MRI Pacing System Recommended for U.S. Regulatory Approval

A new magnetic resonance imaging (MRI) pacing system was designed to address safety concerns around MRI procedures for patients who have implanted pacemakers. The device includes hardware modifications to the device and leads that are designed to reduce or eliminate several hazards produced by the MRI environment.

The U.S. Food and Drug Administration (FDA; Silver Spring, MD, USA) Circulatory System Devices Panel of the Medical Devices Advisory Committee has voted unanimously in favor of approval with conditions of the Revo MRI SureScan pacing system designed as MR Conditional, or safe for use in magnetic resonance imaging (MRI) systems under specified conditions.

MRI procedures are not recommended in the United States for patients who currently have implanted pacemakers; if approved, Revo MRI has the potential to be the first FDA-approved pacing system designed for use in the MRI setting.

The FDA's Circulatory System Devices Panel, which met March 22, 2010, recommended Revo MRI for approval with conditions related to the planned postmarket study, health care professional training, and labeling to reflect MRI scans are to be conducted with the full Revo MRI SureScan pacing system. The FDA will consider the panel's recommendation in its review of Revo MRI; however, it is not bound by its Advisory Committee's recommendations. The pacing system was developed by Medtronic, Inc. (Fridley, MN, USA).

"MRI is critical in the diagnosis of many serious conditions; however, patients with current pacemakers most often do not have access to this vital technology," said Pat Mackin, president of the Cardiac Rhythm Disease Management business and senior vice president at Medtronic. "The result of [this] panel brings Medtronic one step closer to helping address an important unmet patient need. We look forward to working with the FDA during the regulatory process so that we may provide certain pacemaker patients with access to MRI scans.”

The number of MRI scans performed increases each year, as does the number of people with implanted cardiac devices. It is estimated that more than 200,000 patients yearly in the United States have to forego an MRI scan because they have a pacemaker due to the risks involved, including interference with pacemaker operation, damage to system components, lead or pacemaker dislodgement, heating of the lead tips and unintended cardiac stimulation. MRI scans allow physicians to make a wide range of health diagnoses by viewing highly detailed images of internal organs, blood vessels, muscle, joints, tumors, and areas of infection.

The FDA panel reviewed safety and effectiveness data from a prospective, randomized multi-center trial at 42 centers around the world featuring 464 implanted patients. Major inclusion criteria included standard Class I or II dual chamber pacemaker indication, which allowed for pacemaker-dependent patients. Patients were excluded if they had previously implanted medical devices or abandoned leads. Patients were randomized at implant either to receive an MRI or not to receive an MRI.

The primary endpoints evaluated were safety and effectiveness of the Revo MRI pacing system in the MRI environment. For safety, the MRI group was evaluated for MRI procedure-related complications through one-month post-MRI. The primary effectiveness endpoint tested equivalence between MRI versus control for atrial and ventricular pacing capture thresholds and atrial and ventricular sensed amplitudes through one-month post-MRI.

Since MRI scanners may cause traditional pacemakers to misinterpret MRI-generated electrical noise and withhold pacing therapy or deliver unnecessary pacing therapy, this new pacemaker includes a new SureScan feature that sets the device into an appropriate mode for the MRI environment.

The device and leads also contain radiopaque markers, viewable via X-ray, to indicate that the device is MR-conditional. MR-conditional is a term used to indicate that a device may be used in the MRI environment under certain conditions, such as a particular type of MRI scanner and scanner settings.

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Medtronic
U.S. Food and Drug Administration