Device and radiotherapy: a 10-year experience

Radiotherapy is an integral component of oncological treatment and is employed daily in the management of various types of cancer. Due to an aging population and improved survival rates following oncological therapies, an increasing number of patients with cardiac devices, such as PMs or ICDs, are being exposed to radiotherapy. However, these devices present unique challenges during radiotherapy due to the effects of ionizing radiation absorbed during treatment and the electromagnetic interference generated by the procedure. Ionizing radiation can cause temporary or permanent damage to device functions, including sensing, anti-tachycardia therapies, battery longevity, or even complete functional loss. Electromagnetic interference, on the other hand, may lead to device malfunction due to interactions with the external magnetic fields created during therapy. Furthermore, the absence of an on-site electrophysiologist can complicate patient management and compromise safety.To address these challenges, we developed a specific protocol to be implemented prior to treatment. This protocol includes a thorough assessment of the patient’s medical history, the type of device implanted, and the cumulative radiation dose planned during therapy. These measures aim to minimize device malfunctions and ensure optimal management during radiotherapy. Notably, the threshold for radiation-induced damage varies across manufacturers with a a range between 5Gy and 30Gy . However, no linear correlation exists between radiation dose thresholds and device damage; instead, the risk increases with higher doses. In our center, we adhere to precautionary cumulative dose limits of less than 2 Gy for PMs and less than 1 Gy for ICDs, using photon energies not exceeding 6 MV. To standardize our approach regardless of device manufacturer, patients are categorized into risk groups based on cumulative dose: For non-dependent PM patients: Low risk (<2 Gy): No magnet required. Intermediate risk (2–10 Gy): ECG monitoring. High risk (>10 Gy): Cardiac assistance required. For PM-dependent patients: Intermediate risk (<2 Gy): Magnet use recommended. High risk (2–10 Gy): Magnet use combined with cardiac assistance. For ICD patients: Non- dependent PM/ICDs: Magnet placement over the device (if no frequent arrhythmias are recorded) and cardiac assistance for doses <2 Gy. Dependent-PM/ ICDs: Evaluation for reprogramming in asynchronous mode based on patient rhythm; magnet placement over the device if no frequent arrhythmias are recorded. For doses >2 Gy, a multidisciplinary discussion is conducted to explore alternative treatments or consider device relocation. By implementing this protocol, we successfully ensured the safe management of all patients (204 PM and 66 ICD) undergoing oncological radiotherapy without any recorded device-related complications.