title: The incidence and functional consequences of RT-associated cardiac perfusion defects.
abstract: OBJECTIVE
  Radiation therapy (RT) for left-sided breast cancer has been associated with cardiac dysfunction. We herein assess the temporal nature and volume dependence of RT-induced left ventricular perfusion defects and whether these perfusion defects are related to changes in cardiac wall motion or alterations in ejection fraction.
  
  
  METHODS
  From 1998 to 2001, 114 patients were enrolled onto an IRB-approved prospective clinical study to assess changes in regional and global cardiac function after RT for left-sided breast cancer. Patients were imaged 30 to 60 minutes after injection of technetium 99m sestamibi or tetrofosmin. Post-RT perfusion scans were compared with the pre-RT studies to assess for RT-induced perfusion defects as well as functional changes in wall motion and ejection fraction. Two-tailed Fisher's exact test and the Cochran-Armitage test for linear trends were used for statistical analysis.
  
  
  RESULTS
  The incidence of new perfusion defects 6, 12, 18, and 24 months after RT was 27%, 29%, 38%, and 42%, respectively. New defects occurred in approximately 10% to 20% and 50% to 60% of patients with less than 5%, and greater than 5%, of their left ventricle included within the RT fields, respectively (p = 0.33 to 0.00008). The rates of wall motion abnormalities in patients with and without perfusion defects were 12% to 40% versus 0% to 9%, respectively; p values were 0.007 to 0.16, depending on the post-RT interval.
  
  
  CONCLUSIONS
  Radiation therapy causes volume-dependent perfusion defects in approximately 40% of patients within 2 years of RT. These perfusion defects are associated with corresponding wall-motion abnormalities. Additional study is necessary to better define the long-term functional consequences of RT-induced perfusion defects.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA. marks@radonc.duke.edu
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Marks
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Yu
authors.forename: Robert G
authors.initials: RG
authors.lastname: Prosnitz
authors.forename: Su-Min
authors.initials: SM
authors.lastname: Zhou
authors.forename: Patricia H
authors.initials: PH
authors.lastname: Hardenbergh
authors.forename: Michael
authors.initials: M
authors.lastname: Blazing
authors.forename: Donna
authors.initials: D
authors.lastname: Hollis
authors.forename: Pehr
authors.initials: P
authors.lastname: Lind
authors.forename: Andrea
authors.initials: A
authors.lastname: Tisch
authors.forename: Terence Z
authors.initials: TZ
authors.lastname: Wong
authors.forename: Salvador
authors.initials: S
authors.lastname: Borges-Neto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy*; D003326:Coronary Circulation / Q000502:physiology / Q000528:radiation effects; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000528:radiation effects*; D006801:Humans; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology / Q000528:radiation effects*; D011446:Prospective Studies; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013318:Stroke Volume / Q000502:physiology / Q000528:radiation effects; D015899:Tomography, Emission-Computed, Single-Photon