Cardiac implantable electronic device dysfunctions in patients undergoing radiotherapy: A prospective cohort study

Background Increasing numbers of patients with cardiac implantable electronic devices (CIEDs) are undergoing radiotherapy (RT) for cancer. The aim of the study was to prospectively evaluate the incidence, characteristics, and associated factors of CIED dysfunctions related to RT. Methods Between April 2013 and March 2020, all patients with a CIED who underwent >= 1 RT session were enrolled. Patients were monitored according to a systematic protocol, including device interrogation before the first and after each RT session. The primary endpoint was CIED dysfunction, defined as oversensing, total or partial deprogramming, and/or unrecoverable reset. Results We included a total of 92 CIED RT courses: 77 (83.7%) in patients with a pacemaker and 15 (16.3%) in those with an implantable cardioverter-defibrillator. Overall, 13 dysfunctions (14.1%) were observed during 92 courses (1509 sessions), giving an incidence of 0.9 per 100 sessions. These included nine deprogramming (three total resets to back-up pacing mode and six partial deprogramming that were all successfully reprogrammed), three transient oversensing, and one unrecoverable oversensing requiring CIED and leads replacement. There were no adverse clinical events related to device dysfunction. In multivariable analysis, neutron-producing irradiation (odds ratio [OR], 5.59; 95% confidence interval [CI], 1.09-28.65; p = .039) and cumulative tumor dose (OR, 1.05; 95% CI, 1.01-1.10; p = .007) remained significantly associated with CIED dysfunction. Conclusion In this prospective study, transient or permanent subclinical CIED dysfunction occurred in 14.1% of RT courses. Our findings emphasize the importance of high-energy beams and neutron-producing irradiation in risk assessment.