Abstract 183: Safety and Utility Outcomes of Off-label Magnetic Resonance Imaging on Patients With Cardiovascular Implantable Electronic Devices

Background: Off-label magnetic resonance imaging (MRI) for patients with cardiac implantable electrical devices (CIEDs) has been limited due to concerns about safety and unclear diagnostic and prognostic utility. Methods: We evaluated all patients with CIEDs not FDA-approved as MRI-conditional who were referred to our clinical protocol for off-label imaging from June 2014 - October 2016. All referrals were screened by radiology and electrophysiology, with peri-MRI programming and monitoring performed by cardiology. Clinical and device characteristics were abstracted from electronic records. The primary safety outcome was the incidence of major adverse events (loss of pacing, inappropriate shock or anti-tachycardia pacing, need for system revision, or death). The primary clinical outcomes were (1) interpretability and (2) utility of MRI, with the latter graded independently by two reviewers according to whether the MRI changed management, prognosis, or guided intervention. Secondary safety outcomes included or minor adverse events (inappropriate pacing, arrhythmias, power on reset events, or discomfort at the generator site), and clinically significant changes in lead parameters or battery life both (1) immediately post-MRI and (2) at six months. Results: A total of 190 MRIs were performed on 123 patients (63.1% men, mean age 70±18.5 years, 37.0% ICDs, 21.8% pacemaker-dependent) predominantly for brain or spinal conditions (Figure). Nearly one quarter (22.7%) were performed for urgent or emergent indications. Major adverse events were rare: no deaths or system revisions; 1 patient with loss of pacing without clinical sequelae (overall rate, 0.5%). Nearly all (98.4%) studies were interpretable, while 74.9% were determined to change management based on pre-specified criteria. Minor adverse events were unusual (overall rate 1.6%): 2 reports of heating at the generator site; 1 patient with an atrial arrhythmia. No clinically significant changes were observed in device parameters acutely after MRI or at 6 months as compared with baseline across all patient and device categories. Conclusions: Off-label MRIs performed under a strict clinical protocol demonstrated reassuring safety outcomes while providing interpretable imaging that frequently influenced clinical care.