title: Late vascular responses from 2 to 4 years after implantation of sirolimus-eluting stents: serial observations by intracoronary optical coherence tomography.
abstract: BACKGROUND
  Late vascular responses after implantation of drug-eluting stents may play a key role in steadily increasing occurrence of very late stent thrombosis have not yet been fully investigated in human beings.
  
  
  RESULTS
  Serial optical coherence tomography observations at 2 and 4 years were collected for 17 patients treated with 21 sirolimus-eluting stents. Corresponding 376 cross sections within single-stent segments at intervals of 1 mm were selected for analyses, and neointimal thickness on each strut was measured. Extrastent lumen (ESL) was defined as an external lumen of the stent. Area and angle of ESL were measured. A total of 3369 and 3221 struts were identified at 2 and 4 years, respectively. From 2 to 4 years, mean neointimal thickness increased (76.8±75.6 μm versus 123.0±102.5 μm; P<0.0001), whereas frequency of patients with uncovered struts decreased (88% versus 29%; P=0.002). Although prevalence of patients that had ESL was similar (59% of 2 years versus 65% of 4 years; P=1.0), the cross sections with ESL increased (9.6% versus 15.2%; P=0.02). Moreover, area and angle of ESL increased from 2 to 4 years (0.28±0.27 mm(2) versus 0.62±0.68 mm(2) and 16.6±5.4° versus 65.1±38.4°; P<0.01, respectively). The incidence of subclinical thrombus did not decrease (24% at 2 years versus 29% at 4 years; P=1.0). All thrombi were identified in patients who had cross sections with ESL.
  
  
  CONCLUSIONS
  The current serial optical coherence tomography study showed an augmentation of neointimal growth at the late phase of sirolimus-eluting stent implantation. ESL may contribute to thrombus formation and ESL of sirolimus-eluting stents expanded from 2 to 4 years.
authors.affiliation: Cardiovascular Center, Chiba-Hokusoh Hospital, Nippon Medical School, Chiba, 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: Masayuki
authors.initials: M
authors.lastname: Mizuno
authors.forename: Daisuke
authors.initials: D
authors.lastname: Murakami
authors.forename: Toru
authors.initials: T
authors.lastname: Inami
authors.forename: Nakahisa
authors.initials: N
authors.lastname: Kimata
authors.forename: Koji
authors.initials: K
authors.lastname: Murai
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Kentaro
authors.initials: K
authors.lastname: Okamatsu
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; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D054855:Drug-Eluting Stents / Q000009:adverse effects* / Q000706:statistics & numerical data; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000628:therapy; D058426:Neointima / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D020123:Sirolimus / Q000008:administration & dosage / Q000009:adverse effects; D013927:Thrombosis / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D013997:Time Factors; D041623:Tomography, Optical Coherence
chemical_list: D020123:Sirolimus