Comparative performance of uncoated, self-expanding metal biliary stents of different designs in 2 diameters: final results of an international multicenter, randomized, controlled trial.
BACKGROUND
The Wallstent has remained the industry standard for biliary self-expanding metal stents (SEMSs). Recently, stents of differing designs, compositions, and diameters have been developed.


OBJECTIVE
To compare the new nitinol 6-mm and 10-mm Zilver stents with the 10-mm stainless steel Wallstent and determine the mechanism of obstruction.


METHODS
Randomized, prospective, controlled study.


METHODS
Nine centers experienced in SEMS placement during ERCP.


METHODS
A total of 241 patients presenting between September 2003 and December 2005 with unresectable malignant biliary strictures at least 2 cm distal to the bifurcation.


METHODS
Stent occlusions requiring reintervention and death.


RESULTS
At interim analysis, a significant increase in occlusions was noted in the 6-mm Zilver group at the P = .04 level, resulting in arm closure but continued follow-up. Final study arms were 64, 88, and 89 patients receiving a 6-mm Zilver, 10-mm Zilver, and 10-mm Wallstent, respectively. Stent occlusions occurred in 25 (39.1%) of the patients in the 6-mm Zilver arm, 21 (23.9%) of the patients in the 10-mm Zilver arm, and 19 (21.4%) of the patients in the 10-mm Wallstent arm (P = .02). The mean number of days of stent patency were 142.9, 185.8, and 186.7, respectively (P = .057). No differences were noted in secondary endpoints, and the study was ended at the 95% censored study endpoints. Biopsy specimens of ingrowth occlusive tissue revealed that 56% were caused by benign epithelial hyperplasia.


CONCLUSIONS
SEMS occlusions were much more frequent with a 6-mm diameter SEMS and equivalent in the two 10-mm arms despite major differences in stent design, material, and expansion, suggesting that diameter is the critical feature. Malignant tumor ingrowth produced only a minority of the documented occlusions.
Loew
Burr J
BJ
Maine Medical Center, Portland, Maine, USA.
Howell
Douglas A
DA
Sanders
Michael K
MK
Desilets
David J
DJ
Kortan
Paul P
PP
May
Gary R
GR
Shah
Raj J
RJ
Chen
Yang K
YK
Parsons
Willis G
WG
Hawes
Robert H
RH
Cotton
Peter B
PB
Slivka
Adam A
AA
Ahmad
Jawad
J
Lehman
Glen A
GA
Sherman
Stuart
S
Neuhaus
Horst
H
Schumacher
Brigitte M
BM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D001650:Bile Duct Neoplasms / Q000150:complications / Q000473:pathology; D002404:Catheterization / Q000379:methods*; D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000379:methods; D002779:Cholestasis / Q000209:etiology / Q000401:mortality / Q000473:pathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D007391:International Cooperation; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010166:Palliative Care / Q000379:methods*; D018579:Patient Selection; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011788:Quality of Life; D018570:Risk Assessment; D013193:Stainless Steel; D015607:Stents; D016019:Survival Analysis; D019452:Terminally Ill; D016896:Treatment Outcome
D000497:Alloys; D013193:Stainless Steel; C013616:nitinol