How should we evaluate the efficacy of endoscopic closure appropriately? A black box between interventions and outcomes

Endoscopic closure has drawn attention owing to the development and clinical introduction of various endoscopic interventions in the gastrointestinal tract. A mucosal closure is expected to prevent postoperative adverse events, such as bleeding and delayed perforation, in endoscopic intraluminal resection, for example endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). Endoscopic full-thickness resection always necessitates a robust and sustained defect closure. Furthermore, gastrointestinal fistula requires a closure method that is less invasive than surgical interventions. Intentionally created defects become wider, deeper, and harder to close with only conventional methods using endoscopic clips owing to therapeutic endoscopic expansion. Therefore, dedicated suturing devices/techniques need to be further developed.

In the current issue of Endoscopy, Krishnan et al. report on the clinical usefulness of a new endoscopic suturing device, the through-the-scope tack and suture (TTSS) system, which enables mucosal apposition by applying small tacks to the surrounding mucosa and drawing the defect closed with a string [1]. This technique allows defect closure in desirable forms, such as a running pattern or purse-string suturing, without endoscope withdrawal. The authors applied TTSS to several situations, including post-EMR and post-ESD mucosal defect, fistula closure, and stent fixation. This case series of 53 patients demonstrated favorable results in technical success (96 %) as well as clinical success (92 %), although the technique appeared to be less reliable in fistula closure (57 %). The device is easily deployed, technically accessible for endoscopists, and minimally invasive for patients, as well as saving time. Hence, further clinical introduction and indicator expansion are expected.

“...The through-the-scope tack and suture system is advantageous in terms of accessibility and simplicity but requires further investigation in terms of its robustness.”

Every method has pros and cons, although various closure techniques have been introduced so far. Simple closure with conventional clips is easy to perform, but the indication is limited to small mucosal defects; otherwise, a complete closure is almost impossible, or readily dehisces even if possible [2]. Clipping with other accessory devices is technically durable for larger mucosal defects, but a sustained closure remains difficult to obtain [3] [4] [5]. Furthermore, the reliability of the closure maintenance is questionable for a full-thickness defect. The over-the-scope clip can provide a firm and long-lasting closure, particularly for a relatively small defect [6]. The OverStitch (Apollo Endosurgery, Austin, Texas, USA) is widely indicated, but it compromises maneuverability and cost-effectiveness [7]. Endoscopic hand suturing, which is technically identical to surgical suturing, appears promising for providing optimal and sustained closure, although some skills and training are required [8]. Similarly, TTSS is advantageous in terms of accessibility and simplicity but requires further investigation in terms of its robustness.

Theoretically, endoscopic closure is considered effective if tissue apposition lasts long until a natural process of tissue repair stops. Therefore, we need to evaluate the individual technique step by step to prove this hypothesis. Generally, the outcome evaluation in endoscopic closure involves technical success, closure maintenance, and clinical success. The technical success is assessed by the endoscopic achievement of tissue apposition, which is easily judged at the end of the procedure. The clinical success is evaluated by monitoring the postprocedural clinical course, which is easily performed as part of medical practice. Conversely, we can only assess whether the closure is maintained using endoscopic observation during the monitoring period; it cannot be continuously assessed, and the closure site is even harder to assess multiple times given the burden on the patient and the medical costs involved. However, the abovementioned hypothesis cannot be demonstrated with the inadequate “intermediate” assessment, even if the endoscopic closure is technically and clinically successful. No bleeding may be seen, fortunately, even if the closure dehisces because a post-ESD mucosal defect naturally heals within a few months and post-ESD bleeding rarely occurs. Therefore, the efficacy of endoscopic closure should be cautiously interpreted given that closure maintenance is not confirmed, particularly in cases at low risk of postprocedural adverse events. Conversely, the clinical success in fistula closure is likely to indicate closure maintenance because the dehiscence of the fistula closure will immediately show clinical symptoms such as fever and pain.

The durability of the closure can act as a surrogate indicator in clarifying the efficacy of endoscopic closure techniques, and therefore the endoscopic assessment is important to unroof the “black box” of the postprocedural course between the intervention and clinical outcomes. In published papers reporting on endoscopic closure, scheduled follow-up endoscopies are not always performed to assess the post-suturing condition, probably due to various clinical obstacles, particularly in colorectal lesions. In the Krishnan et al. study, less than half of the patients underwent follow-up endoscopies after 3 months or later, when almost all defects heal spontaneously. Performing animal studies may be one of the options available to address this issue [9]. Novel closure techniques will have to be further devised and clinically introduced, along with the expectation of less-invasive approaches using flexible endoscopy. Establishing a standardized methodology that allows investigation and comparison of the efficacy of tissue apposition methods will, hopefully, be forthcoming in the future.

Publication History

Article published online:
03 May 2023

• References

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