title: Evaluation of four-year coronary artery response after sirolimus-eluting stent implantation using serial quantitative intravascular ultrasound and computer-assisted grayscale value analysis for plaque composition in event-free patients.
abstract: OBJECTIVE
  This study sought to evaluate the long-term arterial response after sirolimus-eluting stent implantation.
  
  
  BACKGROUND
  Sirolimus-eluting stents are effective in inhibiting neointimal hyperplasia without affecting plaque volume behind the stent struts at six months.
  
  
  METHODS
  Serial quantitative intravascular ultrasound and computer-assisted grayscale value analysis over four years were performed in 23 event-free patients treated with sirolimus-eluting stents.
  
  
  RESULTS
  In the first two years, the mean plaque volume (155.5 +/- 42.8 mm3 post-procedure and 156.8 +/- 57.7 mm3 at two years, p = 0.86) and plaque compositional change expressed as mean percent hypoechogenic tissue of the plaque behind the stent struts (78.9 +/- 8.6% post-procedure and 78.2 +/- 8.9% at two years, p = 0.67) did not significantly change. However, significant plaque shrinking (change in plaque volume = -18.4 mm3, p = 0.02) with an increase in plaque echogenicity (change in percent hypoechogenic tissue = -7.8%, p < 0.0001) was observed between two and four years. The mean neointimal volume increased over four years from 0 to 8.4 +/- 5.8 mm3 (p < 0.0001). However, no further statistically significant change occurred between two and four years (7.0 +/- 6.7 mm3 vs. 8.4 +/- 5.8 mm3, p = 0.25).
  
  
  CONCLUSIONS
  Between two and four years after sirolimus-eluting stent implantation, peri-stent tissue shrank with a concomitant increase in echogenicity. These intravascular ultrasound findings suggest that late chronic artery responses may evolve for up to four years after sirolimus-eluting stent implantation. In addition, the fact that the neointima does not significantly change from two to four years may suggest that the biological phenomenon of a delayed healing response has begun to subside.
authors.affiliation: Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Jiro
authors.initials: J
authors.lastname: Aoki
authors.forename: Alexandre C
authors.initials: AC
authors.lastname: Abizaid
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
authors.forename: Andrew T L
authors.initials: AT
authors.lastname: Ong
authors.forename: Eric
authors.initials: E
authors.lastname: Boersma
authors.forename: J Eduardo
authors.initials: JE
authors.lastname: Sousa
authors.forename: Nico
authors.initials: N
authors.lastname: Bruining
mesh_terms: D003131:Combined Modality Therapy; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy*; D003936:Diagnosis, Computer-Assisted; D016503:Drug Delivery Systems; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D020123:Sirolimus / Q000008:administration & dosage*; D015607:Stents; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology*; D018084:Ultrasonography, Interventional
chemical_list: D020123:Sirolimus