Neutron-producing radiotherapy caused single-event upset malfunctions in 21% of CIED courses, compared to 0% with non-neutron-producing radiotherapy.
Cohort (n=215)
No
Does neutron-producing radiotherapy increase the risk of CIED malfunction compared to non-neutron-producing radiotherapy in patients with pacemakers or ICDs?
Neutron-producing radiotherapy is associated with a 21% rate of single-event upset malfunctions in CIEDs, whereas non-neutron-producing radiotherapy has a 0% rate, suggesting non-neutron-producing RT should be used when clinically feasible.
Absolute Event Rate: 21% vs 0%
IMPORTANCE: 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. DESIGN, SETTING, AND PARTICIPANTS: 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%). EXPOSURE: 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). MAIN OUTCOMES AND MEASURES: 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 AND RELEVANCE: 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.
Grant et al. (Thu,) conducted a cohort in Cardiovascular implantable electronic devices requiring radiotherapy (n=215). Neutron-producing radiotherapy vs. Non-neutron-producing radiotherapy was evaluated on Malfunction of CIED (single-event upset and delayed effects). Neutron-producing radiotherapy caused single-event upset malfunctions in 21% of CIED courses, compared to 0% with non-neutron-producing radiotherapy.