Fully covered self-expandable metal stents to dilate persistent pancreatic strictures in chronic pancreatitis: long-term follow-up from a prospective study

Background and Aims: Symptomatic main pancreatic duct (MPD) strictures secondary to chronic pancreatitis (CP) may benefit from endoscopic insertion of single or multiple plastic stents. MPD stricture resolution after single plastic stent removal is uncommon. The use of removable fully covered, self-expandable metal stents (FC-SEMSs) to dilate MPD strictures secondary to CP was evaluated. Methods: Patients with CP and symptomatic MPD stricture located in the head of the pancreas persisting for 3 months or more after placement of a single plastic stent were enrolled in a prospective single-arm trial. A nitinol FC-SEMS was inserted and removed after 6 months. The FC-SEMS diameter and length were chosen according to the stricture anatomy and MPD diameter above the stricture. Our primary objective was FC-SEMS removability. Secondary outcomes were MPD stricture resolution rate and adverse events. Results: Between December 2012 and October 2014, 15 patients (10 male, mean age 60 years) were enrolled. Pancreatic calcifications were present in 6 (40%) patients. Four patients (27%) had a history of alcohol abuse. In 10 patients, the FC-SEMS was inserted through the major papilla, whereas 5 patients (3 pancreas divisum, 2 dominant dorsal duct) received the stent through the minor papilla. One patient developed cholangitis after 24 hours due to occlusion of the biliary sphincterotomy from the FC-SEMS; cholangitis resolved after insertion of a plastic biliary stent. Complete distal migration of the FC-SEMS was reported in 7 patients (47%) (5 asymptomatic, 2 symptomatic with recurrence of pancreatitis). All migrations occurred with the 3-cm-long FC-SEMS. Four patients (27%) developed de novo stricture induced by the FC-SEMS at the level of the flared end and were excluded from the follow-up; 1 patient with FC-SEMS migration had failed stricture resolution. One patient was lost to follow-up. Finally, 9 patients with MPD stricture resolution had a mean follow-up of 38.9 months (range, 5.3-55.3 months), and 89% were asymptomatic. Conclusions: FC-SEMS removability from the MPD in CP was feasible in all cases, and 90% of the patients were asymptomatic after 3 years. Migration seems more frequent with the 3-cm-long FC-SEMS. Occurrence of FC-SEMS-induced pancreatic strictures is a major issue and deserves further assessment. According to our experience, pancreatic FC-SEMSs have promising results, but a careful evaluation in the setting of clinical trials is needed.