Can a patient with a pacemaker (permanent artificial cardiac pacemaker) undergo a Magnetic Resonance Imaging (MRI) scan?

Can a Patient with a Pacemaker Get an MRI?

Yes, patients with pacemakers can undergo MRI scanning, but this is no longer an absolute contraindication—it is now a relative contraindication that requires specific protocols based on whether the device is MRI-conditional or conventional. 1, 2

Device Classification Determines Safety Protocol

The critical first step is determining the device's MRI compatibility status:

• MRI-conditional pacemakers (introduced in 2006) can be safely scanned at 1.5 Tesla when following manufacturer's specific instructions 1, 2
• Conventional (non-MRI-conditional) 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 4, 2

The term "MR compatible" is ambiguous and should no longer be used—only MR Safe, MR Conditional, or MR Unsafe classifications are acceptable 1, 3

Absolute Contraindications That Preclude MRI

Even with modern protocols, certain situations remain absolute contraindications:

• Devices implanted less than 6 weeks ago due to risk of lead dislodgement 4, 2, 3
• Epicardial or abandoned leads due to risk of heating 2, 3
• MR Unsafe devices as classified by manufacturer 3
• Implantable defibrillators are usually contraindicated, though some cardiac centers can scan with appropriate monitoring and resuscitation support 1

Mandatory Pre-MRI Protocol

Before any MRI can proceed, the following steps are required:

• Verify the specific device model and MRI-conditional status with manufacturer specifications 2, 3
• Device interrogation to record baseline parameters including impedance, capture threshold, sensing amplitude, and battery voltage 4, 2
• Consultation with electrophysiology specialist is warranted for all cases 2, 3
• Programming adjustments based on pacemaker dependency:
  • Pacemaker-dependent patients: program to asynchronous mode (VOO/DOO) to prevent inappropriate inhibition 3
  • Non-pacemaker-dependent patients: program to inhibited mode (VVI/DDI) or turn off/fixed mode after cardiology team discussion 1, 3

For MRI-conditional devices, automatic programming features may switch modes during MRI without manual intervention 2

Intra-Procedure Requirements

During the MRI scan itself, strict monitoring is mandatory:

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

Post-MRI Protocol

Immediately after scanning:

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

For leadless pacemakers and programmable devices, manufacturer instructions must be strictly followed, and device checks may be required 1, 4

Critical Safety Considerations and Pitfalls

The historical context matters: pacemakers were previously an absolute contraindication due to documented risks including sudden death, but this changed with the introduction of MRI-conditional devices in 2006 1, 2

Common pitfalls to avoid:

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

When MRI Should Proceed Despite Risks

When MRI is necessary for clinical management of serious diseases, the benefit may outweigh the risk, but alternative imaging techniques should be considered first 2, 3. The decision requires interdisciplinary discussion between the ordering physician, cardiologist, diagnostic radiologist, and device manufacturer 3, 5. No serious incidents have occurred when proper precautions are observed 5, 6, 7, 8.