Is magnetic resonance imaging safe in cardiac pacemaker recipients?

Magnetic resonance imaging (MRI) is currently contraindicated in cardiac pacemaker (PM) recipients. The objectives of this prospective study were to (1) reassess the risks of performing an MRI scan in patients with PM, (2) compared the pacing functions before and after the exposure to MRI, and (3) monitor the development of possible adverse effects. Thirteen patients implanted with an Affinity DR model 5330 PMs (St. Jude Medical) connected to a Tendril model 1388 leads (St. Jude Medical) underwent 2.0 T-MRI for a variety of indications. All patients displayed a stable spontaneous rhythm at the time of the MRI scan and were not considered to be PM-dependent. The sensing and pacing functions were analyzed and the impedance of both leads was measured before and after the scan. The MRI scan was performed with all PM programmed in DDD mode. The sensing configuration was bipolar. All patients were monitored utilizing a standard electrocardiographic monitor and direct verbal communication. PM Inhibition, asynchronous pacing, or inappropriately rapid pacing was not observed. No patient reported discomfort, heat, or motion sensation at the PM implant site. There were no significant differences in the sensing, stimulation, AutoCapture threshold, and lead impedance measurements before and after MRI. The results of this study suggest that performing 2.0 T-MRI scans in patients with Affinity DR model 5330 PM connected to a Tendril model 1388 lead is safe.