Researchers find standard pacemakers and defibrillators safe for MRI using a new protocol

MagnaSafe Registry, a new multicenter study led by scientists at The Scripps Research Institute (TSRI), has demonstrated that appropriately screened and monitored patients with standard or non-MRI-conditional pacemakers and defibrillators can undergo MRI at a field strength of 1.5 tesla without harm. These devices are not presently approved by the U.S. Food and Drug Administration (FDA) for MRI scanning.

The researchers observed no patient deaths, device or lead failures, losses of pacing function or ventricular arrhythmias in 1,500 patients who underwent MRI using a specific protocol for device interrogation, device programming, patient monitoring and follow-up designed to reduce the risk of patient harm from MRI effects.

New Study Defines a Protocol for MRI Scanning and Defines the Risk of MRI

The use of MRI poses potential safety concerns for patients with an implanted cardiac device.

These concerns are a result of the potential for magnetic field-induced cardiac lead heating, which could result in cardiac injury and damage to an implanted device. As a result, it has long been recommended that patients with a pacemaker or defibrillator not undergo MRI scanning, even when MRIs are considered the most appropriate diagnostic imaging method for their care.

Despite the development of devices designed to reduce the potential risks associated with MRI, a large number of patients have devices that have not been shown to meet these criteria and are considered ‘non-MRI-conditional.’ At least half these patients are predicted to have the need for MRI after a device has been implanted.

Researchers established the MagnaSafe Registry to determine the frequency of cardiac device-related events among patients with non-MRI-conditional devices, as well as to define a simplified protocol for screening, monitoring and device programming before MRI.

‘Given the great clinical demand for MRI for patients with a standard pacemaker or defibrillator, we wanted to determine the risk,’ said study leader Dr. Robert Russo, an adjunct professor at TSRI and director of The La Jolla Cardiovascular Research Institute.

In the MagnaSafe Registry, researchers at 19 U.S. institutions tested 1,000 cases with a non-MRI-conditional pacemaker (one not approved for use in an MRI) and 500 cases of patients with a non-MRI-conditional implantable cardioverter defibrillator (ICD), a device that can shock the heart in response to a potentially fatal cardiac rhythm. They scanned regions other than the chest, such as the brain, spine or extremities-where MRI is traditionally the best option for imaging.

The researchers tested the devices at an MRI field strength of 1.5 tesla, a standard strength for MRI scanners and reprogrammed some devices according to a prespecified protocol for the MRI examination.

The Scripps Institute