Can a Magnetic Resonance Imaging (MRI) scan be performed on a patient with a pacemaker (Permanent Artificial Cardiac Pacemaker) in place?

MRI Can Be Performed in Patients with Pacemakers Under Specific Conditions

MRI is no longer an absolute contraindication in patients with pacemakers—both MRI-conditional devices and conventional "legacy" devices can safely undergo MRI at 1.5 Tesla when appropriate protocols are followed. 1

Device Type Determines the Approach

MRI-Conditional Pacemakers (Preferred)

• MRI-conditional pacemaker systems can be safely scanned at 1.5 Tesla following manufacturer instructions 1
• These devices have automatic programming features that switch modes during MRI without manual intervention 1
• Leadless pacemakers (such as Micra) are MRI-conditional at both 1.5T and 3.0T and carry substantially lower risks due to absence of transvenous leads 2, 3
• The device must be implanted for at least 6 weeks to ensure lead maturation and position stabilization 1

Conventional "Legacy" Pacemakers

• Conventional pacemakers can be scanned at 1.5 Tesla with a low risk of complications when specific precautions are taken (Class IIb recommendation) 1
• A landmark study of 1,509 patients with legacy devices undergoing 2,103 MRI examinations reported no long-term clinically significant adverse events 4
• The risk-benefit ratio has shifted toward safety when guidelines are followed, though this requires more intensive monitoring than MRI-conditional devices 1

Mandatory Pre-MRI Protocol

Device Assessment

• Verify the specific device model and MRI-conditional status with manufacturer specifications 2, 3
• Exclude patients with leads implanted less than 6 weeks ago (prone to dislodgement) 1
• Exclude patients with epicardial or abandoned leads (prone to heating) 1
• Perform device interrogation to record baseline parameters: impedance, capture threshold, sensing amplitude, and battery voltage 1, 3

Programming Requirements

• For pacemaker-dependent patients: program to asynchronous pacing mode to avoid inappropriate inhibition from electromagnetic interference 1, 4
• For non-dependent patients: program to inhibited (demand) pacing mode to avoid inappropriate pacing 1, 4
• Deactivate all other pacing functions (magnet response, rate response, noise response, AF response) 1
• For ICDs: deactivate tachyarrhythmia monitoring and all therapies (ATP/shock) 1

Intra-Procedure Requirements

Monitoring

• Continuous ECG monitoring throughout the entire procedure by qualified personnel 1, 3
• Monitor peripheral pulse (pulse oximetry, arterial line, or manual palpation) 1
• Maintain direct verbal communication with the patient 5
• Have temporary pacing and defibrillation equipment immediately available 1

MRI Parameters

• Limit scanning to 1.5 Tesla field strength—no data exists for higher field strengths even with MRI-conditional devices 1
• Avoid scanning within 6 weeks of device implantation 1

Post-MRI Protocol

• Re-interrogate the device immediately after MRI and compare all parameters to baseline 1, 3
• Restore original programming settings 1
• Continue monitoring cardiac rate and rhythm with backup equipment available throughout the immediate postoperative period 1

Critical Safety Considerations

Known Risks

• Device reset to backup mode occurred in 0.4% of scans with legacy devices, with only one case requiring device replacement 4
• Most common parameter changes: decreased P-wave amplitude (1-4%), increased capture thresholds (3-4%)—these were not clinically significant and did not require intervention 4
• Historical reports of sudden death exist in patients scanned without proper protocols 1
• Magnetic field strengths exceeding 0.5 mT (5 Gauss) can cause fatal pacemaker malfunction if precautions are not followed 1

Absolute Requirements

• Consultation with electrophysiology specialist is warranted for all cases 1
• When MRI is necessary for clinical management of serious diseases, the benefit may outweigh the risk—alternative imaging techniques (CT, nuclear imaging) must be considered first 1
• The indication for MRI must be established as an interdisciplinary decision 6

Common Pitfall

The most critical error is proceeding without proper device interrogation and programming—this accounts for the historical adverse events. Never assume a device is MRI-safe without verifying manufacturer specifications and following the complete protocol outlined above 1, 6.