Arrhythmias and conduction disturbances
Determining the Risks of Magnetic Resonance Imaging at 1.5 Tesla for Patients With Pacemakers and Implantable Cardioverter Defibrillators

https://doi.org/10.1016/j.amjcard.2012.07.030Get rights and content

Conventional pacemaker and implantable cardioverter-defibrillator product labeling currently cautions against exposure to magnetic resonance imaging (MRI). However, there is a growing clinical need for MRI, without an acceptable alternative imaging modality in many patients with cardiac devices. The purpose of this study was to determine the risk of MRI at 1.5 T for patients with cardiac devices by measuring the frequency of device failures and clinically relevant device parameter changes. Data from a single-center retrospective review of 109 patients with pacemakers and implantable cardioverter-defibrillators (the MRI group) who underwent 125 clinically indicated MRI studies were compared to data from a prospective cohort of 50 patients with cardiac devices who did not undergo MRI (the control group). In the MRI group, there were no deaths, device failures requiring generator or lead replacement, induced arrhythmias, losses of capture, or electrical reset episodes. Decreases in battery voltage of ≥0.04 V occurred in 4%, pacing threshold increases of ≥0.5 V in 3%, and pacing lead impedance changes of ≥50 Ω in 6%. Although there were statistically significant differences between the MRI and control groups for the mean change in pacing lead impedance (−6.2 ± 23.9 vs 3.0 ± 22.1 Ω) and left ventricular pacing threshold (−0.1 ± 0.3 vs 0.1 ± 0.2 V), these differences were not clinically important. In conclusion, MRI in patients with cardiac devices resulted in no device or lead failures. A small number of clinically relevant changes in device parameter measurements were noted. However, these changes were similar to those in a control group of patients who did not undergo MRI.

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Methods

Medical records were reviewed for all patients with permanent pacemakers and ICDs who underwent clinically necessary MRIs from February 2006 to March 2009 at a single institution (the MRI group). MRI was ordered by the patient's treating physician, who determined that there was no acceptable alternative imaging study and that the potential benefit of the diagnostic data obtained by MRI significantly outweighed the potential risk for device failure. Patients who were pacemaker dependent

Results

In the MRI group, 109 patients with pacemakers and ICDs underwent 125 consecutive, clinically indicated MRI studies. A single scan was performed in 95 patients, 12 underwent 2 separate studies on different days, and 2 patients underwent 3 studies on different days. Three patients entered the scanner and were exposed to the static magnet field but did not undergo successful imaging (claustrophobia in 1 patient, unacceptable artifact from a biventricular ICD in 1 patient, and a pacemaker magnet

Discussion

No patient with a permanent pacemaker or ICD who underwent MRI experienced a primary end point event. With respect to our secondary end points, a small number of clinically relevant changes in device parameter measurements were noted. However, these changes were similar to a control group of patients who did not undergo MRI. Only 1 patient required temporary device reprogramming at the time of MRI. For all parameters measured, we selected limiting values that would distinguish between

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This study was funded by a Scripps Clinical Research Development Award, La Jolla, California, and philanthropic grants from the R. E. Hazard, Jr, family, Rancho Santa Fe, California, the Louis Grubb family, Scottsdale, Arizona, the Richard Deihl family, Rancho Santa Fe, California, and the Shultz Steel Company, Long Beach, California. Dr. Cohen was supported by a clinical research fellowship award from the Hewitt Foundation for Medical Research, Newport Beach, California.

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