title: Assessment of the absorption process following bioabsorbable everolimus-eluting stent implantation: temporal changes in strain values and tissue composition using intravascular ultrasound radiofrequency data analysis. A substudy of the ABSORB clinical trial.
abstract: OBJECTIVE
  The main objective was to use IVUS-backscatter radiofrequency (IVUS-RF) to assess the degradation of a bioabsorbable stent by measuring serial changes in dense calcium (DC) and necrotic core (NC) as assessed by intravascular ultrasound-Virtual Histology (IVUS-VH) and in the strain as assessed by palpography.
  
  
  RESULTS
  In the ABSORB trial, 27 patients treated with a single bioabsorbable everolimus-eluting stent (BVS, Abbott Vascular, Santa Clara, CA, USA) were all imaged with IVUS-RF post-stenting and at 6-month follow-up, and 13 and 12 patients were also investigated pre-stenting with IVUS-VH and palpography respectively. From pre- to post-stenting, with VH (n = 13), there was an increase in mean "DC" (9.8 vs. 25.4%, p = 0.0002) and "NC" (15.5 vs. 30.5%, p = 0.0002). In palpography (n = 12), the mean number of frames with Rotterdam Classification (ROC) III/IV per cm decreased from 1.22 +/- 1.91 to 0.12 +/- 0.31 (p = 0.0781) and the mean cumulative strain values (all frames with ROC I-IV scores) changed from 0.50 +/- 0.27 to 0.20 +/- 0.10% (p = 0.0034). Comparing post-stenting with follow-up (n = 27), VH showed a decrease in "DC" (29.7% vs. 21.1%, p = 0.0001). "NC" also decreased (26.9 vs. 21.5%, p = 0.0027). For palpography (n = 25 patients), an increase in the mean number of frames with ROC III/IV per cm was observed from 0.09 +/- 0.26 to 0.22 +/- 0.36 (p = -0.1563) while the mean cumulative strain values (all frames with ROC I-IV scores) changed from 0.15 +/- 0.10 to 0.26 +/- 0.12% (p < 0.0001).
  
  
  CONCLUSIONS
  IVUS-VH changes at 6 months suggest alteration of the BVS with reduction of RF backscattering by polymeric struts. Strained plaques on the palpograms were almost abolished following stent implantation. However, strain values reappeared within 6 months suggesting an increase in endoluminal deformability of the stented vessel.
authors.affiliation: Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Héctor M
authors.initials: HM
authors.lastname: García-García
authors.forename: Nieves
authors.initials: N
authors.lastname: Gonzalo
authors.forename: Ravindra
authors.initials: R
authors.lastname: Pawar
authors.forename: Neville
authors.initials: N
authors.lastname: Kukreja
authors.forename: Dariusz
authors.initials: D
authors.lastname: Dudek
authors.forename: Leif
authors.initials: L
authors.lastname: Thuesen
authors.forename: John A
authors.initials: JA
authors.lastname: Ormiston
authors.forename: Evelyn
authors.initials: E
authors.lastname: Regar
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
mesh_terms: D020341:Absorbable Implants; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation*; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000628:therapy; D002317:Cardiovascular Agents / Q000008:administration & dosage*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000628:therapy*; D054855:Drug-Eluting Stents; D005060:Europe; D000068338:Everolimus; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009520:New Zealand; D011446:Prospective Studies; D011474:Prosthesis Design; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives*; D013314:Stress, Mechanical; D013997:Time Factors; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000295:instrumentation; D014584:User-Computer Interface
chemical_list: D002317:Cardiovascular Agents; D000068338:Everolimus; D020123:Sirolimus