Subcutaneous Implantable Defibrillator Research Articles

Device programing and SMART pass algorithm activation in subcutaneous implantable defibrillator patients: Data from a remote monitoring database.

The programing of subcutaneous implantable cardioverter-defibrillators (S-ICD) in clinical practice has been little studied, as the activation status of the SMART Pass filter, which was implemented to reduce inappropriate shocks. We assessed device programing during follow-up and the rate of detected arrhythmias in consecutive S-ICD recipients. We analyzed data from 670 S-ICD patients followed on the remote network at 17 Italian centers for a median of 31 months (25th-75th percentile: 16-51). The enhanced SMART Pass version, introduced in October 2022, was expected to reduce the unintentional deactivation rate. At the latest remote data transmission, the median conditional zone cut-off was set to 210bpm (25th-75th percentile: 200-220), the shock zone cutoff was 250bpm (25th-75th percentile: 240-250), and the SMART Pass was enabled in 586 (87%) patients. During follow-up, 194 automatic deactivation events were reported in 118 (18%) patients. Shocks were delivered in 129 (19%) patients, and untreated arrhythmias were recorded in 136 (20%) patients. The rate of shocks was lower when SMART Pass was enabled -0.12/patient-year (95% CI: 0.10-0.14) versus 0.20 (95% CI: 0.15-0.26) (p=.002), as it was the rate of untreated arrhythmias -0.12/patient-year (95% CI: 0.11-0.14) versus 0.23 (95% CI: 0.18-0.30) (p=.001). The enhanced SMART Pass version was associated with a lower rate of deactivations -0.04/patient-year (95% CI: 0.02-0.05) versus 0.14 (95% CI: 0.12-0.16) (p<.001), and with a reduction in treated and untreated arrhythmias (Incidence rate ratios: 0.40 (95% CI: 0.28-0.53) and 0.40 (95% CI: 0.30-0.55), respectively (p<.001)). Centers tend to program devices to detect high ventricular rates for arrhythmia detection, to minimize inappropriate shock occurrences. SMART Pass activation is associated with lower rates of detected and treated arrhythmias. The enhanced SMART Pass version seems associated with a lower deactivation rate and with a further decrease in treated arrhythmias.

Left ventricular assist device implantation outcomes in patients with subcutaneous implantable cardioverter-defibrillators: A case series

BackgroundLeft ventricular assist devices (LVADs) may induce electromagnetic interference (EMI) affecting implanted cardiac devices, including more novel subcutaneous implantable cardiac defibrillators (S-ICDs). MethodsIn this case series, the authors retrospectively reviewed courses of 6 patients with S-ICDs who underwent LVAD implantation at a single center. ResultsOf the 6 patients reviewed, 4 experienced inappropriate ICD shocks, of which 3 resulted from EMI. Five of the 6 patients ultimately had S-ICD therapies disabled. ConclusionsDue to EMI resulting in inappropriate shocks and improved tolerability of malignant arrhythmias, deactivation or removal of S-ICDs should be considered in patients undergoing LVAD implantation.

Redefining patient experience: insights from the ATLAS trial on subcutaneous vs. transvenous implantable defibrillators.

Redefining patient experience: insights from the ATLAS trial on subcutaneous vs. transvenous implantable defibrillators.

Electromagnetic force from electric vehicles: Potential electromagnetic interference source for subcutaneous implantable defibrillator.

Electromagnetic interference (EMI) encompasses electromagnetic field signals that can be detected by a device's circuitry, potentially resulting in adverse effects such as inaccurate sensing, pacing, device mode switching, and defibrillation. EMI may impact the functioning of Cardiac Implantable Electronic Devices (CIEDs) and lead to inappropriate therapy. An experimental measuring device, a loop antenna mimicking the implantable cardioverted defibrillator (ICD) antenna, was developed, and validated at the US Food and Drug Administration (FDA) and sent to Wright State University for testing. Two sets of measurements were conducted while the vehicle was connected to a 220-Volt outlet with charging at ON and OFF. Each measurement set involved three readings at various locations, with the antenna oriented in three different positions to account for diverse patient postures. The experiment utilized a Tesla Model 3 electric vehicle (EV), assessing scenarios both inside and outside the car, including the driver's seat, driver's seat floor, passenger's seat, rear seat, rear seat floor, cup holder, charging port (car), and near the charging station. The detected voltage (max 400 to 504 millivolts) around the cup holder inside the car differed from all other measurement scenarios. The investigation highlights the identification of EMI signals originating from an EV) that could potentially interrupt the functionality of a Subcutaneous Implantable Cardioverter-Defibrillator (S-ICD). These signals fell within the R-wave Spectrum of 30-300Hz. Further in-vivo studies are essential to determine accurately the level of interference between S-ICDs and EMI from Electric Vehicles.

Using artificial intelligence and deep learning to optimise the selection of adult congenital heart disease patients in S-ICD screening

IntroductionThe risk of complications associated with transvenous ICDs make the subcutaneous implantable cardiac defibrillator (S-ICD) a valuable alternative in patients with adult congenital heart disease (ACHD). However, higher S-ICD ineligibility and higher inappropriate shock rates-mostly caused by T wave oversensing (TWO)- are observed in this population. We report a novel application of deep learning methods to screen patients for S-ICD eligibility over a longer period than conventional screening. MethodsAdult patients with ACHD and a control group of normal subjects were fitted with a 24-h Holters to record their S-ICD vectors. Their T:R ratio was analysed utilising phase space reconstruction matrices and a deep learning-based model to provide an in-depth description of the T: R variation plot for each vector. T: R variation was compared statistically using t-test. Results13 patients (age 37.4 ± 7.89 years, 61.5 % male, 6 ACHD and 7 control subjects) were enrolled. A significant difference was observed in the mean and median T: R values between the two groups (p < 0.001). There was also a significant difference in the standard deviation of T: R between both groups (p = 0.04). ConclusionsT:R ratio, a main determinant for S-ICD eligibility, is significantly higher with more tendency to fluctuate in ACHD patients when compared to a population with normal hearts. We hypothesise that our novel model could be used to select S-ICD eligible patients by better characterisation of T:R ratio, reducing the risk of TWO and inappropriate shocks in the ACHD patient cohort.

Device programming and SMART pass algorithm activation in subcutaneous implantable defibrillator patients: data from a remote monitoring database

Abstract Background In subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients, a previous study demonstrated very low rates of delivered shocks and inappropriate shocks on programming a conditional zone between 200 and 250 bpm and a shock zone for arrhythmias &amp;gt;250 bpm. The extent to which this programming approach is adopted in clinical practice has been little studied, as the activation status of the SMART Pass filter, that was implemented to reduce inappropriate shocks and enhanced over time. Purpose We assessed device programming during follow-up and the rate of detected arrhythmias in a cohort of consecutive S-ICD recipients. Methods We analyzed data from 670 S-ICD patients followed on the remote network at 17 Italian centers for a median of 31 months (25th-75th percentile: 16-51). The enhanced SMART Pass version was available for all patients after October 2022. It makes the deactivation monitor less sensitive to premature ventricular contractions or other transient amplitude changes while maintaining arrhythmia sensitivity and specificity, and it was expected to reduce unintentional deactivation rate. Results At the last remote data transmission, the median programmed conditional zone cut-off was set to 210 bpm (25th-75th percentile: 200-220), the shock zone cut-off was 250 bpm (25th-75th percentile: 240-250), and the SMART Pass was enabled in 586 (87%) patients. During follow-up, 194 automatic deactivation events (0.10/patient-year) were reported in 118 (18%) patients. The SMART Pass-disabled time was 13% of the total observation period. Shocks were delivered in 129 (19%) patients (rate: 0.13/patient-year), and untreated arrhythmias were recorded in 136 (20%) patients (rate: 0.14/patient-year). The rate of shocks was lower when SMART Pass was enabled – 0.12/patient-year (95% CI: 0.10-0.14) versus 0.20 (95%CI: 0.15-0.26) (p=0.002), as it was the rate of untreated arrhythmias – 0.12/patient-year (95% CI: 0.11-0.14) versus 0.23 (95%CI: 0.18-0.30) (p=0.001). The enhanced SMART Pass version was associated with a lower rate of deactivations – 0.04/patient-year (95%CI: 0.02-0.05) versus 0.14 (95% CI: 0.12-0.16) (p&amp;lt;0.001), and with a reduction in treated and untreated arrhythmias (Incidence rate ratios: 0.40 (95%CI: 0.28-0.53) and 0.40 (95%CI: 0.30-0.55), respectively (p&amp;lt;0.001)). Conclusions In current clinical practice, S-ICD implantation centers often program high cut-off rates for arrhythmia detection. Most patients have SMART Pass consistently enabled during follow-up. This is associated with significantly lower rates of detected and treated arrhythmias. The enhanced SMART Pass version seems associated with lower deactivation rate, and with further decrease in treated and untreated detected arrhythmias.

THE INTELLIGENT USE OF ADRENALINE

Abstract Case Report A 52–year–old patient experienced anterior and inferior ST–elevation myocardial infarction, leading to cardiogenic shock necessitating invasive hemodynamic and pharmacological support. During angiography, an intra–aortic balloon pump (IABP) was inserted, and a norepinephrine infusion along with dobutamine was initiated, showing partial clinical and laboratory improvement. Critical disease in all three vessels was detected, prompting angioplasty with stenting of the right coronary artery and left anterior descending artery. Echocardiography revealed severe reduction in left ventricular systolic function (ejection fraction 10%). Despite revascularization and intensive support, the patient‘s hemodynamic status deteriorated (SCAI D), necessitating the addition of adrenaline (0.03 μg/kg/min) to the ongoing dobutamine infusion, suspending noradrenaline. Subsequent days showed gradual improvement, allowing for withdrawal from amine support and discontinuation of the IABP. Follow–up included a cardiac MRI displaying severe systolic dysfunction (EF 21%), extensive ischemic–pattern delayed enhancement across three–vessel distribution. Given the persistent severe left ventricular dysfunction, the patient underwent subcutaneous defibrillator implantation for primary prevention after optimizing anti–remodeling therapy. Despite optimized medical therapy and cycles of levosimendan, the patient experienced heart failure exacerbation, requiring hospitalization (INTERMACS 3). Considering the clinical condition and absence of contraindications, the patient was listed for heart transplantation. Due to refractory hemodynamic instability despite inotropic agents, a left ventricular assist device was implanted as a bridge to transplantation. Roughly 6 months later, the patient successfully underwent heart transplantation without acute complications. Conclusions Very low doses of adrenaline demonstrate increased sensitivity to β2 receptors over α receptors, thereby enhancing mean arterial pressure and peripheral perfusion. At the cardiac level, it induces an increase in both heart rate and coronary blood flow, while peripherally reducing resistances, predominantly due to the prevalence of β2 receptors in skeletal muscle. This improvement contributes to the enhancement of ventricular–arterial coupling. In conditions characterized by a primary pump deficit, such as cardiogenic shock, the use of low–dose adrenaline emerges as a valid therapeutic option.

DISCONTINUING DAPT: NOT JUST A MATTER OF SCORES BUT OF INTEGRATED EVALUATION? A KEY ROLE OF IMAGING IN A COMPLEX SCENARIO

Abstract The duration of the dual antiplatelet therapy (DAPT) is a widely debated topic within the scientific community. The latest guidelines on acute coronary syndromes have supported the possibility of different therapeutic approaches tailored to patient characteristics. However, the clinical cardiologist‘s decisions are not always based on certain principles. The following case report is a practical example. Discussion: A 31–years–old man came to our attention after a resuscitated cardiac arrest due to ventricular fibrillation during a motorcycle race. His history was characterized by a previous acute myocardial infarction at the age of thirteen due to a traumatic dissection of the proximal left anterior descending (LAD) coronary artery and ascending aorta treated conservatively, with residual transmural necrosis of the mid and subendocardial anterior wall on cardiac MRI. At the admission, ECG showed ST–segment elevation in the anterior leads. Coronary angiography revealed occlusion of the proximal LAD coronary artery, treated with drug–eluting stent (ONYX 5.0 mm), with evidence of dissection and aneurysmal wall of that segment. The patient started a DAPT with aspirin and prasugrel. At discharge, echocardiogram evidenced a moderate left ventricular dysfunction (ejection fraction 34%) with signs of anterior and apical necrosis. Later, the patient was admitted for a subcutaneous defibrillator implantation, due to persistent moderate ventricular dysfunction. One year after revascularization, a lifelong DAPT strategy with downgrading to clopidogrel was considered the best choice for the following considerations: the young age of the patient, the low bleeding risk (PRECISE DAPT score 8), a not elevated DAPT score (value 2), the revascularization in the aneurysmal segment without an appropriate stent apposition (due to absence of a right sizing) and the previous dissection with sign of partial thrombosis at coronary CT. Conclusions: The anatomical complexity of angioplasty procedures and the delicate balance between ischemic and thrombotic risks have led to continuously evolving therapeutic strategies. The clinical scores currently available cannot often account for complex coronary anatomy. Thus, it‘s essential to consider a personalized approach, individualized on clinical and imaging characteristics, that encompasses ischemic and bleeding risk and procedural data for the appropriate treatment for each patient.

Defibrillation threshold in elective subcutaneous implantable defibrillator generator replacements: Time to reduce the size of the pulse generator?

IntroductionThe first step-down defibrillation studies in the subcutaneous implantable cardioverter-defibrillator (S-ICD) described a defibrillation threshold (DFT) of 32.5 ± 17.0 J and 36.6 ± 19.8 J. Therefore, the default shock output of the S-ICD was set at 80 J. In de novo implants, the DFT is lower in optimally positioned S-ICDs. However, a retrospective analysis raised concerns about a high DFT in S-ICD replacements, possibly related to fibrosis. ObjectiveWe aimed to find the DFT in patients undergoing S-ICD generator replacement. MethodsThis prospective study enrolled patients who underwent S-ICD generator replacement with subsequent defibrillation testing. A pre-specified defibrillation testing protocol was used to determine the DFT, defined as the lowest shock output that effectively terminated the induced ventricular arrhythmia. ResultsA total of 45 patients were enrolled, 6.0 ± 2.1 years after initial implant. Mean DFT during replacement in the total cohort was 27.4 ± 14.3 J. In patients with a body mass index (BMI) 18.5–25 kg/m2 (N = 22, BMI 22.5 ± 1.6), median DFT was 20 J (IQR 17.5–30). In 18/22 patients, the DFT was ≤30 J and 5/22 patients were successfully defibrillated at 10 J. One patient with hypertrophic cardiomyopathy had a DFT of 65 J. In patients with a BMI >25 kg/m2 (N = 23, BMI 29.5 ± 4.2), median DFT was 30 J (IQR 20–40). In 15/23 patients, the DFT was ≤30 J and 4/23 patients had a successful defibrillation test at 10 J. ConclusionsThis study eases concerns about a high DFT after S-ICD generator replacement. The majority of patients had a DFT ≤30 J, regardless of BMI, suggesting that the shock output of the S-ICD could be safely reduced.

Subcutaneous Implantable Cardioverter-defibrillator in Preventing Ventricular Arrhythmia and Sudden Cardiac Death – A Single-center Experience

Abstract Introduction: Subcutaneous implantable cardioverter-defibrillator (S-ICD) differs from the transvenous ICD (TV-ICD) system in its extrathoracic and extravascular localization, eliminating the risks arising from vascular access and leading to fewer complications. The objective was to describe the functionality and postoperative complications associated with SICD implants in patients with cardiac dysfunctions. Methods: We enrolled six patients eligible for SICD due to either anterior wall myocardial infarction or left ventricular dysfunction, who reported to our tertiary cardiac care center from June 2020 to March 2022. Preprocedural evaluation for various cardiac parameters was carried out. The procedure was performed under antibiotic prophylaxis. Two incision techniques were used for the SICD placement. The primary and secondary endpoints for the cases were set to evaluate device-related complications and predictive outcomes, respectively. Results: Subcutaneous implantable defibrillator was placed in six male patients aged 36−51 years. The procedure demonstrated an efficient, reliable, and well-accepted modality in eliminating ventricular tachycardia, ventricular fibrillation, and sudden cardiac death. In addition, postoperative complications, such as device infection, pocket hematoma, blood transfusion, prolonged hospitalization, cardiac perforation or tamponade, lead repositioning, or inappropriate shocks, were not reported in the 2 years of follow-up. Conclusion: Subcutaneous implantable defibrillator promises to offer a suitable and safer option for TV-ICD, especially in young patients. It circumvents the need to enter the vasculature or cardiac chambers. As a result, fewer reported lead-related complications, better cosmetic appearance, and greater immediate postoperative comfort as it permits free shoulder movement.

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

Abstract Funding Acknowledgements Type of funding sources: None. Background data on long-term outcome of the intermuscular (IM) two-incision implantation technique for the subcutaneous implantable cardioverted defibrillator (S-ICD) are lacking. Purpose the aim of the present study was to evaluate the outcome of patients underwent S-ICD implantation with the 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 inappropriate shocks (IAS). Lead-associated complications were the most common (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 (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.

Impact of the Covid19 pandemic on implantable cardiac device implants in Spain. Data from the nationwide Covid 19 RM (remote monitoring) Spain registry

Abstract Funding Acknowledgements Type of funding sources: None. Background The Covid-19 pandemic has meant a very significant reduction in all urgent and non-urgent activity, including the implants of Cardiac Implantable electronic devices (CIEDs) throughout 2020. From the end of 2020 and throughout the year 2021, hospital activity has normalised, but it is uncertain whether the devices that were not implanted within 2020 have been delayed in time or actually lost. Purpose We sought to evaluate the pre and post-pandemic trends in CIEDs implantations from a large nationwide database in order to determine the global effect of the COVID-19 pandemic on CIEDs implants in Spain. Methods The Covid-19 Remote Monitoring Spain Registry (Covid-19 RM-Spain) is a survey supported by the Heart Rhythm Association of the Spanish Society of Cardiology to request the whole national data regarding the number of CIED´s implants and remote monitoring activations from the five main manufacturers classified according to each autonomous community (not by institutions).All data were aggregated and anonymized to analyse the total sample. Appropriate permissions were granted to use the data and a confidentiality agreement was signed in order to avoid any transmission of sensitive information. Results No institution objected to the use of their data, so the total number of devices implanted in Spain were obtained, which were 50258, 52994, 47330 and 54490 in 2018, 2019, 2020 and 2021 respectively. When we try to balance the drop in implants during 2020 and the subsequent increase experienced during 2021 against the average of 2018 and 2019, we have observed that approximately 2600 pacemakers (7%) and about 150 defibrillators (3.1%) have been "lost". With regard to the rest of the devices, adding up the differences between 2020 and 2021 and comparing them with the average for 2018-19, an increase of 419 Cardiac Resynchronization defibrillators (18%), 130 Cardiac Resynchronization Pacemakers (9.4%) and 1189 Implantable Loop recorders ( 26%) have been observed. Conclusion(s) In 2020 there was a large reduction in all CIEDs implants. In the most numerous devices (pacemakers), unlike the rest, the increment has not compensated for the reduction in implants that occurred in 2020 by the end of 2021. The marked increase in the number of cardiac resynchronization implants may suggest that the indication for single or dual-chamber defibrillator implantation may have finally evolved in a significant number of patients into an indication for cardiac resynchronization. Abbreviations: CRT-D: Cardiac resynchronization Therapy -Desfibrillator; CRT-P: Cardiac resynchronization Therapy -pacemaker; ICD: Implantable cardiac defibrillators; ILR: Implantable Loop recorders; LLPM: Leadles Pacemakers; PM: Pacemakers; S-ICD: Subcutaneous Implantable cardiac defibrillator.

Covid 19 pandemic: the final boost for remote monitoring of implantable cardiac devices? : analysis from the nationwide remote monitoring registry (Covid-19 rm-spain)

Abstract Funding Acknowledgements Type of funding sources: None. Background Remote monitoring of implantable cardiac devices (CIEDs) has proven to be reliable, more efficient and even safer than conventional in-office follow-ups However, its implementation has not been as desired. The COVID 19 pandemic and the need to keep patients away from hospitals may have been the final boost for this form of monitoring. Purpose We sought to evaluate the pre and post-pandemic trends in CIEDs remote monitoring activations from a large nationwide database in order to determine the global effect of the COVID-19 pandemic on CIEDs implants in Spain. Methods The Covid-19 Remote Monitoring Spain Registry (Covid-19 RM-Spain) is a survey supported by the Heart Rhythm Association of the Spanish Society of Cardiology to request the whole national data, regarding the number of CIED´s implants and remote monitoring activations from the five main manufacturers classified according to each autonomous community (not by institutions).All data were aggregated and anonymized to analyse the total sample. Appropriate permissions were granted to use the data and a confidentiality agreement was signed in order to avoid any transmission of sensitive information. Results The percentage of devices for which remote monitoring was activated was 24.5%; 28.4%, 42% and 49% in 2018, 2019 ,2020 and 2021, which implies that remote monitoring is now activated on more than twice as many devices in Spain as in 2018. The table shows the differences in the percentages of remote monitoring activation between three different periods for each type of device. (Period 1 /pre-lockdown January 2018-February 2021; Period 2/ lockdown: March-June 2020 and Period 3/ lockdown: July 2020-December 2021. Footnotes: Period A vs. B p&amp;lt;0,001 :1 ; Period A vs. C p&amp;lt;0,001:2; Period B vs. C p&amp;lt;0,001:3 Abbreviations : CRT-D: Cardiac resynchronization Therapy -Desfibrillator; CRT-P: Cardiac resynchronization Therapy -pacemaker; ICD: Implantable cardiac defibrillators; ILR: Implantable Loop recorders; LLPM: Leadles Pacemakers; PM: Pacemakers; S-ICD: Subcutaneous Implantable cardiac defibrillator.

P162 ARRHYTHMIC MITRAL VALVE PROLAPSE OCCURRING AS ABORTED SUDDEN CARDIAC DEATH

Abstract Mitral valve prolapse (MVP) is the common valvular heart disease, with a prevalence about 1–3% in the population. MVP is characterized on echocardiography by an abnormal systolic displacement of mitral valve leaflets into left atrium (LA) ≥ 2 mm above the mitral annulus. We described a clinical case of a 15 years–old boy with a first clinical presentation of out–of–hospital cardiac arrest related to ventricular fibrillation (VF) with a successful resuscitation after 2 DC shocks. Retrospectively, an episode of loss of awareness reported as post–minational. No familiar history of sudden cardiac death (SCD) or MVP was noticed. In the emergency room, the patient was hemodynamically unstable and was sedated and intubated. The surface electrocardiogram (ECG) showed sinus rhythm, QRS with fragmentation, and frequent monomorphic isolated premature ventricular contractions (PVCs) with RBBB/LAFB configuration.Frequent monomorphic PVCs with bigeminy was observed during continuous ECG monitoring, so the patient was treated with magnesium sulphate and metoprolol. The patient was subsequently weaned from ventilation support, presenting good gas exchange and without neurological sequalae. The 24h Holter monitoring showed an average of 53 bpm, extremely rare supraventricular extrasystoles, high incidence of monomorphic PVCs (23% of the total beats) with 4 couplets. Transthoracic echocardiography documented normal size and thickness with systolic function (GLS –21%, mild asynchrony of posterior basal segments), bi–leaflet prolapse associated to mild–moderate mitral regurgitation, and mitral annular disjunction (MAD) of 6.2 mm. The late gadolinium enhancement cardiac magnetic resonance showed bi–leaflet prolapse with mild insufficiency and maximum MAD 9 mm, mild LA dilatation, and slightly dilated both ventricles, without regional wall motion abnormalities; no scar or fibrosis at the late gadolinium enhancement was observed. According to guidelines, the patient received a subcutaneous implantable cardiac defibrillator for the secondary prevention of SCD and maintained under betablockers in order to control the arrhythmic burden. The genetic sampling did not show any pathogenetic mutation potentially related to cardiomyopathies or channelopathies. This case show an arrhythmic MVP complex with probably posterior papillary muscle source. The early PVCs with R/T constituted a possible trigger of VF. The betablocker therapy exhibited a full suppression of extrasystolic burden.

PO-03-058 S-ICD GENERATOR EXCHANGE AND PERFORMANCE: A SINGLE TERTIARY CARE EXPERIENCE

Limited data exist on outcomes of subcutaneous implantable cardiac defibrillators (S-ICDs) generator exchange. Few studies have found that shock impedance increases after S-ICD Gen exchange which correlates with increase in DFT and possibly reduction in S-ICD effectiveness. We describe the performance of S-ICDs after generator exchange in a cohort of patients implanted and followed in a single tertiary-care referral center. We reviewed the device clinic interrogation reports of 525 patients who received S-ICDs between 2012 and 2022 and compared device parameters before and after generator exchanges specifically high-voltage impedance and shock efficacy during follow-up using the paired sample t-test with a 95% CI and p-value of 0.05. A total of 525 S-ICDs were implanted at our facility with an average age at implant of 51±16 years, predominantly males (n=348, 66.3%). The majority of S-ICDs were implanted for primary prevention (413, 79%), and ischemic cardiomyopathy (CM) was the most common type of CM (127, 24%). The average ejection fraction (EF) was 30±12%, and comorbidities were prevalent: 56% hypertension, 29% diabetes, 38% with history of coronary artery disease (CAD), and 33% end-stage renal disease (ESRD). Of those, 76 (15%) underwent generator battery exchange at a median time of 4.5± 2 years. Before generator exchange, a total of 114 shocks (22%) were delivered with an impedance of 68± 23Ω. Of those, 89 (78%) were appropriate shocks. Efficacy of the appropriate shocks was 95%. [F1] [IR2] After generator exchange (n=76), 10 appropriate shocks (13%) were administered with an impedance of 82± 29 Ω, and a shock efficacy of 100%. High voltage impedance and shock efficacy were not statistically different before and after Gen exchange (p=0.178 and p=0.158 respectively). The S-ICD generator exchange demonstrates high safety profile with relatively no change in device impedance or shock efficacy pre- and post- Gen exchange.

Reduction in inappropriate therapies through device programming in subcutaneous implantable defibrillator patients: data from clinical practice.

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.

Correlation analysis of deep learning methods in S-ICD screening.

Machine learning methods are used in the classification of various cardiovascular diseases through ECG data analysis. The concept of varying subcutaneous implantable cardiac defibrillator (S-ICD) eligibility, owing to the dynamicity of ECG signals, has been introduced before. There are practical limitations to acquiring longer durations of ECG signals for S-ICD screening. This study explored the potential use of deep learning methods in S-ICD screening. This was a retrospective study. A deep learning tool was used to provide descriptive analysis of the T:R ratios over 24 h recordings of S-ICD vectors. Spearman's rank correlation test was used to compare the results statistically to those of a "gold standard" S-ICD simulator. A total of 14 patients (mean age: 63.7± 5.2 years, 71.4% male) were recruited and 28 vectors were analyzed. Mean T:R, standard deviation of T:R, and favorable ratio time (FVR)-a new concept introduced in this study-for all vectors combined were 0.21 ± 0.11, 0.08 ± 0.04, and 79 ± 30%, respectively. There were statistically significant strong correlations between the outcomes of our novel tool and the S-ICD simulator (p< .001). Deep learning methods could provide a practical software solution to analyze data acquired for longer durations than current S-ICD screening practices. This could help select patients better suited for S-ICD therapy as well as guide vector selection in S-ICD eligible patients. Further work is needed before this could be translated into clinical practice.

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.

The Australian and New Zealand Cardiac Implantable Electronic Device Survey, Calendar Year 2021: 50-Year Anniversary.

A cardiac implantable electronic device (CIED) survey was undertaken in Australia and New Zealand for calendar year 2021. The survey involved pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs). The survey was conducted on the 50th anniversary of the first survey for both Australia and New Zealand in 1972; that initial survey being conducted by two of the current authors. For 2021, there were 19,410 PMs (17,971 in 2017) sold in Australia for new implants and 2,282 (1,811 in 2017) sold in New Zealand. The number of new PM implants per million population was 755 for Australia (745 in 2017) and 446 for New Zealand (384 in 2017). Unlike previous recent surveys, the percentage of PM replacements compared to total sales in both Australia and New Zealand rose. Pulse generator types implanted were predominantly dual chamber; Australia 77% (73% in 2017) and New Zealand 70% (68% in 2017). There were 1,509 biventricular PMs implanted in Australia (1,247 in 2017) and 172 in New Zealand (118 in 2017). Transvenous pacing leads were >90% active fixation in the atrium and ventricle. There was an increase in ICD usage with Australia 4,519 new implants (4,212 in 2017) and New Zealand 449 (396 in 2017). New ICD implants per million population were 187 for Australia (175 in 2017) and 88 for New Zealand (90 in 2017). For the first time the survey included implantable event monitors with 6,933 being implanted in Australia. However, for proprietary reasons, survey figures for subcutaneous implantable defibrillators, leadless pacemakers and conduction system pacing have not been included. Both Australia and New Zealand have high PM and ICD implant numbers compared to the rest of the Asia Pacific region.