ProMRI Study of the Iforia ICD System (Phase C)

Inclusion Criteria: The following initial inclusion criteria must be met for a subject to be enrolled and considered for the MRI-procedure: * Age greater than or equal to 18 years * Able and willing to complete MRI testing * Able to provide written informed consent * Available for follow-up visit at the study site * Implanted with an ICD System consisting only of an Iforia DR-T and Linoxsmart S 65 / Linoxsmart SD 65/18 with Setrox S 53 atrial lead or Iforia VR-T DX and Linoxsmart S DX 65/15 or Linoxsmart S DX 65/17. * ICD implanted pectorally * All ICD system components implanted, repositioned, or exchanged at least 5 weeks prior to enrollment * Underlying rhythm identifiable during sensing test * All pacing thresholds are measureable and are less than or equal to 2.0 V @ 0.4 ms (Criterion does not apply to atrial pacing threshold for subjects with an Iforia DR-T that have AF and are permanently programmed to VVI and for subjects with an Iforia VR-T DX) * Ventricular sensing is measurable and \>6.5mV * Absence of phrenic nerve stimulation at 5.0V and 1.0 ms * Pacing impedance is between 200 and 1500 ohm * Shock Impedance is between 30 and 90 ohm * Able and willing to use the CardioMessenger II At the pre-MRI procedure, the following procedure-related criteria must be met for the subject to undergo the MRI scan: * Absence of phrenic nerve stimulation at 5.0V @ 1.0 ms * \|pacing threshold at Pre-MRI follow-up - pacing threshold at baseline\| ≤ 0.5 V (ICD Lead Only) * All pacing thresholds are measureable and are less than or equal to 2.0 V @ 0.4 ms (Criterion does not apply to atrial pacing threshold for subjects with an Iforia DR-T that have AF and are permanently programmed to VVI and for subjects with an Iforia VR-T DX.) * Ventricular sensing is measurable and \>6.5mV * The ICD system has been implanted for at least six weeks. * Subject did not have an ICD or lead explant, exchange or reposition in the previous 6 weeks. * All lead pacing impedances are between 200 and 1500 ohm * Shock impedance is between 30 and 90 ohm * Battery status is at least 30% of capacity