title: Intracoronary beta-radiation exacerbates long-term neointima formation in balloon-injured pig coronary arteries.
abstract: BACKGROUND
  Long-term biological effects of ionizing radiation on coronary arteries remain poorly defined. We examined late arterial responses 6 months after balloon angioplasty and beta-radiation in normal pig coronary arteries.
  
  
  RESULTS
  Coronary arteries of 25 adult pigs were randomized to receive 20 Gy (n=8) or 30 Gy (n=9) of (186)Re beta-radiation or sham radiation (n=8) immediately after balloon angioplasty. Aspirin was given daily during follow-up. The study vessels were analyzed histopathologically at 6 months. beta-Radiation decreased lumen area (20 Gy, 1.55+/-0.99 mm(2); 30 Gy, 1.03+/-0.82 mm(2); and 0 Gy, 2.05+/-0.80 mm(2); P<0.05) but not overall vessel area. The neointimal area was significantly larger within the injured segment with beta-radiation (20 Gy, 1.92+/-1.23 mm(2); 30 Gy, 1.51+/-0.97 mm(2); and 0 Gy, 0.89+/-0.31 mm(2); 0 Gy versus 20 Gy, P<0.05), and a significant increase of edge stenosis was observed with beta-radiation. Irradiated vessels also had larger thrombus areas within the neointima (30 Gy, 0.24+/-0.61 mm(2); 20 Gy, 0.98+/-1.57 mm2; and 0 Gy, 0.00+/-0.01 mm(2); P<0.05) and larger adventitial areas (20 Gy, 2.25+/-0.75 mm(2); 30 Gy, 2.38+/-0.98 mm(2); and 0 Gy, 1.23+/-0.29 mm(2); 0 Gy versus 20 or 30 Gy, P<0.05) that showed substantial collagen accumulation.
  
  
  CONCLUSIONS
  Intracoronary beta-radiation did not inhibit neointima formation in balloon-injured normal pig coronary arteries 6 months after the interventional procedure. Unresorbed thrombus contributed to, but was not the sole component of, augmented neointima formation. Irradiated vessels demonstrated more adventitial thickening and fibrosis. These observations may have relevance for long-term clinical outcomes after intracoronary beta-radiation.
authors.affiliation: Atlanta Cardiovascular Research Institute, Norcross, GA, USA.
authors.forename: P K
authors.initials: PK
authors.lastname: Coussement
authors.forename: H
authors.initials: H
authors.lastname: de Leon
authors.forename: T
authors.initials: T
authors.lastname: Ueno
authors.forename: M Y
authors.initials: MY
authors.lastname: Salame
authors.forename: S B
authors.initials: SB
authors.lastname: King
authors.forename: N A
authors.initials: NA
authors.lastname: Chronos
authors.forename: K A
authors.initials: KA
authors.lastname: Robinson
mesh_terms: D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects*; D000818:Animals; D001610:Beta Particles / Q000009:adverse effects*; D023903:Coronary Restenosis / Q000209:etiology* / Q000473:pathology; D003331:Coronary Vessels / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D008297:Male; D013552:Swine