Access to MRI for patients with cardiac pacemakers and implantable cardioverter defibrillators

Introduction

Current clinical pathways across multiple domains (neurology, orthopaedics and oncology) include MRI for diagnosis and treatment planning. The presence of a cardiac implantable electronic devices (CIED—pacemaker or implantable cardiac defibrillator (ICD)) was previously considered an absolute contraindication to MRI due to a perceived risk,1 resulting in delays and potentially impacting clinical outcomes. This is a growing problem—there are an estimated 400 000 patients with CIEDs in England with 50 000 new CIED implants annually and an expanding list of clinical indications for MRI across healthcare.2–5

Recent developments have, however, made scanning possible in almost all cases. ‘MR-conditional’ devices are now standard of care for new CIEDs in the UK, and recent studies have demonstrated MRI scanning for patients with legacy (non-MR conditional) CIEDs to be low risk, provided strict protocols are adhered to.6 7 However, patients with CIED report difficulties accessing MRI services worldwide.7 8 An initial survey conducted in 2015 found that although awareness of MR-conditional devices was high, fewer than half of hospitals offered a service with an estimated 50-fold national under provision.9 Reported barriers to service provision included safety concerns and practical issues related to inadequate cardiology support.

Since 2016, the landscape has changed with landmark clinical safety studies for non-MR conditional (‘legacy’) device scanning,6 10 11 international guidelines for best practice,8 12–15 funding approval by Medicare and Medicaid for MRI in almost all patients with CIED (including non-MR conditional devices) in the USA and endorsement by UK National Societies for service provision to reduce inequity.14 16

This study aims to assess the impact of these changes and present an up-to-date evaluation of national MRI provision to patients with CIED in England, to assess any ongoing care gaps or inequality and to propose areas for further needed interventions to improve care.

Methods

Results

Responses were received from 212 of 223 (95%) hospitals, representing 141 of 145 (97%) of acute hospital NHS Trusts within England. Of these, 35 provided data across two of more hospital sites within a single Trust, thus, results are based on a total of 177 responses. The survey was completed by superintendent radiographers (83%), senior radiographers (10%), cardiologists (5%) and radiologists (2%).

Annual CIED MRI volume 2018–2019 and comparison with 2014–2015 data

There were 4896 MRI scans performed in patients with CIEDs in the year to January 2019; of which 4612 (94%) were in patients with MR conditional and 284 (5·8%) non-MR conditional devices. More than half of national provision for nonconditional device scanning was provided by just three hospitals located in London, n=154 (54% of total) scans. Of hospitals performing MRI scans in patients with CIED, median annual scan volume per hospital was 21–50 scans: range 1–210 (figure 1).

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Figure 1

Annual MRI scan volume in patients with CIED by hospital site—comparison of 2014/15 and 2018/19 data. CIED, cardiac implantable electronic device.

The number of NHS hospitals providing CIED–MRI services increased from 47% to 53% from 2014/2015 to 2018/2019, with non-MR conditional provision increasing from 4% to 10%. Overall scan volumes increased 4·5-fold (1090 to 4896 scans annually).

Regional variation in supply of MRI to patients with CIED patients and relationship with estimated scan demand

There was significant regional variation in provision (figure 2). Five STPs (total population >3·5 million people and an estimated 18 750–29 000 patients with CIEDs) possessed no local provision at any NHS site within their borders.

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Figure 2

Geographical distribution of MRI scans performed in patients with CIED by STP in 2014/15 (left) and 2018/19 (right). Annual volume of MRI scans to patients with CIED performed in England demonstrating widespread geographical variation despite recent localised improvements. Total volume of CIED MRI scans performed per 12 months by STP in England by population (2014/15 data taken from Sabzevari et al9). CIED,cardiac implantable electronic device; STP, sustainabilityand transformation partnership.

Although rates of CIED device implantation vary widely between hospitals (median 288, 95% CI 240 to 336, implants per year, range 0–1560), there was no correlation between sites implanting large volumes of CIEDs and provision of MRI scans to patients with CIED (figure 3). Additionally, 64 implanting hospitals (43% sites) offered no MRI scanning for patients with CIED, despite collectively implanting in excess of 13 600 CIEDs per year (~25% of all UK CIED implants).

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Figure 3

Annual CIED implant volume (bars) and CIED MRI scan volume (circles) by individual NHS hospital 2018/19. There is no relationship between the number of CIEDs implanted (demand) and the volume of MRI scans performed (supply) in patients with CIED between individual NHS Hospital Trusts. CIED,cardiac implantable electronic device; NHS, National Health Service.

Discussion

Despite progress, accessing MRI remains challenging for patients with CIED in England, with almost half of hospitals not providing scans to patients with MRI conditional devices. Four years ago, we demonstrated an estimated 50-fold under provision of MRI scans to this patient group.5 Since then, changes to guidelines, pressure from national societies and increased awareness have been aimed at reducing inequity in provision.8 11 13 These data show some improvements with an increase in scanning volume by 4·5-fold. However, the number of centres providing cardiac device MRI services has not increased significantly over the studied period. This suggests that many hospitals are relying on the existing infrastructure currently available in other hospitals, rather than initiating their own services, evidenced by survey data showing that 23 hospitals currently have formal relationships with other hospitals to provide cardiac device MRI to their patients. It is estimated that England needs 50 000 such scans a year meaning there is still an estimated 10-fold under provision.4 15 16 This care gap is uneven geographically (five STPs with no provision) and greatest for patients with legacy non-MR conditional devices where three sites provide half of the national scan volume. There appears to be no relationship between supply and demand of CIED MRI scans—many sites that implant high numbers of devices still do not provide MRI scans to these patients or do so only at small volume. We found that of those centres that do not scan patients with CIED but are high-volume implanting sites (>457 implants per year, top quartile of all UK implanting centres), 25% reported lack of support from cardiology as the main barrier to providing MRI to patients with CIED. The British Heart Rhythm Society Standards for Implanting Centres19 have highlighted the requirement for implanting centres to provide pacing support for local MRI scanning for their patients, and, hence, hopefully should help to redress this current gap. These findings are in line with previous studies from other countries where delivery of MRI to patients with CIED is highly variable between individual centres, and patients still report challenges with accessing scans at every level from referral bias to departmental barriers.20 21

MRI is a fundamental component of many diagnostic and treatment pathways, and these data highlight the work that still must be done to eliminate the inequity still facing cardiac device patients. These data demonstrate that only 0·14% of the total volume of MRI scans acquired annually in England are performed in patients with CIEDS in England currently,22 despite their representing almost 1% of the population and a group with significant comorbidities and, hence, high clinical need for diagnostic imaging. Previous data have shown that the diagnostic yield from MRI in patients with CIED is high,11 23 resulting in changes to diagnosis, prognosis or clinical management in the majority of patients. The current survey also highlights that scanning is safe with very low complication rates even across patients with non-MR conditional CIED (0·06%). These data add to a growing body evidence supporting the safety of expansion of MRI services to all patients with CIED, provided strict protocols are followed.

There is significant regional and institutional variability in service provision, with patients with CIED in several areas having no access to MRI locally. Given this heterogeneity in CIED–MRI activity between institutions, it is important to understand the barriers to service development and expansion while recognising successes. Safety concerns appear no longer to be a major barrier, likely reflecting the increased body of safety data alongside more published guideline recommendations.17 The principal remaining barrier now relates to the logistical burden and coordinating cardiology and radiology teams. Currently, in most MRI departments, imaging is performed as per standardised protocols that obviate the need for the physical presence of a radiologist. This, combined with concerns regarding potential reduced scanner throughput with downstream impact on departmental productivity, means that many radiologists and managers fail to support initiating CIED–MRI services. Digital referral platforms that can centralise patient information and multidisciplinary decision-making may streamline the process. Hospitals scanning high volumes of device patients are generally those with large cardiology departments where collaboration is strong between the departments and where a ‘one-stop’ model can be employed to enable dedicated device MRI lists with cardiac physiologists present in the MRI department.17 However, these data also highlight that it is not essential to have cardiac pacing facilities on site—several hospitals are able to operate device MRI services using visiting cardiac physiologists from neighbouring hospitals/sites to perform device interrogation and reprogramming. Conversely many hospitals that implant large volumes of pacemakers and defibrillators still fail to offer MRI scans, despite clear UK guidelines requiring implanting cardiologists to support radiology departments to deliver MRI services to their patients.14

There is high-level consensus from leading cardiology and radiology groups that cardiac device patients must not be denied their right to equitable access to MRI. A multi-faceted approach will be required to achieve this aim and a Joint Societal Working Group for Cardiac Device MRI has been formed in the UK with representation from the National Societies of all stakeholders involved (patients, radiology, cardiology, medical physics, radiographers, referrers, NHS England). Repeated top-down recommendations to promote change have also provided impetus and mandates for change as demonstrated by the Royal College of Radiologists and British Cardiovascular Society in 2018.16

Other nationwide initiatives to encourage service provision include ongoing work regarding financial remuneration for scans to reflect increased scan complexity, changes to electronic requesting for scans, platforms to facilitate data transfer relating to implanted device details (including mrimypacemaker.com) and formal training of both clinicians and referrers.

Conclusion

Almost half of the hospitals in England do not provide MRI scans to patients with MR conditional CIEDs despite awareness of technological advances and safety data. There remains an estimated 10-fold under provision despite an almost fourfold increase in scan volume over 4 years, with significant regional and institutional variation and little relationship between supply and demand. Barriers to change remain largely logistical and financial; however, these must be addressed to alleviate the current inequity in clinical care that cardiac device patients face.