BIDMC researchers examine how scanners impact pacemakers and implantable defibrillators
Magnetic resonance image (MRI) scans are important for the diagnosis and treatment of numerous medical conditions. But safety concerns regarding the impact of the MRI scanners on electrical devices have prevented many cardiac patients with pacemakers or implantable cardioverter defibrillators (ICDs) from receiving these essential imaging tests.
Cardiologists in the Richard A. and Susan F. Smith Center for Outcomes Research at Beth Israel Deaconess Medical Center recently conducted a study that shows that with careful patient selection and supervision, MRIs can be safely performed on patients with implantable cardiac devices. Their new research is currently published in the journal Heart Rhythm.
"Millions of patients are living with pacemakers and implantable defibrillators, and many of these individuals will have the need for MRI scans,” explains the study’s senior author, Daniel B. Kramer, MD, MPH (right), Director of the Pacemaker and ICD Service in the CardioVascular Institute at BIDMC and faculty member in the Smith Center for Outcomes Research.
“Although a limited number of specially developed ‘MRI-conditional’ cardiac devices have been approved by the U.S. Food and Drug Administration [FDA], the vast majority of pacemakers and implantable defibrillators currently being used are standard MRI devices," he adds. "In practice, this means that MRI scans may be unobtainable for many patients.”
How the Technologies Work
Both pacemakers and ICDs contain wires with electrodes that are connected to one or more of the heart’s chambers. They are designed to act as a backup when the heart’s electrical system fails, or to restore a normal rhythm to the heart by sending electrical impulses through the wires.
Magnetic resonance imaging works by generating a strong magnetic field.
The fear has been that the powerful magnetic fields and radio waves that are part of MRI scans could cause the devices' wires to overheat, potentially damaging heart tissue, explains the study's first author Jordan B. Strom, MD (right), a Research Fellow in the Smith Center. "The other concern is that MRIs might induce unwanted currents that could lead to a potentially dangerous arrhythmia or cause the device to malfunction."
The new study examined 123 patients who underwent a total of 189 MRI scans at BIDMC. This was part of a strict study protocol developed as a collaboration between the Departments of Cardiovascular Medicine and Radiology. The patients were carefully monitored before, during and after undergoing the imaging tests, and the researchers evaluated safety outcomes as well as whether the MRI scans were necessary to help determine patients’ care.
"We found that there were no serious adverse events among any of the patients with cardiac devices who received MRIs," explains Dr. Kramer, who is also Assistant Professor of Medicine at Harvard Medical School. Furthermore, he adds, the study showed that the majority of scans had an important impact on patients’ care. Importantly, the study included relatively high-risk patients who rely on pacemakers to maintain a steady heartbeat, as well as patients who received MRIs of the chest area.
"With appropriate selection and monitoring, the MRIs proved very safe and frequently provided doctors with new diagnoses or led to changes in patients' treatment plans or subsequent procedures," adds Dr. Kramer. “We hope these results build on experiences of other medical centers and help to expand patients’ access to this important imaging tool."
Visual Abstract: Safety and Utility of MRI on Patients with Cardiac Implantable Electronic Devices
Above content provided by the CardioVascular Institute at Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.