MRI Safety for Patients with Implantable Loop Recorders
Patients with implantable loop recorders (ILRs) can safely undergo MRI scanning with appropriate precautions, as MRI does not cause permanent damage to these devices.
Safety Considerations for ILRs and MRI
Implantable loop recorders are different from pacemakers and implantable cardioverter-defibrillators (ICDs) in terms of MRI compatibility. The European Society of Cardiology (ESC) guidelines provide specific recommendations for cardiac devices and MRI compatibility 1:
- While conventional pacemakers and ICDs require special protocols for MRI scanning, ILRs have fewer restrictions
- ILRs do not have leads that can heat up during MRI exposure, which is a major concern with pacemakers and ICDs
Evidence for ILR Safety During MRI
Research has demonstrated that MRI scanning is safe for patients with implantable loop recorders:
- A study of 10 patients with Reveal Plus ILRs who underwent 11 MRI scans showed no harm to patients or permanent damage to the devices 2
- Post-MRI assessment showed no diminished signal integrity, altered programmed parameters, diminished battery status, or inability to communicate or be reprogrammed 2
- Patients reported no sensations of tugging or warmth at the implant site during MRI scanning 2
Important Precautions and Considerations
While MRIs are generally safe for patients with ILRs, there are some important considerations:
1. Potential for Artifacts
The most significant issue with ILRs during MRI is the generation of artifacts that can mimic arrhythmias:
- Both tachyarrhythmias and bradyarrhythmias may appear as artifacts due to ILR exposure to MRI 2
- These artifacts must be excluded to avoid mistakenly attributing symptoms to the artifacts produced from MRI exposure 2
2. Device Interrogation Protocol
To ensure proper functioning of the ILR:
- The ILR should be interrogated and cleared moments before the MRI scan
- Signal integrity and time/date stamp should be verified before the scan
- The device should be reinterrogated immediately after MRI to check for proper functioning 2
3. Rare Complications
While extremely rare, there have been reports of:
- Potential irreversible errors in non-implanted ILRs exposed to MRI magnetic fields 3
- Device migration (though this is not specifically related to MRI exposure) 4
Comparison with Other Cardiac Devices
It's important to distinguish ILRs from other cardiac devices regarding MRI compatibility:
- Pacemakers and ICDs have traditionally been considered contraindications for MRI, though newer MRI-conditional models exist 1, 5
- Coronary artery stents, prosthetic cardiac valves, metal sternal sutures, and epicardial pacing wires are not contraindications for MRI 5
- The primary concern with pacemakers and ICDs is heating of the leads, which is not an issue with ILRs 5, 6
Conclusion
Patients with implantable loop recorders can safely undergo MRI scanning with appropriate precautions. The key is to be aware of potential artifacts that may mimic arrhythmias and to verify device function before and after the scan.