BACKGROUND AND AIMS: Stent migration and subsequent adverse events are frequently observed in the use of fully covered self-expanding metal stents (FCSEMS) for distal biliary stenosis. In this study, we aimed to identify predictors for stent migration based on biomechanical stent characteristics and to associate these findings with clinical outcomes.

METHODS: The migration resistance of FCSEMS was quantified by measuring the pull-out force. We analyzed a single-center retrospective cohort of 178 FCSEMS for treatment success and adverse events occurring during 180 days of follow-up.

RESULTS: Biomechanical measurements revealed a 4-fold higher migration resistance of FCSEMS with anchoring fins (AF, Fmax=14.2+/-0.1 N) compared to FCSEMS with flare ends (FE, Fmax=3.8+/-1.0 N, p<0.0001). Clinically, AF-FCSEMS showed lower rates of migration compared to the FE-FCSEMS (5% vs. 34%, p<0.0001). Unscheduled ERCP due to stent dysfunction was less frequent in the AF-group compared to the FE-group (15% vs. 29%, p=0.046). Cholangitis due to stent dysfunction was observed in 5% of the AF-FCSEMS compared to 19% in the FE-FCSEMS group (p=0.02). Stent patency rates at 1, 3, and 6 months were higher in the AF-group (96 %, 90%, and 80%) compared to the FE-group (90%, 74%, and 66%) (Log-rank test: p=0.03).

CONCLUSIONS: The pull-out force as biomechanical stent property predicts the migration resistance of FCSEMS in distal biliary stenosis and may thus be used to classify stents for this application. AF-FCSEMS showed a significantly lower rate of migration and adverse events compared to FE-FCSEMS.