Multisegmented fully covered esophageal stent: a step to the side

The concept of a fully covered multisegmented esophageal self-expandable metal stent for malignant dysphagia palliation looks to tackle two problems. The first being issues with stent migration and the second being the retrosternal chest pain that is not uncommonly reported by patients. In a multicenter feasibility and safety trial by Koggel et al. (NCT04415463) they report results from 23 patients who had attempted placement of a fully covered multisegmented self-expandable esophageal stent (FCMSEMS) (1). Before getting into their results and conclusions, it is necessary to understand a bit of the history and role of self-expanding metal stents (SEMS) for the management of malignant dysphasia due to esophageal cancer along with incidence of complications.

Esophageal stents have been in use since 1845 (2). While the initial stents were made from ivory, now they are commonly made from a nickel-titanium alloy (i.e., Nitinol). The advantage of Nitinol is that it is a self-expanding metal with unique properties. It is these properties that allow it to be coiled into a very small size for ease of delivery yet expand when deployed to provide therapeutic management for various esophageal pathologies. The initial experience with SEMS was in the setting of inoperable esophageal cancer and palliation of those patients with obstruction (3).

However, stents for malignant dysphagia have not been free of complications. Early complications usually arise within 1–2 weeks of stent placement with the most common being retrosternal chest pain, fever, migration, and perforation. Complications after four weeks are considered “delayed” and are more common (4). The most common delayed complication is migration. However, occlusion from a food bolus, tumor invasion into the stent with resulting occlusion, or stent erosion through the esophagus are all reported. The authors did utilize a similar definition; however, stopping the trial early due to adverse events and the resulting short median follow-up provide only a window into early adverse events for the FCMSEMS.

Stent migration for SEMS has a reported rate of between 24–40% (5,6). Although the clinically relevant migration is reported to occur at about 17% (7). Various endoscopic techniques have been investigated to improve fixation of the esophageal stent (8-13), with most showing a benefit. However, these are in cases where the stent has previously migrated. The benefit of prophylactically fixing a stent at initial placement to prevent migration remains unclear. At present only patients who require a stent and have a history of stent migration are recommended to undergo fixation based upon the current guidelines (14). An innovation that decreases stent migration rates without need for fixation would be an advancement.

It appears that stent migration was decreased in this study by Koggel et al. (1). There were only four reported migrations from the 21 patients (19%) that had a stent appropriately placed. This result is likely even better due to the strict criteria for definition of stent migration used in this trial. Therefore, it is likely that a FCMSEMS is an improvement over other SEMS with a low rate of clinically relevant stent migration. The only issue with migration that this study does not adequately describe is the patient with the esophageal fistula where the trial stent ended up in the mediastinum. As stent deployment could be done with or without endoscopic visualization or fluoroscopy, per supplementary Tab. 2, it is more likely that this specific case was done with guidewire only. A scenario where the guidewire unexpectedly goes through the fistula into the mediastinum and then the stent is placed over a wire and deployed can be envisioned. It is also more plausible than the explanation of “negative pressure in the mediastinal cavity that was created by spontaneous breathing” somehow pulling a fully deployed stent into the mediastinum. Careful evaluation of supplementary Fig. S2B gives clues that are more consistent with the hypothetical scenario presented here then the explanation from the authors. This figure shows the proximal end of the FCMSEMS at the level of the esophageal stricture in the mid-esophagus, which is visualized after placement of a second and separate SEMS in the esophagus. Therefore, the authors comment that a malignant esophageal fistula should be a contraindication to placement of this stent is probably too strong. However, this adverse event highlights the value of endoscopy and that it should be used in 100% of esophageal stent placements, with or without fluoroscopy.

Retrosternal chest pressure or pain is also commonly noted in patients after a stent is placed. In general, it is self-limited and either the patient becomes tolerant or the feeling resolves. This was shown by the authors in that nearly 79% of patients (15 of 19) reported acceptable levels of pain by Numerical Rating Scale score at 2 weeks. While it was not reported as being done in this study, in patients where the pain is intolerable, replacing with a slightly smaller diameter stent can be attempted. However, this tradeoff may result in a higher risk of migration. As in two patients in this study, sometimes the pain is so severe that the stent must be removed (1).

Stent erosion through the esophagus with resulting perforation into the pleural or peritoneal space, airway, mediastinum, or pericardium have been reported (4,15). These are generally associated with either chemotherapy and/or radiation therapy. Unfortunately, the overall follow-up of this study (median of 34 days from stent placement) is likely too short to draw any meaningful associations or conclusions between the FCMSEMS and these types of complications. It is important to note also that death being directly attributed to the stent is reported to be between 4% to 27% (4,16-18). In this study, it was seen in 14% (3 of 21). In two of these three cases, it was the result of hemorrhage. One of these two patients requested palliative care when this occurred and died 4 days later. The third patient is the one where the stent ended up in the mediastinum. It is unsurprising that this patient suffered a mortality shortly thereafter. As the goal of a SEMS in malignant dysphagia is palliation and improvement in dysphagia scores while helping to improve the quality of the remaining life, procedure related death should be avoided, if possible, or at least minimized, at best.

Despite this study being terminated early for severe adverse events, there are some positive findings (1). First, it appears that actual meaningful stent migration is less with a FCMSEMS compared to what is reported in the literature. However, as this was a small trial a larger study would be of value especially if it directly compared SEMS with the novel FCMSEMS. While the authors point to improved dysphagia scores, this is the absolute minimum of what should be accepted as all stents accomplish this endpoint. A concern for a potential trial is the high rate of adverse events; however, a well-designed randomized controlled trial may demonstrate that adverse and serious adverse events are actually similar to what is otherwise reported in trials of SEMS. Only a true randomized controlled trial would be able to compare these real-world results. Finally, the early termination of this trial is likely strongly influenced by the patient with an esophageal fistula that likely had the stent placed directly into the mediastinum and was unretrievable that resulted in the subsequent death of the patient.

The innovation of the FCMSEMS in the treatment of malignant dysphagia may yet show to be an advancement by decreasing the rates of stent migration. Terminating a trial early for safety, while appropriate, also leaves unanswered questions. Hopefully, further advancement with this stent and comparative trials will be in forthcoming.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, AME Clinical Trials Review. The article has undergone external peer review.

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Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://actr.amegroups.com/article/view/10.21037/actr-24-81/coif). S.R.C. has authored a few topics for UpToDate, none of which are relevant to this manuscript. The author has no other conflicts of interest to declare.

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