Clinical Guidance for Managing Patients with Cardiac Implantable Electronic Devices during Neutron-Producing Photon Therapy
Abstract
Purpose
A clear link has been established between exposure to neutron-producing therapies and cardiac implantable electronic device (CIED) malfunction. However, the risk of neutron-induced CIED malfunction under specific clinical conditions has yet to be elucidated. This is particularly important as neutron producing therapy may be optimal for many patients; properly managing such patients requires clinical guidance on risk of device reset.
Methods
Patients with CIEDs treated with neutron-producing photon radiotherapy at MD Anderson Cancer Center between August 2005 and April 2023 were included. Six metrics of neutron exposure were calculated using an analytical model for each CIED exposed during the treatment of these patients. These neutron exposure metrics, 18 MV MU, and CIED implant year were evaluated with each divided into high and low categories by their respective medians. Univariate logistic regression was then used to identify significant predictors of reset. Practical clinical guidance was developed based on risk of reset from CIEDs implanted in 2010 or later.
Results
The reset rate for the 188 CIED included in this study was 9% (95CI: 5% - 14%). Univariate analysis revealed that neutron dose equivalent, total fluence, epithermal fluence, fast fluence, 18 MV MU, and CIED implant year were significant predictors of CIED reset. For clinical management, the risk of reset was defined in terms of number of high-energy Mus for the treatment. For example, the risk of reset can be limited to ≤ 5% if the number of MU for a 30 fraction treatment is ≤ 113 for an 18 MV beam from a Varian LINAC (or 228 MU for 15 MV).
Conclusion
This study identified significant predictors of neutron-induced CIED reset from neutron-producing photon therapy. Significant predictors were used to derive actionable clinical guidelines based on risk of reset that can be implemented to aid clinicians in managing these patients.