The 5086MRI pacing lead, designed for use during Magnetic Resonance Imaging, demonstrates electrical and handling performances comparable to a well-established screw-in pacing lead

Purpose: To compare short and long term electrical and handling performances of the Medtronic 5086MRI and 5076 pacing leads.

Methods: Both leads are silicone, steroid-eluting with an extendable retractable screw. Lead tip and ring electrode surfaces as well as tip-ring spacing are identical. The 5086MRI inner coil was modified for the purposes of increasing its safety in the MRI environment. This resulted in a lead body diameter difference of 0.3 mm (5086MRI: 2.3 mm vs. 5076: 2.0 mm). Pacing capture threshold, sensed amplitude and adverse events of the 5086MRI lead were collected during follow-up in the EnRhythm MRI trial (randomized multi-center). Data from patients (pts) who underwent an MRI at 9-12 weeks post-implant was compared to those that did not. Data was also compared to two studies including many 5076 leads (5076 and Insync III trial). Lead handling was quantitatively assessed through physician feedback in the EnRhythm MRI and 5076 trial.

Results: In total, 466 pts were successfully implanted with the 5086MRI lead in both the atrium and ventricle (mean follow-up 29.8±9.5 months, range 0-44 months). Pts were randomized to either receive an MRI (260 pts) or not (206 pts). The pacing thresholds and P- and R-wave amplitudes of the 5086MRI lead were stable over 3 years of follow-up. The electrical data for the 5086MRI lead was similar whether used in MRI or not (mean ventricular data at 3 years was respectively: 1.1V and 0.9V for pacing thresholds (Δ 0.2V, 95% confidence interval (C.I.) (-0.06, 0.41)), 9.2mV and 10.0mV for sensed amplitudes (Δ -0.8mV, 95% C.I. (-2.24, 0.60))). In total, 316 pts had 5076 leads implanted (316 in atrium, 315 in ventricle, mean follow-up 9.65±6.8 months, range 0-26 months). Mean ventricular pacing thresholds were comparable for the 5086MRI and 5076 (respectively 0.94V and 0.73V at 18 months, Δ -0.21V, 95% C.I. (-0.33, -0.09)). A difference ≤0.5V in threshold was considered clinically insignificant. Mean R-wave amplitude at 18 months were 9.83mV (base to peak) and 15.23mV (peak to peak), respectively. The estimated 5086MRI lead complication-free survival rate at 2 years was 92.0%, which was similar to 5076 lead (89.0%, log-rank p=0.167). 5086MRI lead handling either met or exceeded expectations in approximately 90% of the respondents. Handling for both leads was equivalent (p<0.001).

Conclusions: The 5086MRI lead demonstrated low pacing thresholds and appropriate sensing over time even after undergoing MRI. Pacing properties, lead complication-free survival rate and lead handling of the 5086MRI lead were similar to the 5076 lead.