Abstract 14266: Magnetic Resonance Imaging for Patients with Implanted Cardiac Devices: Prospective Study to Assess Safety and Utility
Background: Most patients with implantable pacemakers and defibrillators are currently denied magnetic resonance imaging (MRI) due to safety concerns. We performed a study to define the safety and diagnostic utility of MRI at 1.5 Tesla in implanted cardiac device recipients.
Methods: A prospective study was conducted at two tertiary care centers between October 2003 and April 2010. Four hundred and thirty eight patients, 54% with pacemaker and 46% with implantable defibrillator systems, previously shown to be MRI safe, underwent 555 MRI studies. Pacing mode was changed to asynchronous for pacemaker-dependent patients and to demand for others. Magnet response and tachyarrhythmia functions were disabled. Blood pressure, ECG, oximetry, and symptoms were monitored.
Results: No episodes of inappropriate inhibition or activation of pacing or therapy delivery were observed. Three devices exhibited power-on-reset events with no clinical sequelae. Immediate device assessment revealed small reductions in right ventricular sensing, lead impedances, and battery voltage (Table). At follow-up (median 214 days), a small increase in right ventricular capture threshold and decrease in right ventricular sensing and battery voltage were noted (Table). Individual and aggregate device parameter changes were below clinically significant thresholds and lead/system revision or device reprogramming was not necessary. Diagnostic imaging questions were answered in 98.8% of non-thoracic and 94.9% of thoracic studies (P=0.012). In patients referred for brain imaging, computed tomography yielded a definite diagnosis in 27% whereas MRI yielded a definite diagnosis in 94% of cases (P<0.001).
Conclusions: MRI can safely be performed with significant diagnostic yield in patients with selected implantable pacemaker and defibrillator systems. Due to the potential for power-on-reset events and changes in device parameters electrophysiology monitoring during MRI is essential.
- © 2010 by American Heart Association, Inc.