Abstract Body (Do not enter title and authors here): Background: Over the last two decades substantial efforts have been aimed at improving acceptability of pacemakers and ICD's in the MRI scanner. Many labs have evaluated the construction, safety, efficacy, reproducibility and more recently, clinical impact value in such legacy devices. In conjunction, there has been extensive effort by the major vendors to develop safe MRI compatible devices. We believe that there remain few reasons for hesitation in more universal useage of any PM/ICD in the MRI bore. Yet, mixing vendor leads and generators remain a major hurdle considerably limiting contemporary MRI usage in nearly all MRI laboratories. Accordingly, we Hypothesize: mixed leads and generators have no distinct safety signal from common devices; whether CIED or non-CIED.

Methods: We undertook a retrospective DB analysis to determine safety signals in those patients possessing mixed vendor leads and devices. Comparisons of impedance, amplitude, threshold and battery voltage and patient safety etc. were performed.

Results: Patients from 5/2004 to 5/2024, representing 2008 pts with CIED (78%) and non-CIED (22%) underwent an MRI in a dedicated CMR Lab. The majority of the mixed cohort were obtained from the non-CIED cohort (>98%), having no need for generator replacement.
Accordingly, 12% of these underwent MRI to include: 76% neurologic, 7% orthopedic and 17% cardiac indications.
In safety signals comparisons between standard and mixed lead/generator implants, there were no differences in any implant parameters either pre-MRI or post-interrogation (p=NS). Similarly, there were no peri-MRI pt events reported in the 30d, 180d and 365 day post-MRI scan (p=NS). Importantly, especially for EP considerations, there were no added complications to interrogations.
Moreover, utilizing a similar approach to manipulation of MRI parameters for maximum safety intrinsic to dependent/non-dependent PM status was employed regardless of lead/generator configuration yielding no complications.

Conclusions: Developing a similar approach to MRI scanning in those patients with mixed vendor lead/generator configurations yielded no difference in a multitude of safety, interrogation, devices and efficacy parameters implementing a similar device interrogation/programming strategy as in traditional devices. This reassurance derived from a large MRI lab suggests, despite inherent incompatibility concerns between vendors while in the magnetic field, suggests no such fears are truly warranted.