title: Intracoronary optical coherence tomography and histology of overlapping everolimus-eluting bioresorbable vascular scaffolds in a porcine coronary artery model: the potential implications for clinical practice.
abstract: OBJECTIVE
  This study sought to assess the vascular response of overlapping Absorb stents compared with overlapping newer-generation everolimus-eluting metallic platform stents (Xience V [XV]) in a porcine coronary artery model.
  
  
  BACKGROUND
  The everolimus-eluting bioresorbable vascular scaffold (Absorb) is a novel approach to treating coronary lesions. A persistent inflammatory response, fibrin deposition, and delayed endothelialization have been reported with overlapping first-generation drug-eluting stents.
  
  
  METHODS
  Forty-one overlapping Absorb and overlapping Xience V (XV) devices (3.0 × 12 mm) were implanted in the main coronary arteries of 17 nonatherosclerotic pigs with 10% overstretch. Implanted coronary arteries were evaluated by optical coherence tomography (OCT) at 28 days (Absorb n = 11, XV n = 7) and 90 days (Absorb n = 11, XV n = 8), with immediate histological evaluation following euthanasia at the same time points. One animal from each time point was evaluated with scanning electron microscopy alone. A total of 1,407 cross sections were analyzed by OCT and 148 cross sections analyzed histologically.
  
  
  RESULTS
  At 28 days in the overlap, OCT analyses indicated 80.1% of Absorb struts and 99.4% of XV struts to be covered (p < 0.0001), corresponding to histological observations of struts with cellular coverage of 75.4% and 99.6%, respectively (p < 0.001). Uncovered struts were almost exclusively related to the presence of "stacked" Absorb struts, that is, with a direct overlay configuration. At 90 days, overlapping Absorb and overlapping XV struts demonstrated >99% strut coverage by OCT and histology, with no evidence of a significant inflammatory process, and comparable % volume obstructions.
  
  
  CONCLUSIONS
  In porcine coronary arteries implanted with overlapping Absorb or overlapping XV struts, strut coverage is delayed at 28 days in overlapping Absorb, dependent on the overlay configuration of the thicker Absorb struts. At 90 days, both overlapping Absorb and overlapping XV have comparable strut coverage. The implications of increased strut thickness may have important clinical and design considerations for bioresorbable platforms.
authors.affiliation: Erasmus University Medical Centre, Rotterdam, The Netherlands.
authors.forename: Vasim
authors.initials: V
authors.lastname: Farooq
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Heo
authors.forename: Bill D
authors.initials: BD
authors.lastname: Gogas
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Onuma
authors.forename: Laura E
authors.initials: LE
authors.lastname: Perkins
authors.forename: Roberto
authors.initials: R
authors.lastname: Diletti
authors.forename: Maria D
authors.initials: MD
authors.lastname: Radu
authors.forename: Lorenz
authors.initials: L
authors.lastname: Räber
authors.forename: Christos V
authors.initials: CV
authors.lastname: Bourantas
authors.forename: Yaojun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Eric
authors.initials: E
authors.lastname: van Remortel
authors.forename: Ravindra
authors.initials: R
authors.lastname: Pawar
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Rapoza
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Powers
authors.forename: Heleen M M
authors.initials: HM
authors.lastname: van Beusekom
authors.forename: Hector M
authors.initials: HM
authors.lastname: Garcìa-Garcìa
authors.forename: Renu
authors.initials: R
authors.lastname: Virmani
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D002317:Cardiovascular Agents / Q000008:administration & dosage*; D003331:Coronary Vessels / Q000473:pathology*; D054855:Drug-Eluting Stents; D000068338:Everolimus; D023421:Models, Animal; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects / Q000295:instrumentation*; D011474:Prosthesis Design; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives*; D013552:Swine; D013997:Time Factors; D041623:Tomography, Optical Coherence
chemical_list: D002317:Cardiovascular Agents; D000068338:Everolimus; D020123:Sirolimus