Every year, millions of patients require magnetic resonance imaging (MRI) to help diagnose and manage various diseases. Up until recent times, MRIs were considered an absolute contraindication in all patients with cardiac implantable electronic devices (CIEDs). Device movement, unanticipated programming changes, inappropriate device therapies in ICDs, and inhibition of pacing output are some of the feared complications of scanning patients with CIEDs.1-3 The strong static magnetic field along with earlier ferromagnetic components, primitive lead design, and software vulnerabilities seen in MRI non-conditional (legacy) devices made these complications possible, and become clinically relevant in patients who are dependent on their devices. In light of these complications, professional societies continued to discourage MRI in CIED patients, except in cases with a strong clinical indication and in which the benefits clearly outweigh the risks.4 However, MRI scans have been performed off label at centers over the years, taking into consideration the risk vs benefit. Patients with serious brain or other organ-related illnesses who needed MRI scans for making better treatment choices fell into this category. Despite the trepidation about the potential maleffects of MRIs on CIED function, several large prospective series have shown relative safety of scanning patients with MRI non-conditional devices using standardized protocols.5,6 It should be emphasized that the pre-specified protocol used in these studies included rigorous patient selection, device programming, and close monitoring.
The advent of MRI-conditional devices has provided further opportunity for allowing diagnostic imaging in patients with a pacemaker and defibrillator. The reduction in ferromagnetic components, coupled with improved lead design and software modifications that automatically trigger appropriate MRI favorable settings, have allowed for the development of MRI-conditional devices. As the name implies, certain pre-specified device and scanner conditions have to be met before safely scanning these patients. However, despite MRI-conditional devices and development of standardized protocols, there continues to be some hesitancy to having these patients undergo MRI due to scanning restrictions as well as workflow limitations between departments.
At the University of Kansas Hospital, the cardiology and radiology departments have developed a collaborative partnership to address concerns and ensure that all patients safely undergo MRI with devices (regardless of being MRI conditional or non-conditional). We have developed protocols and workflows that facilitate providing the safest and most streamlined care for patients with CIEDs undergoing MRI imaging.
Because of the complexity and associated high risks, especially for patients undergoing MRI with a non-conditional CIED, a special taskforce consisting of members from cardiology and radiology was formed. Through teamwork, the taskforce has developed a comprehensive patient-centric approach to ensure that all patients are carefully evaluated and safely undergo MRI. This collaborative work has resulted in streamlined workflows, allowing for the most efficient care in both departments.
On a weekly basis, approximately 7-10 patients with conditional devices and 2-3 patients with non-conditional CIEDs undergo MRI. There are 2 separate workflows for patients with MRI-conditional and non-conditional CIEDs. When an MRI is ordered, radiology scheduling asks the patients if they have a CIED. If the answer is yes, radiology scheduling contacts the Heart Rhythm Management (HRM) team to determine if the device is MRI conditional or non-conditional. The HRM team reviews the patient’s chart, and the appropriate workflow is triggered based on if the device is MRI conditional or non-conditional (Figure 1).
Workflow for Patients Undergoing MRI with MRI-Conditional CIEDs
Regardless of whether the patient has the MRI-conditional device, there are still criteria that need to be met to ensure the patient safely undergoes MRI (i.e., no abandoned leads, leads are electrically intact, etc.). Prior to MRI, all patients must have a full evaluation of their device, leads, and history prior to entering the MRI suite. If the patient has an MRI-approved device that has been implanted and followed by an outside institution, the patient is asked to participate in an electrophysiology (EP) consultation at our hospital, with a full device check and chest x-ray prior to their MRI. At their EP consultation visit, an HRM nurse or technician completes a full device check and starts the MRI-conditional CIED checklist (Figure 2). Next, the patient is seen by the electrophysiologist, who reviews the chest x-ray and the device check, and can recommend programming during the MRI. Prior to the MRI scan, the HRM team is paged and a member of the HRM team programs the patient to the recommended post-MRI settings while the patient is in the MRI suite. Patients are not allowed to leave the MRI suite until their device has been reprogrammed back to pre-MRI settings.
Workflow for Patients Undergoing MRI with MRI Non-Conditional CIEDs
If the patient has an MRI non-conditional device, a different workflow is triggered (Figure 3). Specific members of the HRM team work closely with radiology team members to facilitate scheduling, ensuring the protocol is followed and that appropriate staff are present during the MRI scan. They are also responsible for both programming and monitoring the patient during the MRI.
Because of the perceived high risks associated with patients with MRI non-conditional devices, the risk/benefit ratio must be clearly established and the benefit from the MRI clearly needs to outweigh the risks of the procedure. To ensure this, the radiologist and ordering provider must review and discuss the need for MRI imaging and possible alternative imaging. Once it is deemed that MRI imaging is the best and only imaging modality available, that the benefit clearly outweighs the risks, and it is documented in the chart, an electrophysiology consult is scheduled to determine if the patient can safely undergo MRI from a CIED standpoint.
Similar to the MRI-conditional workflow, the patient is scheduled for an EP consultation visit. A designated HRM nurse completes the full device check and starts the MRI non-conditional CIED checklist (Figure 4). The patient is then seen by the electrophysiologist, who reviews the chest x-ray and the device check, and recommends programming during the MRI. Because of the additional risks, patient consents are obtained from both the cardiologist as well as the radiologist prior to the MRI to ensure that the patient clearly understands the risks/benefits and wishes to proceed.
Once the patient has presented to radiology to undergo MRI, the HRM team is paged and one of the designated team members presents to the MRI suite. After ensuring that there is an electrophysiologist immediately available in case of an adverse event, the HRM nurse programs the patient per the electrophysiologist’s recommendations for their MRI. The radiology service interpreting the examination is responsible for tailoring the MRI examination so as to minimize power deposition, and is also responsible for reviewing the examination for completeness prior to terminating the study. During the MRI, while a nurse from interventional radiology monitors the patient’s vitals, the HRM nurse is responsible for monitoring the patient’s device function throughout the whole scan. Immediately post MRI, the HRM nurse performs and documents a full device evaluation.
If significant changes are seen in the device function (lead sensing, lead impedance, or thresholds), they will notify the electrophysiologist on call for recommendations, which may include admission for close monitoring of CIED function. If any of the following changes (1.0 V increase in pacing lead threshold; >50% decrease in P-wave or R-wave amplitude; >50 Ω change in pacing lead impedance; >5 Ω change in high-voltage [shock] lead) are noted post MRI, the patient will be scheduled for a complete device evaluation within 3-7 days to re-evaluate. If the post-MRI device check continues to demonstrate stable function, all programming settings are returned to pre-MRI settings and the patient is scheduled for a 2-week post-MRI in-office check to ensure the device continues to function appropriately.
As most of the CIEDs implanted prior to 2000 get replaced by MRI-conditional devices, the MRI interaction will become less problematic. Going forward, a closer government-mandated collaboration between MRI and CIED manufacturers is also very important. A recent decision from the Centers for Medicare & Medicaid Services (CMS) to reverse its stand on an archaic rule of not reimbursing for MRI scans in CIEDs is a step forward in the right direction. With technological advancements, we will continue to make greater strides in improving the overall safety of CIEDs as it pertains to the impact of magnetic resonance imaging.
Disclosures: The authors have no conflicts of interest to report regarding the content herein.
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- Levine GN, Gomes AS, Arai AE, et al. Safety of magnetic resonance imaging in patients with cardiovascular devices: an American Heart Association scientific statement from the Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology, and the Council on Cardiovascular Radiology and Intervention: endorsed by the American College of Cardiology Foundation, the North American Society for Cardiac Imaging, and the Society for Cardiovascular Magnetic Resonance. Circulation. 2007;116:2878-2891.
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- Russo RJ, Costa HS, Silva PD, et al. Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator. N Engl J Med. 2017;376:755-764.