MRI Studies Can Be Performed Safely in Patients with Implantable Cardiac Devices
Patients were monitored carefully during magnetic resonance imaging procedures and had no apparent problems.
Magnetic resonance imaging (MRI) studies usually are avoided in patients with implantable cardiac devices because of safety concerns. In this prospective study conducted at one U.S. center and one Israeli center, investigators evaluated whether MRI studies could be performed safely at the commonly used magnetic strength of 1.5 T in patients with implantable cardiac devices who had clinical indications for MRI. The protocol involved changing pacing mode as indicated and disabling tachyarrhythmia functions; symptoms, blood pressure, electrocardiography, and oximetry were monitored by experienced clinicians.
Overall, 438 patients with pacemakers (54%) or implantable cardioverter-defibrillators (ICDs; 46%) who underwent 555 MRI studies participated. In three patients (0.7%), implanted devices reverted to a backup mode that allows the devices to function after loss of programmable memory; none of these patients experienced long-term device dysfunction. Although minor short- and long-term changes in device function were observed (e.g., sensing, lead impedance) in the study group, these changes did not require device revision or reprogramming.
Comment: In this study, MRI procedures were performed safely using a defined protocol in patients who had implantable cardiac devices. Editorialists suggest that the presence of an implantable cardiac device “should no longer be considered an absolute contraindication to MRI.” However, these results should not be extrapolated to MRI scanners with field strengths lower or higher than 1.5 T. Notably, the FDA recently approved a pacemaker designed to function safely in the MRI environment under certain conditions (e.g., at defined MRI magnet strength).
Paul S. Mueller, MD, MPH, FACP
Published in Journal Watch General Medicine October 25, 2011