Cardiac Device Interference Risk 'Low' With Smartphones, Smartwatches

Batya Swift Yasgur MA, LSW

August 06, 2020

The risk for electromagnetic interference (EMI) of smartphones and smartwatches with cardiovascular implantable electronic devices (CIEDs) is low, new research suggests.

Investigators tested CIEDs in 148 patients to see if smartphones and smartwatches produced EMI that might affect the CIEDs. Tests included all possible activation of the smartphones and smartwatches, including standby, dialing, and connecting mode.

Of all the testing scenarios, the investigators observed only one case of mobile-phone-induced electromagnetic interference on a dual-chamber pacemaker, and smartphone-induced telemetry interferences with the device programmer were found in 14%.

In contrast, when they investigated the smartwatch, they found no EMIs with CIEDs or the device programmer.

"Due to technological advances, both in CIEDs and mobile-phone technology, the likelihood of EMIs is currently negligibly small, but physicians should be aware that EMIs of mobiles with device interrogation telemetry are quite common," lead authors Florian Blaschke, MD, Department of Internal Medicine and Cardiology, Charité Universitätsmediz, Berlin, told | Medscape Cardiology.

"The rapid evolution of CIEDs, mobile phones, and smartwatch technology makes it necessary to continually re-evaluate safety recommendations for patients with CIEDs," he said.

The study was published online July 29 in JACC Clinical Electrophysiology.

Obsolete Data

"EMIs can be hazardous for patients with CIEDs, such as or ICDs," Blaschke said. Previous studies have suggested that electromagnetic radiation may lead to inhibition of pacing or inappropriate shock delivery in defibrillators, as well as temporary inactivation of antitachycardia functions, due to a magnet response, the authors state.

"Currently, all manufacturers of CIEDs recommend keeping mobile phones at least 15 cm away from these devices to avoid electromagnetic interferences; however, these recommendations are based on studies conducted over 10 years ago," Blaschke said.

"In these studies, previous generations of mobile phones were used, but due to technological advances, such as the low emission power of modern mobile phones and effective CIED filters, we assumed that these recommendations might be obsolete," he added, noting that there are no recommendations from device manufacturers regarding the use of smartwatches.

The researchers therefore sought to "evaluate the risk and consequences" of EMIs in patients with a CIED using a "contemporary" mobile phone (iPhone 6) and a popular smartwatch (Apple Watch Series 1 [A1553]).

The study involved 148 patients (mean age, 70.8 ± 12.6 years; 74% male) who had a CIED, such as a pacemaker (n = 51), cardiac resynchronization therapy pacemaker (n = 5), ICDs (n = 46), cardiac resynchronization therapy defibrillator (n = 43), or implantable loop recorder (n = 3).

EMI with CIED was defined as "any change in cardiac rhythm on the surface ECG [electrocardiogram] with or without clinical symptoms."

Interference with the device programmer "included any aberrations in the atrial or ventricular EGM [intracardiac electrogram] channels or loss of marker channels."

The 148 participants were subjected to 1352 tests, with the phone or watch in standby, dialing, and connecting modes (telephone connection and internet access).

Individual Testing

Only one patient with persistent atrial fibrillation had EMIs between the iPhone and an implanted dual-chamber pacemaker, and the electromagnetic field induced atrial undersensing. This led to "subsequent inappropriate disabling" of the modes switch, which resulted in ventricular pacing with the upper rate limit. The patient experienced palpitations and dizziness.

In particular, these EMIs occurred when the iPhone was placed directly over the generator and was put in dialing or connecting model; when these modes were discontinued, the atrial undersensing immediately stopped.

None of the patients experienced EMIs between the smartwatch and the CIED, and there was no evidence of a magnet effect caused by proximity of the smartwatch or smartphone.

There was interference with wanded telemetry in 20 (14%) of the patients; however, these interferences with the CIED programmer took place only when the smartphone was placed directly over the CIED in dialing or connecting mode. No interferences were observed with the smartwatch.

"In summary, the risk of electromagnetic interferences of mobile phones and smartwatches with CIEDs is low," Blaschke said.

Nevertheless, "in the ideal case, individual testing of patients with a cardiovascular implantable electronic device for lack of interaction with their own mobile phone and smartwatch could be done," he added.

Reassuring Findings

Commenting on the study for | Medscape Cardiology, Carsten Lennerz, MD, MSc, consultant cardiologist, German Heart Center, Munich, stated that CIED patients "worry a lot about EMI in daily and professional life," so the "presented study is important, as mobile phones were identified as a relevant EMI source 10 to 20 years ago and, consequently, a safety distance of 15 cm is still recommended."

He noted that his group previously demonstrated that the prevalence of EMI with smartphones and CIED is 0.3%, and the present study "confirms this with a reassuring occurrence rate of 0.6%."

In both studies, "the EMI occurred in a 'worst-case scenario,' when placing the smartphone directly on the skin above the generator and when the smartphone rings or connects," said Lennerz, who was not involved with the current study.

However, this situation is "thankfully rare due to the advances in shielding of CIEDs and also changes in smartphone properties."

He added that smartwatches are "unlikely to work as a potential EMI source, due to their properties, but this study provides the first evidence of their safety."

Lennerz recommended that patients be informed that EMI with smartphones "can still occur but are very rare," noting that, although the "current safety distance of 15 cm is likely too strict," it does "ensure complete safety."

Blaschke added that the "rapid evolution" of CIEDs and mobile-phone and smartwatch technologies "makes it necessary to continually re-evaluate safety recommendations for patients with CEIDs."

No source of study funding listed. Blaschke reports no relevant financial relationships. The other authors' disclosures are listed on the original paper. Lennerz reports no relevant financial relationships.

JACC Clin Electrophysiol. Published online July 29, 2020. Abstract

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