Is the Watchman (Left Atrial Appendage Closure) device MRI (Magnetic Resonance Imaging) compatible?

MRI Compatibility of the Watchman Device

The Watchman device is MR Conditional, meaning MRI scans can be safely performed under specific manufacturer-specified conditions, typically at field strengths up to 1.5 Tesla. 1

Understanding MRI Safety Classifications

The safety of medical devices in MRI environments falls into three formal categories:

• MR Safe: Contains no material that would present a hazard at any field strength
• MR Conditional: Safe to scan under specified conditions detailed by the manufacturer
• MR Unsafe: Presents unacceptable risk to patients or staff in the MR environment

The term "MR compatible" is considered ambiguous and should no longer be used in clinical practice. 1

Watchman Device MRI Safety Considerations

The Watchman device, as a left atrial appendage closure device, is classified as MR Conditional. This means:

1. Field Strength Limitation: Generally safe at 1.5 Tesla, though specific manufacturer guidelines should be consulted
2. Timing Considerations: MRI should typically be avoided within 6 weeks of implantation when leads and devices are still settling 1
3. Device Verification: The exact model of the Watchman device should be verified before scanning, as different generations may have different MRI compatibility specifications

Pre-MRI Assessment Protocol

Before proceeding with MRI in patients with a Watchman device:

• Consult with the MR Responsible Person and MR Safety Expert
• Verify the exact model and manufacturer specifications
• Confirm that sufficient time has passed since implantation (typically >6 weeks)
• Ensure the patient is properly screened for any other contraindications

Important Clinical Considerations

Potential Risks and Complications

While the Watchman device is generally MR Conditional, awareness of potential complications is important:

• Device displacement is rare but possible
• Device-related thrombosis has been reported in approximately 3.4% of patients with Watchman devices, though this is not specifically related to MRI exposure 2
• Image artifacts may occur in the area surrounding the device, potentially limiting diagnostic value

Newer Watchman Generations

The Watchman FLX and newer generations like the Watchman FLX Pro have been developed with improved features, including potentially better MRI compatibility, though specific data on MRI performance at higher field strengths (>1.5T) is still limited 3, 4

Practical Recommendations

1. Always consult manufacturer guidelines for the specific Watchman model
2. Coordinate with cardiology before scheduling MRI for patients with Watchman devices
3. Consider alternative imaging modalities when appropriate, such as cardiac CT angiography, which has been shown to be effective for evaluating Watchman devices 5
4. Limit MRI field strength to 1.5 Tesla unless specifically approved for higher field strengths by the manufacturer
5. Document pre- and post-MRI device function when possible

Common Pitfalls to Avoid

• Assuming all cardiac implants have the same MRI compatibility
• Proceeding with MRI without verifying the specific device model and manufacturer guidelines
• Confusing "MR compatible" (outdated term) with "MR Conditional" (current terminology)
• Failing to consider the time since device implantation when scheduling MRI

By following these guidelines and consulting with both the device manufacturer and a multidisciplinary team including cardiology and radiology, MRI can be safely performed in patients with Watchman devices under appropriate conditions.