In Vitro Assessment of 3T MRI Effects on Non-3T-Compatible Cardiac Implantable Electronic Devices

The safety of cardiac implantable electronic devices (CIEDs) during 3-Tesla (3T) MRI remains uncertain, particularly for devices not designed for 3T use. We experimentally evaluated 3T MRI effects on 3T-compatible and non-3T-compatible CIEDs.

Fifty-eight CIEDs (37 pacemakers, 21 ICDs; 3T MRI-conditional n = 31, 1.5-T MRI-conditional n = 14, and non-MRI-conditional n = 13) were tested in a 3T scanner. Each device was immersed in saline with connected leads and programmed to asynchronous or demand pacing with MRI mode ON or OFF. Device interrogation before and after scanning assessed telemetry integrity, parameter retention, and pacing-mode changes.

Most CIEDs completed MRI without malfunction and remained telemetric. However, among pacemakers, telemetry failure or parameter reset occurred in 6 non-MRI-conditional and 3 1.5-T MRI-conditional devices, including some devices with MRI mode ON. Reset or telemetry failure was more frequent in devices with low battery status (≤ 30% to ERI) than in those with higher status (6/11 [55%] vs. 3/22 [14%], p= 0.013). With MRI mode OFF, magnet mode was activated in 11 3T and 7 non-MRI-conditional pacemakers; activation frequency did not differ between asynchronous and demand pacing (16/31 [52%] vs. 18/31 [58%], p= 0.610). In some pacemakers and ICDs, demand pacing led to atrial mode switch or pacing inhibition, but no reset or telemetry failure occurred in ICDs.

In direct in vitro 3T MRI exposure experiments involving non-3T MRI CIEDs, some pacemakers approaching ERI demonstrated an increased risk of telemetry failure or reset, and those with MRI mode turned off showed non-negligible mode switching. However, the majority of devices did not exhibit severe electrical malfunctions necessitating replacement in a clinical setting, and no instances of device reset or telemetry failure were observed in ICDs.