title: Radiotherapy-Induced Malfunction in Contemporary Cardiovascular Implantable Electronic Devices: Clinical Incidence and Predictors.
abstract: OBJECTIVE
  Risk stratification and management paradigms for patients with cardiovascular implantable electronic devices (CIEDs) requiring radiotherapy (RT) vary widely and are based on limited clinical data.
  
  
  OBJECTIVE
  To identify the incidence and predictors of CIED malfunction and describe associated clinical consequences in a large cohort of patients treated with photon- and electron-based RT.
  
  
  METHODS
  Retrospective analysis of all patients with a functioning CIED who underwent RT between August 2005 and January 2014 with CIED interrogation data following RT at an academic cancer center. We identified 249 courses of photon- and electron-based RT in 215 patients (123 pacemakers [57%]; 92 implantable cardioverter-defibrillators [43%]). Substantial neutron production was generated in 71 courses (29%).
  
  
  METHODS
  Implantation of CIED with subsequent therapeutic radiation treatment (neutron producing with 15- or 18-MV photons and non-neutron producing with electrons, GammaKnife, or 6-MV photons).
  
  
  METHODS
  Malfunction of CIED, characterized as single-event upset (data loss, parameter resets, unrecoverable resets), and delayed effects including signal interference, pacing threshold changes, and premature battery depletion.
  
  
  RESULTS
  Malfunction of CIED attributable to RT occurred during 18 courses (7%), with 15 CIEDs experiencing single-event upsets, and 3, transient signal interference. All single-event upsets occurred during neutron-producing RT, at a rate of 21%, 10%, and 34% per neutron-producing course for CIEDs, pacemakers, and implantable cardioverter-defibrillators, respectively. No single-event upsets were found among 178 courses of non-neutron-producing RT. Incident CIED dose did not correlate with device malfunction. Patients treated to the abdomen and pelvis region were more likely to undergo a single-event upset (hazard ratio, 5.2 [95% CI, 1.2-22.6]; P = .03). Six patients with a CIED parameter reset developed clinical symptoms: 3 experienced hypotension and/or bradycardia, 2 experienced abnormal chest ticking consistent with pacemaker syndrome, and 1 developed congestive heart failure. The 3 episodes of signal interference did not result in clinical effects. No delayed malfunctions were directly attributed to RT.
  
  
  CONCLUSIONS
  In a cohort of contemporary CIEDs, all cases of single-event upset malfunction occurred in the setting of notable neutron production, at a rate of 21% for neutron-producing RT and 0% for non-neutron-producing RT. Where clinically feasible, the use of non-neutron-producing RT is recommended. Given the lack of correlation between CIED malfunction and incident dose observed up to 5.4 Gy, invasive CIED relocation procedures in these settings can be minimized.
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Grant
authors.affiliation: medical student at Baylor School of Medicine, Houston.
authors.forename: Garrett L
authors.initials: GL
authors.lastname: Jensen
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Chad
authors.initials: C
authors.lastname: Tang
authors.affiliation: Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Julianne M
authors.initials: JM
authors.lastname: Pollard
authors.affiliation: Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Kry
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Sunil
authors.initials: S
authors.lastname: Krishnan
authors.affiliation: Department of Cardiology, University of Texas MD Anderson Cancer Center, Houston5Division of Cardiovascular Medicine, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston.
authors.forename: Anne H
authors.initials: AH
authors.lastname: Dougherty
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Gomez
authors.affiliation: Department of Cardiology, University of Texas MD Anderson Cancer Center, Houston6Department of Anesthesiology and Perioperative Medicine, University of Texas MD Anderson Cancer Center, Houston.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Rozner
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017147:Defibrillators, Implantable; D004583:Electrons; D005260:Female; D006331:Heart Diseases / Q000150:complications / Q000175:diagnosis / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications / Q000175:diagnosis / Q000532:radiotherapy*; D009502:Neutrons; D010138:Pacemaker, Artificial; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016634:Radiosurgery / Q000009:adverse effects*; D011878:Radiotherapy / Q000009:adverse effects; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013781:Texas; D016896:Treatment Outcome