Background: The HeartLogic algorithm combines multiple implantable cardioverter-defibrillator sensors to identify patients at risk of heart failure (HF) events. We sought to evaluate the risk stratification ability of this algorithm in clinical practice. We also analyzed the alert management strategies adopted in the study group and their association with the occurrence of HF events. Methods: The HeartLogic feature was activated in 366 implantable cardioverter-defibrillator and cardiac resynchronization therapy implantable cardioverter-defibrillator patients at 22 centers. The median follow-up was 11 months [25th–75th percentile: 6–16]. The HeartLogic algorithm calculates a daily HF index and identifies periods IN alert state on the basis of a configurable threshold. Results: The HeartLogic index crossed the threshold value 273 times (0.76 alerts/patient-year) in 150 patients. The time IN alert state was 11% of the total observation period. Patients experienced 36 HF hospitalizations, and 8 patients died of HF during the observation period. Thirty-five events were associated with the IN alert state (0.92 events/patient-year versus 0.03 events/patient-year in the OUT of alert state). The hazard ratio in the IN/OUT of alert state comparison was (hazard ratio, 24.53 [95% CI, 8.55–70.38], P <0.001), after adjustment for baseline clinical confounders. Alerts followed by clinical actions were associated with less HF events (hazard ratio, 0.37 [95% CI, 0.14–0.99], P =0.047). No differences in event rates were observed between in-office and remote alert management. Conclusions: This multiparametric algorithm identifies patients during periods of significantly increased risk of HF events. The rate of HF events seemed lower when clinical actions were undertaken in response to alerts. Extra in-office visits did not seem to be required to effectively manage HeartLogic alerts. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02275637.

A previous randomized study demonstrated that the subcutaneous implantable cardioverter defibrillator (S-ICD) was noninferior to transvenous ICD with respect to device-related complications and inappropriate shocks. However, that was performed prior to the widespread adoption of pulse generator implantation in the intermuscular (IM) space instead of the traditional subcutaneous (SC) pocket. The aim of this analysis was to compare survival from device-related complications and inappropriate shocks between patients who underwent S-ICD implantation with the generator positioned in an IM position in comparison with an SC pocket. We analysed 1577 consecutive patients who had undergone S-ICD implantation from 2013 to 2021 and were followed up until December 2021. Subcutaneous patients (n = 290) were propensity matched with patients of the IM group (n = 290), and their outcomes were compared. : During a median follow-up of 28 months, device-related complications were reported in 28 (4.8%) patients and inappropriate shocks were reported in 37 (6.4%) patients. The risk of complication was lower in the matched IM group than in the SC group [hazard ratio 0.41, 95% confidence interval (CI) 0.17–0.99, P = 0.041], as well as the composite of complications and inappropriate shocks (hazard ratio 0.50, 95% CI 0.30–0.86, P = 0.013). The risk of appropriate shocks was similar between groups (hazard ratio 0.90, 95% CI 0.50–1.61, P = 0.721). There was no significant interaction between generator positioning and variables such as gender, age, body mass index, and ejection fraction. Our data showed the superiority of the IM S-ICD generator positioning in reducing device-related complications and inappropriate shocks. Clinical Trial Registration: ClinicalTrials.gov; NCT02275637.

Patients with cardiomyopathies and channelopathies are usually younger and have a predominantly arrhythmia-related prognosis; they have nearly normal life expectancy thanks to the protection against sudden cardiac death provided by the implantable cardioverter defibrillator (ICD). The subcutaneous ICD (S-ICD) is an effective alternative to the transvenous ICD and has evolved over the years. This study aimed to evaluate the rate of inappropriate shocks (IS), appropriate therapies, and device-related complications in patients with cardiomyopathies and channelopathies who underwent modern S-ICD implantation. We enrolled consecutive patients with cardiomyopathies and channelopathies who had undergone implantation of a modern S-ICD from January 2016 to December 2020 and who were followed up until December 2022. A total of 1338 S-ICD implantations were performed within the observation period. Of these patients, 628 had cardiomyopathies or channelopathies. The rate of IS at 12 months was 4.6% [95% confidence interval (CI): 2.8–6.9] in patients with cardiomyopathies and 1.1% (95% CI: 0.1–3.8) in patients with channelopathies (P = 0.032). No significant differences were noted over a median follow-up of 43 months [hazard ratio (HR): 0.76; 95% CI: 0.45–1.31; P = 0.351]. The rate of appropriate shocks at 12 months was 2.3% (95% CI: 1.1–4.1) in patients with cardiomyopathies and 2.1% (95% CI: 0.6–5.3) in patients with channelopathies (P = 1.0). The rate of device-related complications was 0.9% (95% CI: 0.3–2.3) and 3.2% (95% CI: 1.2–6.8), respectively (P = 0.074). No significant differences were noted over the entire follow-up. The need for pacing was low, occurring in 0.8% of patients. Modern S-ICDs may be a valuable alternative to transvenous ICDs in patients with cardiomyopathies and channelopathies. Our findings suggest that modern S-ICD therapy carries a low rate of IS. URL: http://clinicaltrials.gov/Identifier: NCT02275637.

In subcutaneous implantable cardioverter defibrillator (S-ICD) recipients, the UNTOUCHED study demonstrated a very low inappropriate shock rate on programming a conditional zone between 200 and 250 bpm and a shock zone for arrhythmias >250 bpm. The extent to which this programming approach is adopted in clinical practice is still unknown, as is its impact on the rates of inappropriate and appropriate therapies. We assessed ICD programming on implantation and during follow-up in a cohort of 1468 consecutive S-ICD recipients in 56 Italian centres. We also measured the occurrence of inappropriate and appropriate shocks during follow-up. On implantation, the median programmed conditional zone cut-off was set to 200 bpm (IQR: 200–220) and the shock zone cut-off was 230 bpm (IQR: 210–250). During follow-up, the conditional zone cut-off rate was not significantly changed, while the shock zone cut-off was changed in 622 (42%) patients and the median value increased to 250 bpm (IQR: 230–250) (P < 0.001). UNTOUCHED-like programming of detection cut-offs was adopted in 426 (29%) patients immediately after device implantation, and in 714 (49%, P < 0.001) at the last follow-up. UNTOUCHED-like programming was independently associated with fewer inappropriate shocks (hazard ratio 0.50, 95%CI 0.25–0.98, P = 0.044), and had no impact on appropriate and ineffective shocks. In recent years, S-ICD implanting centres have increasingly programmed high arrhythmia detection cut-off rates, at the time of implantation in the case of new S-ICD recipients, and during follow-up in the case of pre-existing implants. This has contributed significantly to reducing the incidence of inappropriate shocks in clinical practice. Rordorf: Programming of the S-ICD URL: http://clinicaltrials.gov/Identifier: NCT02275637

Subcutaneous implantable cardioverter–defibrillator (S-ICD) therapy is expanding rapidly. However, there are few data on the S-ICD extraction procedure and subsequent patient management. The aim of this analysis was to describe the procedure, management, and outcome of S-ICD extractions in clinical practice. We enrolled consecutive patients who required complete S-ICD extraction at 66 Italian centres. From 2013 to 2022, 2718 patients undergoing de novo implantation of an S-ICD were enrolled. Of these, 71 required complete S-ICD system extraction (17 owing to infection). The S-ICD system was successfully extracted in all patients, and no complications were reported; the median procedure duration was 40 (25th–75th percentile: 20–55) min. Simple manual traction was sufficient to remove the lead in 59 (84%) patients, in whom lead-dwelling time was shorter [20 (9–32) months vs. 30 (22–41) months; P = 0.032]. Hospitalization time was short in the case of both non-infectious [2 (1–2) days] and infectious indications [3 (1–6) days]. In the case of infection, no patients required post-extraction intravenous antibiotics, the median duration of any antibiotic therapy was 10 (10–14) days, and the re-implantation was performed during the same procedure in 29% of cases. No complications arose over a median of 21 months. The S-ICD extraction was safe and easy to perform, with no complications. Simple traction of the lead was successful in most patients, but specific tools could be needed for systems implanted for a longer time. The peri- and post-procedural management of S-ICD extraction was free from complications and not burdensome for patients and healthcare system. URL: http://clinicaltrials.gov/Identifier: NCT02275637.