title: Expansion and malapposition characteristics after bioresorbable vascular scaffold implantation.
abstract: OBJECTIVE
  This study sought to investigate the postdeployment expansion and malapposition characteristics of the bioresorbable vascular scaffold (BVS) in real-world practice.
  
  
  BACKGROUND
  The material construct of the BVS precludes overexpansion, with consequent potential for scaffold underexpansion and malapposition. In metallic stents, these features are associated with an increased risk of adverse events, including stent thrombosis. The postdeployment characteristics of the BVS are yet to be described outside clinical trials, where implantation occurred in straightforward lesion subsets.
  
  
  METHODS
  Data from 25 patients undergoing BVS implantation were analyzed. Optical coherence tomography (OCT) was performed both before and after intervention to assess plaque composition, scaffold expansion and strut apposition. Manufacturer's compliance charts were used to predict expected minimal scaffold diameter and area.
  
  
  RESULTS
  OCT pullback (522.2 mm) was analyzed. Overall, BVS achieved 82.5 ± 8.7 and 79.8 ± 12.3% of predicted minimal stent diameter and cross-sectional area (SCA), respectively, with expansion reduced in middle third of the scaffold (central SCA 76.7 ± 10.9% vs. noncentral SCA 81.5 ± 12.7%, P < 0.0001). Improved measures of SCA were observed with 1:1 balloon:vessel predilatation (1:1 PreD 82.8 ± 9.5% vs. No 1:1 PredD 78.6 ± 13.0%, P < 0.0001). Seven thousand six hundred scaffold struts were identified, of which 470 (6.18%) were malapposed. In fibrocalcific (FCa) plaques, malapposition was observed more frequently (FCa 44.4% vs. Other plaques 7.5%, P < 0.001) and at a greater distance from the vessel wall (FCa 0.17 ± 0.10 mm vs. Other plaques 0.14 ± 0.08 mm, P = 0.002).
  
  
  CONCLUSIONS
  In this study, BVS expansion was significantly improved by 1:1 PreD, while increased rates of malapposition was associated with FCa plaques.
authors.affiliation: Department of Interventional Cardiology, Papworth Hospital NHS Trust, United Kingdom; Department of Cardiovascular Medicine, University of Cambridge, United Kingdom.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Brown
authors.forename: Liam M
authors.initials: LM
authors.lastname: McCormick
authors.forename: Denise M
authors.initials: DM
authors.lastname: Braganza
authors.forename: Martin R
authors.initials: MR
authors.lastname: Bennett
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Hoole
authors.forename: Nick E J
authors.initials: NE
authors.lastname: West
mesh_terms: D020341:Absorbable Implants; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000601:surgery*; D003331:Coronary Vessels / Q000473:pathology / Q000601:surgery*; D054855:Drug-Eluting Stents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D062645:Percutaneous Coronary Intervention; D011474:Prosthesis Design; D054457:Tissue Scaffolds; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome
keywords: bioabsorbable; imaging; optical coherence tomography; percutaneous coronary intervention; stent