MRI Safe with Pacemakers, Defibrillators

The largest-ever study on the effects of magnetic resonance imaging on pacemakers and defibrillators has concluded that the imagers are indeed safe for those with these cardiac rhythm management devices.

That’s the conclusion of a new study published in the October edition of Annals of Internal Medicine. The journal also published an editorial and a summary for patients on the findings.

Millions of Americans live with pacemakers and defibrillators, with hundreds of thousands implanted annually. Because of concerns about MRI machines’ intense magnetic fields causing the devices to malfunction, physicians have avoided MRI scans for such patients, though an estimated 75 percent of such patients could benefit from scans, the authors estimated.

A team led by Saman Nazarian, MD, of Johns Hopkins University, conducted 555 MRI scans on 438 patients with pacemakers (237) or defibrillators (201). Of the 555 MRI examinations, 222 (40 percent) were of the brain, 122 (22 percent) were of the spine, 89 (16 percent) were of the heart, 72 (13 percent) were of the abdomen or pelvis, and 50 (9 percent) were of an extremity. The team monitored patients before, during, and after the scans.

Overall, just three patients experienced problems with the devices, and none had a serious problem.

Patients were selected and treated based on previous safety studies. Therefore, only those with pacemakers manufactured after 1998 and defibrillators manufactured after 2000 were enrolled, and the researchers carefully followed programming and monitoring protocol.