Magnetic resonance imaging in patients with temporary external pacemakers
Authors: Fyenbo DB , Jensen MSK , Kronborg MB , Kristensen J , Nielsen JC , Witt CT 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: Other. Main funding source(s): This work was supported by Aarhus University, the Danish Heart Foundation (grant number R140-A9482-B2407); Health Research Foundation of Central Denmark Region (grant number R64-A3194-B1667); and Gangstedfonden.

Background
Magnetic resonance imaging (MRI) is increasingly becoming the imaging modality of choice for many clinical disorders. According to guidelines, MRI can safely be performed 6 weeks after implantation of a MRI-conditional permanent pacemaker. However, there is no recommendations and only very limited evidence regarding MRI in patients treated with temporary external pacemakers. Such patients thus may be denied the opportunity for well-indicated MRI.

Purpose
To describe safety and feasibility of MRI in patients with temporary external pacemakers.

Method
We reviewed patient records of all patients treated with temporary external pacing between 2016 and 2020 at a tertiary centre. Temporary pacing was established using a transvenous standard active fixation pacing lead inserted percutaneously and connected to a MRI-conditional pacemaker taped to the skin. Information on baseline characteristics, indication, days of hospital and pacemaker function before and after MRI was gathered. Before MRI, devices were programmed according to guidelines for permanent pacemakers and the device was fixated to avoid movement due to the magnetic field of the MRI system. Patients were monitored during MRI. Values are reported as N (%), and continuous variables are presented as median (interquartile range [IQR]) or mean ± SD.

Results
A total of 827 patients received a temporary pacemaker. MRI was performed in 44 (5%) patients. Mean age was 71 ­± 13 years and 13 (30%) were females. Indication for temporary device were atrioventricular block (20 [45%]), aborted cardiac arrest (9 [21%]), infective endocarditis (9 [21%]), and other (6 [14%]). MRI was performed to rule out or confirm structural heart disease (16 [36%]), cerebral disease (9 [20%]), spondylodiscitis (7 [16%]), or other (12 [27%]), which was not able to do with other imaging modalities. Cardiac MRI was performed in 22 (50%) patients, while MRI of cerebrum, spine, abdomen, and lower extremities were performed in the remaining patients. Median (IQR) time from implantation of the temporary device to MRI was 6 (3–11) days. During MRI, we observed no device-related malfunction or arrhythmia. Nor did we detect any change in lead sensing, impedance, or pacing threshold. A final diagnosis was confirmed in 27 (61%) patients after MRI. However, MRI provided information to guide the clinical management in all cases without artifacts compromising the diagnostic image quality. Instead of a dual chamber pacemaker, 7 (22%) patients had implanted a cardiac resynchronization therapy and/or implantable cardioverter defibrillator due to the MRI diagnosis. A permanent pacemaker was implanted in 32 (73%) patients within median (IQR) 12 (7–23) days after temporary pacing was established.

Conclusion
MRI is feasible and safe in patients with temporary external pacing established with a regular MRI-conditional device and a standard active fixation lead. The MRI was helpful in determining type of permanent device.