Feasibility and histological analysis of multi-hole versus fully covered self-expandable metallic stents in a porcine model of hilar biliary obstruction

Conventional fully covered self-expandable metallic stents (FCSEMS) for hilar biliary obstruction (HBO) remains limited due to the potential for side branch obstruction. The multi-hole covered self-expandable metallic stent (MHSEMS) was designed to overcome the limitations of FCSEMS by incorporating side holes into the fully covered membrane. This preclinical study evaluated the feasibility and safety of MHSEMS compared to conventional FCSEMS in a porcine HBO model. HBO was induced via intraductal radiofrequency ablation in eight minipigs. After four weeks, animals were randomized to receive either an MHSEMS or a conventional FCSEMS and were monitored for 12 weeks. Outcomes included technical success, adverse events, stent removability, and histological analysis. Excluding two procedure-related mortalities (one in each group), technical success and 12-week stent removability were achieved in all animals (n = 6). Compared to the FCSEMS group, the MHSEMS group demonstrated trends toward lower total bilirubin levels and reduced histological inflammation score in contralateral ducts (median [range]: 7.5 [7.0-9.0] vs. 9.0 [8.0-10.0], Cliff's delta = 0.67). In conclusion, the MHSEMS was safely and completely removable within a clinically relevant timeframe. This preclinical pilot study suggests a possible signal toward lower histologic injury with the MHSEMS compared with the FCSEMS, supporting the need for larger, adequately powered clinical studies.