Letter to the Editor: Cardiac implanted electronic devices and MRI safety in 2018 – the state of play

by Murray AS, Bassareo PP, Gilligan P (pgilligan@materprivate.ie)

Cardiac implanted electronic devices and MRI safety in 2018—the state of play

We congratulate Ryan Mark Shulman and Ben Hunt for their review on MR imaging of cardiac implanted electronic devices [1]. In addition to pacemakers and automatic implantable cardioverter devices mentioned in their article there are a third newer group of devices which are covered by this term namely implantable loop recorders (ILRs) [2].  ILRs are small oblong devices similar in size to a USB memory stick which are inserted to the subcutaneous tissues in left anterior chest wall under local anaesthesia. They continuously monitor cardiac rhythm for periods up to two years and record arrhythmias. This information can be uploaded by the patient remotely to their clinician. They provide more long term and discrete monitoring of cardiac rhythm versus holter monitors. All ILRs are MR-conditional at both 1.5 T and 3T. They do not require switching to MR-Mode prior to MR imaging, but artifacts can be recorded during MR that mimic asystole, ventricular tachycardia, supraventricular tachycardia or result in deletion of previously recorded data [3]. For this reason, it is recommended prior to MRI that ILRs be evaluated and any desired information be downloaded from the system, and the device cleared post MRI – Class I strong recommendation based on Level B-R moderate quality randomized trial data [3].