MRI Contraindications in Patients with Implants

Classification System for All Implants

The American College of Cardiology and other guideline societies recommend categorizing all implants as MR Safe, MR Conditional, or MR Unsafe before any MRI procedure, with absolute contraindications now limited primarily to MR Unsafe devices, abandoned/epicardial leads, and devices implanted less than 6 weeks prior 1, 2
The modern approach eliminates the ambiguous term "MR compatible" in favor of three precise categories: MR Safe, MR Conditional, and MR Unsafe, as recommended by the American Heart Association 1, 2

The European Society of Cardiology provides a Class IIb recommendation for MRI at 1.5T in conventional pacemakers, indicating a less favorable benefit-risk ratio, and requires mandatory consultation with an electrophysiology specialist before proceeding 3
Pacemaker-dependent patients should be programmed to asynchronous mode (VOO/DOO) to prevent inappropriate inhibition from electromagnetic interference, while non-pacemaker-dependent patients should be programmed to inhibited mode (VVI/DDI) to avoid inappropriate pacing, as recommended by the Heart Rhythm Society 4, 5, 6, 3
The American Society of Anesthesiologists states that MRI is generally contraindicated in patients with CIEDs, requiring consultation with the ordering physician, cardiologist, diagnostic radiologist, and device manufacturer if MRI must be performed 7, 8

Most passive devices, such as prosthetic heart valves and coronary stents, are MR Conditional rather than contraindicated, and are safe at field strengths up to 1.5T, with many safe to 3T, as recommended by the American College of Cardiology 1, 2
Programmable hydrocephalus shunts require mandatory neurosurgical assessment and may need to be reset after the scan, as recommended by the Congress of Neurological Surgeons 1, 2
Neurostimulators, such as vagal nerve and deep brain stimulators, are generally not recommended for MRI but may proceed under controlled conditions when benefits outweigh risks, as recommended by the American Academy of Neurology 1, 2

Every patient requires comprehensive screening, particularly critical for ICU transfers and patients unable to provide accurate history, and should identify the exact make and model of all implants, as recommended by the American College of Radiology 1, 2
The MR Safety Expert may need time to contact the manufacturer or obtain current documentation, and should verify that the device has matured for a minimum of 6 weeks post-implantation, as recommended by the European Heart Rhythm Association 1, 2, 4, 5, 3

The European Heart Journal recommends that the ILR device has been implanted for at least 6 weeks to allow position stabilization, and no abandoned or epicardial leads are present, before proceeding with MRI 9, 10
The American Society of Anesthesiologists states MRI is generally contraindicated in patients with cardiac rhythm management devices, but ILRs have a more favorable safety profile 11

Up to 75% of patients with cardiac devices develop an indication for MRI due to medical comorbidities, and the diagnostic benefit of MRI in patients with syncope or neurological symptoms typically outweighs the minimal risks associated with ILR presence 9, 10
The journal Stroke recommends MRI of the brain to confirm diagnosis in stroke/TIA patients, and ILRs are used in complex patients where extensive investigations have not yielded a diagnosis 12

The American Society of Anesthesiologists recommends coordinating with the device manufacturer, ordering physician, and MRI facility before proceeding, and having qualified personnel available for device interrogation 11
The European Heart Journal recommends verifying the specific ILR model and manufacturer specifications, ensuring MRI personnel are aware of the ILR presence, and documenting the entire process including pre- and post-scan parameters 9, 10