Is it clinically worthy to optimise CRT device programmation? A mid-term follow up study in patients with heart failure and LBBB

pacemakers, ICDs and bi-ventricular ICDs. Methods: Devices included Identity ADx XL DR 5386, Identity ADx DR 5380, Atlas V-243, EpicTM V-236, EpicTM HF V-350, 1688T/ 52-cm atrial and ventricular leads, Riata 1581/65cm high voltage lead, and QuickSite 1056K/75cm left ventricular (LV) lead from St. Jude Medical, Sylmar, CA. Devices were evaluated for magnetic field interactions (force and torque). MRI-related heating was assessed with guidance from ASTM F2182 using various levels of RF power and imaging conditions that included scans on different body regions. Each system was placed in a gelled-saline-filled, head/torso phantom to simulate typical clinical placements and temperatures were recorded using fluoroptic probes. Functional aspects of the devices in DOO and DDD were evaluated immediately before and after MRI was performed utilizing nine different pulse sequences. Imaging artifacts were characterized using T1-weighted and gradient echo pulse sequences. Results: All scans of the “head” and “lumbar” regions resulted in temperature increases less than or equal to 0.5C at SAR (Specific Absorption Rate) levels of 2.0 3.0 W/kg. The temperature increase ranged from 0.4 C 3.6 C at a SAR of 2.0 W/kg when scanning the “chest” region, with a maximumum increase of 0.9 C at the LV tip and 3.6 C at the ICD lead tip in the RVOT. No memory corruption, hardware changes, or changes in device parameters were seen. Oversensing was observed at the most sensitive device settings when programmed to DDD during some of the MRI scans with totally normal function at all other times. Device function was unaffected in DOO. The magnetically induced displacement force was no greater than 0.05 N for the pacemakers and 1.6 N for ICDs. Image artifacts were substantial for the pulse generators and minor for the leads. Conclusion: No physiologically significant heating or magnetic field interactions were observed in the tests performed. There was no permanent effect on the device function. These findings have important implications for patients with these devices and are consistent with recent published articles.