Cardiac MRI is useful for identifying the myocardial scar that is the substrate for ischemic ventricular tachycardia. However, most ischemic ventricular tachycardia mapping procedures are done in patients with implantable cardioverter defibrillators. The absence of a completely MRI-compatible implantable cardioverter defibrillator (or the presence of other contraindication to MRI) is a significant barrier to the routine use of cardiac MRI in this setting. This barrier, however, does not completely exclude the possibility of performing cardiac MRI with a defibrillator in situ. MRI protocols for some implanted cardiac devices have been published with documentation of points of concern as well as statements that MRIs can be obtained without prohibitive image compromise and without adverse effects to the patient or the device (devices implanted on or after the year 2000).27 In the study by Nazarian and Halperin,27 emphasis was placed on the preprocedural review of the chest x-ray to assess all used and abandoned hardware. Lead length and loops were noted to increase current and therefore create heat. A specific absorption rate (SAR) of ≤2.0 W/kg was recommended with the noted caveat that the SAR-to-heat correlation is not consistent among different MRI scanners. Recommendations were also made for the use of the largest acceptable field of view, longest repetition time, minimal flip angle, and minimal acquisition bandwidth. There was notation that magnetic fields can flip reed switches, which may affect the function of certain devices. A full device interrogation was recommended before MRI scanning (checking battery voltage, sensing, impedance, pacing threshold, and programmed parameters) and after MRI scanning to assure stability. Tachycardia detection and tachycardia therapy were programmed off prior to MRI to prevent filling tachycardia counters with noise and to prevent inappropriate tachycardia therapies for electromechanical interference associated with performance of the cardiac MRI. For pacemakers, pacing parameters were programmed to an asynchronous mode (if pacemaker dependent) or VVI/DDI (if underlying rhythm was stable) to avoid inhibition of pacing or tracking of noise, respectively (MRI scanning was not recommended for implantable cardioverter-defibrillator patients if pacemaker dependent). All magnet response features were disabled. Recommendations were made for blood pressure, ECG, oxygen saturation, and symptom monitoring with physicians and advanced cardiac life support equipment present. Imaging planes perpendicular to the device generator with shortened echo time and use of spin-echo and fast spin-echo spoiled gradient recall echo cine were used to reduce qualitative device artifacts. Implantable loop recorders are MRI safe; however, the data recorded on these devices must be downloaded prior to MRI and the memory must be cleared after MRI to avoid overwriting previous useful electrogram data with electromechanical interference and to avoid maintaining arrhythmia logs filled with electromechanical interference, respectively. Temporary pacing wires, abandoned leads, and epicardial leads are not MRI safe. MRI should not be performed within the first 6 weeks after device implant. Although the total number of patients in this study was relatively small, the combination of imaging success and absence of adverse outcomes is encouraging. Underreporting of adverse consequences, however, remains a concern; therefore, prior to attempting MRI with a pacemaker or defibrillator in situ, consideration must be given to the risk-benefit analysis of this endeavor. For further investigation of questions regarding MRI compatibility, useful information can be obtained from the following Website: http://www.mrisafety.com/.