title: Strut protrusion and shape impact on endothelial shear stress: insights from pre-clinical study comparing Mirage and Absorb bioresorbable scaffolds.
abstract: Protrusion of scaffold struts is related with local coronary flow dynamics that can promote scaffold restenosis and thrombosis. That fact has prompted us to investigate in vivo the protrusion status of different types of scaffolds and their relationship with endothelial shear stress (ESS) distributions. Six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb, Abbott Vascular) and 11 Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage, Manli Cardiology) were implanted in coronaries of eight mini pigs. Optical coherence tomography (OCT) was performed post-scaffold implantation and obtained images were fused with angiographic data to reconstruct the three dimensional coronary anatomy. Blood flow simulation was performed and ESS distribution was estimated for each scaffold. Protrusion distance was estimated using a dedicated software. Correlation between OCT-derived protrusion and ESS distribution was assessed for both scaffold groups. A significant difference was observed in the protrusion distances (156 ± 137 µm for Absorb, 139 ± 153 µm for Mirage; p = 0.035), whereas difference remained after adjusting the protrusion distances according to the luminal areas. Strut protrusion of Absorb is inversely correlated with ESS (r = -0.369, p < 0.0001), whereas in Mirage protrusion was positively correlated with EES (r = 0.192, p < 0.0001). Protrusion distance was higher in Absorb than in Mirage. The protrusion of the thick quadratic struts of Absorb has a tendency to lower shear stress in the close vicinity of struts. However, circular shape of the less thick struts of Mirage didn't show this trend in creating zone of recirculation around the struts. Strut geometry has different effect on the relationship between protrusion and shear stress in Absorb and Mirage scaffolds.
authors.affiliation: Department of Interventional Cardiology, Erasmus University Medical Center, Thoraxcenter, Rotterdam, The Netherlands.
authors.forename: Erhan
authors.initials: E
authors.lastname: Tenekecioglu
authors.affiliation: Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Sotomi
authors.affiliation: Department of Mechanical Engineering, University College London, London, UK.
authors.forename: Ryo
authors.initials: R
authors.lastname: Torii
authors.affiliation: Department of Cardiology, University College of London Hospitals, London, UK.
authors.forename: Christos
authors.initials: C
authors.lastname: Bourantas
authors.affiliation: Department of Interventional Cardiology, Erasmus University Medical Center, Thoraxcenter, Rotterdam, The Netherlands.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miyazaki
authors.affiliation: Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Carlos
authors.initials: C
authors.lastname: Collet
authors.affiliation: Department of Cardiology, University College of London Hospitals, London, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Crake
authors.affiliation: Manli Cardiology, Singapore, Singapore.
authors.forename: Solomon
authors.initials: S
authors.lastname: Su
authors.affiliation: Department of Interventional Cardiology, Erasmus University Medical Center, Thoraxcenter, Rotterdam, The Netherlands.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Onuma
authors.affiliation: Department of Interventional Cardiology, Erasmus University Medical Center, Thoraxcenter, Rotterdam, The Netherlands. patrick.w.j.c.serruys@gmail.com.|Imperial College, London, UK. patrick.w.j.c.serruys@gmail.com.|Emeritus Professor of Medicine Erasmus University, Westblaak 98, 3012KM, Rotterdam, The Netherlands. patrick.w.j.c.serruys@gmail.com.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001783:Blood Flow Velocity; D003198:Computer Simulation; D017023:Coronary Angiography; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006439:Hemodynamics; D021621:Imaging, Three-Dimensional; D023421:Models, Animal; D008955:Models, Cardiovascular; D064847:Multimodal Imaging; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects / Q000295:instrumentation*; D011474:Prosthesis Design; D011857:Radiographic Image Interpretation, Computer-Assisted; D013314:Stress, Mechanical; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors; D041623:Tomography, Optical Coherence
keywords: Bioresorbable scaffold; Protrusion; Shear stress; Strut geometry