title: Comparison of in vivo eccentricity and symmetry indices between metallic stents and bioresorbable vascular scaffolds: insights from the ABSORB and SPIRIT trials.
abstract: OBJECTIVE
  To compare the geometrical parameters of a bioresorbable vascular scaffold (BVS) with a standard metallic stent.
  
  
  BACKGROUND
  The introduction of polymeric bioresorbable materials in the design of novel coronary scaffolds may affect some geometrical parameters, such as eccentricity and symmetry indices, previously introduced as IVUS criteria for optimal metallic stent deployment.
  
  
  METHODS
  From ABSORB Cohort A, ABSORB Cohort B, SPIRIT I, and SPIRIT II, all patients implanted with BVS 1.0, BVS 1.1, or XIENCE V, respectively and intravascular ultrasound analyses post-implantation were selected. The eccentricity index was calculated frame by frame and expressed as an average per device (minimum diameter/maximum diameter). The symmetry index of the device was reported as ([maximum diameter - minimum diameter]/maximum diameter). Six months major adverse cardiac events (MACE) were analyzed.
  
  
  RESULTS
  A total of 242 patients were selected (BVS 1.0: n = 28, BVS 1.1: n = 94, XIENCE V: n = 120). The BVS exhibited a significantly lower eccentricity index (BVS 1.0: 0.83 ± 0.09; BVS 1.1: 0.85 ± 0.08; XIENCE V: 0.90 ± 0.06; P < 0.01) and a significantly higher symmetry index (BVS 1.0: 0.30 ± 0.07; BVS 1.1: 0.31 ± 0.06, XIENCE V 0.26 ± 0.07; P < 0.01) as compared to the XIENCE V. An inverse correlation was found between the symmetry and eccentricity indices for both (BVS r = -0.69, P < 0.01; XIENCE V r = -0.61, P < 0.01). No differences in MACE were detected between the groups according to their geometrical parameters.
  
  
  CONCLUSIONS
  The introduction of a new polymeric material in the design of BVS resulted in a lower eccentricity index and a higher symmetry index as compared to metallic stents, without detectable impact in MACE, at 6 months.
authors.affiliation: Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Brugaletta
authors.forename: Josep
authors.initials: J
authors.lastname: Gomez-Lara
authors.forename: Roberto
authors.initials: R
authors.lastname: Diletti
authors.forename: Vasim
authors.initials: V
authors.lastname: Farooq
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: van Geuns
authors.forename: Bernard
authors.initials: B
authors.lastname: de Bruyne
authors.forename: Dariusz
authors.initials: D
authors.lastname: Dudek
authors.forename: Hector M
authors.initials: HM
authors.lastname: Garcia-Garcia
authors.forename: John A
authors.initials: JA
authors.lastname: Ormiston
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
mesh_terms: D020341:Absorbable Implants; D017023:Coronary Angiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D011474:Prosthesis Design; D016037:Single-Blind Method; D015607:Stents; D054457:Tissue Scaffolds; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional