ICDs Rarely Affected by Smartphone Electromagnetic Interference

Man Using Smartphone
Man Using Smartphone
Of 307 patients, only 1 patient's ICD had electromagnetic interference produced by a telephone.

Electromagnetic interference in implantable cardioverter defibrillators (ICDs) from smartphones is relatively uncommon, according to research published in the Journal of the American College of Cardiology.

The researchers hypothesized that current recommendations for the use of these devices may be out of date because of advances in both ICD and smartphone technologies.

Therefore, they conducted a clinical trial (Safety of Smartphones Among Patients With Cardiac Implantable Electronic Devices; ClinicalTrials.gov identifier: NCT01819896) with 307 patients (72% men; mean age, 65.5 years). According to power analysis, the minimum number sufficient to detect at least 1 electromagnetic interference event was 300 patients. The ICDs were screened to confirm normal functionality.

Three brands of smartphones (Samsung Galaxy 3S, Samsung Electronics; Nokia Lumia, Nokia Corp.; and HTC One XL, HTC Corp.) were held directly above the ICDs in random order. (The Apple iPhone was not tested for technical reasons.) The researchers also used maximum transmitting power for all network standards (2G, Global System for Mobile Communication, 3G, Universal Mobile Telecommunication System, 4G, and Long-term Evolution) and modulated the power (50-Hz mode) with a radio communication tester.

Patients were monitored using a 6-lead electrocardiogram and underwent permanent ventricular pacing during testing. The electrocardiogram recordings were independently assessed by 2 cardiologists.

Of the 307 patients, only 1 patient’s ICD was affected by electromagnetic interference (0.3%; 95% CI, 0.01%-1.80%) during exposure to the Nokia and HTC smartphones and 2 standards (Global System for Mobile Communication and Universal Mobile Telecommunication System). As a result, the device repeated pacing inhibition and premature ventricular pacing. Although ventricular inhibition can be dangerous, the ventricular oversensing in this study was not considered clinically significant.

The result that close proximity of telephone placement is capable of producing electromagnetic inference in ICDs is consistent with previous studies that used older mobile telephone models, the researchers noted. However, given that only 1 patient was affected, the researchers were unable to compare interference using different ICDs or device-lead combinations.

“We therefore suggest the current recommendation to maintain a 15-cm gap between phone and generator may be too stringent and thereby cause unnecessary apprehension,” the researchers concluded. “Nonetheless, the rapid evolution of implantable cardiac device and mobile phone technology obliges us to be aware that such safety recommendations require continual re-evaluation.”

Disclosures: Dr Lennerz reports receiving lecture fees and travel support from Biotronik, as well as fees and fellowships from Sorin Group and St. Jude Medical. Dr Pavaci reports receiving educational fellowship support from St. Jude Medical, and Dr Semmler reports receiving travel support from St. Jude Medical, Sorin Group, and Boston Scientific. Dr Reents reports receiving travel support from Boston Scientific, St. Jude Medical, and Biosense Webster. Dr Deisenhofer reports receiving lecture honoraria from St. Jude Medical. Dr Kolb reports receiving lecture honoraria/travel support from Biotronik, Boston Scientific, Medtronic, Sorin Group, and St. Jude Medical; has consulted for Biotronik, Boston Scientific, and Sorin Group; and has conducted clinical studies supported by Biotronik, Medtronic, Boston Scientific, Sorin Group, and St. Jude Medical.

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Lennerz C, Pavaci H, Grebmer C, et al. Electromagnetic interference in cardiac implantable electronic devices. Is the use of smartphones safe? J Am Coll Cardiol. 2017;69(1):108-110. doi: 10.1016/j.jacc.2016.10.046