Department of CardiologyThe Prince Charles HospitalRode RdChermside Qld 4032AustraliaAuthor NoteConflicts of Interest: Institution received research funding for EV FIH study from Medtronic.Funding: NilORCID Number: 0000-0003-4819-6922Removal of EVICD leads are specialized tools required?Implantable Cardiac Defibrillators (ICDs) have improved the survival of patients at risk of sudden death and are widely indicated1]. Up until recently ICDs have been implanted transvenously and unfortunately been associated with a relatively high rate of lead complications during follow up 2. This often requires lead extraction which incurs some risk and is only available at specialized centers3. To overcome some of the limitations of the transvenous lead, Extravascular ICD (EVICD) systems have been developed over the last 15 years. First with a lead placed in the subcutaneous tissues above the sternum4and more recently in the retrosternal extravascular space above the pericardium 5 . Like all implantable cardiac devices these systems do fail and may require removal usually for either infection or lead related issues. Given the limited experience and the unique location of the EVICD lead in the retrosternal space the optimal management and risks associated with removal are still well defined.Sagi et al 6recently reported the largest clinical experience to date with removal of the EVICD lead from the retrosternal space. In 347 patients enrolled in three pre-market approval studies, lead removal was performed in twenty-nine patients at a mean of 12.6 months post implant. The overall success rate was 93.1%. (27/29). Leads with a dwell time of less than one year had a 100% success rate of removal (19/19) and required only simple traction in all cases. Leads with a dwell time of greater than 12 months had a lower success rate of 80% (8/10). Simple traction failed in six cases and extraction tools (laser or mechanical) were used in five cases with a success rate of 80%. One lead was abandoned. The longest dwell time for a successfully removed lead was 36.8 months. Importantly there were no procedural related complications.The paper by Sagi suggests that early removal of the EVICD lead within 12 months of implant is a safe and simple procedure requiring no more that simple traction. For leads longer than 12 months, however the optimal technique is still not clear and simple traction alone was not always successful. Delving into the reasons for failure of simple traction and the use of extraction tools, all appear to be related to the presence of dense adhesions at the sub xiphiod incision or diaphragmatic insertion area rather than the retro sternal space. This suggests that extensive dissection along the lead body to the level of the diaphragmatic insertion may be required before an extraction tool is used. Furthermore, if an extraction tool is used it is likely to be particularly important that the lead and tool be always kept coaxially. The angulation often seen as the lead passes under the sternum may result in the extraction tool damaging the outer insulation, which will cause significant weakening of the tensile strength of the lead which may result in it breaking and failure of removal. In the series by Sagi et al the longest dwell time was 58 months, and this lead was not successfully removed. The premature use of both a laser sheath and mechanical tool to assist the removal procedure, prior to adequate dissection of the sub diaphragmatic space resulted in disruption of the outer insulation, loss of tensile strength and subsequent breaking of the lead which left 6.4 cm remaining in situ. It should be noted the EVICD lead, unlike traditional transvenous leads, is lumenless and hence a locking stylet cannot be used to create a rail and assist with use of extraction tools.In this issue of the journal two case reports from Chauhan7 and de Veld [8] extended the dwell times of EVICD leads successfully removed to 43 and 49 months, respectively. In both reports, the leads were removed with simple traction after the suture sleeve was released and dissection was performed along the lead towards the sub diaphragmatic surface. Both these cases highlight the importance of adequate dissection in the sub diaphragmatic space as most adhesions associated with this lead appear in this region rather than the retrosternal space. It may be best to avoid the use of extraction tools which are not design for the lumenless EVICD lead until adequate dissection has been performed The premature use of the tools prior to adequate dissection of the sub diaphragmatic space may in fact hinder the removal of the lead due to disruption of the outer insulation and loss of tensile strengthThese reports add to the evidence suggesting these leads can be removed safely with simple techniques at a medium term follow up of 4 years, while this is reassuring it must be remembered the experience with removal of these leads is still small and with short dwell times. It is reassuring that the site of all adhesions to date appear to be in the sub xiphiod and sub diaphragmatic space rather than the retrosternal space. Hopefully, this means potentially more serious complications related to cardiac injury during lead removal from adhesions related to the pericardium remain rare. The optimal personnel to perform this procedure (electrophysiologist or cardiac surgeon), location (EP lab or operating room) and even the need for pre removal imaging if any is still not clear. Will leads with dwell times of 10 years or more be as easy to remove. These are all unknowns at present and the answers will only become clearer as the experience grows. For the time being the removal of these leads, especially if older than 12 months, should probably continue to be undertaken, by cardiac teams experienced in implanting the device with a good understanding of the sub diaphragmatic space. With adequate dissection of the lead, transvenous lead extraction tools may be rarely required. To date there continues to be no procedural complications reported with removal of the EVICD lead and with time this may prove to be yet another advantage of the EVICD over traditional transvenous ICD even when implanted in the novel retrosternal space.References1. Zeppenfeld K, Tfelt-Hansen J, De Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J . 2022;43(40). doi:10.1093/eurheartj/ehac2622. Koneru JN, Jones PW, Hammill EF, Wold N, Ellenbogen KA. Risk factors and temporal trends of complications associated with transvenous implantable cardiac defibrillator leads. J Am Heart Assoc . 2018;7(10). doi:10.1161/JAHA.117.0076913. Bongiorni MG, Kennergren C, Butter C, et al. The European Lead Extraction ConTRolled (ELECTRa) study: A European Heart Rhythm Association (EHRA) Registry of Transvenous Lead Extraction Outcomes.Eur Heart J . Published online 2017. doi:10.1093/eurheartj/ehx0804. Bardy GH, Smith WM, Hood MA, et al. An Entirely Subcutaneous Implantable Cardioverter–Defibrillator. New England Journal of Medicine . Published online 2010. doi:10.1056/NEJMoa09095455. Friedman P, Murgatroyd F, Boersma LVA, et al. Efficacy and Safety of an Extravascular Implantable Cardioverter–Defibrillator. New England Journal of Medicine . 2022;387(14). doi:10.1056/nejmoa22064856. Sagi V, Murgatroyd F, Boersma LVA, et al. Comprehensive analysis of substernal lead removal: experience from EV ICD Pilot, Pivotal, and Continued Access Studies. Europace . Published online August 30, 2024. doi:10.1093/europace/euae2257. Chauhan K, Royse A, Goh I, Crozier I, Wynn G. Oldest-in-Human Successful Extraction Experience of a Novel Substernal Extravascular Defibrillator. J Cardiovasc Electrophysiol . Published online November 22, 2024. doi:10.1111/jce.165118. de Veld J, Kooiman K, Knops. Uncomplicated extravascular implantable cardioverter extraction after four years dwell time: a case report. J Cardiovasc Electrophysiol