title: Inter-core lab variability in analyzing quantitative coronary angiography for bifurcation lesions: a post-hoc analysis of a randomized trial.
abstract: OBJECTIVE
  This study sought to evaluate inter-core lab variability in quantitative coronary angiography (QCA) analysis of bifurcation lesions.
  
  
  BACKGROUND
  QCA of bifurcation lesions is challenging. To date there are no data available on the inter-core lab variability of bifurcation QCA analysis.
  
  
  METHODS
  The randomized Tryton IDE (Tryton Pivotal IDE Coronary Bifurcation Trial) compared the Tryton Side Branch Stent (Tryton Medical, Durham, North Carolina) with balloon angioplasty as side branch treatment. QCA was performed in an angiographic subcohort (n = 326) at 9-month follow-up. Inter-core lab variability of QCA analysis between the Cardiovascular Research Foundation and the Cardialysis core labs was evaluated before and after alignment of the used QCA methodology using angiographic data derived from this angiographic follow-up cohort.
  
  
  RESULTS
  In the original analysis, before alignment of QCA methodology, the mean difference between the core labs (bias) was large for all QCA parameters with wide 95% limits of agreement (1.96 × SD of the bias), indicating marked variability. The bias of the key angiographic endpoint of the Tryton trial, in-segment percentage diameter stenosis (%DS) of the side branch, was 5.5% (95% limits of agreement: -26.7% to 37.8%). After reanalysis, the bias of the in-segment %DS of the side branch reduced to 1.8% (95% limits of agreement: -16.7% to 20.4%). Importantly, after alignment of the 2 core labs, there was no longer a difference between both treatment groups (%DS of the side branch: treatment group A vs. group B: 34.4 ± 19.4% vs. 32.4 ± 16.1%, p = 0.340).
  
  
  CONCLUSIONS
  Originally, a marked inter-core lab variability of bifurcation QCA analysis was found. After alignment of methodology, inter-core lab variability decreased considerably and impacted angiographic trial results. This latter finding emphasizes the importance of using the same methodology among different core labs worldwide. (Tryton Pivotal Prospective, Single Blind, Randomized Controlled Study to Evaluate the Safety & Effectiveness of the Tryton Side Branch Stent Used With DES in Treatment of de Novo Bifurcation Lesions in the Main Branch & Side Branch in Native Coronaries [TRYTON]; NCT01258972).
authors.affiliation: Amsterdam Heart Center, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Maik J
authors.initials: MJ
authors.lastname: Grundeken
authors.affiliation: Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ishibashi
authors.affiliation: Cardiovascular Research Foundation, New York, New York.
authors.forename: Philippe
authors.initials: P
authors.lastname: Généreux
authors.affiliation: Cardiovascular Research Foundation, New York, New York.
authors.forename: Laura
authors.initials: L
authors.lastname: LaSalle
authors.affiliation: Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Javaid
authors.initials: J
authors.lastname: Iqbal
authors.affiliation: Amsterdam Heart Center, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Joanna J
authors.initials: JJ
authors.lastname: Wykrzykowska
authors.affiliation: Cardialysis B.V., Rotterdam, the Netherlands.
authors.forename: Marie-Angèle
authors.initials: MA
authors.lastname: Morel
authors.affiliation: Amsterdam Heart Center, Academic Medical Center, Amsterdam, the Netherlands; Cardialysis B.V., Rotterdam, the Netherlands.
authors.forename: Jan G
authors.initials: JG
authors.lastname: Tijssen
authors.affiliation: Amsterdam Heart Center, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Robbert J
authors.initials: RJ
authors.lastname: de Winter
authors.affiliation: Cardialysis B.V., Rotterdam, the Netherlands; First Cardiology Department, Onassis Cardiac Surgery Center, Athens, Greece.
authors.forename: Chrysafios
authors.initials: C
authors.lastname: Girasis
authors.affiliation: Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands; Cardialysis B.V., Rotterdam, the Netherlands.
authors.forename: Hector M
authors.initials: HM
authors.lastname: Garcia-Garcia
authors.affiliation: Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands; Cardialysis B.V., Rotterdam, the Netherlands.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Onuma
authors.affiliation: Cardiovascular Research Foundation, New York, New York.
authors.forename: Martin B
authors.initials: MB
authors.lastname: Leon
authors.affiliation: International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London, London, United Kingdom. Electronic address: patrick.w.j.c.serruys@gmail.com.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
mesh_terms: D000465:Algorithms; D015906:Angioplasty, Balloon, Coronary; D017023:Coronary Angiography / Q000592:standards*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000592:standards*; D015203:Reproducibility of Results; D015607:Stents
keywords: Tryton Side Branch Stent; bifurcation; bifurcation lesions; percutaneous coronary interventions; quantitative coronary angiography