Dual-chamber Implantable Cardioverter-defibrillator Research Articles

Impact of gender on the utilisation implantable cardioverter defibrillators and outcome: results from the German DEVICE registry

Abstract Background Implantable cardioverter defibrillators (ICD) are an established therapy for the primary and secondary prevention of sudden cardiac death. Real world data regarding the impact of gender on ICD implantation and outcome are scarce. Purpose To determine the impact of gender on the ICD implantation and outcome. Methods The German DEVICE registry is a prospective, nationwide database of ICD and CRT devices implantation and revisions. Between March 2007 and February 2014, 3794 patients undergoing a single or dual chamber ICD implantation and revisions were prospectively included in 44 centres and monitored for a median of 17 months. Herein we conducted the gender-based analysis of the ICD recipients. Results A total of 688 (18,1%) women (mean age 62.5 ± 16.0, median BMI 26.7) and 3106 men (mean age 64.6 ± 12.9, median BMI 26.8) were included in this registry. Significantly less women had coronary artery disease (p<0.001), while more women had hypertrophic cardiomyopathy (p=0.024) and primary electrical heart disease (p<0.001), mainly because of a higher incidence of long QT syndrome and arrhythmogenic right ventricular cardiomyopathy. There was a trend towards a higher rate dual chamber ICD in the female population (31.7% vs. 28.1%; p=0.061). Women were less likely to undergo ambulatory interventions (6.4% vs. 9.0%; p=0.026) and had a trend towards higher rate of ICD implantation for secondary prevention (52.3% vs. 48.7%; p=0.086). Females were more likely to have a history of ventricular fibrillation (51.7% vs. 39.4%; p<0.001) and resuscitation (54.7% vs. 46.3%; p=0.006), but less likely to have a history of ventricular tachycardia (33.1% vs. 45.2%; p<0.001). The overall rate of in-hospital complications (5.3% vs. 2.7%; p=0.005) as well as the rate of major periprocedural complications (3.1% vs. 1.3%; p=0.002) was significantly higher among females, mainly driven by a higher incidence of pneumothorax (1.0% vs. 0.1%; p=0.004) and haemothorax (0.4% vs. 0%; p=0.02). The rate of in-hospital device revision and mortality were similar between genders. The Kaplan-Meier estimated 1-year all-cause mortality was 5.2% for women and 7.1% for men (p=0.073; Fig 1), while the estimated incidence of all-cause mortality or device shocks was significantly lower in the female population (15.1% vs. 19.0%; p=0.02). Women were more likely to undergo resuscitation during follow-up (FU; 1.3% vs. 0.3%; p<0.001) and showed a higher fear of receiving device shocks. There was no difference in terms of ICD-shocks, VT-storm and ablation rates at FU. The all- cause, device-related, and other cardiovascular rehospitalisation rates and the incidence of non-arrhythmic adverse events during FU were similar between genders. Conclusions In this real-life patient cohort only a minority of patients were females. Female patients had a higher risk of major periprocedural complications and in-hospital complications and a trend towards a lower all-cause mortality during FU.Fig 1. Kaplan-Meier estimated survival.

Ventricular arrhythmia events in patients with implantable cardioverter-defibrillator before and after the treatment with sodium-glucose co-transporter 2 inhibitors

Abstract Background The role of sodium-glucose co-transporter 2 inhibitors (SGLT2i) in the treatment of chronic heart failure is expanding. However, the timing of implantable cardioverter-defibrillator (ICD) implantation for primary prevention in relation to the use of SGLT2i remains unclear. A small case series has described appropriate shocks from ICD in two patients following the initiation of SGLT2i, but a comprehensive analysis is lacking in the literature. Methods This study aimed to investigate the rate of ventricular arrhythmic burden and appropriate anti-tachycardia therapy from ICD before and after the initiation of SGLT2i therapy. We conducted a retrospective single-center analysis, comparing ventricular events from home monitoring reports three months before and three months after SGLT2i therapy initiation. Results Seventeen patients were enrolled in the study. At baseline, clinical characteristics were as follows: 13 (76%) were male, 9 (53%) had ischemic, 2 (12%) had valvular, and 6 (35%) had idiopathic cardiomyopathy. The mean end-diastolic volume (EDV) was 203 ± 90 ml, and the mean left ventricular ejection fraction was 0.36 ± 0.09. All patients were treated with beta-blockers, 14 (82%) with sacubitril-valsartan, 13 (76%) with aldosterone antagonists, 16 (94%) with furosemide, and 5 (29%) with amiodarone. SGLT2i started with dapagliflozin for 13 patients (76%), empagliflozin for 3 patients (18%), and canagliflozin for 1 patient (6%). Ten patients (59%) had single-chamber or dual-chamber ICDs, and 7 had implantable cardiac resynchronization therapy (CRT) defibrillators. In the three months before SGLT2i treatment, 4/17 patients had non-sustained ventricular tachycardia (NSVT), compared to 8/17 (23% vs. 47%, p-value 0.23) patients with NSVT after treatment. Seven patients (41%) experienced an increase in the rate of NSVT events, with one patient having 28 NSVT events after treatment versus none before treatment. No patients had anti-tachycardia therapy in the three months before treatment, while in the three months after SGLT2i treatment, 1 patient had ventricular tachycardia treated with anti-tachycardia pacing (110 days after the beginning of the treatment), and 2 patients had ventricular tachycardia treated with appropriate shocks (2 and 25 days after the initiation of SGLT2i treatment). Conclusion This small retrospective analysis revealed an increase in ventricular arrhythmic events in the three months following the initiation of SGLT2i. These findings highlight the need for a more extensive analysis to establish a stronger statistical correlation.

Factors influencing inappropriate device therapy in implantable cardioverter defibrillators: a predictive analysis

Abstract Background Implantable cardioverter defibrillator (ICD) implantation and subsequent ICD therapy have shown to be efficacious in the prevention of sudden cardiac death. However, patients with an ICD are at risk of inappropriate device therapy (IDT), which is associated with worse outcomes, reduced quality of life (QoL), and may influence psychosocial and mental wellbeing. Purpose This study aimed to predict which patients are at risk of IDT by investigating the influence of pre-implant clinical parameters on occurrence of IDT. Methods From January 2010 to December 2019, patients who received an ICD in our medical center, were included in a prospective registry. Only patients with ICD (including ICDs used for cardiac resynchronization therapy, i.e. CRT-D) with an atrial lead were included in the current analysis, to better distinguish between appropriate and inappropriate device therapy. After implant, the device was interrogated at least every 6 months and clinical symptoms related to the device, recorded events, and relevant technical setting changes were recorded. IDT was defined as antitachycardia pacing (ATP) or shock delivered for any reason other than ventricular arrhythmia. Follow-up ended after IDT, death, or loss-to-follow-up. Results 428 patients underwent an implantation of a dual chamber ICD or CRT-D of various manufacturers. 14 patients were lost to follow-up within the first year and one patient was excluded because of a dislocated atrial lead, leaving 413 patients (76% male, mean age 67±9.7 years, 39% CRT-D) with a minimum of 1-year follow-up. During a mean of 5.3 (±3.0) years, 136 (32.9%) patients received appropriate therapy and 36 (8.7%) patients received IDT. Of those 36 patients, 18 patients received only ATP, 12 received ATP followed by a shock, and 6 patients received a shock without prior ATP. The median time from implantation to IDT was 2.8 [0.3-5.8] years. Univariate logistic regression on 40 clinical parameters followed by a forward multivariate logistic regression was performed. The area under the ROC curve of the resulting multivariate model was 0.724 (95%CI 0.622-0.826). Cox regression analysis resulted in device type (CRT-D) (HR=0.533, 95%CI 0.234-1.211, p=0.133), use of mineralocorticoid receptor-antagonists (MRA) (HR=0.280, 95%CI 0.104-0.754, p=0.012), use of diuretics (HR=3.378, 95%CI 1.479-7.714, p=0.004), and eGFR (HR=1.217, 95%CI 0.972-1.523, p=0.087) as predictors of IDT. A history of atrial fibrillation was not a significant predictor of IDT. Conclusion This study identified CRT-D and use of MRAs to be protective against IDT, and use of diuretics and lower eGFR as risk factors of IDT. To inform patients optimally, pre-implant assessment of those factors could help identify patients at higher risk of IDT. Furthermore, it could dictate more cautious device programming and consequently reduce rates of IDT, reducing the negative influence of IDT on QoL and wellbeing in the ICD population.

INTERATRIAL BLOCK AS A FIRST CLINICAL PRESENTATION OF ATRIAL CARDIOMYOPATHY RELATED TO A NOVEL LMNA VARIANT: A CASE REPORT

Abstract Interatrial block (IAB) is a conduction delay in Bachmann’s bundle with a well–described association with structural heart disease, supraventricular arrhythmias, and cardiovascular events. We report the case of an asymptomatic 35–year–old man in whom the presence of IAB at electrocardiogram led to a comprehensive evaluation including speckle–tracking echocardiography, 24 h Holter monitoring, and genetic testing. Speckle–tracking echocardiography demonstrated a decrease in the longitudinal strain of interventricular septum, a typical feature of LMNA–related cardiomyopathy, and decreased indices of left atrial deformation. A diagnosis of cardiac laminopathy related to the frame shift variant c.1367 (p.Asn456Thrfs*24) of the LMNA gene was made. A dual–chamber implantable cardioverter defibrillator implantation was performed for the high risk of life–threatening ventricular tachyarrhythmias. This case demonstrates that IAB could be a rare presentation of a life–threatening laminopathy. Strain echocardiography is an essential tool to evaluate the deposition of fibrosis tissue in subclinical cardiomyopathies. Our report describes a novel variant of LMNA gene associated with a high risk of sudden cardiac death.

A VENTRICULAR TACHYCARDIA CASE NOT TREATABLE WITH TRANSCATHETER ABLATION DUE TO APICAL THROMBOSIS OF THE LEFT VENTRICLE RESOLVED WITH RADIOTHERAPY BASED ON THE NON–INVASIVE MAPPING SYSTE

Abstract The clinical case focuses on a 52–year–old man smoker, heavy alcohol consumer. In 2017 he began with sustained ventricular tachycardia (VT) effectively treated with DC–shock. The following ECG showed signs of anterior necrosis. Severe left ventricular (LV) dilatation, apical thrombosis and severe impairment of LV function were found on echocardiogram. Angiography was performed and LAD occlusion was found. Since of 68% necrosis of the LV at myocardial scintigraphy, no revascularization was performed. He underwent to a dual chamber ICD implantation and started oral anticoagulation therapy. In the following years recurrence of arrhythmic episodes, despite the optimization of antiarrhythmic therapy, led the patient to numerous hospitalizations. Unfortunately the persistence of the apical thrombosis, made transcatheter ablation NOT possible. The only chance for the patient remained stereotactic arrhythmia radioablation. But which area of the LV to highlight as responsible for the arrhythmia and how to program the radiotherapy treatment plan was a challenging problem. We proposed in March 2023 non–invasive mapping of arrhythmia using Cardioinsight. The patient performed heart high–resolution computed tomography (CT) for the anatomical reconstruction with precise spatial resolution of all LV aereas and surrounding structures. A 252–electrode vest is applied to the patient’s torso and connected to the system Cardioinsight. A programmed ventricular stimulation was performed using ICD inducing two VT morphologies. Through electroanatomical mapping we identified the mid LV antero–septal and infero–septal sites as target areas. Thanks to multidisciplinary team a personalized treatment plan was created to deliver an effective lesion in the target area and minimize exposure to nearby organs at risk. The treatment was generated, optimized and delivered by TrueBeam, lasted 3 minutes and no complications arose. The patient was quickly discharged in good clinical condition. After 3 months of clinical well–being he was hospitalized for a single episode of VT. Up to now no hospitalizations occurred. This treatment may represent a "bail–out" choice in patients with advanced heart failure with arrhythmic storm who have exhausted all other therapeutic options.

Internal Mammary Artery Graft Flow Steal by a Large Dialysis Arteriovenous Fistula Characterized by Electrical Storm

Background: Steal syndrome describes a condition in which a dilated vessel distal to a smaller artery attempts to compensate for decreased blood flow by “stealing” from the smaller artery. Steal syndrome is not uncommon and can be seen in certain physiologic and pathologic states. The classic example is an occluded atherosclerotic coronary artery resulting in a misdirection of blood flow into the open channels that have developed over time resulting in downstream ischemia. Case Report: A 66-year-old male fourteen years post 4-vessel coronary artery bypass grafting using his left internal mammary artery to bypass a stenotic segment of the left anterior descending artery, along with three saphenous venous conduits to the right coronary artery. He also had a stent placement by PCI. He was on dual antiplatelet therapy with aspirin and clopidogrel. An electrophysiology study revealed inducible VF and he underwent implantation of a dual chamber ICD 9 months prior to presentation. He experienced an unprovoked fall at home and a workup revealed the flow volume through the patient’s fistula increased to such a degree that the patient developed a steal syndrome from his left internal mammary artery graft. In addition, went into a state of electrical storm caused by ischemic damage to cardiac tissue distal to the graft. By ligating the fistula, the patient’s steal syndrome resolved and he did not suffer further ventricular arrhythmias. Conclusion: Both coronary bypass grafting and fistula formation are common and necessary interventions and providers should take care to monitor for interactions between these proposed interventions to best serve their patients without causing additional harm. Increased vascular flow through any portion of the body can induce a steal syndrome from an upstream region. Patients who undergo arteriovenous (AV) fistula placement may develop a steal syndrome from ipsilateral bypass grafts.

Nutritional Status Predicts the Length of Stay and Mortality in Patients Undergoing Electrotherapy Procedures.

(1) Background: Nutritional status is a factor that impacts the patients' outcomes in various medical conditions including cardiovascular patients or surgical procedures. However, there is limited available information about its impact on the short-term outcomes of cardiac implantable electronic device (CIED) implantations. This study aimed to assess the relationship between nutritional status, complications, mortality risk, and length of stay at the hospital in patients undergoing CIED implantations. (2) Material and Methods: 588 patients who underwent CIED implantation in 2022 and 2023 were included in the retrospective analysis. The nutritional status assessment was performed using NRS 2002 and BMI. The implanted devices were single-chamber pacemakers (n = 82), dual-chamber pacemakers (n = 329), one-chamber ICDs (n = 83), dual-chamber ICDs (n = 19), CRT-P (n = 19), and CRT-D (n = 56). (3) Results: The regression analysis showed that the NRS 2002 score predicted the length of stay (age-adjusted: β = 1.02, p = 0.001) among the CIED-implanted patients. The CRT-D subgroup was particularly responsible for this relationship (β = 4.05, p = 0.003 after age adjustment). The analysis also revealed significant differences between the NRS 2002 score in the in-hospital death subgroups (1.75 ± 1.00 points for deaths vs. 1.00 ± 1.00 points for survivors; p = 0.04). There were no significant differences in nutritional status parameters regarding early complications subgroups. (4) Conclusions: This study showed that nutritional risk assessed with NRS 2002 is a predictor of length of stay (particularly for CRT-D) and mortality among patients undergoing CIED implantations. The results of the analysis point out the impact of patients' nutritional status on short-term outcomes of CIED implantations, particularly in CRT-D implants where 1 NRS 2002 point was a predictor of a mean 4.05 days (77.2%) longer hospitalization.

Long QT Syndrome and WPW Syndrome: A Very Rare Association between Two Causes of Sudden Cardiac Death in a Young Patient

Long QT syndrome (LQT) and WPW syndrome are causes of sudden cardiac death (SCD) in the young, and their association has been rarely reported. A 26-year-old woman presented with recurrent syncope. Her ECG showed a short PR interval, wide QRS (150 ms) due to a delta wave, and QT prolongation (QT 580 ms, QTc 648 ms). ECG monitoring documented recurrent salvos of a self-terminating wide QRS tachycardia, generally slightly polymorphic, sometimes with “torsade des pointes” (TdP) appearance, which were linked to the syncopal/presyncope episodes. Electrophysiologic monitoring diagnosed a right para-hisian accessory pathway with a very short ERP (240 ms baseline, <200 ms after isoproterenol). The pathway was ablated successfully. Despite QRS narrowing (80 ms), QT prolongation persisted after ablation (QT 620 ms, QTc 654 ms), with short runs of TdP, despite beta-blocker treatment, which was increased to the maximal dosage. A dual-chamber implantable cardioverter defibrillator (ICD) was implanted. To our knowledge, this is the first case report of an association between LQT and WPW syndrome in which both conditions are associated with an increased risk of SCD.

Appropriateness of implantable cardioverter-defibrillator device implants in the United States

BackgroundThe appropriate use criteria (AUCs) are a diverse group of indications aimed to better evaluate the benefits of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy. ObjectiveThe purpose of this study was to quantify the proportion of ICD and cardiac resynchronization therapy with defibrillator (CRT-D) implants as appropriate, may be appropriate (MA), or rarely appropriate (RA) on the basis of the AUC guidelines. MethodsThis is a multicenter retrospective study of patients within the National Cardiovascular Data Registry undergoing ICD implantation between April 2018 and March 2019 at >1500 US hospitals. The appropriateness of ICD implants was adjudicated using the AUC. ResultsOf 309,318 ICDs, 241,438 were primary prevention implants (78.1%) and 67,880 secondary prevention implants (21.9%); 243,532 (79%) were mappable to the AUC. For primary prevention, 185,431 ICDs (96.4%) were appropriate, 5660 (2.9%) MA, and 1205 (0.6%) RA. For secondary prevention, 47,498 ICDs (92.7%) were appropriate, 2581 (5%) MA, and 1157 (2.3%) RA. A significant number of RA devices were implanted in patients with New York Heart Association class IV heart failure who were ineligible for advanced therapies (53.9%) and those with myocardial infarction within 40 days (18.1%). The appropriateness of the pacing lead was more variable, with 48,470 dual-chamber ICD implants (62%) being classified as appropriate, 29,209 (37.4%) MA, and 448 (0.6%) RA. Among CRT-D implants, 63,848 (82.2%) were appropriate, 9900 (12.7%) MA, and 3940 (5.1%) RA for left ventricular pacing. A total of 99,754 implants were deemed appropriate but excluded from Centers for Medicare & Medicaid Services National Coverage Determination. More than 92% of hospitals had an RA implant rate of <4%. ConclusionIn this large national registry, 95% of mappable ICD and CRT-D implants were considered appropriate, with <2% of RA implants. Nearly 100,000 appropriate implants are excluded by Centers for Medicare & Medicaid Services National Coverage Determination.

PP49 Cost Of Cardiac Implantable Electronic Device (CIED) Infections In Australia: A Private And Public Sector Payer Perspective

IntroductionIn Australia, approximately 200,000 patients have a cardiac implantable electronic device (CIED), and in an aging population that number is rising. CIED-related infections are also increasing, causing considerable morbidity and mortality, and substantial healthcare costs. Internationally, the rate of CIED infection ranges from 1.0 percent to 1.6 percent, while in Australia, the reported range is from less than 1 percent to 7.0 percent. The average hospital cost to treat an infection in the US ranges between USD48,000–USD83,000. To date, few publications have estimated the cost of CIED infections in Australia. Critical appraisal of these studies has highlighted issues in their methodology, making them unreliable sources for use in economic evaluations. The purpose of this study was to utilize Australian routinely collected health data to robustly model costs of CIED infections to reduce uncertainty for future health technology assessment (HTA).MethodsThe cost of treating a CIED infection was modeled for the public and private sector including cost of system removal and re-implantation procedures, hospital and intensive care unit (ICU) stay, and outpatient follow-up. Cost inputs were obtained from the Australian Prostheses List, Medicare Benefits Schedule, Australian Institute of Health and Welfare, and Private Hospital Data Bureau. Other inputs were obtained by surveying Australian clinicians, which were validated with published data. Phone interviews and online surveys were conducted with clinicians to elicit specific Australian practice pathways for patients with a CIED infection.ResultsThe majority of patients with a CIED have their device system removed (95-100%) and re-implanted (83%) once the infection has cleared. In the private sector, cost of infection ranged from AUD80,869 (USD54,384) for a single chamber pacemaker (PM), to AUD140,103 (USD94,248) for a dual chamber Implantable Cardioverter-defibrillator (ICD). Modeled costs of CIED infection were slightly lower in the public sector (AUD73,643-AUD88,446 (USD49,555 – USD59,516) for the same devices).ConclusionsThe cost of a CIED infections to the healthcare system is high and differs by device type. Utilizing local real-world data to estimate costs will improve accuracy of economic evaluations and reduce uncertainty for decision makers.

Choice of cardiac implantable electronic device and age-stratified clinical outcome in patients with known heart failure prior to implant

Abstract Background Patients with heart failure (HF) and bradycardia may be eligible for different types of cardiac implantable devices, depending on presence of AV conduction disease, left ventricular ejection fraction, severity of heart failure symptoms, other comorbidities, and age. Once a pacing device is in place, there is a risk that ensuing heart failure progression or worsening of symptoms do not always prompt a device upgrade to resynchronization or conduction system pacing therapy, even if this should be warranted. We therefore aimed to compare prognosis in a national cohort of patients with prior HF diagnosis, who received a pacemaker or defibrillator with or without resynchronization therapy. Methods All patients with preexisting HF diagnosis who received a pacemaker with a right ventricular lead during the period 2005-2018 in Sweden were identified via the Pacemaker Registry. Data was crossmatched with the population registry and national disease registries. Primary outcome was 5-year mortality, and secondary was mode of death and hospitalization for heart failure. Cox regression and Kaplan Meier curves with log rank test were used for time dependent outcome analyses. Demography variables were compared with Chi2 test or Mann Whitney U test, as appropriate. Adjustment was done for history of atrial fibrillation, diabetes, hypertension, malignancy, age, gender, ischemic heart disease, renal disease, lung disease and cerebrovascular disease. Separate analyses were made for patients with complete AV block, based on the assumption of 100% ventricular pacing in this group, regardless of choice of implanted device. Results 37745 patients were included in the study (see figure 1). Demographic data was similar for the different device groups, except that patients with single chamber pacemaker were older, and all those with single chamber devices (pacemaker, ICD) were more likely to have a history of atrial fibrillation. All listed comorbidities, male sex and higher age were associated with lower 5-year survival in multivariable Cox regression analyses. Unadjusted 5-year mortality was 40% (highest for single chamber pacemakers (61%), and lowest for dual chamber ICDs (17%), p=0.001). When stratified by age group, and adjusted for relevant covariables, patients with single-chamber pacemakers still had higher mortality in all age decile groups (ranging from &amp;lt;60 to &amp;gt;90 years old, all p&amp;lt;0.001). Proportion of device upgrades to CRT was very low; 2.9% for dual- and 0.8% for single-chamber pacemakers. 17% of patients with traditional pacemakers died from HF, and 31% were hospitalized for HF. Conclusions Survival for patients with prior HF diagnosis who receive traditional pacemakers is poor, risk of HF hospitalization is high, whereas upgrades to CRT are scarce. This highlights the need for choosing correct device type at the primary implant, if ventricular pacing is anticipated.Flowchart of included patientsAge stratified survival per device group

Abstract 13000: Twiddler’s Syndrome - A Rare Cause of Pacemaker Malfunction

Description of Case: A 76-year-old female with a past medical history of chronic atrial fibrillation and symptomatic tachycardia and bradycardia status-post dual-chamber pacemaker with right atrial and ventricular leads who presented with dyspnea on exertion. TTE showed normal biventricular function and no significant valvular abnormalities. Upon further evaluation of her pacemaker, she was found to have a very high ventricular capture threshold suggesting RV lead failure. The patient underwent RV lead replacement. The inspection of the pacemaker pocket during the procedure showed manual dislodgement of both tie-down sleeves and the pacemaker leads required untangling. A new RV lead was subsequently placed. Upon further imaging review, displacement of the previous RV lead was evident from initial placement. In addition, the patient had previously had a history of interval diaphragmatic stimulation as well. Overall, the presentation was felt to be consistent with Twiddler’s Syndrome. Discussion: Twiddler’s or Reel Syndrome occurs when conscious or subconscious self-manipulation and spinning of the pulse generator result in lead dislodgement and loss of pacing and pacemaker malfunction. The reeling of the leads around the generator can also cause stimulation of the brachial plexus or phrenic nerve stimulation and subsequent rhythmic arm twitching or diaphragmatic pacing, respectively. It has previously been reported in cases of single- and dual-chamber ICDs, deep brain stimulators, and spinal nerve stimulators with varying presentation. The diagnosis requires clinical suspicion based on history, physical exam, imaging, or surgical inspection suggesting the displacement of leads with evidence of coiling of the wires around the pacemaker. Treatment often requires revision and focus should be maintained on patient education for both primary and secondary prevention of Twiddler’s Syndrome.

Abstract 16616: Automatic Measurement of Short-Term Variability of Repolarization Captures Modulation by Pacing on Human Intracardiac Electrograms

Introduction: Short-term variability of repolarization (STV) increases prior to ventricular arrhythmias (VA) both in humans and in animal models of VA, and is therefore a promising tool for real-time monitoring of arrhythmic risk. To integrate this concept in cardiac devices, a method to automatically determine STV on intracardiac electrograms (EGM) was developed. This STV algorithm demonstrated high efficacy in predicting life-threatening VA in animal studies, but still needs to be evaluated on human signals. Objective: To assess the performance of the novel automatic method of STV measurement on human EGMs during sinus rhythm (SR) and pacing. Methods: ECG and EGM signals with a 1 kHz sampling frequency were recorded in 14 dual chamber implantable cardioverter-defibrillator (ICD) patients during implantation (n=4) or replacement (n=10) procedures. Recordings were obtained in SR, atrial pacing at 80 beats per minute (AAI80) and atrioventricular pacing at the same frequency (DDD80). STV was calculated over 31 consecutive beats as Σ

Abstract 14731: T-wave Oversensing Secondary to an Inappropriate ICD Shock Resulting in Subsequent Unnecessary Shocks

Introduction: Inappropriate ICD shocks commonly result from persistent atrial arrhythmias or oversensing. We report a scenario where an ICD shock for a rapid, sustained atrial tachycardia (AT) resulted in T-wave oversensing (TWO), triggering further inappropriate shocks. Presentation: A 69-year-old woman with secondary prevention dual chamber ICD underwent pulmonary vein isolation for symptomatic paroxysmal atrial fibrillation (AF). The patient remained free of AT/AF off antiarrhythmics for 3 months after the procedure when she was admitted with four consecutive ICD shocks. Electrolytes were within normal limits. Device interrogation showed that the first shock was triggered by a rapid, sustained AT (cycle length: 270 msec) detected in the VF zone (single zone device; 280 msec cut-off) and failed ATP. Following the first shock, an irregular AT ensued, with cycle length ranging from 280-370 msec, but now with high amplitude T-waves in the RV channel, resulting in TWO and three subsequent inappropriate shocks (Figure). She received IV metoprolol and digoxin with subsequent resolution of AT and TWO. Beta-blocker dosing was increased and she has remained free of AT/AF at 6 month follow-up. Conclusions: ICD shocks can trigger marked repolarization changes in near-field intracardiac RV electrograms resulting in TWO and subsequent appropriate shocks. Further studies are warranted to understand the mechanism underlying this phenomenon and potential risk for these events.

The Pacemaker and Implantable Cardioverter-Defibrillator Registry of the Italian Association of Arrhythmology and Cardiac Pacing - Report 2022

The Pacemaker (PM) and Implantable Cardioverter-Defibrillator (ICD) Registry of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC) collects information about demographics, clinical characteristics, main indications for PM/ICD therapy and device types from the voluntary Italian collaborating centers. For the year 2022 main data about national PM and ICD implantation activity were obtained on the basis of European Cards and subsequently analyzed to create a standard report. PM Registry: data about 17 800 PM implantations were collected (14 191 first implants and 3609 replacements). The number of collaborating centers was 152. Median age of treated patients was 81 years (75 quartile I; 86 quartile III). Main ECG indications included atrioventricular conduction disorders in 46.0% of first PM implants, sick sinus syndrome in 17.7%, atrial fibrillation plus bradycardia in 7.7%, other unspecified ECG and electrophysiological abnormalities in 43.0%. For first PM implants, pacing in DDDR mode was reported in 42.2%, followed by DDD mode (20.6%), VVIR mode (25.1%), VVI mode (11.1%) and finally VDD-VDDR (5.1%). Median value of longevity of explanted PMs was 8.3 years. ICD Registry: data about 5210 ICD implantations were obtained (3656 first implants and 1554 replacements). The number of collaborating centers was 301. Median age of treated patients was 72 years (63 quartile I; 79 quartile III). Primary prevention indication was reported in 72.4% of first implants, secondary prevention in 27.6% (cardiac arrest in 4.6% of records). A single-chamber ICD was used in 30.3% of first implants, dual-chamber ICD in 30.0% and biventricular ICD in 39.7%. Median value of longevity of explanted ICDs was 7.0 years. In the calendar year 2022, the Italian PM Registry showed stable electrocardiographic and symptom indications, with an important prevalence of dual-chamber pacing. The ICD Registry documented a large use of prophylactic and biventricular ICDs, reflecting a favorable adherence in clinical practice to trials and guidelines. The ICD longevity and the number of recalls demonstrated a favorable trend.

Single- Versus Dual-Chamber Implantable Cardioverter-Defibrillator for Primary Prevention of Sudden Cardiac Death in the United States.

Background Routine addition of an atrial lead during an implantable cardioverter-defibrillator (ICD) implantation for primary prevention of sudden cardiac death, in patients without pacing indications, was not shown beneficial in contemporary studies. We aimed to investigate the use and safety of single- versus dual-chamber ICD implantations in these patients. Methods and Results Using the National Inpatient Sample database, we identified patients with no pacing indications who underwent primary-prevention ICD implantation in the United States between 2015 and 2019. Sociodemographic and clinical characteristics, as well as in-hospital complications, were analyzed. Multivariable logistic regression was used to identify predictors of in-hospital complications. An estimated total of 15 940 patients, underwent ICD implantation for primary prevention of sudden cardiac death during the study period, 8860 (55.6%) received a dual-chamber ICD. The mean age was 64 years, and 66% were men. In-hospital complication rates in the dual-chamber ICD and single-chamber ICD group were 12.8% and 10.7%, respectively (P<0.001), driven by increased rates of pneumothorax/hemothorax (4.6% versus 3.4%; P<0.001) and lead dislodgement (3.6% versus 2.3%; P<0.001) in the dual-chamber ICD group. Multivariable analyses confirmed atrial lead addition as an independent predictor for "any complications" (odds ratio [OR], 1.1 [95% CI, 1.0-1.2]), for pneumo/hemothorax (odds ratio, 1.1 [95% CI, 1.0-1.4]), and for lead dislodgement (odds ratio, 1.3 [95% CI, 1.1-1.6]). Conclusions Despite lack of evidence for clinical benefit, dual-chamber ICDs are implanted for primary prevention of sudden cardiac death in a majority of patients who do not have pacing indication. This practice is associated with increased risk of periprocedural complications. Avoidance of routine implantation of atrial leads will likely improve safety outcomes.

Cardiac Magnetic Resonance Imaging-Derived Left Atrial Characteristics in Relation to Atrial Fibrillation Detection in Patients With an Implantable Cardioverter-Defibrillator.

Background Among patients with an implantable cardioverter-defibrillator, a high prevalence of atrial fibrillation (AF) is present. Identification of AF predictors in this patient group is of clinical importance to initiate appropriate preventive therapeutic measures to reduce the risk of AF-related complications. This study assesses whether cardiac magnetic resonance imaging-derived atrial characteristics are associated with AF development in patients with a dual-chamber implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator, as detected by the cardiac implantable electronic device. Methods and Results This single-center retrospective study included 233 patients without documented AF history at the moment of device implantation (dual-chamber implantable cardioverter-defibrillator [63.5%] or cardiac resynchronization therapy defibrillator [36.5%]). All patients underwent cardiac magnetic resonance imaging before device implantation. Cardiac magnetic resonance-derived features of left atrial (LA) remodeling were evaluated in all patients. Detection of AF episodes was based on cardiac implantable electronic device interrogation. During a median follow-up of 6.1 years, a newly diagnosed AF episode was detected in 88 of the 233 (37.8%) patients with an ICD. In these patients, increased LA volumes and impaired LA function (LA emptying fraction and LA strain) were found as compared with patients without AF during follow-up. However, a significant association was only found in patients with dilated cardiomyopathy and not in patients with ischemic cardiomyopathy. Conclusions LA remodeling characteristics were associated with development of AF in patients with dilated cardiomyopathy but not patients with ischemic cardiomyopathy, suggesting different mechanisms of AF development in ischemic cardiomyopathy and dilated cardiomyopathy. Assessment of LA remodeling before device implantation might identify high-risk patients for AF.

Cardiac resynchronization therapy: potential for arrhythmic risk modification

Aim. To evaluate the impact of cardiac resynchronization therapy (CRT) on the risk of sustained ventricular tachyarrhythmias (VT) in patients with heart failure (HF) with a implantable cardioverter-defibrillator (ICD) for the primary prevention of sudden cardiac death.Material and methods. This single-center prospective clinical study included 470 patients (men, 84%) with HF at the age of 57 (51-62) years with a left ventricular ejection fraction (LVEF) of 29 (25-33)%. There were following exclusion criteria: indications for cardiac surgery, known channelopathies, previously registered VT. Depending on intraventricular conduction disorders, dual-chamber ICDs (42%) or CRT-D (58%) were implanted. After ICD implantation, patients were followed up for 24 months to register the end point — a first-time sustained paroxysm of VT detected by the ICD. A positive response to CRT was established in the case of an increase in LVEF by ≥5% of the initial level.Results. A total of 388 patients underwent full postoperative follow-up. The studied arrhythmic endpoint occurred on average 21 (0,6) months after implantation in 104 patients (27%) with higher frequency in the ICD group. However, the differences in the VT rate in the study groups were statistically unreliable (30% in the ICD group versus 24% in the CRT-D group, p=0,142). It was found that the VT rate was reliably lower in CRT-responders (118 patients, 53%): 15% compared to 32% in the group of inefficient CRT. A 5% increase in the LFEF reduced the probability of VT occurrence by 3 times (odds ratio [OR]=0,34; 95% of CI: 0,13-0,86; p=002). Significant modification of arrhythmic risk was verified by increasing LFEF to 36-40% (OR=0,72; 95% CI: 0,63-0,82; p=0,04).Conclusion. The results obtained indicate that effective CRT has the potential to modify arrhythmic risk in patients with HF, especially with an increase in LVEF to the level of 36-40%.

Non-elective heart failure hospitalization in patients with cardiac resynchronisation therapy or dual chamber implantable cardioverter defibrillators in England: a retrospective cohort study

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): BIOTRONIK SE &amp; Co. KG Background Limited real-world data are available on the risk of non-elective heart failure-related hospitalization (HFH) in patients with de-novo cardiac implantable electronic devices. Purpose The aim of this study was to quantify and compare the risk of HFH in two distinct HF cohorts: those with cardiac resynchronisation therapy devices including a defibrillator (CRT-D) and those with dual chamber implantable cardioverter defibrillators (DR-ICD). Methods Linked primary care data from the Clinical Practice Research Datalink (CPRD), secondary care data from Hospital Episode Statistics (HES) and mortality statistics from the Office of National Statistics (ONS) were used, reflecting a representative sample of patients treated within NHS England. Patients with a diagnosis or treatment for HF who received a de-novo CRT-D or DR-ICD between 1 April 2016 and 31 October 2019 were included. The study follow-up period extended to 31 October 2020. We calculated the median time to first post-implantation HFH and for those affected, the time from first-to-second and second-to-third admission. Univariable and multivariable Cox proportional hazards regression models were used to derive hazard ratios (HRs) and quantify the association between device type and admission. Results were adjusted for age, sex, and comorbidities. Results Data were analysed from 2,883 CRT-D (mean age 68.8 years, 79% male, median follow-up 39 months) and 1,643 DR-ICD (mean age 66.6 years, 80% male, median follow-up 41 months) patients. The CRT-D cohort had more baseline comorbidities. At 12 and 36-months post-implantation, the percentage of patients with at least one all-cause or CV-related hospital admission was similar between cohorts, but the percentage with a HFH differed. The risk of first HFH was greater in the CRT-D cohort than the DR-ICD cohort (HR=1.18; CI: 1.07–1.29; p&amp;lt;0.001). Median time to event was 19.8 months (IQR 4.9-38) for the CRT-D cohort and 26.6 months (IQR 6.5-44.6) for the DR-ICD cohort. However, there was no difference in the risk of subsequent HFH between the two cohorts (second admission: HR=0.99; CI: 0.88–1.17; p&amp;gt;0.9; third admission HR=1.05; CI: 0.86–1.27; p=0.6). The incident HFH risk for the CRT-D cohort increased from 17.3 per 100 person years for a first event to 46.6 per 100 person years for a second event and further increased to 76.3 per 100 patient years for the third event. Conclusions Patients implanted with a CRT-D are at greater risk of first post-implant HFH, likely due to these patients having more severe HF. However, when the population is restricted to patients with a previous post-implant HFH, the risk is similar in patients with CRT-D and DR-ICD devices. For both devices, any HFH is associated with an increased risk of subsequent HFH. Future research should seek to identify strategies to reduce repeated HFH in these patient groups.

Atrial fibrillation diagnosis in patients with single- and dual chamber ICD devices in England: a real-world cohort study

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): BIOTRONIK SE &amp; Co. KG Background and Purpose Atrial fibrillation (AF) detection and subsequent treatment is known to be sub-optimal in the general population. It is unclear how implanted devices with atrial sensing contribute to AF diagnosis. This study compares real-world AF diagnosis rates in patients with ICDs without (single chamber ICD, VR ICD) and with atrial sensing (dual chamber ICD, DR ICD) and contrasts them with detection rates in trials which are estimated to be 200 per 1000 person years (Reinhold, 2018). Methods Linked primary care data from the Clinical Practice Research Datalink (CPRD), secondary care data from Hospital Episode Statistics (HES) and mortality statistics from the Office of National Statistics (ONS) were used. All patients who received a VR- or DR ICD between 1 April 2016 and 31 October 2020, with at least 12 months primary care registration and no AF diagnosis prior to ICD implant were included in the analysis. Time to AF detection was calculated; in Cox proportional hazards regression analysis comorbidities, age, gender, and disease aetiology were adjusted for. Stroke rates were estimated for the total cohort. Results 835 patients with a VR ICD and 1034 patients with a DR ICD were identified. Both patient groups had similar comorbidity profiles, with VR ICD patients being on average younger (mean 57.5±13.9 vs 61.5±15.4 years). During 2700 and 3600 person-years follow-up the incidence of new AF diagnoses was 45.6 (CI: 37.6-53.7) per 1000 person years in VR ICD and 54.7 (CI: 47.1-62.4) per 1000 person-years in DR ICD patients. Median time to AF diagnosis was also similar at 36.3 (IQR: 26-49.6) and 36.9 (IQR: 25.2-51.5) months, respectively. In the adjusted analysis, ICD-10 or SNOMED coded diagnosis of AF was not significantly different between groups (HR: 0.88 [95% CI 0.70-1.10]; p-value=0.3). Stroke rates in the total cohort (with or without AF) were 5.7% in the VR ICD and 3.4% in the DR ICD cohort at 36 months. Conclusion The analysis highlights a difference between the rate of clinically relevant AF observed in patients with cardiac implanted electronic devices (CIED) in clinical trials and in real-world practice. The occurrence of stroke appears to also be higher in real world practice than in clinical trial populations and this is particularly marked in patients with VR ICD. These findings could indicate low use of remote monitoring or clinician uncertainty about the clinical relevance of CIED-detected AF in the real world. The latter may be because of a still accumulating body of predictive evidence towards the surveillance of AF. We propose that consistent use of remote monitoring with daily transmission in combination with CIEDs with atrial sensing will enable improvement of care.