Over the last several decades, magnetic resonance (MR) imaging has become the diagnostic modality of choice for several conditions, cardiac and non-cardiac. However, MR uses a static magnetic field, gradient magnetic fields and pulsed radiofrequency energy, all of which may interact with metallic and electronic components within the field. As such, patients with cardiac implantable electronic devices (CIEDs) have traditionally been precluded from MR imaging given the potential harm from mechanical force and torque, heating and tissue damage, unwanted myocardial stimulation or electrical reset. Necessity, therefore, drove researchers to study the safety of MR in CIED recipients in vitro and in vivo, and later in patients. This work, in turn, led device manufacturers to make changes to the design of CIEDs and develop MR conditional systems.1 These changes include reducing ferromagnetic components, changing three-dimensional coil configurations, and adding heat-dissipating filters to the generator and leads. In light of accumulating evidence demonstrating its safety, numerous professional societies now support MR in patients with CIEDs, when using safety protocols.2 3

In this edition of Heart, 11 British medical societies (ie, the Joint British Society (JBS)) from the fields of cardiology, cardiac electrophysiology, radiology and medical products regulation, provide recommendations and guidance for MR in patients with CIEDs. The fundamental principle underlying these recommendations is that when benefits of MR outweigh its risks, the scan should be performed after taking all appropriate safety measures. This principal follows the low rates of adverse events reported in large clinical studies that follow a safety protocol and numerous technological advances rendering CIEDs less susceptible to electromagnetic interference, coupled with the potential risks associated with invasive tests and missed or delayed diagnoses when using alternative imaging modalities. Moreover, MR conditional labelling infers that generator and leads were tested in specific combinations and scanning parameters. …