Determining the Risks of Magnetic Resonance Imaging at 1.5 Tesla for Patients With Pacemakers and Implantable Cardioverter Defibrillators
What are the risks of magnetic resonance imaging (MRI) in patients with non-MRI-compatible cardiac devices?
One hundred and nine patients (mean age 74 years) with a pacemaker or implantable cardioverter-defibrillator (ICD) underwent 125 MRI studies (most often brain or spine) using a 1.5 Tesla scanner. Device interrogation was performed immediately before and after the MRI. If the patient was pacemaker-dependent, the pacemaker was programmed to the asynchronous mode. Antitachycardia pacing was disabled in ICDs. A control group of 50 patients (mean age 75 years) with a pacemaker or ICD underwent two device interrogations 60 minutes apart.
There were no device or lead failures, new arrhythmias, losses of capture, or device resets during the MRI studies. There were no changes in battery voltage or pacing thresholds in the MRI or control group, except for a 0.1 V increase in left ventricular pacing threshold in the MRI group. There were minor changes in mean P- and R-wave amplitude in both groups, with no significant differences between the two groups. Pacing lead impedance fell significantly by a mean of 6.2 ohms during MRI.
The authors concluded that MRI can be performed without major complications in patients with non-MRI-compatible cardiac devices.
There were no device resets in this study, but in a recent study of 438 patients with a cardiac device who underwent 555 MRI studies, there were three instances of reversion to a back-up pacing mode. Although an MRI-compatible pacemaker is now approved for use in the United States, it is reassuring to know that with appropriate precautions, MRI is feasible in patients with a conventional pacemaker or ICD.
Keywords: Pacemaker, Artificial, Magnetic Resonance Imaging
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