Endoscopic papillary large-balloon dilation: when and how?Referring to Karsenti D et al. p. 968–976
27 September 2017 (online)
Endoscopic sphincterotomy (EST) is the standard method for enlarging the papillary orifice before extraction of bile duct stones. Endoscopic papillary balloon dilation can be considered as an alternative to EST in patients with small stones and no anatomical or clinical contraindications . These conventional techniques achieve complete bile duct clearance in approximately 95 % of cases. However, high success rates can only be obtained if additional endoscopic procedures, in particular mechanical lithotripsy, are used in up to one third of cases for the management of difficult stones. Mechanical lithotripsy is time-consuming and cumbersome, and it may increase the risk of adverse events.
Endoscopic papillary large-balloon dilation (EPLBD) combined with EST was introduced to overcome these limitations and to facilitate the removal of large or complex bile duct stones. An international consensus guideline for EPLBD provides detailed recommendations for its appropriate use in clinical practice . It is based on more than 30 EPLBD studies, 6 randomized controlled trials (RCTs), and several meta-analyses and systematic reviews. The level of evidence is high in terms of important outcomes parameters. The overall success rates of EPLBD, with or without EST, for bile duct clearance are comparable to those of EST alone. The main advantage of EPLBD is the reduced need for mechanical lithotripsy to facilitate the procedure in patients with difficult stones. The overall rate of adverse events seems to be equivalent or even lower for EST plus EPLBD than for EST alone.
The level of recommendations is limited, however, for deciding when and how EPLBD should be applied. Selection criteria and techniques were different among the studies, which makes interpretation difficult. EPLBD can be performed as the initial method in all cases with identified large bile duct stones . This approach was used in the RCTs. Dilation was done with no EST or after EST limited to one third to one half of the size of the papilla. However, the routine use of EPLBD for all difficult bile duct stones increases the overall procedural costs and offers no advantages in about two thirds of the cases that are manageable with standard techniques without mechanical lithotripsy. To avoid unnecessary applications, EPLBD could alternatively be limited to cases in which a conventional approach has failed. This supplementary use was reported in early uncontrolled trials [3, 4]. However, EPLBD would then be performed after a complete EST, which may increase the risk of adverse events. A systematic review of 32 EPLBD studies indicated a significantly higher rate of bleeding for EPLBD with large EST than for EPLBD with limited EST (odds ratio [OR] 3.3; P < 0.001) or no EST (OR 2.2; P < 0.049) . In addition, it may be more time-consuming and could require more radiation exposure to try to remove difficult stones with conventional techniques, including a more frequent need for mechanical lithotripsy compared with a routine use of EPLBD.
“A large-scale randomized trial seems to be mandatory to compare the cost-effectiveness and safety of endoscopic papillary large-balloon dilation as an initial approach against its use after failure of conventional extraction of difficult bile duct stones before performing mechanical lithotripsy.”
According to a recent review of a few reports, the initial success rate of EPLBD without EST is lower compared with EPLBD with EST but there is no difference in terms of adverse events . A recent RCT showed a similar efficacy and safety between both techniques with respect to removal of large stones . Both techniques result in persistent and comparable loss of sphincter of Oddi function.
In this issue of Endoscopy, Karsenti et al. report on a well-designed multicenter RCT for comparison of EST plus EPLBD with EST alone (conventional group) for large common bile duct stones with a diameter of ≥ 13 mm . Patients with known risk factors for EPLBD (e. g. those with distal bile duct strictures) were excluded. In contrast to previous randomized trials, a complete sphincterotomy instead of limited EST or no EST was performed before balloon dilation. Within a study period of 4.5 years, 150 patients were included in the study at 21 centers in France. Patients were switched to EPLBD if the conventional approach failed. There were no significant differences in baseline characteristics between the two groups. The results showed a significant superiority of EPLBD compared with the conventional approach in terms of the primary end point, which was defined as stone clearance within one endoscopy session (96 % vs. 74 %; P < 0.001). Mechanical lithotripsy was less frequently needed in the EPLBD group (4 % vs. 36 %; P < 0.001). There were no significant differences between the groups in terms of morbidity, procedural duration, and costs. However, the interventions were more time-consuming and expensive in the one third of cases that required mechanical lithotripsy after EST alone compared with the EPLBD group. The success rate of a rescue EPLBD after failure of a conventional approach was 79 %.
These excellent results suggest that EPLBD with complete EST for large bile duct stones is simple, reproducible, safe, and effective. It could be recommended as the initial approach. However, the authors of the trial draw another conclusion, and propose EPLBD only for patients in whom complete EST alone cannot achieve bile duct clearance without mechanical lithotripsy. They argue that their data did not show an increased risk of balloon dilation after a large EST. Limiting the use of EPLBD to cases in which a conventional approach has failed would save costs in the two thirds of patients in whom difficult stones can be extracted without mechanical lithotripsy after EST alone.
How do the results of the French multicenter trial compare to current knowledge on EPLBD and recommendations on timing and techniques? A strength of the study is the multicentric design. However, each center enrolled an average of only 1.6 patients with difficult bile duct stones per year. A maximum of 10 cases were included in 16 of the 21 centers within 4.5 years. Data on the overall number of cases with biliary stones and an intention-to-treat analysis were not provided. Therefore, a favorable selection of patients with stones that were larger than ≥ 13 mm but not considered “difficult” could be possible. The average stone size was comparable to other randomized EPLBD trials . However, in this large series there should have been complex cases, for example impacted stones that could not be entrapped in a basket – a problem that cannot be overcome with balloon dilation. The results suggest that not a single patient with a complex common bile duct stone had to undergo further measurements for lithotripsy or surgery in any of the centers. A favorable selection may explain the extremely high success rate in the EPLBD group, with bile duct clearance of 96 % within a single session and a need for mechanical lithotripsy in only 4 % of cases. Five RCTs had shown an average ductal clearance rate for EPLBD within one session of 82 %, and use of mechanical lithotripsy in 16 % of cases . A favorable selection should also produce better results for the conventional approach compared with previous trials but this was not observed. Therefore, from this French trial, it remains difficult to interpret the significant superiority of EPLBD in terms of stone clearance rates that has so far been reported in only a single randomized study .
The authors emphasize that they studied large-balloon dilation for the first time after a complete EST in a randomized comparison with complete EST alone. However, patients were unfortunately not randomized after but before EST. There is a potential bias that a smaller EST was performed, both in the EPLBD group and in the conventional group in the knowledge that a switch to balloon dilation was possible according to the protocol. The study design does not allow a comparison of complete EST vs. limited EST before EPLBD. According to the suggested algorithm of the authors, EPLBD should be limited to failure of stone extraction after complete EST before proceeding to mechanical lithotripsy. They conclude from their data that this approach is safe. However, the trial was not powered for an analysis of adverse events. Furthermore, the results do not allow the overriding of a recent recommendation (grade C, evidence level 2 + + ) that EPLBD with large EST may increase the risk of bleeding .
In conclusion, this French multicenter trial re-confirms current recommendations that EPLBD can be safely used as the initial method when large bile duct stones have been identified provided that there are no contraindications (e. g. distal bile duct strictures). The success rate is similar or even better compared with EST alone, with the advantage that mechanical lithotripsy is less frequently required. When conventional stone extraction after EST fails, subsequent EPLBD achieves stone clearance in most of the cases. In contrast to EPLBD combined with a limited EST, its use without EST or with a complete EST has not yet been widely studied. Limiting the use of EPLBD to cases in which a conventional approach has failed may save costs compared with use as an initial application. However, this potential advantage has to be balanced against the increased risk of bleeding caused by balloon dilation after a complete EST, according to the current literature. A large-scale randomized trial seems to be mandatory to compare the cost-effectiveness and safety of EPLBD as an initial approach against its use after failure of conventional extraction of difficult bile duct stones before performing mechanical lithotripsy.