The risk of electromagnetic interference to cardiovascular implantable electronic devices (CIEDs) from smartwatches and mobile phones is low—although close proximity between an iPhone 6 and an implanted device can cause telemetry interference. These are the conclusions of Philipp Lacour (Charité Universitätsmedizin Berlin, Berlin, Germany) and colleagues, in a study published online in JACC: Clinical Electrophysiology looking at the incidence of interference from smart devices in patients with CIEDs.
“CIEDs such as pacemakers and implantable cardioverter-defibrillators (ICDs) are known to be susceptible to malfunction in the presence of electromagnetic fields,” write Lacour and colleagues, explaining that this is due to electromagnetic fields that can be misinterpreted as intrinsic cardiac electrical activity. The study aimed to evaluate the risk and consequences of electromagnetic interferences in patients with CIED using a contemporary mobile phone (iPhone 6, Apple) and a popular smartwatch (Apple Watch Series 1, Apple).
The study team enrolled 148 patients, with all subjects undergoing initial testing to ensure normal operation of all components and functions of their implanted devices. EMI with the CIED was defined as any change in cardiac rhythm seen on the surface ECG with or without clinical symptoms such as palpitations, dizziness, syncope, or discomfort. Interferences with the device programmer included any aberrations in the atrial or ventricular EGM channels, or loss of marker channels. After all testing was completed, CIEDs were reinterrogated to rule out EMI-triggered changes in CIED programming.
Analysed CIEDs included 51 pacemakers, five cardiac resynchronisation therapy pacemakers, 46 ICDs, 43 cardiac resynchronisation therapy defibrillators, and three implantable loop recorders from Medtronic, Boston Scientific Massachusetts, and Biotronik. The study team found that in one patient with persistent atrial fibrillation (AF), electromagnetic interference was observed between the iPhone and an implanted dual-chamber pacemaker (Relia, Medtronic), which induced atrial undersensing with subsequent inappropriate disabling of the mode switch changing the device to dual-chamber, rate modulated mode, resulting in ventricular pacing with the upper rate limit. The patient developed symptoms of palpitations and dizziness. The electromagnetic interference occurred while placing the iPhone in dialling or connecting mode directly over the generator. Atrial undersensing immediately stopped on termination of dialling or connecting mode.
However, in none of the patients was electromagnetic interference observed between the Apple Watch and the CIED. Furthermore, no evidence of magnet effect resulting from the proximity of the Apple Watch and iPhone was observed.
Interference events with the CIED programmer were classified as: noise in the atrial and ventricular channels; loss of intracardiac electrogram; loss of marker channel assignment; and miss annotations (missed or skipped annotations) in the atrial or ventricular marker channel without corresponding interference on the electrocardiogram channel. In total, interference with wanded telemetry occurred in 20 of the patients—18 pacemakers or cardiac resynchronisation therapy pacemakers and 2 ICDs or cardiac resynchronisation therapy defibrillators. In all cases, the study team notes, interferences with the CIED programmer only occurred when the iPhone was placed directly over the CIED in dialling or connecting mode, whereas no interferences were observed with the Apple Watch.
Lacour and colleagues wrote that the study demonstrates a very low risk of electromagnetic between the iPhone and CIEDs, whereas telemetry interferences occurred relatively frequently. “This is in line with previous published data in the last five years. However, investigating the Apple Watch, we found neither interferences with CIEDs nor the programmer. Due to technological advances such as low emission power of modern mobile phones and effective CIED filters, the risk probably remains low for future generations of mobile phones, wearables, and CIEDs. However, the rapid evolution of CIEDs and mobile phone and wearables technology makes it necessary to continually re-evaluate safety recommendations for patients with CIEDs. Ideally, individual testing of patients for EMIs between their cell phone and wearable and their CIED could be performed,” they conclude.