Introduction: The Biotronik DX lead is a defibrillator lead that has been in use since 2010. It offers atrial sensing from the floating dipole as it passes through the atrium. This improves tachyarrhythmia discrimination and can provide atrioventricular synchrony in patients who develop a need for pacing with a single ventricular lead in situ. Our operators noticed a series of failed DX leads at our centre and so we aimed to compare outcomes of the DX lead with a comparator group, non-DX Biotronik defibrillator leads.
Methods: The electronic health record was interrogated for all patients with a new Biotronik implantable cardioverter defibrillator (ICD) device, generator change or lead revision at our centre from 1 January 2012 to 31 December 2021. Lead failure was defined as need for replacement or revision.
Results: A total of 275 patients were identified (81.4% male, age 66 ± 12 years). Six patients were excluded (5 DX leads) due to being followed up out of area, leaving 269 patients. Overall, 99 had DX leads and 170 had non-DX leads; 81 (30.1%) had an atrial lead. Data showed that 22/269 patients (8.2%) experienced 25 lead failures over a median follow-up of 1436 days (841–2,387). Overall, 3/99 of the DX leads failed over 1,938 days (872–2462) and 22/170 of the non-DX leads over 1,262 days (848–2,275) (3.0% vs 12.9%; p=0.007). Median time to failure across both groups was 1,736 days (808–2421). None of the 99 DX leads and 4/170 non-DX leads displaced within 2 weeks of implant (0% vs 2.4%; p=0.30). One lead displaced 10 days after implant and then failed at 4.6 years and was replaced. Excluding acute lead displacement only as a cause of failure, lead failure remained lower in the DX group: DX 3/99 vs non-DX 19/170 (3% vs 11.1%; p=0.0199) (Table 1). Four of the 25 (16%) lead failures resulted in inappropriate shocks due to late displacement (n=1) and noise (n=3). There were no adverse events due to lead repositioning. One patient had an occluded subclavian that prevented new lead insertion. Programming data were unavailable for 3 DX leads. Of the remaining 96, 29 (30.2%) had the SMART tachyarrhythmia discrimination function disabled and 68/96 (70.8%) had been re-programmed VVI due to atrial sensing issues or onset of permanent AF; 25 (26.0%) had both SMART deactivation and reprogrammed VVI and hence used none of the DX function. Vascular access was achieved using cephalic (177/269, 65.8%), axillary (35/269, 13.0%) or subclavian (57/269, 21.2%) approaches. Of the failed leads, a cephalic (13/25, 52.0%), axillary (5/25, 20%) and subclavian approach (7/25, 28%) was used. Conclusion: Although most patients with DX leads were reprogrammed due to problems with sensing (70.8%), DX leads failed at a lower rate than non-DX Biotronik leads (3.0% vs 12.9%; p=0.007) over similar follow-up periods. We presume that the sensing issues introduced a bias against DX leads and our findings highlight the importance of collecting objective data. Our data show that real-world ICD failure rates are higher than those quoted in the Biotronik product performance report (2022 first edition), which are between 0.48% and 2.4% for DX leads and 0.87%–5.9% for non-DX leads. The incidence of inappropriate shocks from failed leads was low (16%), and lead repositioning and replacement was safe and possible in most cases.