Loop Recorder and Brain MRI Compatibility
A loop recorder (implantable loop recorder/ILR) does not interfere with brain MRI performance and can be safely scanned, though it will generate ECG artifacts that mimic arrhythmias during the scan. 1, 2
Safety Profile
The evidence consistently demonstrates that MRI scanning in patients with implantable loop recorders is safe from both a patient and device perspective:
- No patient harm occurs during MRI scanning with an ILR in place, with no reports of device movement, heating at the implant site, or cardiopulmonary symptoms 1, 2
- Device integrity remains intact after MRI exposure, with no diminished signal quality, altered programmed parameters, battery depletion, or communication/reprogramming issues 1, 2
- One exception exists: A single case of irreversible device error occurred in a non-implanted ILR exposed to MRI magnetic fields, suggesting theoretical risk, though this has not been replicated in implanted devices 3
Critical Caveat: ECG Artifacts
The major issue is not interference with the MRI itself, but rather artifacts recorded by the loop recorder that can be misinterpreted:
- Artifacts mimicking both tachycardia and bradycardia appear universally in ILR patients undergoing MRI, regardless of the anatomical region being scanned 1, 4, 2
- These artifacts can mimic both wide complex and narrow complex tachycardias, creating false recordings that could be mistaken for genuine arrhythmic events 4, 2
- Cranial MRI may produce fewer artifacts than peripheral scans (shoulder, knee, spine), though artifacts can still occur 1, 4
Essential Pre- and Post-MRI Protocol
To avoid misdiagnosis of artifact as true arrhythmia, follow this algorithm:
- Before MRI: Clear the ILR memory and verify signal integrity and time-date stamp 1, 2
- During MRI: Document the exact timing of the MRI scan 1
- After MRI: Immediately interrogate the device to assess for any changes and identify artifact periods 1, 2
- Critical step: Any arrhythmias recorded during the MRI timeframe must be assumed to be artifact and excluded from clinical decision-making to avoid mistakenly attributing syncope or palpitations to these false recordings 1
Clinical Bottom Line
The brain MRI can proceed without concern for patient safety or permanent device damage. However, you must inform the patient and document that any ECG recordings captured during the MRI scan are invalid and should be disregarded. The ILR will continue to function normally for genuine arrhythmia detection after the scan is complete.