title: Radiotherapy Induces Development of Fragmented QRS in Patients with Breast Cancer.
abstract: BACKGROUND
  Myocardial fibrosis is a well-known side effect of radiotherapy. Fragmented QRS (fQRS) has been shown to be a marker of myocardial fibrosis. We postulated that radiotherapy induces development of fQRS in breast cancer patients.
  
  
  METHODS
  Breast cancer patients receiving locoregional radiotherapy were enrolled. Patients who had fQRS on electrocardiography (ECG) before radiotherapy were excluded. All patients were revaluated for the development of fQRS at 1-year follow-up. An age-matched healthy group served as controls.
  
  
  RESULTS
  A total of 52 breast cancer patients receiving locoregional radiotherapy were included (median age 49 years, interquartile range (IQR) 13). Of these, 19 (37%) had developed fQRS at 1-year follow-up. Compared with the control group, prevalence of fQRS was significantly higher in the irradiated group (37 vs. 12%; p < 0.002). Median total cardiac radiation dose was significantly higher in patients who had developed fQRS (5 Gy, IQR 5.2 vs. 1.7 Gy, IQR 4.4; p = 0.003). Cardiac radiation dose, entered either as a continuous variable (odds ratio (OR) 1.35, 95% confidence interval (CI) 104-1.74) or as a dichotomized variable (≥ 2.2 Gy, OR 6.48, 95% CI 1.47-28.61), was independently associated with the development of fQRS at 1-year follow-up.
  
  
  CONCLUSIONS
  Radiotherapy for breast cancer induces development of fQRS on ECG. Cardiac radiation dose is independently associated with the development of fQRS.
authors.affiliation: Cardiology Clinic, Karabuk University Hospital, Karabuk, Turkey.
authors.forename: Adem
authors.initials: A
authors.lastname: Adar
authors.affiliation: Department of Radiation Oncology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Emine
authors.initials: E
authors.lastname: Canyılmaz
authors.affiliation: Department of Cardiology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Abdulkadir
authors.initials: A
authors.lastname: Kiris
authors.affiliation: Department of Cardiology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Abdulselam
authors.initials: A
authors.lastname: Ilter
authors.affiliation: Department of Radiation Oncology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Lasif
authors.initials: L
authors.lastname: Serdar
authors.affiliation: Department of Radiation Oncology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Yahyahan
authors.initials: Y
authors.lastname: Memis
authors.affiliation: Department of Radiation Oncology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Zumrut
authors.initials: Z
authors.lastname: Bahat
authors.affiliation: Cardiology Clinic, Karabuk University Hospital, Karabuk, Turkey.
authors.forename: Orhan
authors.initials: O
authors.lastname: Onalan
keywords: Breast cancer; Fragmented QRS; Radiotherapy