MRI Scanning in Patients with Pacemakers

Introduction to Pacemaker MRI Compatibility

The American Heart Association recommends that patients with pacemakers can undergo MRI scanning, but this requires specific protocols based on whether the device is MRI-conditional or conventional, with a strength of evidence level of B 1, 2

MRI-conditional pacemakers can be safely scanned at 1.5 Tesla when following manufacturer's specific instructions, with a Class I recommendation (strong benefit-risk ratio) 1, 2
Conventional pacemakers can be scanned at 1.5 Tesla with a low risk of complications when specific precautions are taken, though this carries a Class IIb recommendation (less favorable benefit-risk ratio) 2, 3
Leadless pacemakers are MRI-conditional at both 1.5T and 3.0T and carry substantially lower risks due to absence of transvenous leads, with a strength of evidence level of A 4, 2

Devices implanted less than 6 weeks ago are an absolute contraindication due to risk of lead dislodgement, with a Class III recommendation (harm or no benefit) 4, 2, 3
Epicardial or abandoned leads are an absolute contraindication due to risk of heating, with a Class III recommendation (harm or no benefit) 2, 3
MR Unsafe devices, as classified by manufacturer, are an absolute contraindication, with a Class III recommendation (harm or no benefit) 3

Verify the specific device model and MRI-conditional status with manufacturer specifications, with a strength of evidence level of B 2, 3
Device interrogation to record baseline parameters including impedance, capture threshold, sensing amplitude, and battery voltage, with a strength of evidence level of B 4, 2
Consultation with electrophysiology specialist is warranted for all cases, with a strength of evidence level of B 2, 3

Continuous ECG monitoring throughout the entire procedure by qualified personnel, with a strength of evidence level of B 2
Peripheral pulse monitoring using pulse oximetry, arterial line, or manual palpation, with a strength of evidence level of B 2
Temporary pacing and defibrillation equipment must be immediately available, with a strength of evidence level of B 2
Field strength limitation to 1.5 Tesla for conventional devices, though MRI-conditional devices may be safe up to 3T, with a strength of evidence level of B 1, 2

Re-interrogate the device and compare to baseline parameters, with a strength of evidence level of B 4, 2
Restore original programming settings, with a strength of evidence level of B 4, 2
Monitor cardiac rate and rhythm with backup equipment available throughout the immediate postoperative period, with a strength of evidence level of B 2

Magnetic field strengths exceeding 0.5 mT (5 Gauss) can cause fatal pacemaker malfunction if precautions are not followed, with a strength of evidence level of A 2
Historical reports of sudden death exist in patients scanned without proper protocols, with a strength of evidence level of A 2
Never assume a device is MRI-conditional without verifying manufacturer documentation, with a strength of evidence level of B 3
Programmable hydrocephalus shunts may have their pressure settings changed by MRI, requiring neurosurgical assessment before and after scanning, with a strength of evidence level of B 5, 1, 3

The American Society of Anesthesiologists recommends confirming the patient's pacemaker dependence status, with pacemaker-dependent patients requiring asynchronous pacing mode activation 6
Patients who are status-post cardiac ablation do not have additional contraindications for MRI, unless epicardial leads were placed during the procedure 7, 8

The American Society of Anesthesiologists suggests having backup cardioversion-defibrillation equipment ready for immediate use 6