Spotlight on S-ICD™ therapy: 10 years of clinical experience and innovation.

Subcutaneous ICD (S-ICD™) therapy has been established in initial clinical trials and current international guideline recommendations for patients without demand for pacing, cardiac resynchronization, or antitachycardia pacing. The promising experience in 'ideal' S-ICD™ candidates increasingly encourages physicians to provide the benefits of S-ICD™ therapy to patients in clinical constellations beyond 'classical' indications of S-ICD™ therapy, which has led to a broadening of S-ICD™ indications in many centres. However, the decision for S-ICD™ implantation is still not covered by controlled randomized trials but rather relies on patient series or observational studies. Thus, this review intends to give a contemporary update on available empirical evidence data and technical advancements of S-ICD™ technology and sheds a spotlight on S-ICD™ therapy in recently discovered fields of indication beyond ideal preconditions. We discuss the eligibility for S-ICD™ therapy in Brugada syndrome as an example for an adverse and dynamic electrocardiographic pattern that challenges the S-ICD™ sensing and detection algorithms. Besides, the S-ICD™ performance and defibrillation efficacy in conditions of adverse structural remodelling as exemplified for hypertrophic cardiomyopathy is discussed. In addition, we review recent data on potential device interactions between S-ICD™ systems and other implantable cardio-active systems (e.g. pacemakers) including specific recommendations, how these could be prevented. Finally, we evaluate limitations of S-ICD™ therapy in adverse patient constitutions, like distinct obesity, and present contemporary strategies to assure proper S-ICD™ performance in these patients. Overall, the S-ICD™ performance is promising even for many patients, who may not be 'classical' candidates for this technology.

Validation of the PRAETORIAN score in a large subcutaneous implantable cardioverter-defibrillator collective: Usefulness in clinical routine.

BACKGROUND: To assess the risk of unsuccessful conversion of ventricular fibrillation during defibrillation testing (DFT) with the subcutaneous implantable cardioverter-defibrillator (S-ICD), the PRAETORIAN score has been proposed. OBJECTIVE: The purpose of this study was to validate the PRAETORIAN score in a large S-ICD collective. METHODS: A retrospective single-center analysis of S-ICD patients receiving intraoperative DFT was performed. DFT was performed using a stepwise protocol with 65-J standard polarity, change of polarity, increase to 80 J, and repositioning if necessary. If all DFTs failed, we switched to a transvenous ICD. RESULTS: Overall, 398 patients were analyzed (268 male [67.3%]; mean age 42.4 ± 15.9 years; mean body mass index [BMI] 25.9 ± 4.8 kg/m2). Successful DFT with the first ICD shock was observed in 264 patients (66.3%). One hundred fourteen patients were defibrillated with the second (n = 104) or third (n = 10) DFT after changing shock polarity and/or shock energy. Overall, 20 patients needed at least 3 DFT (ie, 80 J and/or re-positioning). The majority (n = 88 [65.7%]) of DFT failures occurred before 2015 with the first-generation S-ICD. PRAETORIAN score was an independent predictor of DFT failure (odds ratio [OR] 1.007; 95% confidence interval [CI] 1.003-1.011 P ≤.001), while whereas BMI alone was not (P = .31). Presence of hypertrophic cardiomyopathy (HCM) (OR 2.6; 95% CI 1.3-4.4; P = .004) was predictive for at least 1 unsuccessful DFT in our multivariate regression analysis. CONCLUSION: PRAETORIAN score proved to be a useful and valid predictive tool for successful DFT, whereas BMI only had a limited role. Patients with HCM were at increased risk for DFT failure or needed higher DFT energy.

Role of implantable cardioverter defibrillator therapy in patients with acquired long QT syndrome: a long-term follow-up.

AIMS: The use of implantable cardioverter defibrillators (ICD) in patients with torsade de pointes (TdP) and ventricular fibrillation in the presence of acquired long QT syndrome (aLQTS) is under debate, partly due to the fact that aLQTS is potentially reversible and currently no long-term follow-up data are available. We aimed to evaluate the long-term follow-up of patients with acquired long QT syndrome (aLQTS) who had received an implantable cardioverter defibrillator (ICD) for secondary prevention of sudden cardiac arrest (SCA). METHOD AND RESULTS: Over a 10 year period, 43 patients with an ICD after survived cardiac arrest (SCA) due to an aLQTS were included [female n= 27 (63%); mean age 61 ± 16 years]. There was no clinical evidence for congenital LQTS (Schwartz score 1.25 ± 0.8). Structural heart disease was present in 29 patients (47%; ischaemic n= 13; dilated cardiomyopathy n= 9; mean EF 41%± 12). The most common proarrhythmic trigger happened to be antiarrhythmic drugs (n= 34; 79%). Other triggers included contrast agent (n= 1), haloperidol (n= 2), severe hypokalaemia (n= 2), drug abuse/alcohol (n= 2), and mere severe bradycardia (n= 2). Under trigger QTc interval measured 536 ± 58 vs. 438 ± 33 ms without trigger (P< 0.001). During a mean follow-up of 84 ± 55 months, appropriate shocks occurred in 19 patients (44%); inappropriate shocks in 13 patients (30%; only inappropriate n= 3). Appropriate shocks were almost as common in patients without as in those with structural heart disease (35 vs. 48%; P= 0.32). None of the patients were re-exposed to the initial trigger during the follow-up period. Beta-blocker medication did not prevent ICD shocks (12 of 19 vs. 11 of 24 on medication). CONCLUSION: Appropriate ICD shocks are a common finding in patients with aLQTS and SCA irrespective of the underlying cause or structural heart disease. Thus, even in the presence of relevant acquired proarrhythmia ICD may be beneficial.

Totally subcutaneous implantable cardioverter defibrillator with an alternative, right parasternal, electrode placement.

The totally subcutaneous implantable cardioverter-defibrillator (S-ICD) is an entirely novel defibrillation device that avoids the direct contact of device electrodes with the heart and the cardiovascular system. Here, we present a particular case of a young woman with congenital long-QT syndrome in which we implanted the electrode alternatively, right parasternally. This decision was based on the thoracic anatomy of the patient and on findings of a model of S-ICD electrodes in an adult torso. In conclusion, in some patients an alternative subcutaneous electrode position may be carefully considered but should not be taken to outweigh the standard left-sided placement.

Candida tropicalis defibrillator endocarditis: A case report and review of current literature.

We provide a review of current literature and report on a case of electronic device infective endocarditis with C. tropicalis. A 64-year-old man presented for revision of his implantable cardioverter defibrillator. Echocardiography revealed extensive vegetations attached to the Eustachian valve and in the right ventricular apex. Microbiological findings presented C. tropicalis on the explanted material. The patient refused additional surgical intervention. We successfully treated the patient with liposomal Amphotericin B and Flucytosine for 8 weeks.

Right versus left parasternal electrode position in the entirely subcutaneous ICD.

OBJECTIVES: The subcutaneous implantable cardioverter defibrillator (S-ICD®) has been established as an alternative to conventional transvenous ICD for the prevention of sudden cardiac death. Initial studies have shown safety and efficacy of the system with a left parasternal (LP) electrode. However, several case studies reported a right parasternal (RP) position. The purpose of this study was to analyze shock efficacy and safety of an RP electrode position. METHODS: Between June 2010 and May 2016, 120 S-ICD® were implanted at our institution. On the basis of the heart location on preoperative chest radiography (CXR), the investigators decided on an RP (n = 52) or LP electrode position (n = 68). All perioperative induced VF episodes, and spontaneous appropriate and inappropriate episodes during follow-up were analyzed. RESULTS: Patients with an RP electrode did not differ in terms of age, sex, or ejection fraction. A statistically significant difference in underlying cardiac disease was observed between the RP and LP electrode group, with more patients with channelopathies in the RP electrode group and more patients with non-ischemic cardiomyopathy in the LP electrode group. During a mean follow-up of 24.3 ± 19.5 months, 27 appropriate (19 in the LP group and 8 in the RP group) and 28 inappropriate (18 LP and 10 RP) ICD shocks occurred (p value = NS). CONCLUSIONS: In the present study, an RP electrode position was chosen on the basis of chest radiographic characteristics and was efficient in terms of sensing and shock efficacy. Thus, a right-sided electrode implant might be an alternative if a left-sided electrode implant is inadequate. It might also be favorable for young patients with narrow heart silhouettes in the midsagittal position.

Two different therapeutic strategies in ICD lead defects: additional combined lead versus replacement of the lead.

OBJECTIVES: Implantation of an additional HV-P/S lead versus extraction of the defective HV-P/S lead and implantation of a new one is one possible therapeutic approach in cases of a defective high-voltage pace/sense lead (HV-P/S). No information is available on potential differences in clinical outcome in these different approaches. METHODS: Between January 2000 and February 2006, 86 patients with HV-P/S lead defect received either an additional transvenous HV-P/S lead (n = 33, group 1) or the HV-P/S lead was replaced (n = 53, group 2). The duration of the initially implanted leads was significantly different in the two groups (7.4 +/- 2.9; group 1 and 4.1 +/- 3.4 years; group 2). The outcome of these two groups of patients was retrospectively analyzed. RESULTS: Seventy-three patients [85%] survived until the end of follow-up of 29 +/- 15 (group 1) and 33 +/- 21 (group 2) months (P = ns), respectively. Thirteen patients died: six in group 1 and seven in group 2 (P = ns). Fourteen patients experienced perioperative complications (group 1: six; group 2: eight; P = ns). ICD system-related complications occurred in 22 patients (group 1: seven; group two: 15; P = ns). The event-free cumulative survival of patients with additional and replaced HV-P/S lead for postoperative events (including death) after 1, 2, and 3 years was 82%, 70%, 70%, and 86%, 81%, 66%, respectively (P = 0.93). CONCLUSIONS: Implantation of an additional HV-P/S lead or replacement of the HV-P/S lead in case of HV-P/S lead failure is statistically not different concerning mortality and morbidity. There are no predictors for further lead defects. Implantation of an additional HV-P/S lead should not be recommended in young patients or patients with greater likelihood of living many years. Predictors for death were an age over 70 years and renal insufficiency.

Pediatric assist with the Medos and Excor systems in small children.

Pediatric long-term ventricular support with paracorporeal assist devices is performed in only a few institutions. We report on our experience with two pediatric paracorporeal devices, which have been implanted in neonates, infants, and small children. Seven children with ages ranging from 2 weeks to 6 years and a body weight of 3 to 19 kg were provided with either a Medos or a BerlinHeart System. The underlying heart diseases included dilative cardiomyopathy (n = 3), endocardial fibroelastosis (n = 2), Ebstein anomaly, and status post redo aortic valve replacement (n = 1). All children were in New York Heart Association class IV and were inotrope dependent. Three children were provided with a Medos system and 4 children with a BerlinHeart Excor device. In 6 cases, left ventricular support, and in 1 case, right ventricular support was performed. All patients were stabilized with univentricular mechanical support. The perioperative course was uneventful, and end-organ function was well recovered. Reexploration for bleeding and evacuation of mediastinal blood clots was necessary in all three neonates but not in any of the older infants. Severe thromboembolic events were only noticed in the neonates. Successful bridge to transplantation was performed in 6 of the 7 patients (87.5%). Our late results have been quite encouraging, as they readily prove that pediatric long-term mechanical support is possible with a high quality of life and an acceptable low complication rate.

Long-term follow-up of subcutaneous ICD systems in patients with hypertrophic cardiomyopathy: a single-center experience.

BACKGROUND: The totally subcutaneous implantable defibrillator (S-ICD) was introduced as a new alternative to conventional implantable defibrillators and is employed worldwide. This system is especially attractive for young patients. However, in patients with hypertrophic cardiomyopathy (HCM), T-wave oversensing may occur. To address the question whether the S-ICD system is suitable for HCM patients, the data of a standard of care prospective single-center S-ICD registry were evaluated. METHODS AND RESULTS: In the present study, 18 HCM patients who received an S-ICD for primary (n = 14) or secondary prevention (n = 4) and a minimal follow-up duration of 6 months were analyzed. The mean follow-up duration was 31.7 ± 15.4 months. Ventricular arrhythmias were adequately detected in 4 patients (22%). In 7 patients (39%), T-wave oversensing was noticed and led to at least one inappropriate shock in 4 patients (22%). Further adverse events included surgical revision due to a mobile sensing electrode and resulting noise detection as well as one case of early battery failure requiring pulse generator change. CONCLUSION: Patients with HCM and S-ICD systems have an increased risk of T-wave oversensing and inappropriate shock delivery. Thorough monitoring as well as exercise tests may help to improve device settings and thereby prevent T-wave oversensing.

Intraoperative Defibrillation Testing of Subcutaneous Implantable Cardioverter-Defibrillator Systems-A Simple Issue?

BACKGROUND: The results of the recently published randomized SIMPLE trial question the role of routine intraoperative defibrillation testing. However, testing is still recommended during implantation of the entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) system. To address the question of whether defibrillation testing in S-ICD systems is still necessary, we analyzed the data of a large, standard-of-care prospective single-center S-ICD registry. METHODS AND RESULTS: In the present study, 102 consecutive patients received an S-ICD for primary (n=50) or secondary prevention (n=52). Defibrillation testing was performed in all except 4 patients. In 74 (75%; 95% CI 0.66-0.83) of 98 patients, ventricular fibrillation was effectively terminated by the first programmed internal shock. In 24 (25%; 95% CI 0.22-0.44) of 98 patients, the first internal shock was ineffective and further internal or external shock deliveries were required. In these patients, programming to reversed shock polarity (n=14) or repositioning of the sensing lead (n=1) or the pulse generator (n=5) led to successful defibrillation. In 4 patients, a safety margin of <10 J was not attained. Nevertheless, in these 4 patients, ventricular arrhythmias were effectively terminated with an internal 80-J shock. CONCLUSIONS: Although it has been shown that defibrillation testing is not necessary in transvenous ICD systems, it seems particular important for S-ICD systems, because in nearly 25% of the cases the primary intraoperative test was not successful. In most cases, a successful defibrillation could be achieved by changing shock polarity or by optimizing the shock vector caused by the pulse generator or lead repositioning.

Implantable cardioverter-defibrillator therapy in patients with congenital long-QT syndrome: a long-term follow-up.

OBJECTIVES: The purpose of this study was to evaluate retrospectively a single-center experience with the use of ICDs in patients with long QT syndrome (LQTS) concerning outcome, complications, and optimal programming. BACKGROUND: Use of implantable cardioverter-defibrillator (ICD) in patients with congenital LQTS is controversial but is generally accepted in high-risk patients. METHODS: We enrolled 27 symptomatic patients with LQTS undergoing ICD therapy (QTc 540 +/- 64 ms(1/2); 85% female, 63% cardiac arrest; 33% syncope despite beta-blockers; 4% with severe phenotype) and 81 genotyped patients with LQTS undergoing conventional drug therapy (28 LQT1, 39 LQT2, 1 LQT3, 13 LQT5). During a mean follow-up of 65 +/- 34 months, one death occurred in the ICD group that was not LQTS related. A total of 178 appropriate shocks were observed in 10/27 patients (37%), mostly in survivors of cardiac arrest (in 58% of cardiac arrest patients vs. in 20% of non-cardiac arrest patients). RESULTS: In a logistic regression analysis, only QTc interval (121/178 shocks (68%) for QTc > 500 ms(1/2)) and "survived cardiac arrest" were prognostic for ICD shocks. In 30% of patients in the ICD group, multiple shocks occurred and could be reduced after increase of antibradycardia pacing rate, adding beta-blocker therapy, or starting the rate-smoothing algorithm (average 7.1 shocks before to 0.75 shocks after additional intervention annually). CONCLUSION: ICD therapy is a safe and useful tool in high-risk patients with LQTS. QTc interval and cardiac arrest survivors were prognostic factors for appropriate ICD shocks. The results of this large single-center experience suggest that beta-blockers should always be added to ICD therapy. In addition, some patients might benefit from additional antibradycardia pacing, prolonged detection time, and a rate-smoothing algorithm to prevent recurrent episodes.

Aminoterminal pro type B natriuretic peptide as a predictive and prognostic marker in patients with chronic heart failure.

BACKGROUND: B-type natriuretic peptide (BNP) is released from the cardiac ventricles in response to increased wall tension. We studied the relation of NT-proBNP to Heart Failure Survival Score (HFSS) and New York Heart Association (NYHA) class in patients with chronic heart failure (CHF). We also studied the impact for recipient selection for cardiac transplant and assessed it as a predictive and prognostic marker of CHF. METHODS: A total of 550 patients with dilative cardiomyopathy (n = 323), and coronary artery disease (n = 227) were prospectively examined. All patients underwent spiroergometry, echocardiography, right heart catheterization, and electrocardiogram. Routine blood levels and NT-proBNP were measured. The clinical selection for cardiac transplant candidates was adjudicated by 2 independent cardiologists who were blinded to the results of NT-proBNP assays. Clinical outcome and predictive power of NT-proBNP were analyzed. RESULTS: NT-proBNP levels in patients clinically considered for cardiac transplantation were significantly higher (2293 ng/ml vs 493 ng/ml; p < 0.001). The receiver operating characteristic (ROC) analysis regarding transplant candidacy showed an area under the ROC curve (AUC) of 0.84 +/- 0.01 for HFSS, 0.86 +/- 0.001 for NYHA, and 0.96 +/- 0.01 for NT-proBNP. Patients with increasing NT-proBNP levels or remaining elevated levels despite adequate heart insufficiency treatment were maintained with left ventricular assist device implantation (n = 10) or urgent heart transplantation (n = 2). Patients with NT-proBNP levels above 5000 pg/ml had a mortality rate of 28.4% per year. Twenty-eight patients died during the observation period; all these patients were within NYHA Classes 3 and 4 (NT-proBNP 5423 +/- 423 ng/ml). CONCLUSIONS: NT-proBNP discriminates patients at high likelihood of being a candidate for transplantation and provides prognostic informations in patients with CHF. NT-proBNP levels above 5000 pg/ml at admission were associated with death, and these levels markedly discriminated candidates for left ventricular assist devices or urgent transplantation.

Implantation and follow-up of totally subcutaneous versus conventional implantable cardioverter-defibrillators: a multicenter case-control study.

BACKGROUND: The approval of an entirely subcutaneous implantable-cardioverter defibrillator (ICD) system (S-ICD) has raised attention about this promising technology. It was developed to overcome lead failure and infection problems of conventional transvenous ICD systems. Nevertheless, lead migration of the initial design and inappropriate shock rates have raised concerns regarding its reliability and safety. OBJECTIVE: The purpose of this study was to report the largest multicenter series to date of patients with the new device in comparison with a matched conventional transvenous ICD collective with focus on perioperative complications, conversion of induced ventricular fibrillation (VF), and short-term follow-up. METHODS/RESULTS: Sixty-nine patients (50 male and 19 female; mean age 45.7 ± 15.7 years) received an S-ICD in three German centers and were randomly assigned to 69 sex- and age-matched conventional ICD patients. The indication was primary prevention in 41 patients (59.4%) without difference between groups (34 control patients; P = .268). The predominant underlying heart disease was ischemic cardiomyopathy in 11 (15.9%), dilated cardiomyopathy in 25 (36.2%), and hypertrophic cardiomyopathy in 10 (14.5%) in the S-ICD group. Mean implantation time was 70.8 ± 27.9 minutes (P = .398). Conversion rates of induced VF were 89.5% for 65 J (15-J safety margin) and 95.5% including reversed shock polarity (15-J safety margin) in the study group. Termination of induced VF was successful in 90.8% (10-J safety margin, device dependent) of the control patients (P = .815). Procedural complications were similar between the 2 groups. Mean follow-up was 217 ± 138 days. During follow-up, 3 patients with S-ICD were appropriately treated for ventricular arrhythmias. Three inappropriate episodes (5.2%) occurred in 3 S-ICD patients due to T-wave oversensing, whereas atrial fibrillation with rapid conduction was the predominant reason for inappropriate therapy in conventional devices (P = .745). CONCLUSION: The novel S-ICD system can be implanted safely with similar perioperative adverse events compared with standard transvenous devices. Our case-control study demonstrates a 10.4% failure of conversion of induced VF with the S-ICD set to standard polarity and 15-J safety margin and comparable inappropriate shock rates during short-term follow-up.

Explantation of implantable defibrillator leads using open heart surgery or percutaneous techniques.

BACKGROUND: To remove failing or infected implantable cardioverter defibrillator leads, percutaneous techniques and open heart surgery are two common approaches. However, well-defined indications for either technique are not available. We summarize our experience with implantable cardioverter defibrillator system explantation using open heart surgery and percutaneous lead removal. METHODS: A total of 1,391 transvenously introduced implantable cardioverter defibrillator systems were implanted during the analyzed time interval from January 1995 to June 2005 in our institution. In 21 patients (1.5%), open heart surgery for implantable cardioverter defibrillator lead and generator explantation was applied (group A), and in 53 patients (3.8%), a percutaneous lead removal was possible (group B). The log-rank test was used to calculate differences in survival between both patient groups, and the Student's t test was applied for differences in nonlethal complications. RESULTS: The 30-day, 6-month, 12-month, and 5-year survival rates were 91%, 91%, 81%, and 71%, respectively, for group A patients, and 100%, 100%, 94%, and 78%, respectively, for group B patients, which was not statistically different (p = 0.11). After open heart surgery, survival was comparable for cases with lead removal because of lead infection and those with lead malfunction (p = 0.28); however, patients with open heart surgery had a longer hospital stay (p = 0.03). Student's t test revealed no statistical difference in nonlethal complications between both patient groups (p = 0.37). CONCLUSIONS: As open heart surgery yielded similar results with regard to survival and complications, implantable cardioverter defibrillator lead removal using extracorporeal circulation may be well justified as a last therapeutic option, eg, in case of large bacterial vegetations.

[ICD lead defects: diagnosis and therapeutical options]. / Diagnostik und Therapie von ICD-Elektrodendefekten.

The number of cardioverter/defibrillator (ICD) implantations has been steadily increasing; thus, ICD lead-associated complications are an important issue. No clear recommendations for the diagnosis and management are available. This article gives an overview of how to diagnose and manage an ICD lead defect. Possible therapeutic options are discussed by reviewing the literature.

Incidence of complications in patients with implantable cardioverter/defibrillator who receive additional transvenous pace/sense leads.

BACKGROUND: Implantation of an additional pace/sense (P/S) lead is commonly used in patients with implantable cardioverter/defibrillators (ICDs) to overcome P/S defects of integrated defibrillation leads (HV-P/S leads). No information is available about the clinical outcome and the incidence of complications in these patients. METHODS: Retrospective analysis was performed in 151 patients (125 male, age 54.9 +/- 13.6 years, LVEF 48.1 +/- 17.8%, CAD in 86 [57%], DCM in 24 [16%], ARVCM in 11 [7%]) who received an additional P/S lead between 1990 and 2002 (54 patients with abdominal and 97 patients with pectoral ICD system). Statistical analysis was done using Kaplan-Meier survival curves. RESULTS: The average follow-up (FU) after implantation of the additional P/S lead was 43 +/- 27 months. In total 117 patients [77.5%] remain implanted; 22 patients died due to cardiac-related reasons. After a FU of 23 +/- 23 months, 43 patients [28.5%] experienced lead-related problems after implantation of the additional P/S lead: oversensing in 23 [53.5%], insulation defect in 3 [7.0%], fracture in 1 [2.3%], system infection in 4 [9.3%], and defect of the HV-P/S lead in 6 [14.0%] patients. The event-free cumulative survival of the additional P/S lead after 1, 2, and 5 years was 87.0%, 79.8%, and 59.4%, respectively (for pectoral leads: 89.6%, 82.0%, and 60.0%, respectively). CONCLUSIONS: Implantation of an additional P/S lead in case of failure of an HV-P/S lead is safe. However, it is associated with a substantial rate of complications during FU. Therefore, extraction of damaged defibrillation leads instead of implantation of P/S leads should be favored.