Subcutaneous Implantable Cardioverter-defibrillator Implantation Research Articles

Third-generation subcutaneous implantable cardioverter defibrillator and intermuscular two-incision implantation technique in patients with Arrhythmogenic cardiomyopathy: 3-year follow-up

BackgroundLong-term data on the potential advantages of combining the third-generation subcutaneous implantable cardioverter defibrillator (S-ICD) with modern software upgrade including the “SMART Pass”, modern programming strategies and the intermuscular (IM) two-incision implantation technique in arrhythmogenic cardiomyopathy (ACM) with different phenotypic variants are lacking. In this study we evaluated the long-term outcome of patients with ACM who underwent third-generation S-ICD (Emblem, Boston Scientific) and IM two-incision technique. MethodsThe study population included 23 consecutive patients [70% male, median age 31 (24–46) years] diagnosed with ACM with different phenotypic variants who received third-generation S-ICD implantation with the IM two-incision technique. ResultsDuring a median follow-up of 45.5 months [16–65], 4 patients (17.4%) received a at least one inappropriate shock (IS), with median annual event rate of 4.5%. Extra-cardiac oversensing (myopotential) during effort represented the only cause of IS. No IS due to T-wave oversensing (TWOS) were recorded. Only one patient (4.3%) experienced device-related complication consisting of premature cell battery depletion requiring device replacement. No device explantation because of need for anti-tachycardia pacing or ineffective therapy occurred. There was no significant difference between patients who did and did not experienced IS with regard to baseline clinical, ECG and technical characteristics. Five patients (21.7%) received appropriate shocks on ventricular arrythmias. ConclusionsAccording to our findings, although the third-generation S-ICD implanted with the IM two-incision technique appears to be associated with a low risk of complications and IS due to cardiac oversensing, the risk of IS due to myopotential mainly during effort should be considered.

Intermuscular technique for implantation of the subcutaneous implantable defibrillator: a propensity-matched case-control study.

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.

Reduction in defibrillation threshold by modifications to the subcutaneous implantable-cardioverter defibrillator coil

The subcutaneous implantable cardioverter defibrillator (S-ICD) is approved as an alternative to the traditional transvenous ICD (T-ICD). The S-ICD has higher average defibrillation threshold (DFT) than the T-ICD, related primarily to greater distance from shocking coil to ventricular myocardium with the S-ICD. The S-ICD therefore utilizes a larger device capable of generating an 80J shock, compared to 35-40J maximal shock output typical for T-ICDs, and defibrillation efficacy testing is generally recommended for the S-ICD 1 Wilkoff B, Fauchier L, Stiles M, et al. 2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing. Heart Rhythm 2016;13;e50-86. Google Scholar . We previously published computer modeling of predictors of defibrillation efficacy with the S-ICD, which determined that minimal fat underlying the S-ICD coil and generator (reducing shock impedance), and posterior generator position (better directing the shock vector across the ventricles), are predictors of lower DFT 2 Heist E. Belalcazar A. Stahl W. et al. Determinants of Subcutaneous Implantable Cardioverter-Defibrillator Efficacy. J Am Coll Cardiol EP. 2017; 3: 405-414 Google Scholar . Those findings formed the basis for the PRAETORIAN score, which is utilized in clinical S-ICD implantation to reduce DFT 3 Quast A.-F.B.E. Baalman S.W.E. Brouwer T.F. et al. A novel tool to evaluate the implant position and predict defibrillation success of the subcutaneous implantable cardioverter-defibrillator: The PRAETORIAN score. Heart Rhythm. 2018; 16: 403-410 Abstract Full Text Full Text PDF PubMed Scopus (65) Google Scholar . A previously published computer modeling study examined the impact of dual S-ICD electrodes and electrode arrays, as well as variations in generator and lead location; results demonstrated reduced DFT with some configurations compared to the standard S-ICD 4 Jolley M. Stinstra J. Tate J. et al. Finite Element Modeling of Subcutaneous Implantable Defibrillator Electrodes in an Adult Torso. Heart Rhythm. 2010; 7: 692-698 Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar . In this current study, we performed computer modeling to determine whether design modifications to the S-ICD coil could result in reductions to S-ICD DFT.

Intermuscular two-incision technique for implantation of the subcutaneous implantable cardioverter defibrillator: a 3-year follow-up.

The aim of the present study was to evaluate the outcome of patients underwent subcutaneous implantable cardioverter defibrillator (S-ICD) implantation with the intermuscular (IM) two-incision technique during 3-year follow-up. the study population consisted of 105 consecutive patients (79 male; median 50 [13-77] years) underwent S-ICD implantation with the IM two-incision technique. The composite primary end point of the study consisted of device-related complications and inappropriate shocks (IAS). Secondary end points included the individual components of the primary end point, death from any cause, appropriate therapy, major adverse cardiac events, hospitalization for heart failure, and heart transplantation. According to the PRAETORIAN score, the risk of conversion failure was classified as low in 99 patients (94.3%), intermediate in 6 (5.7%).Ventricular fibrillation was successfully converted at ≤65 J in 97.4% of patients. During a median follow-up of 39 (16-53) months, 10 patients (9.5%) experienced device-related complications, and 9 (8.5%) patients reported IAS. Lead-associated complications were the most common (5 patients, 4.7%), including 2 cases of lead failure (1.9%). Pocket complications were reported in 2 patients (1.9%). Extra-cardiac oversensing (3.8%) represented the leading cause of IAS. No T-wave oversensing episodes were recorded. Twelve patients (11.4%) experienced appropriate shocks. Eight patients (7.6%) died during follow-up. IAS or device-related complications did not impact on mortality. The overall device-related complications and IAS rates over 3 years of follow-up were 9.5% and 8.5%, respectively. According to our findings, the IM two-incision technique allows for optimal positioning of the device achieving a low PRAETORIAN score with a high conversion rate. IM two-incision technique allows low incidence of pocket complications, shifting the type of complications towards lead-related complications, which represent the most common complications. The IM two-incision technique would not seem to impact the occurrence of IAS. Management of complications are safe without impact on the outcome.

Subcutaneous implantable cardioverter-defibrillator implantation position predicts successful defibrillation in obese and non-obese patients.

Subcutaneous implantable cardioverter-defibrillators (S-ICD) are an alternative to transvenous ICDs for patients without a need for cardiac pacing. Obese patients have been proposed to be at higher risk for conversion failure with S-ICDs due to subcutaneous fat underneath the device. Optimal device positioning may promote equivalent outcomes between obese and non-obese patients by minimizing the effects of excess adipose tissue. A retrospective analysis of patients undergoing defibrillation testing at the time of S-ICD implantation was performed. The primary endpoint was the rate of successful conversion of ventricular fibrillation (VF) at the time of implant. The secondary endpoint was shock impedance. A total of 184 patients were included in the study. The rate of successful conversion of VF was 90.3% for obese patients (n = 72) and 96.4% for non-obese patients (n = 112) (p = 0.086). Compared to non-obese patients, obese patients had a higher mean PRAETORIAN score (78.5 ± 58.1 vs. 48.8 ± 35.5, p < 0.001) and higher measured mean impedance (82.0 ohms ± 26.5 vs. 69.8 ohms ± 19.3, p < 0.001). Patients with a PRAETORIAN score < 90 all had successful defibrillation testing regardless of BMI. In this study, a PRAETORIAN score < 90 was associated with a 100% success rate of defibrillation testing following S-ICD implantation regardless of patient body mass index (BMI). Thus, the impact of obesity on impedance and the risk of failed shocks may be minimized with close attention to implantation technique to achieve a low PRAETORIAN score.

197 INTERMUSCULAR TWO-INCISION TECHNIQUE FOR IMPLANTATION OF THE SUBCUTANEOUS IMPLANTABLE DEFIBRILLATOR: 3-YEAR FOLLOW-UP

Abstract Background The aim of the present study was to evaluate the outcome of patients underwent subcutaneous implantable cardioverter defibrillator (S-ICD) implantation with the intermuscular (IM) two-incision technique during 3-year follow-up. Methods the study population consisted of 105 consecutive patients (79 male; median 50 [13-77] years) underwent S-ICD implantation with the IM two-incision technique. Results according to the PRAETORIAN score, the risk of conversion failure was classified as low in 99 patients (94.3%), intermediate in 6 (5.7%). Ventricular fibrillation was successfully converted at ≤65 J in 97.4% of patients. During a median follow-up of 39 (16-53) months, 10 patients (9.5%) experienced device-related complications and 9 (8.5%) patients reported shocks (IAS). Lead-associated complications were the most common (3.8%), including 2 cases of lead failure (1.9%). Pocket complications were reported in 2 patients (1.9%). Extra-cardiac oversensing (3.8%) represented the leading cause of IAS. No T-wave oversensing episodes were recorded. Twelve patients (11.4%) experienced appropriate shocks. Eight patients (7.6%) died during follow-up. IAS or device-related complications did not impact on mortality (HR 0.5;95%CI 0-4.3;P=0.5; HR 0.7;95%CI 0.1-6.0;P=0.8, respectively). Conclusions according to our findings, the IM two-incision technique allows for optimal positioning of the device achieving a low PRAETORIAN score with a high conversion rate. IM two-incision technique allows low incidence of pocket complications, shifting the type of complications towards lead-related complications, which represent the most common complications. The IM two- incision technique would not seem to impact the occurrence of IAS. Management of complications are safe without impact on the outcome.

220 MANAGING CARDIAC ARREST SECONDARY TO SPONTANEOUS CORONARY ARTERY DISSECTION: SHOULD WE ROUTINELY CONSIDER ICD IMPLANTATION?

Abstract Introduction Cardiac arrest secondary to a spontaneous coronary artery dissection (SCAD) represents a challenging scenario. It deserves specific considerations due to the dramatic presentation and the need for secondary sudden cardiac death prevention. Methods We collected clinical data of four women admitted during the last two years in the Coronary Care Unit of Parma University Hospital, whose presentation of SCAD were cardiac arrest due to ventricular fibrillation. Results Three patients survived the acute phases. One patient, being considered at high risk of SCAD recurrence, received a subcutaneous implantable cardioverter-defibrillator (S-ICD). Acute management of cardiac arrest related to SCAD deserves specific considerations. Our case series illustrates the importance of prompt resuscitation manoeuvres and early defibrillation. We propose a flow chart of management of cardiac arrest in patient with suspect of SCAD. Evaluating risk of SCAD recurrence and sudden cardiac death The management of SCAD patients complicated by malignant ventricular arrhythmias and cardiac arrest is challenging. Looking at published registries, it appears that SCAD patients are more likely to suffer from ventricular arrythmia or sudden cardiac death than non-SCAD MI patients. The risk-benefit ratio of ICD implantation in these patients remain uncertain . Evaluation of scar burden with CMR can help stratify the global arrhythmic risk, especially as extensive myocardial scar with a residual impaired LVEF increases the risk of future arrhythmic events. In our series, only one patient underwent S-ICD implantation, and the decision was mainly driven by the finding of underlying arteriopathy affecting other vascular territories, suggesting a potentially higher rate of SCAD recurrence. For this particular subset of patients, we propose an algorithm that combines predisposing factors and myocardia injury quantification data that could be useful for the estimate of the risk of malignant arrythmias, as well as the risk of recurrence of SCAD, but needs to be validated in larger case studies. Conclusions The acute management of cardiac arrest related to SCAD deserves specific consideration. The residual myocardial damage, predisposing and precipitants factors should be evaluated in order to estimate the SCAD recurrence and sudden cardiac death risks.

Propofol dose and efficacy of defibrillation testing during implantation of subcutaneous implantable cardioverter-defibrillators: Aretrospective, single center cohort study.

Defibrillation testing (DFT) is recommended during subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. Previous studies analyzing the potential interference of propofol with defibrillation threshold are inconsistent. The purpose of this study was to analyze whether propofol affects DFT post S-ICD placement. All patients with S-ICD implantation between 01/2017 and 11/2020 at the University Heart Center Freiburg were retrospectively analyzed. Two groups were generated depending on the success of the first shock during DFT. Implantation characteristics and dose of anesthetics were analyzed. In 12 of the included 80 (15%) patients, first shock during DFT failed. The absolute dose of propofol was significantly higher in patients with first shock failure (median 653 mg [IQR 503-855]) compared to patients with first shock termination (376 mg [200-600]; p = 0.027). Doses of opioids and midazolam as well as type of anesthesia did not differ between the groups. A multivariable binary logistic regression analysis confirmed an independent association of first shock termination and propofol dose (per 100 mg: OR 0.73 (95% CI: 0.56-0.95); p = 0.021). There is an independent association of propofol dose and first shock failure in routineS-ICD defibrillation testing.

Abstract 12931: Contemporary Trends of Subcutaneous Implantable Cardioverter Defibrillator Utilization in the United States: Insights From the National Inpatient Sample 2016-2019

Introduction: The subcutaneous implantable cardioverter defibrillator (S-ICD) has emerged as an alternative to the transvenous ICD with comparable efficacy and complication rates in clinical trials. Adoption of this technology and real-world clinical experience are less well described. Methods: This was a retrospective descriptive cohort study using data from National Inpatient Sample (NIS) for calendar years 2016-2019. Outcomes were cardiovascular adverse events, all-cause mortality, 30-day readmission, and resource utilization in patients who had S-ICD implantation. Results: We identified 6655 patients who had S-ICD implantation between 2016-2019. S-ICD implant rates remained between 10-12% of total ICD implants in the US over the study period (Figure 1a), though hospital implant rates were widely distributed (Figure 1b). The mean (SD) age of the population was 56.1 ± 15.9 years, and 2002 patients (30.1%) were female. Median length of stay (IQR) was 6.0 (4.0, 10.0). Hospitalization costs were $ 245937.1 ± 206047.3. Adverse cardiovascular events associated with the hospitalization were: pericardial perforation/cardiac tamponade (0.2%), hemothorax/pneumothorax (1.1%), stroke/TIA (0.5%), cardiogenic shock (8.6%), cardiac arrest (11%), and vascular complications (1.3%). A total of 48 patients (0.7%) died. Non-elective readmission within 30 days post-procedure occurred in 15.7% of cases. Conclusion: S-ICD implant rates were stable over time but varied widely among hospitals. Hospitalization-associated adverse cardiovascular events may be more a reflection of the vulnerable population undergoing S-ICD implant than risk of the procedure.

Clinical outcomes of subcutaneous vs. transvenous implantable defibrillator therapy in a polymorbid patient cohort.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has been designed to overcome lead-related complications and device endocarditis. Lacking the ability for pacing or resynchronization therapy its usage is limited to selected patients at risk for sudden cardiac death (SCD). The aim of this single-center study was to assess clinical outcomes of S-ICD and single-chamber transvenous (TV)-ICD in an all-comers population. The study cohort comprised a total of 119 ICD patients who underwent either S-ICD (n = 35) or TV-ICD (n = 84) implantation at the University Hospital Frankfurt from 2009 to 2017. By applying an inverse probability-weighting (IPW) analysis based on the propensity score including the Charlson Comorbidity Index (CCI) to adjust for potential extracardiac comorbidities, we aimed for head-to-head comparison on the study composite endpoint: overall survival, hospitalization, and device-associated events (including appropriate and inappropriate shocks or system-related complications). The median age of the study population was 66.0 years, 22.7% of the patients were female. The underlying heart disease was ischemic cardiomyopathy (61.4%) with a median LVEF of 30%. Only 52.9% had received an ICD for primary prevention, most of the patients (67.3%) had advanced heart failure (NYHA class II-III) and 16.8% were in atrial fibrillation. CCI was 5 points in TV-ICD patients vs. 4 points for patients with S-ICD (p = 0.209) indicating increased morbidity. The composite endpoint occurred in 38 patients (31.9 %), revealing no significant difference between patients implanted with an S-ICD or TV-ICD (unweighted HR 1.50, 95 % confidence interval (CI) 0.78-2.90; p = 0.229, weighted HR 0.94, 95% CI, 0.61-1.50, p = 0.777). Furthermore, we observed no difference in any single clinical endpoint or device-associated outcome, neither in the unweighted cohort nor following inverse probability-weighting. Clinical outcomes of the S-ICD and TV-ICD revealed no differences in the composite endpoint including survival, freedom of hospitalization and device-associated events, even after careful adjustment for potential confounders. Moreover, the CCI was evaluated in a S-ICD cohort demonstrating higher survival rates than predicted by the CCI in young, polymorbid (S-)ICD patients.

Intermuscular technique for implantation of the subcutaneous implantable defibrillator: a propensity-matched case-control study

Abstract Background A previous randomized study (PRAETORIAN) 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. Purpose 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 a SC pocket. Methods We analyzed 1577 consecutive patients who had undergone S-ICD implantation from 2013 to 2021 and were followed up until December 2021. SC patients were propensity-matched with patients of the IM group, and their outcomes were compared. Results SC implantations were performed in 367 (23%) patients. These patients were propensity-matched with 367 IM patients. Intra-procedural complications were reported in 9 (2.5%) patients in the SC Group and 7 (1.9%) in the IM Group. During a median follow-up of 29 months, device-related complications were reported in 55 (7.5%) patients and inappropriate shocks were reported in 54 (7.4%) patients. The risk of the composite primary endpoint was lower in the matched IM Group than in the SC Group (unadjusted hazard ratio 0.67, 95% CI 0.45–0.99, p=0.042), while the risk of appropriate shocks was similar between groups (unadjusted hazard ratio 0.99, 95% CI 0.60–1.64, p=0.976). There was no significant interaction between generator positioning and variables such as gender, age, body mass index, ejection fraction and generation of the device. Conclusions In this experience, IM S-ICD generator positioning was superior to SC positioning in reducing device-related complications and inappropriate shocks. Funding Acknowledgement Type of funding sources: None.

Air entrapment as a cause of S-ICD inappropriate shocks.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is noninferior to the transvenous ICD concerning device-related complications or inappropriate shocks (IASs) in patients with an indication for defibrillator therapy and not in need of pacing. 1 Knops R.E. Olde Nordkamp L.R.A. Delnoy P.P.H.M. et al. Subcutaneous or transvenous defibrillator therapy. N Engl J Med. 2020; 383: 526-536 Crossref PubMed Scopus (149) Google Scholar The main causes of IAS in S-ICD recipients are T-wave oversensing, oversensing of ventricular tachycardia/ventricular fibrillation below the therapy zone, myopotentials, and low-amplitude signals. 2 Burke M.C. Aasbo J.D. El-Chami M.F. et al. 1-Year prospective evaluation of clinical outcomes and shocks. JACC Clin Electrophysiol. 2020; 6: 1537-1550 Crossref PubMed Scopus (15) Google Scholar ,3 Gold M.R. Lambiase P.D. El-Chami M.F. et al. Primary results from the Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction (UNTOUCHED) trial. Circulation. 2021; 143: 7-17 Crossref PubMed Scopus (45) Google Scholar Subcutaneous air entrapment has recently been considered an underdiagnosed cause of early postimplant IAS, accounting for a part of oversensing of low-amplitude signals. 4 Chinitz J.S. Nadraus P. Darge A. Cacciabaudo J. Altman E.J. Inappropriate shocks within 24 hours after implantation of a subcutaneous defibrillator with a two-incision technique. J Innovations Card Rhythm Manag. 2016; 7: 2295-2298 Crossref Google Scholar ,5 Nishinarita R. Kishihara J. Matsuura G. et al. Early inappropriate shock in a subcutaneous cardiac defibrillator due to subcutaneous air. J Arrhythm. 2019; 35: 682-684 Crossref PubMed Scopus (2) Google Scholar Few data are available about the incidence, prevention, and management of postprocedural IAS due to subcutaneous air entrapment. We searched for case reports on IAS due to subcutaneous air entrapment published in PubMed, Google Scholar, Scopus, and EMBASE from 2012 to December 2021. For each of them, we analyzed the patients’ clinical characteristics, the S-ICD implantation technique, the timing and mode of IAS diagnosis, and the management of complications. A total 15 patients with S-ICD (66% male) with a median age of 55 years (interquartile range 17–75 years) were included. The indication for S-ICD implantation was primary prevention in 6 patients (40%) and secondary prevention in 9 patients (60%). A 3-incision technique was used in 7 patients (46.6%) and a 2-incision technique in 6 patients (40%). IAS was experienced on the same day of the procedure in 66.6% of cases and after discharging in 33.3%, always within 4 days of S-ICD implantation. Intraprocedural chest radiography was performed for checking the correct S-ICD system positioning in 40% of cases; in none of them, the presence of air entrapment has been reported. Subcutaneous air entrapment was diagnosed by postoperative chest radiography in 11 cases (73.3%), whereas the diagnosis was based on device interrogation and reproduction of the electrogram alterations by manipulation in 2 cases (13.3%). The most common localization of air entrapment was around the proximal electrode (46.6%, n = 7), followed by the distal electrode (26.6%, n = 4) and ICD generator (20.0%, n = 3); in 1 case, the precise localization was not investigated. Reprogramming the sensing vector and waiting the time necessary for oversensing resolution and air reabsorption were the most common strategies used to manage this complication (80.0%, n = 12). After 2 weeks, in 73.3% of patients, no further shocks occurred and chest radiography did not show residual air. Table 1 summarizes patients’ clinical characteristics, timing and management of IAS from 14 case reports/case series. On the basis of these data, the air entrapment should be considered an early complication (<24 hours) and an uncommon cause of IAS in S-ICD recipients, even if its epidemiology may be biased by misdiagnosing and underreporting. The relationship between air entrapment and S-ICD implantation technique is still controversial; however, a slightly increased incidence with the 3-incision technique was shown. The diagnosis should be made by performing a systematic approach including device interrogation, provocative maneuvers, and chest radiography. Reprogramming a different sensing vector or temporally switching off the S-ICD system, until air reabsorption, are part of the management of acute complications. Reassessing patients at 2 weeks with further device interrogation during provocative maneuvers may be useful. Value are presented as mean ± SD or n (%). DCM = dilatative cardiomyopathy; HCM = hypertrophic cardiomyopathy; IAS = inappropriate shock; ICD = implantable cardioverter-defibrillator; IHD = ischemic heart disease; PMs = physical maneuvers.

Clinical impact of ECG changes on oversensing of subcutaneous implantable cardioverter-defibrillators.

Inappropriate shocks delivered by subcutaneous implantable cardioverter-defibrillators (S-ICDs) are most frequently caused by cardiac oversensing. However, the predictors for oversensing of S-ICD remain unclear. We aimed to investigate the predictors for oversensing of S-ICD, especially clinical impact of an electrocardiographic (ECG) change. We retrospectively enrolled 99 consecutive patients who underwent S-ICD implantation between 2013 and 2021. Oversensing events were defined as inappropriate charge of the capacitors induced by cardiac or noncardiac signals other than tachycardia. During a median follow-up period of 34 months (interquartile range 20-50 months), 11 of 99 patients (11%) experienced 34 oversensing events and 4 patients (4%) received inappropriate shocks during their events. Six patients exhibited ECG changes (bundle branch block, 3; ventricular pacing, 1; inverted T wave, 1; poor R-wave progression, 1) during the follow-up period. Oversensing events were observed in 4 of 6 patients with ECG change (67%), and 3 patients underwent S-ICD removal because of inevitable shock. Contrastingly, of the remaining patients without ECG change, all 7 patients who experienced oversensing events could continue using S-ICD with the reprogramming sensing vector and/or restriction of excessive exercise. Logistic regression analysis showed that lower voltage of Sokolow-Lyon ECG (V1S + V5R) was the predictor of oversensing in patients without ECG change. When the cutoff value was 2.1 mV, the sensitivity, specificity, positive predictive value, and negative predictive value were 85.7%, 62.7%, 15.7%, and 98.1%, respectively. Unavoidable oversensing resulting in S-ICD removal is caused by ECG change. Oversensing in patients without ECG change can be managed.

Safety and Tolerability of Implanted Subcutaneous Cardioverter-Defibrillator Systems

Aim. To study the safety and tolerability of the subcutaneous implantable cardioverter defibrillator (S-ICD) after implantation.Material and methods. The results of 33 patients with implanted S-ICD 6 months follow-up. The criteria for inclusion in the observational study were: age over 18 years, indications for primary or secondary prevention of sudden cardiac death. The exclusion criteria were indications for implantation of transvenous ICD (patients with sustained monomorphic ventricular tachycardia, the need for anti-bradycardia or resynchronization therapy), as well as patients with a QRS complex of more than 130 msec. All patients underwent a standard preoperative examination (routine blood tests, chest X-ray, transthoracic echocardiography), quality-of-life questionnaires and transesophageal echocardiography. At follow-up, patients were examined after 6 months after implantation, the device was interrogated and a quality-of-life questionnaire was completed. All episodes of shock therapy and complications were documented.Results. Male patients predominated (84%), with a mean age of 57 [43;62] years. Left ventricular ejection fraction was 30% [26;34]. The mean QRS duration was 100 [94;108] msec. According to the of 24-hour Holter ECG monitoring, episodes of unstable VT were recorded in 42.4% of patients. The most common indications for S-ICD implantation were dilated (33%) and ischemic cardiomyopathy (42%). Primary prevention was indicated in 97% of patients. At the end of the implantation of the S-ICD, the patients underwent a defibrillation test and device configuration. In 63.6% of cases, during automatic tuning, the device selected the primary perception vector. In 27.2% of patients, optimal recognition of the subcutaneous signal was observed in the secondary vector, and in 9.2% of patients, the alternative vector was favorable. All patients underwent two-zone programming. The conditional shock zone was programmed at an average rate of 192 beats/min (range 180-210 beats/min) and the shock zone was programmed at an average rate of 222 beats/min (range 220-240 beats/min). Perioperative complications occurred in two patients. During the follow-up period, no shocks were recorded in 27 patients. Adequate shocks for 6 months were recorded in two patients. During 6 months of observation, one lethal outcome was noted due to complications of viral pneumonia. During the observation period, there were no rehospitalizations for cardiovascular diseases.Conclusion. The use of S-ICD, even in patients with structural myocardial disease who do not require antibradycardia pacing, is effective in preventing SCD. The number of inadequate discharges and the number of complications in clinical practice is comparable to the data of multicenter studies. S-ICD implantation was not accompanied by a decrease in quality of life. Careful selection of candidates, along with state-of-the-art device programming, is an important parameter for the selection and success of S-ICD application.

EP News: Clinical

Lambiase et al (Eur Heart J 2022;43:2037, PMID 35090007) evaluated 5-year outcomes of EFFORTLESS registry patients with early generation subcutaneous implantable cardioverter-defibrillator (S-ICD) devices. Overall, 984 of 994 enrolled patients (28% female; mean age 48 ± 17 years; ejection fraction 43% ± 18%) underwent S-ICD implantation. The median follow-up was 5.1 years. All-cause mortality was 9.3% at 5 years; 703 patients remained in follow-up on study completion, 171 withdrew including 87 (8.8%) with device explanted, and 65 (6.6%) lost to follow-up.

Process mapping strategies to prevent subcutaneous implantablecardioverter-defibrillator infections.

BackgroundInfection remains a major complication of cardiac implantable electronic devices and can lead to significant morbidity and mortality. Implantable devices that avoid transvenous leads, such as the subcutaneous implantable cardioverter‐defibrillator (S‐ICD), can reduce the risk of serious infection‐related complications, such as bloodstream infection and infective endocarditis. While the 2017 AHA/ACC/HRS guidelines include recommendations for S‐ICD use for patients at high risk of infection, currently, there are no clinical trial data that address best practices for the prevention of S‐ICD infections. Therefore, an expert panel was convened to develop a consensus on these topics.MethodsAn expert process mapping methodology was used to achieve consensus on the appropriate steps to minimize or prevent S‐ICD infections. Two face‐to‐face meetings of high‐volume S‐ICD implanters and an infectious diseases specialist, with expertise in cardiovascular implantable electronic device infections, were conducted to develop consensus on useful strategies pre‐, peri‐, and postimplant to reduce S‐ICD infection risk.ResultsExpert panel consensus on recommended steps for patient preparation, S‐ICD implantation, and postoperative management was developed to provide guidance in individual patient management.ConclusionAchieving expert panel consensus by process mapping methodology for S‐ICD infection prevention was attainable, and the results should be helpful to clinicians in adopting interventions to minimize risks of S‐ICD infection.

Current clinical practice of subcutaneous implantable cardioverter-defibrillator: Analysis using the JROAD-DPC database

Current evidence describing the characteristics of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy, its trend, and perioperative outcomes compared with transvenous implantable cardioverter-defibrillator (TV-ICD) based on a real-world, large-scale database is scarce. The purpose of this study was to identify the characteristics of current S-ICD therapy using a nationwide database. A retrospective analysis of ICD implantation was performed using a nationwide database obtained between 2016 and 2020. A total of 8690 patients implanted with ICD (median age 65 [52-72] year; 6902 men; 2021 S-ICD recipients) were analyzed. Younger patients were more prone to have S-ICD (P <.001). A history of ventricular fibrillation (VF) (odds ratio [OR] 2.45; 95% confidence interval [CI] 2.04-2.93), nonsustained ventricular tachycardia (VT) (OR 1.73; 95% CI 1.36-2.21), Brugada syndrome (BrS) (OR 3.14; 95% CI 2.48-4.00), and dialysis treatment (OR 2.02; 95% CI 1.44-2.82) were independent predictors of S-ICD selection on mixed-model logistic analysis. The proportion of S-ICD implantations has been increasing (P <.001), especially in patients with BrS (P <.001) and dialysis (P = .04). The proportion of combined complications after S-ICD implantation was low (1.3%) in the unmatched cohort and was comparable to TV-ICD in the 1:1 propensity-matched cohort of 3354 patients (1.5% vs 2.3%; OR 0.65; 95% CI 0.38-1.10). S-ICD was more likely to be implanted in younger patients and those with a history of VF, nonsustained VT, BrS, and dialysis treatment. The proportion of S-ICD implantation increased, especially in patients with BrS. The incidence of in-hospital complications was low in S-ICD recipients.

The subcutaneous defibrillator in patients with low BMI - insights from a large European multicenter registry

Abstract Funding Acknowledgements Type of funding sources: None. Background The subcutaneous implantable cardioverter defibrillator (S-ICD) has become an alternative to transvenous ICDs (tv-ICD), especially in young patients without a need for pacing. One of the current limitations of the S-ICD is the relatively large size of the generator compared to tv-ICDs. There is little evidence whether the size of the current S-ICD generator is associated with an elevated risk of device-related complications in patients with a low body mass index (BMI). Purpose To compare the device-related complications and long-term outcomes in a large real world cohort of S-ICD recipients in patients with a BMI &amp;lt;18 kg/m2 compared to patients with a BMI &amp;gt;18 kg/m2. Methods The iSuSI registry is a European, multi-center, open-label, independent, and physician-initiated observational registry. A total of twenty-two Public and Private Healthcare Institutions from 4 different countries in Europe were involved in the registry. All consecutive patients meeting current guideline indications for ICD implantation and undergoing implantation of a S-ICD device (Boston Scientific, Marlborough, Massachusetts, USA) at 21 European institutions enrolled in the registry were used for the current analysis. Patients were classified into two cohorts, depending on the BMI at the time of device implantations: BMI &amp;lt; 18 kg/m2 versus &amp;gt; 18 kg/m2. Results Out of a total of 1497 pts, 58 pts (3.9%) had a BMI &amp;lt; 18 kg/m2. Patients with BMI &amp;lt;18 kg/m2 were younger (44.6±2.4 vs 50.8±0.4; p=0.004) and more frequently female (58.6% vs 22.3%, p&amp;lt;0.001). No differences in any of the other baseline characteristic were observed. Implantation techniques resulted comparable between the groups (Rates of 2-incision technique: 87.8% vs 91.9%; p=0.256; inter-muscular placement: 89.7% vs 83.3%; p=0.198). Of note, the mean PRAETORIAN score at implantation of patients with BMI &amp;lt;18 kg/m2 was significantly lower (33.8±9.1 vs 54.1±47.3; p=0.035), although the vast majority of pts in both cohorts qualify as at low risk of conversion failure (100% vs 91.4%; p=0.436). Over a median follow up time of 22.4 [11.6–36.8] months, both overall device-related complications (5.2% vs 7.4%) and rates of inappropriate shocks (12.0% vs 8.8%) resulted comparable between the two groups (p =0.517 and p=0.385, respectively). Figure1 reports Kaplan-Meier curves reporting the combined incidence of device-related complications and inappropriate shocks in the two groups (log-rank p = 0.576). Conclusion No difference in device-related complications and long-term outcomes after S-ICD implantation were observed in patients with BMI &amp;lt;18 kg/m2 compared to the remaining recipients from a large, multi-centered S-ICD registry. Figure 1: Kaplan-Meier-survival curve for the combined endpoint of inappropriate shocks (IAS) and device-related complications (DRC)

How to better identify patients at high risk of inappropriate shocks before S-ICD implantation: Results from a multicenter experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Despite the recent improvements, inappropriate shocks (IAS) in patients implanted with subcutaneous implantable cardioverter-defibrillator (S-ICD) remain a challenge in "real-life" practice. The purpose of this study was to assess the preoperative predictive factors of IAS with the latest generation of S-ICD, with a particular focus on data obtained during the screening procedure. Methods Between January 2017 and March 2020, 300 patients implanted with Generation 3 S-ICD system for primary and secondary prevention were included in this multicentric study. Follow-up (FU) of at least 6 months and preoperative screening procedure data were mandatory for all patients. Results After a mean follow-up of 22.8 (±11.4) months, appropriate therapies occurred in 12.3% patients; while 26 patients (8.7%) experienced inappropriate therapies (incidence 4.9 per 100 patient-years). The total number of inappropriate shock episodes was 48; 9 patients experienced multiple episodes. Causes of IAS were: supraventricular arrhythmias (34.6%), cardiac (30.7%) and extra-cardiac noise oversensing (38.4%). In univariate analysis, availability of all 3 sensing vectors during preoperative screening significantly reduced inappropriate therapies occurrence (hazard ratio [HR], 0.32; 95% confidence interval [CI], 0.12-0.89, P=0.028). Clinical preoperative S-ICD inappropriate shocks predictors were: history of Supraventricular Tachycardia (SVT)(HR, 4.42; 95% CI, 1.45-13.47; P=0.009); overweight (BMI&amp;gt;25: HR, 1.93; 95% CI, 0.83-0.4.48; P=0.13); QRS duration (HR, 1.01; 95% CI, 0.1-1.03; P=0.14) and lower QRS/T wave ratio in lead I (for a threshold &amp;lt; 3: HR, 4.44; 95% CI, 1.88-10.48; P=0.001). By multivariate analysis, independent factors associated with IAS were: the availability of less than 3 sensing vectors during preoperative screening (p&amp;lt;0.05), a low QRS/T wave ratio in lead I (for a threshold &amp;lt;3; p&amp;lt;0.001), history of SVT (p&amp;lt;0.001) and overweight (BMI&amp;gt; 25; p&amp;lt;0.05). Conclusion Automatic preoperative screening data is of high interest as a predictor of IAS with a quantitative value. ECG specificities in association with other clinical factors should be taken into consideration to identify patients at high risk for IAS.

S-ICD in heart failure patients: real-world data from a multicenter, european analysis

Abstract Funding Acknowledgements Type of funding sources: None. Background Data on patients with heart failure (HF) and subcutaneous implantable cardioverter defibrillator (S-ICD) are very scarce and limited to a single prospective analysis from the UNTOUCHED trial. Purpose Aim of this study was to assess clinical outcomes of the S-ICD in HF patients, comparing them with a no-HF population, in a real-world analysis from the largest European retrospective S-ICD registry (ELISIR registry). Methods All consecutive patients undergoing S-ICD implantation at 20 European institutions enrolled in the ELISIR registry were used for the current analysis. According to European Guidelines, the registry population was classified into two groups: the HF cohort (further classified as HF with reduced and mid-range ejection fraction – HFrEF and HFmrEF) vs the no-HF group. The primary outcome of the study was the inappropriate shock (IS) rate across the two cohorts. As secondary outcomes, appropriate shocks, cardiovascular mortality and device-related complications during follow-up were assessed. Results A total of 1409 patients from the ELISIR registry were included in this analysis; HF patients represented 57.3% of the entire cohort (n=701, 86.9% HFrEF; n=106,13.1% HFmrEF). As expected, the HF cohort showed significantly higher rates of cardiovascular risk factors and comorbidities when compared to the no-HF cohort. Over a median follow-up of approximately 2 years, a total of 133 inappropriate shocks were observed in the entire cohort, without significant differences among the two groups (9.2% vs 9.8%, p=0.689). 133 complex ventricular arrhythmias were adequately recognized and treated in the overall cohort, showing similar rates of appropriate shocks (9.2% vs 9.8%, p=0.689). Inappropriate and effective shocks-free survival has been represented in Figure 1, showing Kaplan-Meier estimates comparing HF vs no-HF patients, also stratified by left ventricular ejection fraction (LVEF). The impact of baseline and procedural characteristics on the primary outcome was tested through univariable and multivariable Cox regression analysis in HF patients; at multivariate analysis, only age (HR=0.974 [0.955–0.992], p=0.005), LVEF (HR=0.954 [0.926-0.984], p=0.003), ARVC (HR=3.364 [1.206-9.384], p=0.020) and smart pass algorithm "on" (HR=0.321 [0.184-0.560], p&amp;lt;0.001) remained associated with inappropriate shocks (Figure 2). A low number of patients (n=76) experienced device-related complications, more frequently in the HF cohort (6.2% vs 3.8%, p=0.031) with no significant differences regarding any specific outcome of interest: lead infection (1.1% vs 0.7%, p=0.381), pocket infection (1.9% vs 0.8%, p=0.107), pocket hematoma (3.2% vs 2.8%, p=0.668). Conclusion The rate of inappropriate shocks seems to be comparable in both HF and non-HF patients implanted with S-ICD. However, the rate of device-related complications was slightly more frequent in HF patients.