title: Impact of polymer formulations on neointimal proliferation after zotarolimus-eluting stent with different polymers: insights from the RESOLUTE trial.
abstract: BACKGROUND
  Polymer formulation may affect the efficacy of drug-eluting stents. Resolute, Endeavor, and ZoMaxx are zotarolimus-eluting stents with different stent platforms and different polymer coatings and have been tested in clinical trials. The aim of this analysis was to compare the efficacy of zotarolimus-eluting stents with different polymers.
  
  
  RESULTS
  Data were obtained from the first-in man trial or first randomized trials of each stent, The Clinical RESpOnse EvaLUation of the MedTronic Endeavor CR ABT-578 Eluting Coronary Stent System in De Novo Native Coronary Artery Lesions (RESOLUTE), Randomized Controlled Trial to Evaluate the Safety and Efficacy of the Medtronic AVE ABT-578 Eluting Driver Coronary Stent in De Novo Native Coronary Artery Lesions (ENDEAVOR II), and ZoMaxx I trials. Follow-up intravascular ultrasound analyses (8 to 9 months of follow-up) were possible in 353 patients (Resolute: 88, Endeavor: 98, ZoMaxx: 82, Driver: 85). Volume index (volume/stent length) was obtained for vessel, stent, lumen, peristent plaque, and neointima. Cross-sectional narrowing was defined as neointimal area divided by stent area (%). Neointima-free frame ratio was calculated as the number of frames without intravascular ultrasound-detectable neointima divided by the total number of frames within the stent. At baseline, vessel, lumen, and peristent plaque volume index were not significantly different among the 4 stent groups. At follow-up, percent neointimal obstruction was significantly lower in Resolute compared with Endeavor, ZoMaxx, and Driver (Resolute: 3.7±4.0, Endeavor: 17.5±10.1, ZoMaxx: 14.6±8.1, Driver: 29.4±17.2%; P<0.001). Greater maximum cross-sectional narrowing and higher neointima-free frame ratio, suggesting less neointimal coverage, were observed in Resolute compared with other stent groups. Multiple regression analysis confirmed that the biodurable polymer used in Resolute independently correlated with neointimal suppression among 3 zotarolimus-eluting stents.
  
  
  CONCLUSIONS
  The different polymer formulations significantly affect the relative amount of neointima for zotarolimus-eluting stents.
  
  
  BACKGROUND
  URL: http://www.clinicaltrials.gov. Unique identifier: NCT00248079.
authors.affiliation: Stanford University, Stanford, CA 94305, USA.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Waseda
authors.forename: Junya
authors.initials: J
authors.lastname: Ako
authors.forename: Masao
authors.initials: M
authors.lastname: Yamasaki
authors.forename: Tomomi
authors.initials: T
authors.lastname: Koizumi
authors.forename: Ryota
authors.initials: R
authors.lastname: Sakurai
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Hongo
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
authors.forename: John
authors.initials: J
authors.lastname: Ormiston
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Worthley
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Whitbourn
authors.forename: Darren L
authors.initials: DL
authors.lastname: Walters
authors.forename: Ian T
authors.initials: IT
authors.lastname: Meredith
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Fitzgerald
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Honda
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D049109:Cell Proliferation; D017023:Coronary Angiography; D054855:Drug-Eluting Stents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058426:Neointima / Q000473:pathology*; D011108:Polymers / Q000737:chemistry*; D012044:Regression Analysis; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives*; D018084:Ultrasonography, Interventional
chemical_list: D011108:Polymers; C489443:zotarolimus; D020123:Sirolimus