Effect of radiation therapy on permanent pacemaker and implantable cardioverter-defibrillator function.

BACKGROUND

Radiation therapy's (RT's) effects on cardiac implantable electronic devices (CIEDs) such as implantable cardioverter-defibrillators (ICDs) and pacemakers (PMs) are not well established, leading to device removal or relocation in preparation for RT.

OBJECTIVE

To determine the effect of scattered RT on CIED performance.

METHODS

We analyzed 69 patients--50 (72%) with PMs and 19 (28%) with ICDs--receiving RT at the University of Michigan. Collected data included device model, anatomic location, and treatment beam energies, treatment type, and estimated dose to the device. Patients were treated with either high-energy (16-MV) and/or low-energy (6 MV) photon beams with or without electron beams (6-16 MeV). The devices were interrogated with pre- and post-RT and/or weekly with either in-treatment or home interrogation, depending on the patient's dependence on the device and the estimated or measured delivered dose. Outcomes analyzed were inappropriate ICD therapies, device malfunctions, or device-related clinical events.

RESULTS

The PMs were exposed to 84.4 ± 99.7 cGy of radiation, and the ICDs were exposed to 92.1 ± 72.6 cGy of radiation. Two patients with ICDs experienced a partial reset of the ICD with the loss of historic diagnostic data after receiving 123 and 4 cGy, respectively. No device malfunction or premature battery depletion was observed at 6-month follow-up from RT completion.

CONCLUSIONS

CIED malfunction due to indirect RT exposure is uncommon. Regular in-treatment or home interrogation should be done to detect and treat these events and to ensure that diagnostic data are preserved.