Discussion
post-ERCP, post-ERCP pancreatitis, GWs
ADVERSE EVENTS, STRICTURE, PANCREATITIS, REGRESSION, BENDING
Nowadays, GW is widely used for facilitating selective biliary access and reducing the rate or severity of post-ERCP pancreatitis. However, the clinical efficacy study of GWs during biliary cannulation has some limitations because GWs can vary in diameter, body stiffness, tip shape, and flexibility according to the manufactures. Selection of GWs is usually decided by the preference of physicians and the availability of manufactures. Although such GWs have been devised and commercialized, clinical studies on 0.025-inch GWs based on mechanical properties of each GW are insufficient.Therefore, we first planned this clinical trial according to the basic property analysis of GWs, although there were limitations to conducting clinical studies with the purpose of obtaining an objective understanding of new product characteristics. The strength of the present study was that it was a randomized trial following mechanical property analysis of available 0.025-inch GWs. According to the best results of mechanical property analysis including a newly developed GW in experimental group, we compared it with a high performance GW, VisiGlide 2 previously studied in numerous reportsIn basic mechanical property analysis of 0.025-inch GWs (Table Our clinical trial revealed that the primary WGC success rate of experimental GW was non-inferior and the overall technical success was not different from that of the control GW, VisiGlide 2. However, when we analyzed the primary outcome including the cross-over, primary technical success was higher in the experimental GW group (Chi-square test). This difference was associated with the rate of DBC, which was statistically lower in the experimental GW group. DBC according to the criteria can be developed in various situations such as patients’ factor, physician’s experience, or devices. Baseline characteristics were not different. The level of physicians’ experience was also similar. Multivariate logistic regression showed that conventional GW was also a meaningful negative factor affecting the DBC. Although results of mechanical property test for experimental and conventional GW were similar, the friction force was relatively lower in the experimental GW group. Lower friction force in the tip of GW might influence DBC because complex mucosal features of intrapapillary ducts including columnar-shaped mucosal reduplications and pocket-like mucosal folds might be the main reasons for DBC during mechanical contact of tip of GW to duodenal major papillaRegarding adverse events, another primary concern of this study was the rate of post-ERCP pancreatitis. It was not different between the two groups because of a relatively lower rate of pancreatitis. However, slightly higher tendency was shown in the control group, although it was not statistically significant. DBC rate might result in this tendency.WGC is now popular as the initial biliary cannulation method instead of traditional contrast injection method. ESGE guideline also suggests WGC as a primary cannulation method. WGC can facilitate technical success rate of selective biliary cannulation. It may reduce the severity or frequency of post-ERCP pancreatitisTherefore, in our study, we tried to compare mechanically superior GWs with each other. Previous studies of GWs usually showed technical outcomes and adverse events without clearly showing the evidence of mechanical property difference. Besides stiff core material of 0.025-inch GWs that was similar to that of 0.035-inch GWs (Fig. Limitations of presented clinical study are as follows. First, because of a non-inferiority trial, a relatively small number of patients were enrolled. We set a margin of noninferiority for a biliary cannulation success rate of 15%, which might be a large difference. However, the estimated large number of patients to show the efficacy of these two GWs was difficult because there were no comparative studies between 0.025-inch GWs. Further superiority trials or large comparative studies are warranted. Second, we compared only one control GW because multiple comparison of GWs was limited. To overcome this limitation, we analyzed technical properties of available 0.025-inch GWs for the comparison before clinical trial. However, mechanical reports cannot follow clinical efficacy exactly. Third, although this study was performed by experienced endoscopists and nursing staff, preference of second procedures and timing might be different. Finally, available 0.025-inch GWs might be different according to countries.In conclusion, WGC using a newly developed GW showed similar efficacy and adverse events with a higher performance than existing GW. However, the rate of DBC was relatively lower than the control GW. We found the mechanical property of a GW may affect the DBC. Therefore, ERCP physicians could recognize the mechanical property and limitations of each GWs in WGC for the reduction of DBC and prevention of possible post-ERCP pancreatitis. Also, based on tests of mechanical properties in 0.025- inch GW, we could develop more ideal GW with lower friction load, higher tip load, and higher bending force for facilitating selective cannulation or stricture negotiation.