An increasing number of patients with implantable cardiac rhythm devices undergo radiotherapy (RT) for cancer and are thereby exposed to the risk of device failure. Current safety recommendations seem to have limitations by not accounting for the risk of pacemakers and implantable cardioverter defibrillators malfunctioning at low radiation doses. Besides scant knowledge about optimal safety measures, only little is known about the exact prevalence of patients with devices undergoing RT. In this review, we provide a short overview of the principles of RT and present the current evidence on the predictors and mechanisms of device malfunctions during RT. We also summarize practical recommendations from recent publications and from the industry. Strongly associated with beam energy of photon RT, device malfunctions occur at ∼3% of RT courses, posing a substantial issue in clinical practice. Malfunctions described in the literature typically consist of transient software disturbances and only seldom manifest as a permanent damage of the device. Through close cooperation between cardiologists and oncologists, a tailored individualized approach might be necessary in this patient group in waiting time for updated international guidelines in the field.

Patients treated with IMRT for bladder cancer had significantly less acute diarrhoea compared to those treated with CRT, but there was no significant difference in late morbidity between the groups. The risk of acute diarrhoea was related to the volume of bowel irradiated.

The animal model is feasible for investigating RT effects on implanted cardiac devices. During irradiations with 37 Gy, one recoverable malfunction was present in the tested devices. Additional animal studies could provide supplementary evidence for treating ICD patients, including recommendations for reprogramming of the ICD during RT and avoidance of relocating the device.

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