title: A subgroup analysis of the Scripps Coronary Radiation to Inhibit Proliferation Poststenting Trial.
abstract: BACKGROUND
  In the Scripps Coronary Radiation to Inhibit Proliferation Poststenting (SCRIPPS) Trial, 192Ir significantly reduced angiographic, ultrasonographic, and clinical endpoints of restenosis. The objective of this analysis was to quantitate the impact of patient, lesion and technical characteristics on late angiographic outcome.
  
  
  METHODS
  Patients with restenotic, stented coronary lesions were randomized to receive either 192Ir or placebo sources. Late luminal loss and loss index were calculated for several patient subgroups, including patients with diabetes, in-stent restenosis, multiple previous percutaneous transluminal coronary angioplasty (PTCA) procedures, longer lesion lengths, saphenous vein grafts, small vessel diameters, and minimum dose exposures < 8.00 Gy. Two-factor analysis of variance was used to test for an interaction between patient characteristics and treatment effect.
  
  
  RESULTS
  In the treated group, late loss was particularly low in patients with diabetes (0.19 mm), in-stent restenosis (0.17 mm), reference vessel diameters < 3.0 mm (0.07 mm), and patients who received a minimum radiation dose to the entire adventitial border of at least 8.00 Gy. The loss index in each of these subgroups was similarly low at -0.02, 0.03, -0.02, and 0.03, respectively. By 2-factor analysis of variance, a significant interaction between subgroup characteristic and treatment effect (late loss) was found in patients with in-stent restenosis (p = 0.035), and patients receiving a minimum dose of 8.00 Gy to the adventitial border (p = 0.009).
  
  
  CONCLUSIONS
  In this pilot study, patient characteristics associated with a more aggressive proliferative response to injury appeared to confer an enhanced response to radiotherapy. Furthermore, a dose threshold response to 192Ir was found with an enhanced response occurring when the entire circumference of the adventitial border was exposed to at least 8.00 Gy.
authors.affiliation: Division of Cardiovascular Diseases, Scripps Clinic, La Jolla, CA 92037, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Teirstein
authors.forename: V
authors.initials: V
authors.lastname: Massullo
authors.forename: S
authors.initials: S
authors.lastname: Jani
authors.forename: J J
authors.initials: JJ
authors.lastname: Popma
authors.forename: G S
authors.initials: GS
authors.lastname: Mintz
authors.forename: R J
authors.initials: RJ
authors.lastname: Russo
authors.forename: R A
authors.initials: RA
authors.lastname: Schatz
authors.forename: E M
authors.initials: EM
authors.lastname: Guarneri
authors.forename: S
authors.initials: S
authors.lastname: Steuterman
authors.forename: D A
authors.initials: DA
authors.lastname: Cloutier
authors.forename: M B
authors.initials: MB
authors.lastname: Leon
authors.forename: P
authors.initials: P
authors.lastname: Tripuraneni
mesh_terms: D000704:Analysis of Variance; D003131:Combined Modality Therapy; D003327:Coronary Disease / Q000532:radiotherapy* / Q000628:therapy; D004307:Dose-Response Relationship, Radiation; D004311:Double-Blind Method; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D010865:Pilot Projects; D019275:Radiopharmaceuticals / Q000627:therapeutic use*; D012008:Recurrence; D015607:Stents
chemical_list: D007496:Iridium Radioisotopes; D019275:Radiopharmaceuticals