Inappropriate Shocks In Patients Research Articles

Modern physiological approach to inappropriate ICD shocks due to atrial fibrillation with very fast ventricular response. A case report

BackgroundFast-conducting atrial fibrillation misinterpreted as ventricular tachycardia is the leading cause for inappropriate shocks in patients with implantable cardiac defibrillators (ICD). These inappropriate shocks are associated with significant morbidity and mortality and cause great discomfort and stress.Case presentationWe report the case of a patient with ischemic cardiomyopathy, permanent atrial fibrillation, and a single-chamber DF-1 ICD implanted for the primary prevention of sudden cardiac death, who presented for multiple inappropriate internal shocks due to very fast-conducting atrial fibrillation, which was mislabeled as ventricular fibrillation by the ICD. Since the patient was under maximal atrioventricular nodal blocking medical therapy (beta-blockers and digitalis) and we didn`t find any reversible causes for the heart rate acceleration, we opted for rate control with atrioventricular node ablation. To counteract the risk of pacing-induced cardiomyopathy in this patient who would become totally pacemaker-dependent, we successfully performed left bundle branch area pacing. Because the patient`s ICD had a DF-1 connection and the battery had a long life remaining, we connected the physiological pacing lead to the IS-1 sense-pace port of the ICD. The 6-month follow-up showed an improvement in left ventricular function with no more inappropriate shocks.ConclusionsLeft bundle branch area pacing and atrioventricular node ablation in patients with an implantable single-chamber DF-1 defibrillator and fast-conducting permanent atrial fibrillation is a cost-efficient and very effective method to prevent and treat inappropriate shocks, avoiding the use of an additional dual-chamber or CRT-D device.

How likely is the sense-B-noise to affect patients with subcutaneous implantable cardioverter-defibrillators and can we solve that problem in every case?

Sense-B-noise is a newly reported possible cause of inappropriate shocks in patients with subcutaneous implantable cardioverter-defibrillators (S-ICDs). The nature of that noise is unknown, it is not related to mechanical failure of the S-ICD system. Reprogramming to the secondary sensing vector is suggested by the producer as a possible solution. We analyzed the medical records of S-ICD recipients from two university clinical centers (Gdansk and Szczecin, Poland). Our aim was to determine the rate of sense-B-noise, and whether the secondary sensing vector would be available for reprogramming if such a problem occurred in our patients. The sense-B-noise issue affected three patients in our cohort (3%), which corresponds to the incidence of 0.012 events per patient-year of follow-up. The primary vector was permanently used in 47 patients (52%), secondary in 28 (31%), and alternate in 16 (17%), respectively. Therefore, the total number of patients potentially vulnerable to sense-B noise (with the primary or alternate vector programmed permanently) was 63 (69%). Among those 63 patients, 51 individuals (81%) had also the secondary vector available for permanent use. The sense-B-noise affected 3% of patients in our cohort, with an incidence of 0.012 per patient-year of follow-up. Most patients potentially vulnerable to sense-B noise could be reprogrammed to the secondary sensing vector, if necessary. Further investigation of the sense-B-noise issue is needed.

Three varieties of sense-B-noise, a novel cause of inappropriate shocks in patients treated with a subcutaneous cardioverter-defibrillator.

Three varieties of sense-B-noise, a novel cause of inappropriate shocks in patients treated with a subcutaneous cardioverter-defibrillator.

PO-03-170 INAPPROPRIATE SHOCKS IN PEDIATRIC PATIENTS WITH ICDS

Implantable-cardioverter defibrillators (ICDs) can deliver shocks under inappropriate clinical circumstances [including supraventricular tachycardia (SVT)]. Delayed detection programming has been studied in adults to reduce inappropriate shocks, but the data is limited in the pediatric population. Evaluate the incidence and risk factors for inappropriate shocks in patients (pts) <19 years of age at time of ICD implant Retrospective study of pts <19 years of age at time of ICD implant between 2010-2020. Treatment zones were defined as “conventional” if programmed with a threshold of 180bpm for <5 seconds (sec) or 200bpm <3 sec; and “delayed” if 180bpm ≥5 sec, 200bpm ≥3sec or 220bpm ≥1sec. A total of 126 pts were included with a median age of 15 (range 0.5, 18.8) years at first ICD implant. Transvenous devices accounted for 113 (90%), epicardial 10 (8%), subcutaneous 3 (2%); 39 (31%) were for secondary prevention. Diagnoses included cardiomyopathy 62 (49%), channelopathy 21 (17%), congenital heart disease 16 (13%), acquired 7 (6%), and other 20 (15%). Delayed programming was present in 88 (70%) with 98 (78%) having detection thresholds of ≥220 bpm. Appropriate shocks were delivered in 21 (17%) pts, inappropriate 7 (6%), and both 3 (2%). Inappropriate shocks were delivered for sinus tachycardia (3), atrial flutter (2), atrial fibrillation (2) and other SVT (3). There were no shocks for lead malfunction. Conventional programming had a greater but not statistically significant risk for an inappropriate shock (p=0.14). Patients with a history of SVT had a statistically significant increased risk for inappropriate shock (Fig 1) - neither antiarrhythmic use, nor use of ICD discriminators had an effect. Risk for inappropriate shock was 5% at 1 year, 9% at 5 years after implant. Risk for appropriate shock was 4% and 22%, respectively. The majority of children with ICDs are programmed with high detection rates for therapy. The burden of inappropriate shocks is low, with no modifiable risk factors (i.e. antiarrhythmics, treatment zones). The majority of inappropriate therapy resulted from SVT, raising the potential for performing programmed atrial stimulation at implant to identify those patients who may benefit from an early ablation strategy.

Device-Related Complications and Inappropriate Therapies Among Subcutaneous vs. Transvenous Implantable Defibrillator Recipients: Insight Monaldi Rhythm Registry

IntroductionIn the context of randomized clinical trials, subcutaneous implantable cardiac defibrillators (S-ICDs) are non-inferior to transvenous ICDs (T-ICDs) concerning device-related complications or inappropriate shocks in patients with an indication for defibrillator therapy and not in need of pacing. We aimed at describing the clinical features of patients who underwent S-ICD implantation in our clinical practice, as well as the ICD-related complications and the inappropriate therapies among S-ICD vs. T-ICD recipients during a long-term follow-up.Materials and MethodsAll patients undergoing ICD, both S-ICD and TV-ICD, at Monaldi Hospital from January 1, 2015 to January 1, 2019 and followed up at our institution were included in the present analysis. The clinical variables associated with S-ICD implantation were evaluated by logistic regression analyses. We collected the ICD inappropriate therapies, ICD-related complications (including both pulse generator and lead-related complications), ICD-related infections, appropriate ICD therapies, and overall mortality. Kaplan-Meier (KM) analyses were performed to assess the risk of clinical outcome events between the two subgroups. A time-dependent Cox regression analysis was performed to adjust the results.ResultsTotal 607 consecutive patients (mean age 53.8 ± 16.8, male 77.8%) with both TV-ICD (n: 290, 47.8%) and S-ICD (n: 317, 52.2%), implanted and followed at our center for a mean follow-up of 1614 ± 1018 days, were included in the study. At multivariate logistic regression analysis, an independent association between S-ICD implantation and ionic channel disease [OR: 6.01 (2.26–15.87); p < 0.0001] and ischemic cardiomyopathy [OR: 0.20 (0.12–0.35); p < 0.0001] was shown. The KM analysis did not show a significantly different risk of the inappropriate ICD therapies (log rank p = 0.64) between the two subgroups; conversely, a significant increase in the risk of ICD-related complications (log rank p = 0.02) and infections (log rank p = 0.02) in TV-ICD group was shown. The adjusted risk for ICD-related infections [OR: 0.07 (0.009–0.55), p = 0.01] and complications [0.31 (0.12–0.81), p = 0.01] was significantly lower among patients with S-ICD.ConclusionsThe choice to implant S-ICD was mainly driven by younger age and the presence of ionic channel disease; conversely ischemic cardiomyopathy reduces the probability to use this technology. No significant differences in inappropriate ICD therapies were shown among S-ICD vs. TV-ICD group; moreover, S-ICD is characterized by a lower rate of infectious and non-infectious complications leading to surgical revision or extraction.

Subserratus implantation of the subcutaneous implantable cardioverter-defibrillator.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) (Boston Scientific, Marlborough, MA) was designed as an alternative to a traditional transvenous implantable cardioverter-defibrillator (TV-ICD) to avoid complications associated with transvenous lead implantation1,2 and extraction.3 The S-ICD has been demonstrated to be noninferior with respect to device-related complications or inappropriate shocks in patients without an indication for pacing.4 However, certain challenges remain, such as a higher rate of inappropriate shocks,5 limited data on defibrillation testing (DFT) at the time of generator change,6 and suboptimal aesthetics, particularly in younger and smaller patients.

Significantly less inappropriate shocks in ischemic patients compared to non-ischemic patients: The S-ICD experience of a high volume single-center.

The subcutaneous cardioverter-defibrillator (S-ICD) continues to be preferentially used in relatively young patients, with less advanced heart disease. We, therefore, studied the short and long-term efficacy and safety of the S-ICD in subgroups of patients, which are underreported at present. A total of 218 patients between November 2010 and February 2019 undergoing S-ICD with a follow up of at least 6 months implantation were included in a prospective registry. Mean follow up was 38 months. The most common indication for S-ICD implantation was ischemic cardiomyopathy (n=106, 49%). Complication rate needing invasive intervention was 9% (n=21). Appropriate shock rate in patients with an S-ICD was 3.5%/year. A total of 30 inappropriate shocks (IAS) occurred in 19 patients (8.7%; 2.7%/year). The proportion of appropriate and inappropriate shock rates in patients with different cardiomyopathies shows remarkable variances. There were significant more IAS (3.6%/year vs. 1.7%/year, p=.048) in patients with non-ischemic cardiomyopathy versus patients with ischemic cardiomyopathy. Multivariate analysis identified, besides type of cardiomyopathy, atrial fibrillation (AF) as predictor for IAS. In this real-world prospective registry we analyzed S-ICD performance in the more traditional ICD patient. Patients with ischemic cardiomyopathy had significantly less inappropriate therapy compared to patients with non-ischemic cardiomyopathy and appear to be appropriate patients for this type of device.

Exercise-optimized programming after S-ICD implantation contributes to a lower risk of inappropriate shocks in the latest generation S-ICDs

Abstract Funding Acknowledgements Type of funding sources: None. Background Implantable cardioverter-defibrillator (ICD) therapy is associated with the risk of inappropriate shocks (IAS). IAS, defined as any shock on a different rhythm than VT or VF, cause psychological stress, decrease the quality of life and may provoke ventricular arrhythmias. In the subcutaneous ICD (S-ICD) the majority of IAS are caused by T-wave oversensing (TWOS), often during exercise. Exercise-optimized programming during an exercise ECG test (X-ECG) after implantation has shown to be successful in reducing IAS in patients known with TWOS. In recent years, new discrimination algorithms in the latest generation S-ICDs have significantly reduced the risk of TWOS. The benefit of performing an X-ECG in these latest generation S-ICDs to reduce IAS is unclear. Purpose We aim to describe the effect of exercise-optimized programming after S-ICD implantation on inappropriate shock rate in the latest generation S-ICDs. Methods In this retrospective multicenter study, data were collected from two experienced S-ICD hospitals in the Netherlands. All patients underwent an S-ICD implantation of second or third generation between February 2015 and December 2020. Patients younger than 21 years were excluded. Patients with an X-ECG after implantation were compared with patients without X-ECG after implantation. Total number of patients with IAS and cause of the first IAS were evaluated. Results In total, 262 patients were included in the X-ECG group and 61 in the no X-ECG group. The median follow-up time was 22 months in the X-ECG group (IQR 9-33) and 23 months in the no X-ECG group (IQR 12-33, P = 0.9). Mean age was 51 ± 15 years and 61 ± 15 years respectively (P&amp;lt; 0.001). Primary prevention indication was similar in both groups (56% for the X-ECG group versus 49% for the no X-ECG group, P = 0.4). A total of 8 patients (3.1%) experienced IAS in the X-ECG group; 3 first shocks (1.15%) were due to TWOS, 2 (0.8%) were given on a SVT and 3 (1.15%) on other non-cardiac activity. In the no X-ECG group, 6 patients (9.8%) experienced IAS; 1 first shock (1.6%) was due to TWOS, 4 (6.6%) were given on a SVT and 1 (1.6%) on other non-cardiac activity. Patients with an X-ECG had a significantly lower risk of IAS compared to patients in the no X-ECG group (hazard ratio 0.32; 95% CI 0.1 to 0.9; P = 0.027). The Kaplan-Meier estimate of IAS-free survival for the X-ECG group was 61 months (95% CI 59 to 62) and 50 months (95% CI 46 to 55) for the no X-ECG group. Results are shown in the figure. Conclusion This study shows that, in the latest generation S-ICDs, exercise-optimized programming after S-ICD implantation results in a significantly lower risk of IAS in adults. Patients with an X-ECG after S-ICD implantation were younger, which may have affected the outcome. Further prospective data with more equal groups is necessary. Until then, we recommend considering exercise testing after S-ICD implantation in the latest generation S-ICDs. Abstract Figure.

Prognostic impact of subcutaneous implantable cardioverter-defibrillator appropriate and inappropriate shocks

Abstract Funding Acknowledgements Type of funding sources: None. Background Previous studies have shown an adverse prognosis for patients with transvenous implantable cardioverter-defibrillators (ICD) who receive both appropriate and inappropriate shocks. There is a paucity of data regarding the prognosis of inappropriate shocks in patients with a subcutaneous ICD (S-ICD). Purpose To assess and characterize S-ICD appropriate (AS) and inappropriate shocks (IAS) and their impact on mortality. Methods Single center observational registry of 162 consecutive patients who underwent S-ICD implantation for primary and secondary prevention between November 2009 and September 2020. Only follow-up data of at least 6 months was analysed to identify predictors of both IAS and AS and their mortality impact. Results A total of 144 patients were included in the analysis. Mean age was 42.2 ± 16.6 years and 75% of the patients were male. One hundred and four patients (72.2%) implanted the S-ICD in primary prevention. The most common etiology was ischemic cardiomyopathy (22.9%) followed by hypertrophic cardiomyopathy (18.8%) and dilated idiopathic cardiomyopathy (14.6%). During a mean follow-up of 42.3 ± 29.9 months a total of 48 patients (33.3%) experienced at least one S-ICD shock. Twenty-nine (20.1%) patients received AS due to VT/VF and 31 patients (21.5%) received IAS. Eighteen (58.1%) of the IAS were due to oversensing/noise/discrimination errors and the remaining due to supraventricular tachycardia. Overall, patients with AS (HR 4.93, 95% CI 1.58-15.36, p = 0.006) and higher number of total AS (HR 1.10, 95% CI 1.00-1.20, p = 0.044) were associated with higher mortality during follow-up. S-ICD IAS therapy did not affect overall mortality (HR 1.71, 95% CI 0.21-14.0, p = 0.616). Conclusions: In patients with S-ICD, those who receive AS, in contrast to IAS, seem to have a worse prognosis. Large scale studies are needed to confirm this hypothesis and to explain this findings. Abstract Figure. Survival curves for AS and IAS

Usefulness of subcutaneous implantable cardioverter-defibrillator therapy in patients with Brugada syndrome.

Implantable cardioverter-defibrillators (ICDs) are the main therapy to prevent sudden cardiac death in patients with Brugada syndrome (BrS). The subcutaneous ICD (S-ICD) can eliminate lead-associated complications compared with transvenous ICD (TV-ICD). However, S-ICD is susceptible to T-wave oversensing (TWOS) and may result in more frequent inappropriate shocks in patients with BrS. This study aimed to compare inappropriate shocks between TV-ICD and S-ICD in patients with BrS. We enrolled 32 patients with BrS (including one woman; mean age 52 ± 18years) who were implanted with ICD (23 TV-ICDs and 9 S-ICDs) between January 2002 and November 2018 in Oita University Hospital. We carried out a standard surface electrocardiogram (ECG) screening tests in both supine and standing positions prior to S-ICD implantation. The patients received routine clinical review every month and device monitoring every 4months. The period of follow-up was 129 ± 51months. Six patients with BrS and TV-ICDs experienced inappropriate shocks (26%) with their ICD therapy. In contrast, two patients with BrS and S-ICDs experienced inappropriate shocks (22%). There was no significant difference between the two groups (P = 0.82). Although one case in the S-ICD group experienced TWOS-induced inappropriate shock, SMART Pass (new high-pass filter) prevented the subsequent recurrence of inappropriate shocks during ICD therapy. Our results suggest that S-ICD is not inferior to TV-ICD in the incidence of inappropriate shocks. SMART Pass may be a useful tool to prevent inappropriate ICD shocks by TWOS in patients with BrS.

Automated electrocardiographic quantification of myocardial scar in patients undergoing primary prevention implantable cardioverter-defibrillator implantation: Association with mortality and subsequent appropriate and inappropriate therapies

Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The Selvester QRS score has been developed to estimate myocardial scar from the 12-lead electrocardiogram. We aimed to assess the value of an automated version of the Selvester QRS score for the prediction of implantable cardioverter-defibrillator (ICD) therapy and death in patients undergoing primary prevention ICD implantation. Unselected patients undergoing primary prevention ICD implantation were included in this retrospective, observational, multicenter study. The QRS score was calculated automatically from a digital standard preimplantation 12-lead electrocardiogram and was correlated to the occurrence of death and appropriate and inappropriate shocks during follow-up. Analyses were performed in groups defined by QRS duration < 130 ms vs ≥ 130 ms. Overall, 1047 patients (872 [83%] men; median age 64 years IQR [55-71]) with ischemic (648, 62%) or nonischemic (399, 38%) cardiomyopathy were included. The median QRS duration was 123 ms (interquartile range [IQR] 111-157 ms), and the median QRS score was 5 (IQR 2-8). The QRS duration was <130 ms in 59% and ≥130 ms in 41%. During a median follow-up of 45 months (IQR 24-72 months), a QRS score of ≥5 was independently associated with a significantly higher risk of mortality (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.05-2.66; P = .031) and appropriate (HR 1.83; 95% CI 1.07-3.14; P = .028) and inappropriate (HR 2.32; 95% CI 1.04-5.17; P= .039) shocks in patients with QRS duration ≥ 130 ms. No association of the QRS score and outcome was observed in patients with QRS duration < 130 ms (P > .05). The automatically calculated Selvester QRS score, an indicator of myocardial scar burden, predicts mortality and appropriate and inappropriate shocks in patients undergoing primary prevention ICD implantation with a prolonged QRS duration.

Incidence, mechanisms, and clinical impact of inappropriate shocks in patients with a subcutaneous defibrillator.

Inappropriate shocks (IAS) remain a challenge for patients and physicians after implantation of the subcutaneous implantable cardioverter-defibrillator (S-ICD). The aims were to assess and characterize different patterns of IAS. Two hundred and thirty-nine patients were implanted with an S-ICD between 2010 and 2018 for primary and secondary prevention. Follow-up data of at least 6 months were analysed. During a mean follow-up of 34.9 ± 16.0 months, a total of 73 shocks occurred in 38 patients (6%). Forty-three (59%) shocks were considered appropriate due to ventricular tachycardia/ventricular fibrillation, while 30 (41%) were inappropriate and occurred in 19 patients (8%). Myopotentials/noise was the most frequent cause of inappropriate shocks (n = 8), followed by T-wave oversensing (n = 6) and undersensing of the QRS, resulting in adaptation of the automatic gain control and inappropriate shock (n = 5). Seventy-four percent of all IAS occurred on the primary vector, while no IAS occurred on the alternate vector. In seven of eight patients (88%), IAS related to myopotentials have occurred on the primary sensing vector. Multivariate analysis identified taller patients, primary sensing vector and first-generation S-ICD device as predictors for IAS. SMART pass effectively reduced the occurrence of IAS in the second-generation S-ICD system. Inappropriate therapies are less frequently observed on the alternate vector. The primary vector seems to be unfavourable with regard to oversensing caused by myopotentials. Inappropriate shocks were associated with an increased rate of rehospitalization but not mortality. These observations have implications for the prevention of inappropriate S-ICD shocks.

Prevention of Recurrent Ventricular Tachycardia in Patients With Implantable Cardioverter Defibrillators-A Network Meta-analysis.

The optimal management for the prevention of recurrent ventricular tachycardia in patients with implantable cardioverter-defibrillators (ICDs) offers a challenge with no set guidelines regarding which therapy offers a best safety and efficacy profile. Which therapeutic strategy, among antiarrhythmic drugs and catheter ablation (CA), offers the most effective and safe approach in patients with ICDs? Randomized controlled trials (RCTs) comparing the efficacy and safety of antiarrhythmic drugs or CA against a placebo group. RCTs were identified from a comprehensive search in PubMed, Embase, and Cochrane library. Our outcomes of interest were reductions in appropriate ICD shocks, inappropriate ICD shocks, and overall mortality. We used the event rates in both groups, and then using a frequentist approach employing a graph theory methodology, we constructed a network meta-analysis model. Fourteen RCTs with 3815 participants and 6 different interventions treatments were included in our network meta-analysis. The most effective treatment for the prevention of recurrent ventricular tachycardia after ICD is amiodarone followed by CA. Amiodarone is most effective in the reduction of appropriate and inappropriate ICD shocks with an odds ratio (OR) of 0.29 [95% confidence interval (CI), 0.11-0.74] and 0.15 (95% CI, 0.04-0.60), respectively. CA was effective in the reduction of appropriate ICD shocks (OR, 0.41; 95% CI, 0.20-0.87), whereas sotalol was effective in the reduction of inappropriate ICD shocks (OR, 0.46; 95% CI, 0.22-0.95). There was no significant reduction in the overall mortality from any therapy. There was a trend of increased mortality associated with amiodarone therapy (OR, 2.40; 95% CI, 0.92-6.26). Amiodarone remains the most efficacious therapy for the reduction of appropriate and inappropriate shocks in patients with ICD. No therapy resulted in mortality reduction, but amiodarone showed a trend toward increased mortality.

PREDICTORS OF INAPPROPRIATE SHOCKS FROM IMPLANTABLE CARDIOVERTER-DEFIBRILLATORS

Introduction: Inappropriate shocks in patients with an implantable cardioverter-defibrillator (ICD) are associated with significant psychological and physical consequences and increased long-term mortality. The aim: To assess predictors associated with inappropriate high-energy discharges of implantable cardioverter-defibrillators. Material and Methods: Retrospective data analysis of 150 patients aged 64.2±12.8 years (84.7% male) admitted to the Hospital Emergency Department due to at least one cardioverter-defibrillator discharge was performed. All of the discharges were inappropriate in the group of 33 patients, and in the group of 117 patients at least one discharge was appropriate. The following data: age, gender, concomitant diseases, type of ICD implantation (primary vs. secondary prevention), type of discharge, number of discharges, serum potassium, and sodium concentration were collected. Results: Patients with only inappropriate discharges were younger, significantly more often had chronic atrial fibrillation, a significantly higher number of discharges, and ischaemic cardiomyopathy. Logistic regression analysis revealed that the occurrence of only inappropriate discharges was related to the number of discharges over three, the age of patients below 60 years, the serum sodium concentration between 135 mEq/L and 142 mEq/L, and the primary type of prevention of sudden cardiac death. Conclusions: 1. Predictors of inappropriate discharges include: age, serum sodium concentration, and primary type of indications for cardioverter-defibrillator implantation. 2. Further research is necessary to determine the influence of disturbances in the sodium economy on the occurrence of appropriate and inappropriate interventions of implantable cardioverter-defibrillators.

GW29-e1838 Impact of atrioventricular node ablation on inappropriate defibrillation shocks in patients with atrial fibrillation

To evaluate the incidence of inappropriate shocks in patients with ICD/CRT-D, and the efficacy of atrial-ventricular node (AVN) ablation for preventing inappropriate shocks and improving heart function. We enrolled consecutive patients implanted with ICD or CRT-D from Nov, 2005 to Jan, 2017.

GW29-e1464 Inappropriate Shock therapy of Implantable Cardioverter Defibrillator and Cardiac Resynchronization Therapy Defibrillator in patients with Atrial Fibrillation, and the Impact of Atrial Ventricular Node Ablation on the Outcome

To evaluate the incidence of inappropriate shocks in patients with ICD/CRT-D, and the efficacy of atrial-ventricular node (AVN) ablation for preventing inappropriate shocks and improving heart function. We enrolled consecutive patients who implanted ICD or CRT-D from Nov, 2005 to Jan, 2017.

Management of inappropriate shocks/T-wave-oversensing in S-ICD®-patients

Inappropriate shocks are afeared complication after implantable cardioverter-defibrillator (ICD) implantation and have a tremendous impact on quality of life. Inappropriate shocks in patients with subcutaneous ICD (S-ICD®, Boston Scientific, Marlborough, MA, USA) have various underlying causes. This review summarizes the current literature on this topic and lists possible treatment options.

Abstract 20898: The Value of Sensing Optimization During Exercise After S-ICD Implantation

Introduction: T-wave oversensing (TWOS) is the main cause of inappropriate shocks (IAS) in patients with a subcutaneous ICD (S-ICD). Sensing optimization during exercise post S-ICD implantation may prevent IAS caused by TWOS. In our tertiary center, sensing optimization after S-ICD implantation has been used as standard of care since 2014. Improved detection and sensing algorithms, like high pass filter designs, are expected to overcome the problem of TWOS, but the value of sensing optimization during exercise is unknown. Hypothesis: Sensing optimization during exercise prevents TWOS-related IAS in patients implanted with an S-ICD. Methods: Sensing optimization was performed within two months in all patients who underwent S-ICD implantation or replacement. Sensing was evaluated during maximal exercise and a new QRS morphology template was stored. The optimal sensing vector was determined based on absence of TWOS and optimal R-T ratio. Follow-up data on IAS was divided into a group before and a group after introduction of the high pass filter, and compared with data of S-ICD patients and IAS in our institution before 2014. Results: We analyzed 65 patients (69% male, mean age 45 years, ischemic cardiomyopathy in 25%, genetic arrhythmia disease in 37%). Mean maximal heart rate (maxHR) was 142 bpm. A new template was stored in 61 patients (94%). TWOS was observed in 12 patient (18%), but not in the programmed sensing vector selected by the post implant automatic setup. The sensing vector was changed in nine patients (14%) (mean age 35 years, maxHR 163 bpm) based on drop in QRS amplitude in five patients, variable QRS amplitudes in two, an inferior R-T ratio in one and sensing of myopotentials in one. The IAS incidence caused by TWOS declined from 11.6% in 2012 to 2.0% and 0% before and after the introduction of the high pass filter, respectively. Conclusions: There is a decrease in TWOS-related IAS. Sensing optimization during exercise may be an additional tool to overcome TWOS-related IAS in S-ICD patients. Future studies may identify patients, such as those capable of reaching high heart rates, who are most likely to benefit from sensing optimization during exercise.

Inappropriate implantable cardioverter-defibrillator shocks in Brugada syndrome: Pattern in primary and secondary prevention

BackgroundInappropriate implantable cardioverter-defibrillator (ICD) shocks is a common complication in Brugada syndrome. However, the incidence in recipients of ICD for primary and secondary prevention is unknown. Method and resultsWe compared the rate of inappropriate shocks in patients with Brugada syndrome that had an ICD for primary and secondary prevention. We studied 51 patients, 86.5% of whom were males. Their mean age at diagnosis was 47 ± 11 years. Eighteen (35%) were asymptomatic, while 25 (49%) experienced syncope prior to implantation. Eight (16%) patients were resuscitated from ventricular fibrillation before implantation. During a mean follow-up of 78 ± 46 months, none of the asymptomatic patients experienced appropriate therapy, whereas 21.6% of symptomatic patients had ≥1 shock. Inappropriate shock occurred in 7 (13.7%) patients, with a mean IS of 6.57 ± 6.94 shocks per patient occurring 16.14 ± 10.38 months after implantation. There was a trend towards higher incidence of inappropriate shock in the asymptomatic group (p = 0.09). The interval from implantation to inappropriate shock occurrence was 13.91 ± 12.98 months. The risk of IS at 3 years was 13.7%, which eventually plateaued over the time. ConclusionInappropriate shock is common in Brugada syndrome during the early periods after an ICD implantation, and seems to be more likely in asymptomatic patients. This finding may warrant a review of the indications for ICD implantation, especially in the young and apparently healthy population of patients with Brugada syndrome.

T-wave oversensing in patients with Brugada syndrome: true bipolar versus integrated bipolar implantable cardioverter defibrillator leads: multicenter retrospective study.

It is thought that dedicated bipolar are more susceptible to T-wave oversensing when compared with integrated bipolar leads. This could be of extreme importance in patients with Brugada syndrome (BrS) because T-wave oversensing in this population is more frequent when compared with other implantable cardioverter defibrillator (ICD) recipients without BrS. We aimed to compare the incidence of T-wave oversensing in patients with BrS according to the type of lead (integrated bipolar versus true/dedicated bipolar). All patients diagnosed with BrS with an ICD implant in 10 tertiary hospitals between 1993 and 2013 were included in the study. A total of 480 patients were included (mean age, 45.6±14 years). During a mean follow-up of 74.9±51.7 months (median, 69; range, 2-236), 28 patients had T-wave oversensing (5.8%), leading to inappropriate shock in 18 (3.8%). All these events occurred in patients with true bipolar ICD leads (P=0.01) and in 2 patients it was solved instantaneously by changing the configuration from a dedicated to an integrated bipolar sensing configuration. In the stepwise multivariate models, only integrated bipolar ICD leads (hazard ratio, 0.34; 95% confidence interval, 0.171-0.675; P=0.002) was independent predictor of non-T-wave oversensing. T-wave oversensing is a potential reason of inappropriate shocks in patients with BrS receiving ICDs. In the vast majority it can be solved by reprogramming. However, in some patients it still requires invasive intervention. Importantly, incidence is significantly lower using an integrated bipolar lead system when compared with a dedicated bipolar lead system and hence the latter should be routinely used in BrS cases.