title: Serial intravascular ultrasound analysis of the impact of lesion length on the efficacy of intracoronary gamma-irradiation for preventing recurrent in-stent restenosis.
abstract: BACKGROUND
  The relation between lesion length and effectiveness of brachytherapy is not well studied.
  
  
  RESULTS
  We compared serial (postintervention and follow-up) intravascular ultrasound findings in 66 patients with native coronary artery in-stent restenosis (ISR) who were treated with (192)Ir (15 Gy delivered 2 mm away from the radiation source). Patients were enrolled in the Washington Radiation for In-Stent Restenosis Trial (WRIST; ISR length, 10 to 47 mm; n=36) or Long WRIST (ISR length, 36 to 80 mm; n=30). External elastic membrane, stent, lumen, and intimal hyperplasia (IH; stent minus lumen) areas and source-to-target (intravascular ultrasound catheter to external elastic membrane) distances were measured. Postintervention stent areas were larger in WRIST and smaller in Long WRIST patients (P:<0.0001). At follow-up, maximum IH area significantly increased in both WRIST and Long WRIST patients (P:<0.0001 for both), but this increase was greater in Long WRIST patients (P:=0.0006). Similarly, minimum lumen cross-sectional area significantly decreased in both WRIST and Long WRIST patients (P:<0.05 and P:<0.0001, respectively), but this decrease was more pronounced in Long WRIST patients (P:=0.0567). The maximum source-to-target distance was longer in Long WRIST than in WRIST, and it correlated directly with ISR length (r=0.547, P:<0.0001). Overall, the change in minimum lumen area and the change in maximum IH area correlated with the maximum source-to-target distance (r=0.352, P:=0.0038 and r=0.523, P:<0.0001 for WRIST and Long WRIST, respectively). The variability (maximum/minimum) in IH area at follow-up also correlated with the maximum source-to-target distance (r=0.378, P:<0.0001).
  
  
  CONCLUSIONS
  Brachytherapy may be less effective in longer ISR lesions because of the greater variability and longer source-to-target distances in diffuse ISR.
authors.affiliation: Cardiovascular Research Institute, Washington Hospital Center, Washington, DC, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Ahmed
authors.forename: G S
authors.initials: GS
authors.lastname: Mintz
authors.forename: R
authors.initials: R
authors.lastname: Waksman
authors.forename: N J
authors.initials: NJ
authors.lastname: Weissman
authors.forename: B
authors.initials: B
authors.lastname: Leiboff
authors.forename: A D
authors.initials: AD
authors.lastname: Pichard
authors.forename: L F
authors.initials: LF
authors.lastname: Satler
authors.forename: K M
authors.initials: KM
authors.lastname: Kent
authors.forename: M B
authors.initials: MB
authors.lastname: Leon
mesh_terms: D001918:Brachytherapy / Q000592:standards; D023903:Coronary Restenosis / Q000517:prevention & control; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000517:prevention & control / Q000532:radiotherapy*; D003331:Coronary Vessels / Q000000981:diagnostic imaging; D005500:Follow-Up Studies; D005720:Gamma Rays / Q000627:therapeutic use*; D006801:Humans; D006965:Hyperplasia; D007496:Iridium Radioisotopes / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D015607:Stents; D016896:Treatment Outcome; D017539:Tunica Intima / Q000000981:diagnostic imaging; D018084:Ultrasonography, Interventional / Q000379:methods
chemical_list: D007496:Iridium Radioisotopes