Abstract 2804: Pacemaker and Implantable Cardioverter Defibrillator Safety for Patients Undergoing Magnetic Resonance Imaging (The MagnaSafe Registry)
Magnetic resonance imaging (MRI), the diagnostic modality of choice without acceptable alternative for many disease states, has been contraindicated due to safety concerns for patients with pacemakers (PM) and implantable cardioverter defibrillators (ICD). The MagnaSafe Registry is a prospective study to determine the safety of MRI for patients with PMs and ICDs. The MagnaSafe Registry protocol includes: Informed consent obtained by a cardiologist who is present during the exam; non-invasive monitoring during the study; available ACLS equipment; and device interrogation before and after MRI. Prior to imaging, all ICD tachycardia therapies are programmed to monitor only. Patients with symptomatic bradycardia or pacemaker dependence are programmed to an asynchronous pacing mode (DOO or VOO). Pts with sinus rhythm >50/minute are programmed to no pacing. Initial device parameters are restored immediately after imaging. Pacing thresholds, lead impedance, P and R wave amplitude, battery voltage, are recorded pre and post MRI. From January 2006 to April 2008, during the single center phase, 51 pts (age 55±17 yrs) underwent a total of 61 scans; 17 had coronary disease (33%) and 1 was pacer dependent (2%). A change in battery voltage occurred in 6 of 19 pts (37%) with complete data sets. Four experienced a decrease in battery voltage and 2 an increase (range −0.05– 0.04). Complete lead impedance data were available for 47 leads (75%). The mean change in impedance was −5.3±27.5 Ω. Complete threshold data were available for 34 leads (15 atrial, 16 RV, and 3 LV) with 8 threshold increases and 2 decreases (range 0.125– 0.75V). No patient had more than one lead affected. One device with a 0.75V threshold rise required reprogramming. None of the 4 pts undergoing cardiac MRI had threshold changes and there was no association between the scan performed and the occurrence of a threshold change. Of 8 pts with a threshold increase, 2 also had a change in battery voltage. One patient had a magnet response and was removed from the scanner. Preliminary results of the MagnaSafe Registry demonstrate an acceptable safety profile and a low incidence of battery voltage, lead impedance, and pacing threshold change after MRI in patients with PMs or ICDs.