title: Incomplete stent apposition causes high shear flow disturbances and delay in neointimal coverage as a function of strut to wall detachment distance: implications for the management of incomplete stent apposition.
abstract: BACKGROUND
  Lack of re-endothelialization and neointimal coverage on stent struts has been put forward as the main underlying mechanism leading to late stent thrombosis. Incomplete stent apposition (ISA) has been observed frequently in patients with very late stent thrombosis after drug eluting stent implantation, suggesting a role of ISA in the pathogenesis of this adverse event. The aim of this study was to evaluate the impact of different degrees of ISA severity on abnormal shear rate and healing response with coverage, because of its potential implications for stent optimization in clinical practice.
  
  
  RESULTS
  We characterized flow profile and shear distribution in different cases of ISA with increasing strut-wall detachment distance (ranging from 100 to 500 μm). Protruding strut and strut malapposed with moderate detachment (ISA detachment distance <100 μm) have minimal disturbance to blood flow as compared with floating strut that has more significant ISA distance. In vivo impact on strut coverage was assessed retrospectively using optical coherence tomography evaluation on 72 stents (48 patients) sequentially at baseline and after 6-month follow-up. Analysis of coverage revealed an important impact of baseline strut-wall ISA distance on the risk of incomplete strut coverage at follow-up. Malapposed segments with an ISA detachment <100 μm at baseline showed complete strut coverage at follow-up, whereas segments with a maximal ISA detachment distance of 100 to 300 μm and >300 μm had 6.1% and 15.7% of their struts still uncovered at follow-up, respectively (P<0.001).
  
  
  CONCLUSIONS
  Flow disturbances and risk of delayed strut coverage both increase with ISA detachment distance. Insights from this study are important for understanding malapposition as a quantitative, rather than binary phenomenon (present or absent) and to define the threshold of ISA detachment that might benefit from optimization during stent implantation.
authors.affiliation: From the International Centre for Circulatory Health, NHLI, Imperial College London, London, United Kingdom (N.F., S.S., S.N., R.P., C.K., D.P.F., J.E.D., P.W.S.); National Heart Centre Singapore, Singapore (N.F., P.W.); ThoraxCenter, Erasmus Medical Center, Rotterdam, The Netherlands (J.L.G.-C., S.N., C.V.B., Y.O., H.M.G.-G., P.W.S.); Ludwig-Maximilian Universität, München, Germany (J.L.G.-C.); Department of Mechanical Engineering, University College London, London, United Kingdom (R.T.); NIHR, BRU, Royal Brompton and Harefield NHS Trust, London, United Kingdom (M.G., C.D.M.); and Cardialysis, Rotterdam, The Netherlands (H.M.G.-G., P.W.S.).
authors.forename: Nicolas
authors.initials: N
authors.lastname: Foin
authors.forename: Juan Luis
authors.initials: JL
authors.lastname: Gutiérrez-Chico
authors.forename: Shimpei
authors.initials: S
authors.lastname: Nakatani
authors.forename: Ryo
authors.initials: R
authors.lastname: Torii
authors.forename: Christos V
authors.initials: CV
authors.lastname: Bourantas
authors.forename: Sayan
authors.initials: S
authors.lastname: Sen
authors.forename: Sukhjinder
authors.initials: S
authors.lastname: Nijjer
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.forename: Chrysa
authors.initials: C
authors.lastname: Kousera
authors.forename: Matteo
authors.initials: M
authors.lastname: Ghione
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Onuma
authors.forename: Hector M
authors.initials: HM
authors.lastname: Garcia-Garcia
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.forename: Philip
authors.initials: P
authors.lastname: Wong
authors.forename: Carlo
authors.initials: C
authors.lastname: Di Mario
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
mesh_terms: D000368:Aged; D003198:Computer Simulation; D003324:Coronary Artery Disease / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D003331:Coronary Vessels / Q000473:pathology / Q000503:physiopathology*; D054855:Drug-Eluting Stents / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D057446:Hydrodynamics; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D058426:Neointima / Q000473:pathology / Q000503:physiopathology*; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects*; D012039:Regional Blood Flow / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D033081:Shear Strength / Q000502:physiology*; D013927:Thrombosis / Q000453:epidemiology / Q000473:pathology; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome
keywords: angioplasty; blood flow velocity; stents; thrombosis