title: Subclinical cardiotoxicity detected by strain rate imaging up to 14 months after breast radiation therapy.
abstract: OBJECTIVE
  Strain rate imaging (SRI) is a new echocardiographic modality that enables accurate measurement of regional myocardial function. We investigated the role of SRI and troponin I (TnI) in the detection of subclinical radiation therapy (RT)-induced cardiotoxicity in breast cancer patients.
  
  
  METHODS
  This study prospectively included 75 women (51 left-sided and 24 right-sided) receiving adjuvant RT to the breast/chest wall and regional lymph nodes. Sequential echocardiographs with SRI were obtained before RT, immediately after RT, and 8 and 14 months after RT. TnI levels were measured on the first and last day of RT.
  
  
  RESULTS
  Mean heart and left ventricle (LV) doses were both 9 ± 4 Gy for the left-sided patients and 4 ± 4 Gy and 1 ± 0.4 Gy, respectively, for the right-sided patients. A decrease in strain was observed at all post-RT time points for left-sided patients (-17.5% ± 1.9% immediately after RT, -16.6% ± 1.4% at 8 months, and -17.7% ± 1.9% at 14 months vs -19.4% ± 2.4% before RT, P<.01) but not for right-sided patients. When we considered left-sided patients only, the highest mean dose was given to the anterior left ventricular (LV) wall (25 ± 14 Gy) and the lowest to the inferior LV wall (3 ± 3 Gy). Strain of the anterior wall was reduced after RT (-16.6% ± 2.3% immediately after RT, -16% ± 2.6% at 8 months, and -16.8% ± 3% at 14 months vs -19% ± 3.5% before RT, P<.05), whereas strain of the inferior wall showed no significant change. No changes were observed with conventional echocardiography. Furthermore, mean TnI levels for the left-sided patients were significantly elevated after RT compared with before RT, whereas TnI levels of the right-sided patients remained unaffected.
  
  
  CONCLUSIONS
  In contrast to conventional echocardiography, SRI detected a regional, subclinical decline in cardiac function up to 14 months after breast RT. It remains to be determined whether these changes are related to clinical outcome. In the meantime, we encourage the use of radiation techniques that minimize the exposure of the anterior LV wall in left-sided patients.
authors.affiliation: Department of Radiotherapy, University Hospital Gasthuisberg, Leuven, Belgium. katrien.erven@uzleuven.be
authors.forename: Katrien
authors.initials: K
authors.lastname: Erven
authors.forename: Anca
authors.initials: A
authors.lastname: Florian
authors.forename: Pieter
authors.initials: P
authors.lastname: Slagmolen
authors.forename: Caroline
authors.initials: C
authors.lastname: Sweldens
authors.forename: Ruxandra
authors.initials: R
authors.lastname: Jurcut
authors.forename: Hans
authors.initials: H
authors.lastname: Wildiers
authors.forename: Jens-Uwe
authors.initials: JU
authors.lastname: Voigt
authors.forename: Caroline
authors.initials: C
authors.lastname: Weltens
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006321:Heart / Q000503:physiopathology / Q000528:radiation effects*; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D013997:Time Factors; D019210:Troponin I / Q000097:blood
chemical_list: D019210:Troponin I