Acute human defibrillation performance of a subcutaneous implantable cardioverter-defibrillator with an additional coil electrode

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) delivers 80 J shocks from an 8 cm left-parasternal coil to a 59 cm3 left lateral pulse generator (PG). A system that defibrillates with lower energy could significantly reduce PG size. Computer modeling and animal studies suggested that a second shock coil either parallel to the left-parasternal coil or transverse from the xiphoid to the PG pocket would significantly reduce the defibrillation threshold. Objective: The purpose of this study was to acutely assess the defibrillation efficacy of parallel and transverse configurations in patients receiving an S-ICD. Methods: Testing was performed in patients receiving a conventional S-ICD system. Success at 65 J was required before investigational testing. A second electrode was temporarily inserted from the xiphoid incision connected to the PG with an investigational Y-adapter. Phase 1 (n = 11) tested the parallel configuration. Phase 2 (n = 21) tested both parallel and transverse configurations in random order.Results: This study enrolled 35 patients (28 males (80%); mean age 51 ± 17 years; left ventricular ejection fraction 40% ± 15%; body mass index 26 ± 4 kg/m2; prior myocardial infarction 46%; congestive heart failure 49%; cardiomyopathy 63%). Compared to the conventional S-ICD system, mean shock impedance decreased for both parallel (69 ± 15 Ω vs 86 ± 20 Ω; n = 33; P &lt; .001) and transverse (56 ± 14 Ω vs 81 ± 21 Ω; n = 20; P &lt; .001) configurations. Shock success rates at 20, 30, and 40 J were 55%, 79%, 97%, and 25%, 70%, 90% for parallel and transverse configurations, respectively. Defibrillation threshold testing was well tolerated with no serious adverse events. Conclusion: Adding a second shock coil, particularly in the parallel configuration, significantly reduced the impedance and had a high likelihood of defibrillation success at energies ≤40 J. This may enable the development of a smaller S-ICD.</p

Trends in adoption of extravascular cardiac implantable electronic devices:the Dutch cohort

Introduction: Conventional implantable cardioverter-defibrillators (ICDs) and pacemakers carry a risk of pocket- and lead-related complications in particular. To avoid these complications, extravascular devices (EVDs) have been developed, such as the subcutaneous ICD (S-ICD) and leadless pacemaker (LP). However, data on patient or centre characteristics related to the actual adoption of EVDs are lacking. Objective: To assess real-world nationwide trends in EVD adoption in the Netherlands. Methods: Using the Netherlands Heart Registration, all consecutive patients with a de novo S‑ICD or conventional single-chamber ICD implantation between 2012–2020, or de novo LP or conventional single-chamber pacemaker implantation between 2014–2020 were included. Trends in adoption are described for various patient and centre characteristics. Result: From 2012–2020, 2190 S‑ICDs and 10,683 conventional ICDs were implanted; from 2014–2020, 712 LPs and 11,103 conventional pacemakers were implanted. The general use has increased (S-ICDs 8 to 21%; LPs 1 to 8%), but this increase seems to have reached a plateau. S‑ICD recipients were younger than conventional ICD recipients (p &lt; 0.001) and more often female (p &lt; 0.001); LP recipients were younger than conventional pacemaker recipients (p &lt; 0.001) and more often male (p = 0.03). Both S‑ICDs and LPs were mainly implanted in high-volume centres with cardiothoracic surgery on-site, although over time S‑ICDs were increasingly implanted in centres without cardiothoracic surgery (p &lt; 0.001). Conclusion: This nationwide study demonstrated a relatively quick adoption of innovative EVDs with a plateau after approximately 4 years. S‑ICD use is especially high in younger patients. EVDs are mainly implanted in high-volume centres with cardiothoracic surgery back-up, but S‑ICD use is expanding beyond those centres.</p

Five-year safety and efficacy of leadless pacemakers in a Dutch cohort

BACKGROUND: Adequate real-world safety and efficacy of leadless pacemakers (LPs) have been demonstrated up to 3 years after implantation. Longer-term data are warranted to assess the net clinical benefit of leadless pacing.OBJECTIVE: The purpose of this study was to evaluate the long-term safety and efficacy of LP therapy in a real-world cohort.METHODS: In this retrospective cohort study, all consecutive patients with a first LP implantation from December 21, 2012, to December 13, 2016, in 6 Dutch high-volume centers were included. The primary safety endpoint was the rate of major procedure- or device-related complications (ie, requiring surgery) at 5-year follow-up. Analyses were performed with and without Nanostim battery advisory-related complications. The primary efficacy endpoint was the percentage of patients with a pacing capture threshold ≤2.0 V at implantation and without ≥1.5-V increase at the last follow-up visit.RESULTS: A total of 179 patients were included (mean age 79 ± 9 years), 93 (52%) with a Nanostim and 86 (48%) with a Micra VR LP. Mean follow-up duration was 44 ± 26 months. Forty-one major complications occurred, of which 7 were not advisory related. The 5-year major complication rate was 4% without advisory-related complications and 27% including advisory-related complications. No advisory-related major complications occurred a median 10 days (range 0-88 days) postimplantation. The pacing capture threshold was low in 163 of 167 patients (98%) and stable in 157 of 160 (98%).CONCLUSION: The long-term major complication rate without advisory-related complications was low with LPs. No complications occurred after the acute phase and no infections occurred, which may be a specific benefit of LPs. The performance was adequate with a stable pacing capture threshold.</p

Subcutaneous or Transvenous Defibrillator Therapy.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (ICD) was designed to avoid complications related to the transvenous ICD lead by using an entirely extrathoracic placement. Evidence comparing these systems has been based primarily on observational studies. METHODS: We conducted a noninferiority trial in which patients with an indication for an ICD but no indication for pacing were assigned to receive a subcutaneous ICD or transvenous ICD. The primary end point was the composite of device-related complications and inappropriate shocks; the noninferiority margin for the upper boundary of the 95% confidence interval for the hazard ratio (subcutaneous ICD vs. transvenous ICD) was 1.45. A superiority analysis was prespecified if noninferiority was established. Secondary end points included death and appropriate shocks. RESULTS: A total of 849 patients (426 in the subcutaneous ICD group and 423 in the transvenous ICD group) were included in the analyses. At a median follow-up of 49.1 months, a primary end-point event occurred in 68 patients in the subcutaneous ICD group and in 68 patients in the transvenous ICD group (48-month Kaplan-Meier estimated cumulative incidence, 15.1% and 15.7%, respectively; hazard ratio, 0.99; 95% confidence interval [CI], 0.71 to 1.39; P = 0.01 for noninferiority; P = 0.95 for superiority). Device-related complications occurred in 31 patients in the subcutaneous ICD group and in 44 in the transvenous ICD group (hazard ratio, 0.69; 95% CI, 0.44 to 1.09); inappropriate shocks occurred in 41 and 29 patients, respectively (hazard ratio, 1.43; 95% CI, 0.89 to 2.30). Death occurred in 83 patients in the subcutaneous ICD group and in 68 in the transvenous ICD group (hazard ratio, 1.23; 95% CI, 0.89 to 1.70); appropriate shocks occurred in 83 and 57 patients, respectively (hazard ratio, 1.52; 95% CI, 1.08 to 2.12). CONCLUSIONS: In patients with an indication for an ICD but no indication for pacing, the subcutaneous ICD was noninferior to the transvenous ICD with respect to device-related complications and inappropriate shocks. (Funded by Boston Scientific; PRAETORIAN ClinicalTrials.gov number, NCT01296022.)

A new era for cardiac rhythm management devices: Solutions for transvenous lead complications

Both pacemakers and cardiac defibrillators (ICD) have been designed to treat cardiac arrhythmias. These arrhythmias often lead to life-threatening conditions. Numerous studies have shown the benefits on survival and quality of life of these cardiac rhythm management (CRM) devices. These devices rely on a transvenous intracardiac lead for sensing and to deliver therapy. Unfortunately the lead is the Achilles-heal of this therapy. Most complications of CRM therapy are related to implantation, malfunction or infection of these leads. Some complications even have fatal consequences. This is obviously in contradiction with one of the most important rules in medicine: First Do No Harm! This thesis describes the introduction of three new technologies designed to overcome these complications. In part I the initial experience in The Netherlands is presented with the wearable cardiac defibrillator. In part II the introduction and further widespread use of the subcutaneous ICD is discussed together with chapters on new implantation techniques and on management of inappropriate therapy. In part III the clinical experience with two different leadless pacemakers is being analyzed and in part IV successful animal experiments with a system consisting of an S-ICD communicating with a leadless pacemaker open the door to a new era for cardiac rhythm management. In this new era leads will probably not be necessary anymore to treat cardiac arrhythmias which will lead to less complications and better patient outcome

End-of-life Management of Leadless Cardiac Pacemaker Therapy

The clinically available leadless pacemakers for patients with a single-chamber pacing indication have shown to be safe and effective. However, the optimal end-of-life strategy of this novel technique is undefined. Suggested strategies comprise of (a) placing an additional leadless device adjacent to the leadless pacemaker, or (b) retrieving the non-functioning leadless pacemaker and subsequently implanting a new device. Although initial studies demonstrate promising results, early experience of acute and mid-term retrieval feasibility and safety remains mixed. We suggest that the approach of leadless pacemaker retrieval is more appealing to limit the amount of non-functioning intracardiac hardware. In addition, potential risks for device-device interference, and unknown long-term complications associated with multiple intracardiac devices are prevented. The potential inability to retrieve chronically implanted leadless pacemakers limits the application of this novel technology. Therefore, long-term prospective analysis is required to define the most optimal end-of-life strateg