Cardiovascular Magnetic Resonance in Patients With Magnetic Resonance-Conditional Cardiac Implantable Electronic Devices: What Can We See?

Abstract

Patients with pacemakers and implantable cardioverter defibrillators (ICDs) have been commonly withheld from magnetic resonance imaging (MRI) procedures because of magnetic resonance (MR) safety concerns. In response to this clinical need, MR-conditional pacemakers and ICDs have been developed to allow these patients access to MRI. The potential interactions between MRI and recently developed MR-conditional implantable electronic devices have been extensively studied and reviewed.1–4 These interactions include magnetic force and torque, radio frequency-induced heating, induction of electric currents, and electromagnetic interference. Medical device manufacturers have modified the designs of pacemakers and ICDs by using less ferromagnetic material, developing innovative lead wires to reduce radio frequency heating, and advancing circuitry and shielding to reduce electromagnetic interference. The safety and efficacy of these MR-conditional devices have been the primary end point of the EnRhythm,5 Advisa,6 and Evera-MRI7 trials, among others. See Article by Schwitter et al The Evera-MRI trial was a multicenter, international, randomized clinical study with 275 enrolled subjects in 42 centers. The focus of the clinical study was to confirm the safety and efficacy of an MR-conditional ICD system (Evera MRI ICD Medtronic, Inc, Minneapolis, MN) in patients subjected to a 1.5T MRI examination.7 In this issue of Circulation: Cardiovascular Imaging , Schwitter et al8 report on the diagnostic quality of cardiovascular magnetic resonance (CMR) images acquired in patients enrolled in the Evera-MRI trial. Steady-state–free precession (SSFP) and fast gradient echo (FGE) cine CMR pulse sequences were used to acquire images of the left ventricle and right ventricle (RV) and graded for image quality. In a similar previous study by the same group, Schwitter et al9 reported on the impact of the Advisa MRI pacing system on the quality of CMR images and found that high-quality CMR images were attainable in the …