The use of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs) has increased dramatically in recent years, due in part to expanded indications for their use, and an aging society. Furthermore, as many as 75% of patients who currently have an implantable cardiac electronic device will need MRI during their lifetime.
In the past, cardiac pacemakers and other types of implantable cardiac device have been regarded as one of the few absolute contraindications for MRI examination, such was the concern that the powerful magnetic and radiofrequency fields used during the imaging process might damage the device, inhibit pacemaker function or deliver inappropriate shocks. However, thanks to advances in MRI-compatible device technology, and an increase in collaboration between clinical specialties and device manufacturers, such devices are now no longer absolute contraindications and departments such as The Heart Hospital Imaging Centre and Chenies Mews Imaging Centre in London are now offering this vital service. Whilst the use of MRI for patients with cardiac devices is still not seen as being a ‘routine’ examination, great progress has been made in developing practices and protocols which ensure patient safety and minimise risk so as to make this important and often irreplaceable form of medical imaging available to a group of patients who historically, have been turned away from MRI departments.
In a recent joint consensus paper published online (15th February 2017) in the German Journal RoFo: Fortschritte auf dem Gebiet der Rontgenstrahlen und der Bildgebenden Verfahren (Progress in the field of X-ray and Imaging techniques), the German Rontgen Society and the German Cardiac Society both offered several points of consideration for departments and clinicians aiming to offer an MRI service to these patients. These included:
- The adoption of procedural management which includes the assessment of the individual risk/benefit, comprehensive informed consent and extensive precautions to reduce risk to the greatest extent possible.
- Strict determination as to the validity of the MRI indication and a critical review of the risk/benefit ratio in each patient.
The authors underscore that their overall aim is to “optimise patients safety and to improve legal clarity in order to facilitate access of pacemaker/ICD patients to MR imaging”. They state that this complex subject requires “close collaboration between radiology and cardiology”.
Whilst it is likely that MRI conditional pacemakers and possibly ICDs will become standard in the near future, there is a significant section of population who in the interim will rely on departments such as ours, who are taking this innovative step forward to offer them a safe MRI service.