Evaluation of a second-generation intercostal extravascular implantable cardioverter defibrillator lead with a pectoral pulse generator for sensing, defibrillation, and anti-tachycardia pacing

Abstract

Aims: Intercostal extravascular implantable cardioverter defibrillator (EV-ICD) leads may work better in contact with the pericardium thereby directing pacing and defibrillation energy towards excitable myocytes. We report 3-month safety and performance outcomes with a second-generation intercostal EV-ICD lead paired with standard, commercially available ICD pulse generators (PGs).

Methods and results: Subjects undergoing a transvenous ICD (TV-ICD) procedure received a concomitant intercostal EV-ICD lead system. The intercostal EV-ICD lead was connected sequentially to a PG in a left pectoral and then a left mid-axillary location. Extravascular ICD lead assessment included sensing and defibrillation of induced ventricular arrhythmias and pacing capture. The intercostal EV-ICD system was followed in a 'recording-only' mode and the control TV-ICD system in 'therapy delivery' mode to compare stored events. Devices were evaluated prior to hospital discharge, 2 weeks, 1 month, 2 months, and 3 months post-implant. Defibrillation testing was repeated prior to lead removal; 20/20 (100%) were successfully implanted (median implant time of 9 min). Two major lead complications were reported over a mean of 82 days: (i) lead movement and (ii) infection of both the TV-ICD and EV-ICD systems. Intraoperative pacing capture was achieved with the integrated bipolar configuration in 19 of 20 (95%) subjects. Pacing capture with the EV-ICD system was tolerated in all subjects, with over 90% feeling no pain after a 1-month recovery from the procedure. Induced VF episodes were sensed in all subjects and defibrillated successfully in 17 of 17 patients (100%) with a left mid-axillary PG and 19 of 20 patients (95%) with a left pectoral PG. Sensing and defibrillation were successful in 18 of 18 (100%) tested prior to lead removal.

Conclusion: In this pilot experience with a second-generation intercostal EV-ICD lead implantation, sensing and defibrillation of induced VF were successful when paired with a standard ICD PG from either a left mid-axillary or pectoral pocket.

Clinical trial registration: NCT number: NCT05791032; URL: https://clinicaltrials.gov/study/NCT05791032.

Keywords: Anterior mediastinum; Defibrillation; Extravascular; ICD; Intercostal.

Graphical Abstract

Figure 1

The STEP ICD Study enrolled patient disposition. EV-ICD, extravascular implantable cardioverter defibrillator; TV-ICD, transvenous implantable cardioverter defibrillator.

Figure 2

Acute defibrillation performance with a mid-axillary PG. Cumulative percentage of subjects successfully converting induced ventricular fibrillation at incrementally higher energy levels from a mid-axillary implanted PG. The maximum energy from the implanted PGs ranged from 36–41 J. J, Joules.

Figure 3

Extravascular ICD pace termination of induced ventricular tachycardia post-implant. The recorded electrogram illustrates an ATP entrainment of induced (programmed stimulation) monomorphic ventricular tachycardia at a cycle length of 480–520 ms. The top ECG is a surface lead. The middle tracing is the device’s marker channel. The bottom ECG is an extracardiac electrogram. The slow ventricular tachycardia is entrained with overdrive pacing at 350 ms and exhibits a Type I termination to sinus rhythm post extracardiac pacing.

Figure 4

Patient-reported pacing sensation at maximum output of the EV-ICD PG. This graphic shows the patient reported sensation during maximum pacing output from the implanted commercial ICD PG connected to the EV-ICD lead over the entire term of implant. The trend demonstrates a lack of intolerable pain during pacing post discharge. The pacing sensation shows a clear improvement in tolerability and sensation to high-output pacing over time. EV-ICD, extravascular implantable cardioverter defibrillator; Intolerable, intolerable pain; MAX, maximum.