Safety of omitting defibrillation efficacy testing with subcutaneous defibrillators: a propensity matched case-control study

Funding Acknowledgements

Type of funding sources: None.

Background

Defibrillation efficacy testing (DT) is recommended at implantation of subcutaneous implantable cardioverter–defibrillators (S-ICD). However, prior works found that adherence to this recommendation is declining in clinical practice.

Purpose

To compare survival from all-cause death and first ineffective shock (primary endpoint) and the composite of all-cause death, ineffective shock, inappropriate shock and device-related complication (secondary endpoint) between patients who underwent DT and those with omitted DT.

Methods

We analyzed 1652 consecutive patients who underwent S-ICD implantation in 60 Italian centers from 2013 to 2019.

Results

DT was not performed in 325 (20%) patients (no-DT patients). As compared with the DT group, these patients were older (51 ± 16 vs. 48 ± 15 years; p < 0.01) and had lower ejection fraction (37 ± 16% vs. 46 ± 16%; p < 0.01). The 325 no-DT patients were propensity matched with 325 patients of the DT group. During a median follow up of 19 months, 27 (4.2%) patients died for any-cause. During follow-up, 34 (5.2%) patients received appropriate shocks to treat discrete episodes of VT/VF. The first shock was effective in 30 out of 34 patients (88%), whereas a second shock was required to terminate VT/VF in 3 patients and a third shock in the last one. The primary endpoint occurred in 31 (4.8%) patients, and the risk was not significantly increased in the no-DT cohort (HR = 1.26, 95%CI:0.62-2.55, p = 0.522). Inappropriate shocks were reported in 36 (5.5%) patients and device-related complications in 25 (3.8%) patients during follow-up. Survival from the composite secondary endpoint was comparable between groups (HR = 0.86, 95%CI:0.57-1.32, p = 0.500).

Conclusions

Our data confirmed that DT is frequently omitted in current clinical practice, especially in older patients with worse systolic function. A strategy that omits DT did not appear to compromise the effectiveness of the S-ICD and no additional risk seems associated with DT omission at a mid-term follow-up. These data suggest that routine DT at S-ICD implant might not be necessary. Randomized trials are needed to confirm this finding.

P538Single- and Multi-Site Pacing Strategies for Optimal Cardiac Resynchronization Therapy: Impact on Device Longevity and Therapy Cost

Funding Acknowledgements

No funding

Introduction

Multiple left ventricular pacing strategies have been suggested for improving response to cardiac resynchronization therapy (CRT). However, these programming strategies can be obtained by accepting configurations with high pacing threshold and accelerated battery drain. We assessed the feasibility of predefined pacing programming protocols and we evaluated their impact on device longevity and their cost-impact.

Methods

We estimated battery longevity in 167 CRT-D (RESONATE, Boston Scientific) patients based on measured pacing parameters and according to multiple programming strategies: single-site pacing associated with lowest threshold, non-apical location, longest interventricular delay, pacing from two electrodes. To determine the economic impact of each programming strategy, we applied the results of a published model-based cost analysis to a 15-year time-horizon.

Results

Selecting the electrode with the lowest threshold resulted in a median device longevity of 11.5 years. Non-apical pacing and interventricular delay maximization were feasible in most patients (99% non-apical pacing, 65% RV-to-LV interval >80ms), and were obtained at the price of a few months of battery life. Device longevity of >10 years was preserved in 87% of cases of non-apical pacing and in 77% on pacing at the longest interventricular delay. The mean reduction in battery life when the second electrode was activated was 1.5 years. Single-site pacing strategies increased the therapy cost by 4-6%, and multi-site pacing by 12-13%, in comparison with the best-case scenario.

Conclusions

Modern CRT-D systems ensure effective pacing and allow multiple optimization strategies for maximizing service life or for enhancing effectiveness. Single- or multi-site pacing strategies can be implemented without compromising device service life and at an acceptable increase in therapy cost.

Abstract Figure. Image1

P1149Subcutaneous implantable cardioverter-defibrillator when Transvenous ICD is not a viable option

Funding Acknowledgements

NO FUNDING

OnBehalf

RHYTHM DETECT Registry

Background

The class of recommendation for S-ICD implantation in patients who have inadequate vascular access is I according to AHA-ACC-HRS Guidelines and IIb according to ESC Guidelines. Data are lacking about the use of S-ICD for patients in which a transvenous ICD is not a viable option because of the inability to deploy a transvenous lead.

Purpose

To describe current practice and to measure outcomes associated with S-ICD use in patients in which a transvenous ICD is not a viable option.

Methods

942 consecutive patients underwent S-ICD implantation at 22 Italian centers from 2014 to 2019. We identified 101 (11%) patients who received S-ICD because of the reported impossibility of deploying a transvenous lead.

Results

21 patients presented with inadequate vascular access but no previous device in place. One patient had a mechanical prosthesis in tricuspid position. The remaining 79 patients received the S-ICD after removal of a prior system implanted, and venous occlusion was diagnosed after lead extraction, or partially or completely failed lead removal. In 24 of these patients a functional transvenous pacing system was left in place for persisting pacing needs. Patients were 60 ± 15 years old, 85% were male, 77% had ischemic or non-ischemic dilated cardiomyopathy, ejection fraction was 36 ± 13%. At implantation, acute conversion test was performed in 64 patients and shock energy of ≤65J was successful in 62 (96.9%) patients. During a median follow-up of 18 months, 6 patients died for non-device related reasons and 1 patient underwent heart transplantation. One patient underwent device replacement for battery depletion and one patient underwent leadless pacemaker implantation. Minor complications (hematomas not requiring system revision) were reported in 2 patients. Appropriate therapies were delivered in 4 patients and 8 patients experienced inappropriate therapies (in 3 patients due to double counting during pacing); all resolved with device reprogramming. Conclusions: In current clinical practice, a minority of S-ICD patients receive the device because of inadequate vascular access. The profile of these patients is similar to that of the typical ICD population in the context of primary sudden death prevention, but many of them present with pacing indications. Acute and mid-term efficacy of S-ICD seemed high. Few complications occurred during follow-up. Particular attention must be paid to device programming for those patients with concomitant pacing systems, in order to prevent inappropriate therapies.