Implantable Cardioverter Defibrillator Technology Research Articles

Mortality Benefit Among Primary Prevention Implantable Cardioverter-Defibrillator Recipients on Contemporary Heart Failure Treatment

BackgroundPast clinical trials have shown the benefit of implantable cardioverter-defibrillators (ICDs) for reducing sudden cardiac death in at-risk patients. However, heart failure management and ICD technology have changed since these trials were first published. An updated assessment of ICD mortality benefit is needed. ObjectivesThe purpose of this study was to compare mortality rates between patients with a primary prevention (PP) indication for an ICD who did or did not receive an ICD using a contemporary, real-world data set. MethodsData was obtained from a large electronic health record data set covering patients in the United States from 2012 through 2020 who had a PP indication for an ICD and survived at least 1-year postindication. ResultsA total of 25,296 patients were identified as having a PP indication for ICD implantation, of which 2,118 (8.4%) were treated with an ICD within a year. Treated patients were younger than nontreated patients (age 63.4 years vs 66.1 years) with a smaller proportion of women (25.0% vs 36.7%). After 4-to-1 propensity matching, treated patients had similar clinical characteristics to nontreated patients. A Cox proportional hazard model estimated a 24.3% lower risk of all-cause mortality in patients when treated vs not treated with an ICD (HR: 0.757; 95% CI: 0.678-0.835; P <0.001). There was no detectable difference in ICD benefit between patients with ischemic and nonischemic heart disease (P = 0.50). ConclusionsICD treatment of patients with a PP indication is associated with improved mortality even in the context of evolving adjunctive HF treatment, consistent with earlier landmark trials.

Potential of remote monitoring to prevent sensing and detection failures in implantable cardioverter defibrillators

Sensing malfunction and misinterpretation of intracardiac electrograms (IEGMs) in patients with implantable cardioverter defibrillators (ICDs) may lead to inadequate device activity such as inappropriate shock delivery or unnecessary mode-switching. Remote monitoring has the potential for early detection of sensing malfunction or misclassification and may thus prevent adverse device activity. Therefore, the authors analyzed the amount, nature, and distribution of misclassification in current ICD and cardiac resynchronization therapy defibrillator technology using the device transmissions of the IN-TIME study population. All transmitted tachyarrhythmic episodes in the 664 IN-TIME patients, comprising 2214 device-classified atrial fibrillation (DC-AF) episodes lasting ≥ 30 s and 1330 device-classified ventricular tachycardia or fibrillation (DC-VT/VF) episodes, were manually analyzed by two experienced cardiologists. After evaluation of all DC-VT/VF episodes, atotal of 300 VT/VF events (23.1%) were false-positive, with supraventricular tachycardia being the most frequent cause (51.7%), followed by atrial fibrillation (21.3%) and T‑wave oversensing (21.0%). Atotal of 15patients with false-positive DC-VT/VF received inappropriate shocks. According to the inclusion criteria, 616 IEGMs with DC-AF were assessed. Atotal of 19.7% were false-positive AF episodes and R‑wave oversensing was the most common reason (55.9%). Remote monitoring offers the opportunity of early detection of signal misclassification and thus early prevention of adverse device reaction, such as inappropriate shock delivery or mode-switching with intermittent loss of atrioventricular synchrony, by correcting the underlying causes.

Long-term follow-up of adult patients with congenital heart disease and an implantable cardioverterdefibrillator.

Sudden cardiac death is common in the adult congenital heart disease (ACHD) population. Knowledge and experience about the use of implantable cardioverter defibrillators (ICD) in ACHD patients is very limited. We aimed to characterize a cohort of patients with ACHD and ICDs. Thirty consecutive ACHD patients submitted to an ICD implantation in a single tertiary center were evaluated. Data on baseline clinical features, heart defect, indication for ICD, type of device, appropriate therapies, ICD-related complication, and mortality during follow-up were collected. Of the 30 patients,56.7% received appropriate therapies due to ventricular tachycardia (VT) or ventricular fibrillation (VF). The rate of inappropriate therapies and device-related complications was 33.3%. Secondary prevention and primary prevention patients with class I indications for ICD had more appropriate therapies than complication, but this relationship was reversed for patients with class II indications. Remote monitoring played an important role in diagnosing new atrial arrhythmias before scheduled visits in 46.2% of patients, leading to a change in medication. VT/VF episodes were associated with a composite of death, cardiac transplantation, and hospital admission (OR 13.0; 95% CI: 2.1-81.5). ICDs are not only useful in preventing SCD, but also have a major role in diagnosing atrial tachyarrhythmias ahead of scheduled visits. Although improvements in ICD technology might reduce complications and inappropriate therapies, adequate selection of candidates for primary prevention still remains difficult because of the lack of clear indications.

The Subcutaneous Defibrillator.

The transvenous implantable cardioverter-defibrillator (ICD) has been shown in multiple studies to be effective in the prevention of sudden cardiac death in select populations. The Achilles heel of traditional ICD technology has been the transvenous lead. The subcutaneous ICD provides effective sudden death protection while avoiding lead-related complications of traditional transvenous systems. The subcutaneous ICD is a reasonable option for patients with an ICD indication who do not need bradycardia pacing or cardiac resynchronization therapy.

Knowledge of Implantable Cardioverter Defibrillator Purpose and Function Among Nurses in the United States.

Nurses play a crucial role in patient education and adaptation to having an implantable cardioverter defibrillator (ICD). The aim of this study was to assess cardiology nurses' knowledge and confidence in providing education and support to ICD recipients. A cross-sectional descriptive survey was used to assess nurses' knowledge and experience caring for ICD recipients in 2 academic medical centers in the Pacific Northwest, using an instrument developed in 2004 in the United Kingdom. Nurses (N = 74) worked on cardiology units or clinics, primarily held a baccalaureate degree or higher (85%), and had 16 years or more of nursing experience and 6 to 10 years of cardiology experience. The overall average knowledge score was 77%, with knowledge about modern ICD technology averaging 55%. Nurses' confidence, using 10-point scale, in preparing patients to receive an ICD implant was 6.32 ± 2.56, for preparing patients for discharge was 6.14 ± 2.43, and for providing education about ICD shocks was 6.63 ± 2.50. Nurses were most knowledgeable about factors that affect patient retention of knowledge and ICD-related environmental hazards. Nurses lacked knowledge about the basic ICD components, purpose of cardiac resynchronization, and dual-chamber ICDs. Factors associated with higher knowledge scores included past experience caring for a patient with an ICD and working in an electrophysiology outpatient clinic. The ICD knowledge of US nurses in 2015 was similar to that reported in the United Kingdom in 2004, with limited knowledge about the complexities of modern ICD devices. Such deficits in knowledge may affect the quality of education provided to ICD recipients in preparing them to live safely with an ICD.

Mark Josephson and the ICD: A Personal Perspective.

Mark Josephson dedicated his career to the prevention of premature sudden cardiac death (SCD). Toward that goal, he was an early adopter of the implantable cardioverter defibrillator (ICD) and indefatigable advocate for better ICD technology,[1] both as a clinical tool and as living laboratory to study SCD in ambulatory patients. With characteristic intellectual integrity and analytical rigour, he sought an honest and balanced appraisal of the life-saving benefits and serious complications of this unique therapy.

Wszczepialne kardiowertery-defibrylatory — czy test skuteczności defibrylacji jest jeszcze potrzebny?

Test defibrylacji (DT) od ponad 20 lat stanowil integralną cześc procedury implantacji wszczepialnych kardiowerterow- -defibrylatorow (ICD). Indukcja migotania komor w czasie DT ma na celu potwierdzenie adekwatnego marginesu bezpieczenstwa pomiedzy maksymalną energią generowaną przez ICD, a energią defibrylacji wymaganą dla przerwania zagrazających zyciu arytmii komorowych. Aktualnie postep technologiczny sprawil, ze skutecznośc kliniczna terapii antyarytmicznej ICD siega 90% co wplywa na staly trend do rezygnacji z wykonywania DT. Tematem artykulu są aktualne pytania związane z problemem podwyzszonego progu defibrylacji (DFT) oraz koniecznością i bezpieczenstwem dalszego rutynowego wykonywania DT.

CHANGING PROFILE OF YOUNG PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY RECEIVING IMPLANTABLE CARDIOVERTER DEFIBRILLATORS

BACKGROUND: Implantable cardioverter defibrillator (ICD) therapy is increasingly -utilized for prevention of sudden cardiac death (SCD) in young patients with hypertrophic cardiomyopathy. The indications and ICD technology have changed significantly over the past 20 years, with downsized generators and leads more suitable for smaller patients. OBJECTIVE: Describe changes in pattern of implant indications and appropriate therapies during the last two decades in young HCM patients. METHODS: Multicenter and retrospective review of young HCM patients who underwent ICD implant for HCM. RESULTS: 120 HCM patients 21 years of age (14.2 years [0.9-21.8]) who underwent ICD implant between 1990 and 2010 were included. During a median follow up of 2.4 years (0.1-13.4), 7 patients died and 7 underwent heart transplant. Appropriate and inappropriate therapies were delivered in 33/120 patients (28%) and 37/120 (31%), respectively. Freedom from appropriate shocks at 2, 4 and 6 years was 37%, 19% and 19% for secondary prevention patients (n1⁄424) compared to 84%, 72% and 63% for primary prevention patients (n1⁄496). Patients were divided according to decade of ICD implant date ([1990-2000] and [20012010]). Secondary prevention indications decreased between the two decades (34% vs 12%, p<0.01). For primary prevention patients, time from diagnosis to implant was longer (4.2 vs 1.8 yrs, p1⁄40.02) and age at implant was older (14.3 vs 12.6 yrs, p1⁄40.04) in the recent era compared to the older era. This occurred despite similar SCD risk profiles using classic risk factors (p1⁄40.7). Time to first appropriate shock for primary prevention patients was shorter in the earlier era (p1⁄40.04). CONCLUSION: Over the last 20 years, ICD implant in young HCM patients for primary prevention has increased. Risk scores are comparable between both decades, suggesting an increase in number of patients referred for primary prevention ICD implant rather than broadening of indications.

Virtual 3D Heart Models to Aid Pacemaker Implantation in Children

Virtual 3D Heart Models to Aid Pacemaker Implantation in Children

Who Should Receive the Subcutaneous Implanted Defibrillator?

The evolution of implantable cardioverter defibrillator (ICD) technology for the past 3 decades has been nothing short of explosive, incorporating progressively transvenous leads, multizone programming, dual chamber antibradycardia pacing, antitachycardia pacing (ATP), sophisticated single- and dual-chamber discrimination algorithms, cardiac resynchronization therapy (CRT), and programmable options numbering into the thousands. As a consequence, ICDs have been used to treat patients with a variety of clinical needs, including those with a known history of ventricular tachycardia (VT), survivors of out of hospital cardiac arrest, patients with requirements for pacing or resynchronization with concomitant indications for an ICD, and patients who do not fit within these categories but are at risk for sudden cardiac death (SCD). Response by Rav Acha and Milan on p 1244 Typically, the efficacy of most cardiac therapies is assessed initially on the sickest patients or those at highest risk. Such was the case for the ICD that was initially approved only for patients who had survived cardiac arrest. These early systems had epicardial leads and no pacing capabilities. Subsequently, transvenous lead systems and other advances were made in ICD technology, as noted above. However, these devices were approved and used based on the demonstration of the ability to detect and to terminate VT and ventricular fibrillation (VF). In fact, more complex therapies are not always better for patient outcomes. The Dual Chamber and VVI Implantable Defibrillator (DAVID) trial showed that indiscriminate right ventricular pacing is associated with increased risk of heart failure hospitalization and death, and more recent analyses continue to question the overuse of dual chamber devices.1,2 Similarly, CRT may be associated with more heart failure hospitalization among patients without QRS prolongation.3 The landmark prospective randomized trials showed a mortality benefit of ICDs for both primary and secondary prevention of SCD. The early …

Most Important Outcomes Research Papers on Device Therapies for Cardiomyopathies

Disorders of the cardiac muscle or cardiomyopathies are a broad, yet collectively common, group of conditions. Despite the heterogeneous etiologies, mode of death from these conditions is remarkably similar - progressive decline in cardiac function leading to intractable heart failure (HF) and sustained ventricular arrhythmias resulting in sudden cardiac death (SCD). Nearly 50% of patients die within 5 years of a HF diagnosis.1 Indeed, in the United States, HF alone is thought to cause 55,000 deaths per year2 and further contribute to 1 in 9 deaths overall.1 However, while advanced HF and the risk of SCD were once thought to be untreatable, technological advances has seen the emergence of device therapies as viable treatment options. Specifically, implantable cardioverter-defibrillator (ICD) therapy for treatment of ventricular arrhythmias, cardiac resynchronization therapy (CRT) for restoring cardiac synchrony and mechanical efficiency, and ventricular assist device (VAD) therapy to temporarily or permanently replace the function of the failing heart, have all emerged as highly efficacious therapies. The expanding use of device therapies, however, poses many challenges. First, while the indications for these devices are well summarized in clinical guidelines,3,4 considerable hurdles remain in ensuring eligible patients receive these therapies.5 By the same token, establishing the safety and effectiveness of these therapies in populations that are found in clinical practice, yet commonly excluded from trials, such as the elderly6 and uncommon forms of cardiomyopathies,7 is a high priority. Second, rapid dissemination of technologies frequently results in disparities in care. Indeed, age, gender, and racial disparities, in both receipt of these devices and outcomes following implantation, have been well documented. Whether these disparities have persisted, and the potential causative mechanisms underlying these disparities, however, are uncertain.8,9 Third, these devices are not without significant untoward effects; understanding …

United Kingdom national experience of entirely subcutaneous implantable cardioverter-defibrillator technology: important lessons to learn

The aim of this study was to describe the early phase United Kingdom (UK) clinical experience with a novel entirely subcutaneous implantable cardioverter-defibrillator (S-ICD). A questionnaire was sent to all UK hospitals implanting S-ICDs. Nineteen of 25 (76%) hospitals responded with the details of 111 implanted patients [median 5/hospital (range 1-18)]. Mean duration of follow-up was 12.7 ± 7.1 months. Median patient age was 33 years (range 10-87 years). Underlying pathology was primary electrical disease in 43%, congenital heart disease 12%, hypertrophic cardiomyopathy 20%, ischaemic cardiomyopathy 14%, idiopathic dilated cardiomyopathy 5%, and other cardiomyopathies 7% patients. Nineteen (17%) patients required 20 re-operations, including permanent device explantation in 10 (9%). Twenty-four appropriate shocks were delivered in 13 (12%) patients, including 10 for ventricular fibrillation. One patient suffered arrhythmic death, but there were no failures to detect or terminate ventricular arrhythmias above the programmed detection rate. Fifty-one inappropriate shocks were delivered in 17 (15%) patients. Forty-one (80%) were for T-wave over-sensing and 1 (2%) for atrial flutter-wave over-sensing. The 11 patients who received inappropriate shocks due to T-wave over-sensing were significantly younger than patients who did not (24 ± 10 vs. 37 ± 19 years; P = 0.02). The S-ICD is an important innovation in ICD technology. However, these data indicate that adverse event rates are significant during early clinical adoption. Important lessons in patient selection, implant technique, and device programming can be learnt from this experience.

Implantable cardioverter-defibrillator shock reduction: The new paradigm

Through scientific investigation, substantial understanding has been acquired into the natural history of cardiovascular disease. This is quite apparent in the field of cardiac rhythm disturbances, particularly in the area of ventricular arrhythmias leading to sudden cardiac death. In a little over the past decade, a number of management recommendations have led to reductions in arrhythmic death in those with left ventricular (LV) dysfunction, in no small part due to the development of the implantable cardioverter-defibrillator (ICD). Since its conception, advancements in ICD technology have allowed for smaller-sized devices capable of transvenous implantation routes, delivering tiered therapies and providing superior diagnostic information, to name a few such enhancements. Accordingly, these developments have been associated with greater acceptance by patients and clinicians alike. Shocks burden and increased mortality in implantable cardioverter-defibrillator patientsHeart RhythmVol. 8Issue 12PreviewImplantable cardioverter-defibrillator (ICD) shocks are associated with an increased risk of death. It is unclear whether ICD shocks are detrimental per se or a marker of higher risk patients. Full-Text PDF

Charge Circuit Timeout

Since the advent of the implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death, much attention has been given to the possibility of ICD or lead hardware failures resulting in inappropriate ICD function. Less attention has been given to the potential for software programming errors resulting in inappropriate device behavior. We report a case of a software programming error that led to a premature “end of service” alert that triggered a “lock-up” of the device antitachycardia therapies. Typically, the capacitor charge time for the Medtronic Secura ICD in anticipation of a full energy shock is about 7.7 to 9.2 seconds, depending on how close the device is to the elective replacement time and other factors.1 A charge circuit timeout indicates that at least 1 charging period exceeded 30 seconds. When 3 consecutive charging periods each exceed 30 seconds, the ICD charge circuit becomes inactive, and all automatic therapy functions and manual system tests become disabled except for emergency VVI pacing, all for the purpose of conserving battery voltage for pacemaker dependent patients when the generator reaches end of service.1 An alert is displayed to indicate that the time allotted to reach the programmed output energy (30 seconds) has been exceeded. A charge circuit timeout usually occurs when the battery voltage is depleted below the “elective replacement indicator.” In this specific instance, the charge circuit timeout occurred because of a glitch in the software. Three events occurred almost simultaneously, exposing the software programming error.2 These events occurred during an episode of tachycardia in the brief time span between the end of charging the capacitors and redetection/confirmation before delivery of a shock. The 3 events are:

150 Implantable cardioverter-defibrillator lead complications and clinical effectiveness in patients with inherited cardiac conditions

<h3>Background</h3> Implantable cardioverter-defibrillator (ICD) therapy can reduce sudden death due to ventricular arrhythmia (VT/VF) but is not without complication, particularly in young patients who live for many years with a device in situ. We aimed to determine the ICD complication rate in our inherited cardiac condition (ICC) population compared with international reports. Particular importance was given to inappropriate shock therapy due to lead failure as there are new ICD technologies available. <h3>Methods</h3> Patients with ICCs who had ICD implantation or box change between January 2006 and September 2009 were included. Data on clinical characteristics, complications and ICD therapies were obtained from pacing and hospital records. We compared our data with several ICD studies of patients with specific ICCs (Abstract 150 table 1). <h3>Results</h3> 101 patients (mean age 44.1±14.8 years; 59 male) were included (idiopathic VF 15%; DCM 17%; ARVC 22%; HCM 21%; long QT syndrome 17%; Brugada syndrome 6%; others 2%). During a mean follow-up of 74.0±53.2 months 2 patients died (1 inappropriate shocks; 1 stroke). Indications were secondary prevention in 71.3% of patients. ICD types were 56.4% single chamber; 39.6% dual chamber; 4.0% biventricular. Appropriate therapy successfully terminated VT/VF in 27 (26.7%) patients 34.7% of secondary and 6.9% of primary prevention patients received appropriate therapy. Inappropriate therapy occurred in 18 (17.8%) patients and lead failure (noise/wear/fracture) in 22 (20.8%) patients (Abstract 150 table 2). 12 out of 18 inappropriate shocks were due to lead failure, 5 sensing errors (1 T-wave oversensing; 4 AF), 1 generator fault. 10/22 leads that failed were Medtronic Sprint Fidelis and these were responsible for 8/12 patients receiving inappropriate shocks including one death due to lead fracture. Comparison with other studies indicates a high lead failure rate due to the long follow-up period, similar to the LQT Study which reports 25% lead failure over 87 months (Abstract 150 table 1). With lead failure excluded the complication rate is comparable to shorter follow-up studies. Inappropriate and appropriate therapy rates are similar among all studies. <h3>Conclusions</h3> There is a significant rate of ICD lead failure in patients with ICCs, which may be expected given the high frequency of Sprint Fidelis leads implanted during this period and the long follow-up. Our results compare favourably to other similar studies. The high rate of appropriate therapy highlights the clinical effectiveness of ICD intervention in secondary prevention. Lead complications may be lower with the use of new ICD technology in selected patients.

ICD in Brugada Syndrome

The therapeutic approach of the Brugada syndrome is highly debated especially in asymptomatic patients. Although there is a consensus to implant symptomatic patients with ICDs, the choice of appropriate treatment for asymptomatic patients is very difficult, principally because of a limited ability to identify those individuals at high risk of sudden cardiac death. It may be either follow-up with no treatment or implantation of an implantable cardioverter-defibrillator (ICD). As a consequence of improved recognition of this condition and advances in ICD technology, implantation rates among the young increased. Although the successful prevention of sudden cardiac death by device implantation is often paramount in the mind of the cardiologists, some studies show that the morbidity burden associated with both the diagnosis and the treatment is high. The decision to implant an ICD is not straightforward. Patient selection, device implantation, and programming must be meticulous to minimize the morbidity of this therapy. The last recommendations are probably no more appropriate. A better risk stratification of arrhythmic events in Brugada syndrome is eagerly awaited.

Perioperative management of outpatients with implantable cardioverter defibrillators

Implantable cardioverter defibrillators (ICDs) are increasingly being placed in patients worldwide. These patients pose significant perioperative challenges and are at an increased risk of complications; the suitability of ambulatory surgery in this patient population remains controversial. The purpose of the present review is to examine the potential challenges and optimal perioperative care of patients with an ICD. The American Society of Anesthesiologists Advisory for the perioperative management of patients with cardiac rhythm management devices as well as the American College of Cardiologists/American Heart Association guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery recommend that the tachyarrhythmia treatment algorithms of the ICD should be programmed off prior to surgery. However, these recommendations contradict those by the manufacturers and recent reports probably because they are based on data on early generation ICDs. Improvement in ICD technology and better understanding of ICD functions and awareness of potential electromagnetic interference-related problems can reduce ICD-related complications, and improve perioperative safety. Anesthesia practitioners involved in the care of patients with ICDs should familiarize themselves with the response to magnets application on ICD function as well as understand the situations in which magnet use is not advisable. Perioperative communication with the patient's cardiologist and surgeon is critical in reducing adverse outcome.

Heartbeat International: Making “poor” hearts beat better

Heartbeat International is a little-known 501(c)(3) charitable organization, which for the past 25 years has been responsible for the implantation and follow-up of cardiac implantable electronic devices in over 9000 indigent recipients in predominantly developing countries. Although the concept was founded in Guatemala over 30 years ago, it took the vision and drive of Dr. Henry D. McIntosh, M.D., M.A.C.C, to create Heartbeat International in 1984. The organization works through Pacemaker Banks established by local Rotary International chapters and other civic organizations in 24 countries over four continents and is dependent on the generosity of the implantable device manufacturers and teams of dedicated physicians and hospital personnel in the countries of operation. Since the vast majority of personnel are voluntary, 90 cents of every donated dollar directly supports the provision, implantation of devices, and follow-up care. Each US$500 provides a pacemaker to one needy patient. The organization's co-mission is also to educate and train implanting physicians in pacing and implantable cardioverter-defibrillator technology. The program remains dependent on the pacemaker manufacturers, who work in an environment of regulatory constraint and economic imperatives. With an ever growing demand for these devices, Heartbeat International will in the future need to increase its operating budget to purchase implantable inventory.

Implantable Cardioverter Defibrillator‐Related Complications in the Pediatric Population

The recognition that implantable cardioverter-defibrillator (ICD) therapy in children can prolong life coupled with the development of smaller devices and transvenous lead technology has increased the number of ICDs implanted in children and young adults. ICD complications in the pediatric population are reviewed. ICD complications in the pediatric population include those related to the implantation procedure, the ICD system, as well as psychosocial issues. Inappropriate ICD therapy and ICD lead failures are the most frequent complications. Identifying complications is the prerequisite for advances in ICD technology and effective management strategies need to be developed to avoid their recurrence.

Testing New ICD Technology

To the Editor: In their Perspective article in this issue of the Journal, Hauser and Almquist1 discuss issues involved in the testing of implantable cardioverter–defibrillators (ICDs). The authors contend that “the decision by the FDA [Food and Drug Administration] and industry to forgo premarketing clinical testing of the [new quadripolar,2 or IS-4] connector is not in the best interest of patients.” This is an incorrect description of the position of the FDA. The FDA has made no absolute decision that all implantable leads with IS-4 connectors will not require new clinical data. When we are evaluating an application for a . . .