Abstract 11603: Reexamining the Incidence and Predictors of Radiation Induced Cardiac Implantable Electronic Device Malfunction in Cancer Patients and Streamlining Management

Abstract

Background: Historically, the reported incidence of Cardiac Implantable Electronic Device (CIED) malfunction during Radiotherapy (RT) is estimated to range from 3% to 20%. However, most of these studies had small sample sizes and may have overestimated the clinical impact of this problem. In this retrospective study, we examined the incidence of device reset and transient signal interference due to RT in a large cohort of patients. In addition, we studied the feasibility of a novel method of monitoring CIEDs during RT: pulse check method (PCM). Methods: From 1/2015 to 4/2023, patients with CIEDs requiring RT at a tertiary cancer center were identified. CIEDs were checked prior to RT. Candidate patients were managed with PCM, which involves programming the lower pacing rate at 75 bpm (slightly faster than lower rate of pacing during reset mode). Pulse checks were performed after each fraction of RT. Patients with heart rate less than 75 bpm had immediate device interrogation to assess for reset. After completion of RT, devices were interrogated and CIED programming returned to original settings. Results: Our study reviewed 720 patients with CIEDs undergoing 837 courses (560 pacemakers and 277 defibrillators) of RT, of which the majority (85%) were managed with PCM. Neutron producing RT (proton and photon with >10MV beam energy) was used in 189 (22.6%) cases, and 9 (1.1%) devices experienced reset. All resets were recoverable and occurred in the setting of neutron-producing radiation, especially proton therapy [OR 12.06 (3.37 - 43.10), p-value 0.0001]. Site of radiation, type of device, and number of RT fractions did not predict reset. No transient signal interference or oversensing events occurred during RT. Conclusions: CIED malfunction is a rare complication of RT, occurring in the setting of neutron producing radiation, with no serious clinical consequence. Transient signal interference and oversensing during RT was not observed to be a clinical concern in contemporary devices. Thus, asynchronous pacing in pacer dependent patients and deactivation of defibrillator tachy-therapy during RT is not necessary. PCM is a practical and cost-effective way to monitor CIEDs during RT.