Cardiovascular Implantable Electronic Device Malfunction Linked to Neutron-Producing RT

Radiotherapy’s impact on cardiovascular implantable electronic devices examined

medwireNews: Research suggests that the risk of electronic malfunction in patients with cardiovascular implantable electronic devices (CIEDs) during radiotherapy (RT) is restricted to those undergoing neutron-producing treatment.

“In the absence of clinical benefit for higher-energy RT, the use of non-neutron-producing RT is recommended to avoid single-event upsets”, say Jonathan Grant, from the University of Texas MD Anderson Cancer Center in Houston, USA, and co-authors in JAMA Oncology.

“If higher RT energies provide clinical benefit, however, the error rates and outcomes that we report will aid clinicians in weighing the risks of using neutron-producing RT.”

In their cohort of 215 patients, CIED malfunction resulting in data loss or parameter reset occurred in 7% of 249 courses of radiotherapy.

But all events occurred during the 71 treatments producing “substantial neutron fluence”, defined as 10 MV or above, giving a rate of 21% versus 0% for the 178 radiotherapy courses based on electrons, gamma knife or 6 MV photons.

Although signal interference was not symptomatic, CIED parameter reset in 10 patients was associated with three cases of hypotension and/or bradycardia and two cases of abnormal ticking associated with pacemaker syndrome. One patient developed congestive heart failure.

Multivariate analysis indicated that patients receiving RT to the abdomen and pelvis were 5.2 times more likely to experience a single event upset than those undergoing treatment to the head and neck or chest.

By contrast, CIED type did not significantly predict malfunction, and no correlation between dose and malfunction was observed for an incident dose of up to 5.4 Gy.

“Given the associated expense and potential morbidity, it may be safe to decrease the number of relocation procedures performed”, the authors suggest.

In an editor’s note, Charles Thomas Jr, observes that the study examined for CIED events occurring after changes to the “memory state of the circuitry” but did not include real-time and continuous monitoring of cardiac rhythms.

“Hence, there exists an opportunity to design trials that incorporate next-generation and commercially available electronic monitoring devices in this patient population in order to detect more subtle dysrhythmias, device sensor adjustments, and/or transient threshold alterations”, he writes.

References

Grant JD, Jensen GL, Tang C, et al. Radiotherapy-induced malfunction in contemporary cardiovascular implantable electronic devices. Clinical incidence and predictors. JAMA Oncol 2015; Advance online publication 25 June 2015. doi:10.1001/jamaoncol.2015.1787

Thomas Jr CR. Safe delivery of radiotherapy to patients with pacemakers or cardioverter-defibrillator devices. JAMA Oncol 2015; Advance online publication 25 June. doi:10.1001/jamaoncol.2015.1788

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