Walled-off necrosis treatment: additional evidence

"...this study further emphasizes the importance of using a biflanged metal stent for initial drainage of WON, particularly when the WON contains significant solid debris…"

Infected walled-off necrosis (WON) is the most severe complication of acute pancreatitis and is responsible for delayed morbidity and mortality. Over the past two decades, there has been a paradigm change in the management of WON. A minimally invasive step-up approach has proven to be superior to open necrosectomy and endoscopic access has been shown to be superior to a percutaneous surgical approach, reducing new onset multiorgan failure, duration of hospital stay, incidence of late fistulae, and costs [1] [2].

Endoscopic ultrasound (EUS)-guided drainage is the current mainstay for WON management and there has been an ongoing debate regarding the use of lumen-apposing metal stents (LAMSs) or biflanged metal stents (BFMSs), instead of multiple plastic stents, for initial drainage. The advantages of metal stents include their larger diameter, which allows better drainage of necrotic debris, access for direct necrosectomy, if needed, and direct hemostasis in rare cases of severe bleeding at the puncture site. These stents have been approved for transmural drainage of fluid collections; however, although some overenthusiastic physicians use them for non-necrotic pancreatic fluid collections (PFCs), it is widely accepted that their use should be limited to necrotic collections containing solid debris. One drawback to their use is that they must be removed within 4–6 weeks and exchanged, in selected cases, for a plastic stent.

Previous randomized controlled trials (RCTs) comparing plastic stents versus LAMSs for EUS-guided WON drainage did not demonstrate any differences in overall clinical success, complications, and length-of-stay, but identified a need for more frequent early reintervention [3] or more planned procedures during treatment with plastic stents [4]. In addition, diathermic LAMS use is associated with a reduction in procedure duration [3], a feature that cannot be expected when using non-diathermic BFMSs.

Koduri et al., in this issue of Endoscopy, provide additional evidence from an RCT that included 92 patients recruited from a high volume tertiary center over just 18 months [5]. Although they mention the fact that it was a single-center study as a possible shortcoming, the short duration of recruitment ensures, from my point of view, the homogeneity of techniques used for management. The trial defined reintervention-free clinical success at 4 weeks as the primary outcome and demonstrated a benefit for patients who were treated initially with BFMSs over plastic stents (67% vs. 43%), with lower numbers of reinterventions and shorter hospital stays, while overall clinical success was similar in both groups. The authors concluded that BFMSs should be chosen for initial drainage of WON.

This RCT obviously helps to improve our clinical practice, although it is difficult to include all the subtleties associated with the management of complex cases in the inclusion criteria of a prospective trial. The devil may be in the detail, and interventions in such cases must be individualized according to clinical status, and initial and follow-up imaging. The authors included patients with <50% solid debris, with a median of 25% (evaluated by magnetic resonance imaging [MRI] or ultrasound). In terms of management, a localized peripancreatic collection containing less than 20% solid debris is obviously different from a large and complex collection extending towards the left retroperitoneal space and containing 50% solid debris. It is probable that the first case could be adequately treated with any kind of transmural drainage, while the second case would require not only an initial BFMS but also nasocystic catheters for lavage, additional stents to reach more distal parts of the collection, and possible necrosectomy. It would have been interesting to know more about the correlation between initial imaging and clinical outcome in the two groups.

It is also interesting to note that many of the reinterventions (17 in the plastic stent arm and eight in the BFMS arm) consisted of the placement of a nasocystic drain, accounting for a large proportion of the total reinterventions. The historical series have always recommended the placement of a nasocystic drain in combination with plastic stents for cases involving collections with debris [6] and this is clearly still important. As expected, this is also needed in selected cases in association with BFMSs.

Another important aspect of this study is the similarly low rate of recurrence at 6 months observed in both groups. Interestingly, the patients had an MRI at 1 month and, in cases of disconnected pancreatic duct syndrome (DPDS), either the plastic stents were left in place or the BFMS was replaced with plastic stents. DPDS increases the risk of recurrence of PFCs after removal of transmural plastic or metal stents; this policy has been recommended after resolution of PFCs [7] [8]. This is in contrast, however, to a previous publication from the same group in which they did not observe any difference in recurrence whether or not a plastic stent was placed at the time of removal of the BFMS [9].

A last point related to the prospective design of the study is the fact that, in the plastic stents group, if a reintervention was needed to further eliminate debris (e.g. nasocystic drain placement, necrosectomy), new plastic stents were implanted per protocol. In clinical practice, however, most physicians, including the authors, would probably have chosen a BFMS or LAMS at this time to reduce the need for additional reinterventions.

Taken together, this study further emphasizes the importance of using a BFMS for initial drainage of WON, particularly when the WON contains significant solid debris, keeping in mind that additional procedures may be needed and should be individualized to the patient’s clinical course and imaging.

Publication History

Article published online:
05 September 2024

• References

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