. However, if the prediction is not strong enough? We should also keep in mind that endoscopic pyloromyotomy is a very safe procedure. If it does not have good clinical effect, it does not harm the patients. Moreover, as already mentioned, all treatment modalities in gastroparesis have limited efficacy. For example, electrical stimulation is effective in about 60% of patients and reliable predictors of efficacy are not well established [7].

Finally, several studies identified different predictors based on clinical or other aspects related to gastroparesis. These include presence or absence of specific symptoms (less nausea, more fullness and bloating), severity of symptoms, severity of gastric retention rate on gastric scintigraphy, etiology of gastroparesis etc. [8]. As with FLIP, there is significant inconsistency in what may predict treatment success/failure. Such inconsistency likely reflects the complexity of gastroparesis as a disease. It is obvious that gastroparesis is not only about the pylorus, and endoscopists should keep this in mind.

Publication History

Article published online:
22 July 2025

• References

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