title: Appearance of lipid-laden intima and neovascularization after implantation of bare-metal stents extended late-phase observation by intracoronary optical coherence tomography.
abstract: OBJECTIVE
  We examined the neointimal characteristics of bare-metal stents (BMS) in extended late phase by the use of optical coherence tomography (OCT).
  
  
  BACKGROUND
  The long-term neointimal features after BMS implantation have not yet been fully characterized.
  
  
  METHODS
  Intracoronary OCT observation of BMS segments was performed during the early phase (<6 months, n = 20) and late phase (>or=5 years, n = 21) after implantation. Internal tissue of the BMS was categorized into normal neointima, characterized by a signal-rich band without signal attenuation, or lipid-leaden intima, with marked signal attenuation and a diffuse border. In addition, the presence of disrupted intima and thrombus was evaluated. Neovascularization was defined as small vesicular or tubular structures, and the location of the microvessels was classified into peristent or intraintima.
  
  
  RESULTS
  Normal neointima proliferated homogeneously, and lipid-laden intima was not observed in the early phase. In the late phase, lipid-laden intima, intimal disruption, and thrombus frequently were found in comparison with the early phase (67% vs. 0%, 38% vs. 0%, and 52% vs. 5%, respectively; p < 0.05). Persistent neovascularization demonstrated a similar incidence between the 2 phases. The appearance of intraintima neovascularization was more prevalent in the late phase than the early phase (62% vs. 0%, respectively; p < 0.01) and in segments with lipid-laden intima than in nonlipidic segments (79% vs. 29%, respectively; p = 0.026).
  
  
  CONCLUSIONS
  This OCT study suggests that neointima within the BMS often transforms into lipid-laden tissue during an extended period of time and that expansion of neovascularization from peristent to intraintima contributes to atherosclerotic progression of neointima.
authors.affiliation: Division of Cardiology, Nippon Medical School, Tokyo, Japan. takanom@nms.ac.jp
authors.forename: Masamichi
authors.initials: M
authors.lastname: Takano
authors.forename: Masanori
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Inami
authors.forename: Daisuke
authors.initials: D
authors.lastname: Murakami
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ohba
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Seino
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Mizuno
mesh_terms: D000368:Aged; D050197:Atherosclerosis / Q000000981:diagnostic imaging / Q000473:pathology*; D019917:Blood Vessel Prosthesis Implantation; D017023:Coronary Angiography; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000473:pathology*; D015607:Stents / Q000009:adverse effects*; D041623:Tomography, Optical Coherence; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology*