Inappropriate Implantable Cardioverter-defibrillator Shocks Research Articles

Remote monitoring of implantable cardioverter defibrillators: a systematic review and meta-analysis of randomised controlled trials

Abstract Background Remote monitoring (RM) of implantable cardioverter defibrillators (ICD) has been widely adopted as the standard follow-up strategy [1]. Observational data [2,3] has suggested morbidity and mortality reduction associated with RM compared to traditional in-person ICD follow-up, however, randomised controlled trials (RCTs) demonstrate heterogeneous results. Purpose To assess the impact of RM of ICDs on morbidity and mortality through a systematic review and meta-analysis of RCTs comparing RM versus in-person follow-up. Methods PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL) and reference lists were searched for RCTs evaluating RM compared to in-person follow-up of patients with ICDs or cardiac resynchronisation therapy with defibrillator (CRT-D) devices. Meta-analyses of all-cause mortality, cardiovascular (CVD) hospitalisation and inappropriate ICD shock rates were performed. Results Literature search identified 1011 relevant publications, out of which 15 RCTs [4-18] involving a total of 7579 patients (13 RCTs reporting mortality rate, 7 RCTs reporting CVD hospitalisation rate, 6 RCTs reporting inappropriate ICD shock rate) met the inclusion criteria. Pooled analyses demonstrated that RM is not associated with a significant reduction in all-cause mortality (OR 0.95; 95% CI 0.78-1.16; p=0.60)(Figure 1, panel a) or odds of CVD hospitalisation (OR 0.95; 95% CI 0.72-1.25; p=0.70) (Figure 1, panel b). RM was, however, shown to be associated with significantly lower odds of receiving an inappropriate ICD shock compared to the control group (OR 0.63; 95% CI 0.46-0.88; p=0.006) (Figure 1, panel c). The IN-TIME study (the only RCT that independently reached statistical significance in terms of RM effect on mortality) enrolled patients exclusively with a Biotronik ICD or CRT-D; this raised the question as to whether the choice of vendor had an impact on mortality. Our subgroup analysis of the Biotronik device studies demonstrated that there was no significant all-cause mortality benefit (OR 0.87, 95% CI 0.59-1.27; p=0.46). Conclusions This meta-analysis of 15 RCTs including 7579 patients suggests that RM of ICDs is associated with a reduction in inappropriate ICD shocks, without a significant reduction in mortality or CVD hospitalisation when compared to in-person follow-up. Further studies comparing different RM processing and alert response models are warranted.

Atrial cardiomyopathy resulting from loss of plakophilin-2 expression: Response to adrenergic stimulation and implications for the exercise response.

Atrial arrhythmias occur in 20-40% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and are associated with an increased risk of sustained ventricular arrhythmias and inappropriate implantable cardioverter-defibrillator shocks. The pathophysiology of atrial arrhythmias in ARVC remains unclear. Most cases of gene-positive ARVC are linked to pathogenic variants in the desmosomal gene plakophilin-2 (PKP2). Here, we test the hypothesis that loss of PKP2 expression leads to pro-arrhythmic changes in atrial cardiomyocytes. Atrial cells/tissue were obtained from a cardiac-specific, tamoxifen-activated model of PKP2 deficiency (PKP2cKO). By contrast to PKP2cKO ventricular myocytes, PKP2cKO atrial cardiomyocytes presented no significant differences in intracellular calcium (Ca2+ i) transient dynamics, sarcoplasmic reticulum load or action potential morphology. PKP2cKO atrial cardiomyocytes showed elevated reactive oxygen species levels, increased frequency and amplitude of Ca2+ sparks, and increased diastolic [Ca2+]i compared to control; the latter two parameters were further increased by isoproterenol exposure and reversed by exposure to ryanodine receptor blocker dantrolene. We speculate that these isoproterenol-dependent effects may impact on the exercise-related atrial arrhythmia risk in ARVC patients. Despite absence of changes in Ca2+ i transient dynamics, PKP2cKO atrial cardiomyocytes showed enhanced sarcomere shortening and impaired sarcomere relaxation. Orthogonal transcriptomic analysis of human(GTEx) and PKP2cKO atrial tissue led to identification of 41 transcripts depending on PKP2 expression. Biochemical follow-up confirmed reduced abundance of sarcomeric protein myosin binding protein C, potentially playing a role in cellular shortening and relaxation changes observed. Our findings provide novel insights into the role of PKP2 in atrial myocardium with potential implications to therapeutic management of atrial fibrillation in patients with PKP2-related ARVC. KEY POINTS: Atrial arrhythmias occur in a large group of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), a cardiac disease mostly caused by pathogenic variants in the desmosomal gene plakophilin-2 (PKP2). Exercise is considered to be an independent risk factor for arrhythmias consequent to PKP2 deficiency. Weshow that loss of PKP2 expression affects cellular calcium handling and electrophysiology differently in left atrial vs. ventricular myocardium and causes extensive atrial fibrosis. PKP2-deficient atrial cardiomyocytes present increased spontaneous sarcoplasmic reticulum calcium release events, furtherenhancedby isoproterenol exposure and reversiblebya ryanodine receptor blocker(dantrolene). In addition, PKP2-deficient atrial myocytes exhibit impaired relaxation and enhanced sarcomere shortening, most probably related to reduced abundance of myosin binding protein C. We speculate that cellular effects reported upon isoproterenol impact on the exercise-related atrial arrhythmia risk in ARVC patients. We further propose that therapeutic approaches aimed at mitigating ventricular damage may be effective to treat the atrial disease in ARVC.

Risk of atrial arrhythmias in patients with ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy

BackgroundIn arrhythmogenic right ventricular cardiomyopathy (ARVC), risk of atrial arrhythmias (AAs) persists after ventricular tachycardia (VT) ablation. ObjectiveThe purpose of this study was to determine the type, prevalence, outcome, and risk correlates of AA in ARVC in patients undergoing VT ablation. MethodsProspectively collected procedural and clinical data on ARVC patients undergoing VT ablation were analyzed. Risk score for typical atrial flutter was determined from univariate logistic regression analysis. ResultsOf 119 consecutive patients with ARVC and VT ablation, 40 (34%) had AA: atrial fibrillation (AF) in 31, typical isthmus-dependent atrial flutter (AFL) in 27, and atrial tachycardia/atypical flutter (AT) in 10. Seventeen patients (43%) with AA experienced inappropriate defibrillator therapy, with 15 patients experiencing shocks. Ablation was performed for typical AFL in 21 (53%), AT in 5 (13%), and pulmonary vein isolation for AF in 4 (10%) patients and prevented AA in 78% and all AFL during additional mean follow-up of 65 months. Risk score for typical flutter included age >40 years (1 point), ≥moderate right ventricular dysfunction (2 points), ≥moderate tricuspid regurgitation (2 points), ≥moderate right atrial dilation (2 points), and right ventricular volume >250 cc (3points), with score >4 identifying 50% prevalence of typical flutter. ConclusionAAs are common in patients with ARVC and VT, can result in inappropriate implantable cardioverter-defibrillator shocks, and typically are controlled with atrial ablation. A risk score can be used to identify patients at high risk for typical AFL who may be considered for isthmus ablation at the time of VT ablation.

Risk prediction of inappropriate implantable cardioverter-defibrillator therapy using machine learning

Abstract Background Inappropriate shock from implantable cardioverter-defibrillators (ICDs) undermines quality of life and increases all-cause mortality risk. Various predictors of inappropriate ICD shock have also been indicated in previous studies. Nevertheless, no prediction model by machine learning has been reported. Purpose We developed ML models for evaluating the risk of inappropriate ICD therapy, and proposed easily calculable risk scoring. Methods In total, 182 consecutive cases implanted with ICD were enrolled. The predictive models were based on 16 statistically significant factors out of 189 items including electrocardiogram parameters and clinical features after ICD implantation. Statistical analysis and 14 ensemble learning methods were performed. Shapley additive explanation (SHAP) method was performed to extract important features in the best ML model, and easily calculable score was established from the features. Results Twenty-five patients (13.7%) underwent inappropriate therapy. The extra-trees classifier demonstrated the highest area under the receiver operating characteristic curve (AUROC; 0.839). The top six features were history of atrial arrhythmia, ischemic cardiomyopathy (ICM), no diabetes mellitus (DM), cardiac resynchronization therapy (CRT), and V4- and V5 R-wave amplitudes. From the six features, the Cardi45 score was developed (+6.5 points for history of atrial arrhythmia, -2.0 points for ICM, -1.0 points for DM, -0.5 points for CRT, and +0.5 points for V4 T-wave amplitude ≥1200 μV and V5 R-wave amplitude ≥1400 μV). The AUROC for the Cardi45 score was 0.886, which was higher than that of extra-trees classifier. Conclusion Our study demonstrates that the ML approach can provide a good prediction model and Cardi45 score was powerful predictors for inappropriate ICD therapy. Cardi45 score, derived from this model, may be used to judge whether an aggressive rhythm control strategy should be implemented or ICD implantation should be avoided in some patients.Picture 1Picture 2

Low Risk of Inappropriate Shock Among Pediatric Patients With an Implantable Cardioverter Defibrillator: A Single Center Experience.

Implantable cardioverter-defibrillators (ICD) are increasingly being used among the pediatric population for indications of both primary and secondary prevention. There is limited long-term data on the outcomes of pediatric patients following ICD implantation. The aim of this study was to investigate the characteristics of this population, burden of appropriate and inappropriate shock and complication rate in a large tertiary pediatric medical center. Included were children under the age of 18years who underwent ICD implantation and had clinical follow up at our center. Data were retrospectively collected between study period 2005-2020. Primary outcome was the incidence of ICD shock appropriate and inappropriate. Secondary outcome was defining our patient population characteristics. Our cohort included 51 patients who underwent ICD implantation. Mean age at implantation was 10.9 ± 4.7years and average follow-up time was 67months. Diagnoses of implanted patients were: 28 (55%) patients with syndromes with risk for sudden death, cardiomyopathy in 14 patients (27%) and congenital heart disease (CHD) in 9 patients (18%). Forty-two (82%) patients had an ICD implanted for secondary prevention after experiencing a life-threatening arrhythmia and 9 (18%) for primary prevention. An endocardial system was implanted in 39 (76%) patients and an epicardial systems in 12 (24%) patients. A total of 20 (39%) patients received appropriate shocks for ventricular fibrillation(VF). 5 patients received inappropriate shocks, 4 due to sinus tachycardia and 1 due to rapidly conducted atrial fibrillation. Those who received an inappropriate shock had a significantly shorter ICD-programmed VF detection cycle length compared to those who did not receive an inappropriate shock (320ms versus 270ms, p = 0.062). This single center study demonstrates a high rate of appropriate ICD shocks (39%) and a low rate of inappropriate ICD shocks. Accurate programming of ICD devices in the pediatric population is paramount to avoid inappropriate ICD shocks.

Effect of Carvedilol vs Metoprolol on Atrial and Ventricular Arrhythmias Among Implantable Cardioverter-Defibrillator Recipients

BackgroundBoth selective and nonselective beta-blockers are used to treat patients with heart failure (HF). However, the data on the association of beta-blocker type with risk of atrial arrhythmia and ventricular arrhythmia (VA) in HF patients with a primary prevention implantable cardioverter-defibrillator (ICD) are limited. ObjectivesThis study sought to evaluate the effect of metoprolol vs carvedilol on the risk of atrial tachyarrhythmia (ATA) and VA in HF patients with an ICD. MethodsThis study pooled primary prevention ICD recipients from 5 landmark ICD trials (MADIT-II, MADIT-CRT, MADIT-RIT, MADIT-RISK, and RAID). Fine and Gray multivariate regression models, stratified by study, were used to evaluate the risk of ATA, inappropriate ICD shocks, and fast VA (defined as ventricular tachycardia ≥200 beats/min or ventricular fibrillation) by beta-blocker type. ResultsAmong 4,194 patients, 2,920 (70%) were prescribed carvedilol and 1,274 (30%) metoprolol. The cumulative incidence of ATA at 3.5 years was 11% in patients treated with carvedilol vs 15% in patients taking metoprolol (P = 0.003). Multivariate analysis showed that carvedilol treatment was associated with a 35% reduction in the risk of ATA (HR: 0.65; 95% CI: 0.53-0.81; P < 0.001) when compared to metoprolol, and with a corresponding 35% reduction in the risk of inappropriate ICD shocks (HR: 0.65; 95% CI: 0.47-0.89; P = 0.008). Carvedilol vs metoprolol was also associated with a 16% reduction in the risk of fast VA. However, these findings did not reach statistical significance (HR: 0.84; 95% CI: 0.70-1.02; P = 0.085). ConclusionsThese findings suggests that HF patients with ICDs on carvedilol treatment experience a significantly lower risk of ATA and inappropriate ICD shocks when compared to treatment with metoprolol.

Atrioventricular nodal ablation is an effective management strategy for atrial fibrillation in patients with hypertrophic cardiomyopathy

Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HCM) and can be challenging to manage. Atrioventricular nodal (AVN) ablation may be an effective management strategy for AF in these patients. The purpose of this study was to assess the efficacy of AVN ablation in HCM patients who have failed medical therapy and/or catheter ablation for AF. A multicenter study with retrospective analysis of a prospectively collated HCM registry was performed. AVN ablation patients were identified. Baseline characteristics and device and procedural indications were collected. Symptoms defined by New York Heart Association and European Heart Rhythm Association classification and echocardiographic findings during follow-up were assessed. Fifty-nine patients were included in the study. Indications for AVN ablation were 6 (10.2%) inappropriate implantable cardioverter-defibrillator shock, 35 (59.3%) ineffective rate control, and 18 (30.5%) to regularize rhythm for symptom improvement. During post-AVN ablation follow-up of 79.4 ± 61.1 months, left ventricular ejection fraction (LVEF) remained stable (pre-LVEF 48.9% ± 12.6% vs post-LVEF 50.1% ± 10.1%; P = .29), even in those without a cardiac resynchronization therapy (CRT) device (pre-LVEF 54.3% ± 8.0% vs post-LVEF 53.8% ± 8.0%; P = .65). Forty-nine patients (83.1%) reported an improvement in symptoms regardless of AF type (17/21 [81.0%] paroxysmal vs 32/38 [84.2%] persistent; P = 1.00), presence of baseline left ventricular impairment (22/26 [84.6%] LVEF ≤50% vs 27/33 [81.8%] LVEF ≥50%; P = 1.00) or CRT device (27/32 [84.4%] CRT vs 22/27 [81.5%] no CRT; P = 1.00). Symptoms improved in 16 patients (89.0%) who underwent AVN ablation to regularize rhythm. AVN ablation improved symptoms without impacting left ventricular function in the majority of patients. The data suggest that AVN ablation is an effective and safe management approach for AF in HCM and should be further evaluated in larger prospective studies.

Appropriate Implantable Cardioverter-Defibrillator Therapy in Patients with Ventricular Arrhythmia of Unclear Cause in Secondary Prevention of Sudden Cardiac Death.

In this study, we sought to investigate the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapies and inappropriate shocks in secondary prevention ICD recipients with ventricular arrhythmia of unclear cause and ventricular arrhythmia in the context of underlying heart disease. In this retrospective study, consecutive patients with an ICD implanted for secondary prevention in the University Medical Center Groningen (UMCG), the Netherlands between 1 January 2012 and 31 December 2018 were included. Patients were classified as having ventricular arrhythmia of unclear cause if no clear cause was found which could explain the index ventricular arrhythmia. The primary outcome was appropriate ICD therapy. The study population consisted of 257 patients. In 220 patients, an underlying heart disease could be identified as the cause of ventricular arrhythmia, while 37 patients had an unclear cause of ventricular arrhythmia. The median age was 64 years (interquartile range (IQR) 53-72 years). Forty-five (18%) patients were women. During a median duration of follow-up of 6.2 years (IQR 4.8-7.8 years), appropriate ICD therapy occurred in 95 (37%) patients. This number was 90 (41%) in the group with a clear etiology and 5 (14%) in the group with an unclear etiology. In multivariable analysis, index ventricular arrhythmia of unclear cause was associated with fewer appropriate ICD therapies (HR 0.37 [95% CI 0.14-0.99]; p = 0.048), as well as an increased risk of inappropriate ICD shocks (HR 3.71 [95% CI 1.17-11.80]; p = 0.026). Index ventricular arrhythmia of unclear cause was significantly associated with fewer appropriate ICD therapies.

PO-05-079 SMOKING AND THE RISK OF VENTRICULAR TACHYARRHYTHMIAS AMONG IMPLANTABLE CARDIOVERTER DEFIBRILLATOR RECIPIENTS FOR PRIMARY PREVENTION OF SUDDEN CARDIAC DEATH

Smoking has been linked to increased morbidity and mortality in patients with cardiovascular disease. However, limited data exist regarding the arrhythmic effects of smoking in patients at risk for sudden cardiac death (SCD). We aimed to evaluate the relationship between smoking and the risk of ventricular tachyarrhythmias and SCD. The study population comprised 5,015 patients implanted with an implantable cardioverter defibrillator (ICD) from five landmark randomized ICD trials (MADIT-II, MADIT-CRT, MADIT-RIT, MADIT-RISK, and RAID trials). Patients were categorized into three groups based on smoking status at the time of ICD implantation: non-smokers, past smokers, and current smokers. The primary endpoint was the first occurrence of ventricular tachycardia ≥170 bpm or fibrillation (VT/VF). Secondary endpoints included the composite endpoint of VT/VF or SCD and inappropriate ICD shocks. A competing risk analysis was carried out using the Fine and Gray method to generate cumulative incidence function (CIF) curves and regression models for the defined endpoints. The 5-year cumulative incidence of a first episode of VT/VF was higher in current smokers (32%) than in past- (29%) and non-smokers (25%) (p=0.009, [Figure, left panel]). Consistent results were obtained for the endpoint of inappropriate ICD shocks (10%, 9%, 6%%, respectively; p=0.007, [Figure, right panel]). Multivariate current smoking vs. non-smoking was associated with a significant 25% increased risk of VT/VF (HR=1.25, p=0.034); with a corresponding 28% increased risk of the composite endpoint of VT/VF or SCD (HR=1.28, p=0.014); and with a 49% increased risk of inappropriate ICD shocks (HR=1.49, p=0.03). Conversely, the risk of the aforementioned endpoints was not significantly difference between past-smokers and never-smokers. Patients who smoke at the time of ICD implantation experience a significantly increased risk of VT/VF and inappropriate ICD shocks.

Ventricular fibrillation induced by inappropriate antitachycardia pacing during charging for atrial fibrillation.

Antitachycardia pacing (ATP) during charging, which delivers ATP for rapid ventricular tachycardia (VT) while charging for a shock of an implantable cardioverter defibrillator (ICD), has been used as an adjunctive therapy to terminate VT. We report a rare complication of ATP during charging, in which ventricular fibrillation was induced by inappropriate ATP during charging for rapid atrial fibrillation (AF) in a patient with hypertrophic cardiomyopathy. The present case suggests that AF increases not only the risk of inappropriate ICD shock, but also that of degeneration to VF due to the inappropriate ATP. This article is protected by copyright. All rights reserved.

INCREASED DISPERSION OF ATRIAL REFRACTORINESS PREDICTS MOST OF THE INAPPROPRIATE IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR SHOCKS

Background and aim: Despite the proven survival benefits of implantable cardioverter-defibrillators, inappropriate shocks limits their benefits due to adverse effects on quality of life, potential arrhythmogenesis an deven on mortality. Atrial fibrillation (AF) is the most common cause of inappropriate shocks. Therefore, to predict and treat AF may prevent inappropriate shocks and their hazardous potentials. This paper aimed to show that by measuring atrial refractoriness, we could predict the patients who may experience inappropriate implantable cardioverter-defibrillator shocks.\n Material and methods: 186 consecutive patients who underwent initial ICD implantation underwent coronary angiography and also underwent electrophysiologic (EP) study before the ICD implantation. \nResults: Of 169 patients who could be followed, 34 received (20%) at least 1 inappropriate shocks during the mean follow-up of 30 months. Majority of these shocks were due to AF (68%). Atrial effective refactory periods (AERPs) and AERP dispersion were the most significant predictors for these inappropriate shocks. \nConclusion: We found that simple EP study parameters measuring atrial refractoriness may define the patients carrying higher risk for future inappropriate shocks due to AF. In these patients, by either device programming or pharmocological treatments or ablation procedures, we could prevent inappropriate shocks and their hazardous results.

Diagnosis and treatment of the rare procedural complication of malpositioned pacing leads in the left heart: a single center experience

Objectives. This study assessed the management approach and outcome of the pacemaker or implantable cardioverter-defibrillator (ICD) leads malpositioned in the left heart. Malpositioned leads (MPLs) may have deleterious consequences, and appropriate management remains uncertain. Methods. The study population included all patients referred to a single institution for MPL in the left side of the heart after pacemaker or ICD implantation during the period from 2015 to 2021. The approach and outcome of lead management were retrospectively assessed. Results. During the study period, 6887 patients underwent device implantation. MPL was diagnosed in five patients (0.07%). In four cases, the pacing lead was placed in a coronary sinus (CS) branch, while the pacing lead was inside the left ventricle (LV) in one case. Symptoms suggestive of lead malposition were reported by 2 patients (40%). One of the patients presented with recurrent TIAs. Another presented with inappropriate ICD shocks. In one asymptomatic case, an ICD lead changed position from the right ventricle to the CS, suggesting idiopathic lead migration. In 4/5 patients, the leads were removed or repositioned by percutaneous approach, with no major periprocedural complications. Conclusions. In this series of MPL in the left heart, two patients presented with thromboembolic events or inappropriate ICD shocks. These serious complications highlight the critical need for early correct diagnosis and proper management of MPL.

Outcomes of implantable cardioverter-defibrillator implantation in HIV-infected patients: A single-center retrospective cohort study.

BackgroundHIV‐infected individuals have a known increased risk of sudden cardiac death (SCD) compared to uninfected individuals. Implantable cardioverter‐defibrillators (ICDs) are standard therapy for preventing SCD; however, there is limited data on the outcomes of ICDs in HIV‐infected individuals.HypothesisHIV‐infected subjects receive a higher number of appropriate ICD therapies than uninfected controls.MethodsThis is a retrospective cohort study of 35 consecutive HIV‐Infected patients and 36 uninfected controls matched by age, race, and gender who were treated at the University of North Carolina Medical Center in the outpatient or inpatient setting from 2014 to the present and had undergone ICD implantation. For HIV‐infected subjects, a multivariate Poisson regression analysis was performed to evaluate the association between covariates and ICD therapies.ResultsAmong HIV‐infected subjects, the mean CD4 count was 582.5 cells/mm3 and 69% had an undetectable viral load. The median follow‐up was 6.4 years. HIV‐infected subjects had both a higher number of appropriate ICD shocks or antitachycardia pacing (ATP) therapy per person‐year as well as a higher number of inappropriate ICD shocks per person‐year than uninfected controls (1.512 vs. 0.590 and 0.122 vs. 0.0166, respectively, p < .001 for both comparisons). After multivariate adjustment, the presence of detectable/unsuppressed viral load at the time of ICD implantation was an independent predictor of both of the following in HIV‐infected subjects: (1) appropriate ICD discharge (p = .004), and (2) appropriate ICD discharge or appropriate ATP therapy (p < .001).ConclusionHIV‐infected subjects had a higher number of appropriate ICD discharge or ATP therapy per person‐year than matched uninfected controls.

Cardiac resynchronization therapy in patients with congenital heart disease and systemic right ventricle.

Although patients with systemic right ventricle (SRV) represent a significant proportion of patients with congenital heart disease (CHD) implanted with cardiac resynchronization therapy (CRT), there are limited and conflicting data in this specific patient group. We aimed to analyze outcomes of patients with SRV implanted with a CRT device. Data were analyzed from an observational, retrospective, multicenter cohort study including all patients with CHD implanted with a CRT device from 6 French centers from 2004 to 2020. Response to CRT was defined as an increase in systemic ventricular ejection fraction of ≥10% and/or an improvement in New York Heart Association functional class by at least 1 grade. A total of 85 patients with CHD were enrolled (mean age 39.8 ± 20.0 years; 55 [64.7%] males; 25 defibrillators [29.4%]), including 31 patients with SRV (36.5%) (mean age 43.9 ± 19.8 years; 16 [51.6%] males). The mean change in QRS duration after implantation was similar as compared with patients with systemic left ventricle (-46 ± 26 ms vs -35 ± 32 ms; P = .16). During a mean follow-up of 5.1 ± 3.5 years, late complications included 2 lead dysfunctions (6.5%), 3 CRT-related infections (9.7%), and 1 inappropriate implantable cardioverter-defibrillator shock (3.2%). The proportion of CRT responders at 6, 12, and 24 months were 82.6%, 80.0%, and 77.8% in patients with SRV vs 66.7%, 64.3%, and 69.6% in patients with systemic left ventricle (P = NS). In this multicenter cohort, one-third of patients with CHD implanted with a CRT device had SRV. CRT in patients with SRV was associated with a high rate of responders, comparable to that of patients with systemic left ventricle.

Implantable cardioverter-defibrillators in heart transplant patients: a systematic review and meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Background Whilst implantable cardioverter-defibrillator (ICD) implantation is beneficial in a select group of patients, heart transplant patients were excluded from landmark clinical trials. Thus, controversy remains about the utility of ICD in high-risk heart transplant patients. Purpose To understand the utility, benefits and side-effects of ICD in heart transplant patients. Methods Five electronic databases were systematically searched from their inception to August 2021, in order to identify all studies which explored the role of ICD in heart transplant patients. We used a random-effects model for data analysis based on event rates (ER) and 95% confidence interval (CI). Publication bias was assessed using funnel plots and Egger’s regression analysis. Results Eleven studies with 4648 heart transplant patients, 129 of whom received ICD, met the inclusion criteria for the meta-analysis. Studies included two multicentre retrospective cohort studies, four single centre retrospective cohort studies, two case series and three case reports. Of the 129 heart transplant patients with ICD, 74% were men, mean age at ICD implantation was 48.5 years, mean time from transplant to ICD was 99 months, and mean follow-up duration was 40 months. The indication for ICD implantation was often multifactorial and included severe allograft vasculopathy (40%), the presence of left ventricular systolic dysfunction (37%), documented VT/VF (14%), unexplained syncope (14%), and history of cardiac arrest (13%). Appropriate ICD therapy for patients occurred as an average event rate of 19% (95% CI 13%-27%) (I2 = 0% p = 0.66), Figure 1. Inappropriate therapy for patients occurred as an average event rate of 9% (95% CI 5%-16%) (I2 = 0% p = 0.96), Figure 2. There was no evidence of publication bias. In total, nine ICD-related complications were reported including pocket haematoma (n = 1), pocket site infection (n = 2), infection of the ICD system (n = 1), lead displacement (n = 2) and lead fracture (n = 1). Mortality occurred in 28 patients, with heart failure being the leading primary cause of death (n = 10), followed by sepsis (n = 6), arrhythmia (n = 3) and electromechanical disassociation (n = 3). Conclusion Heart transplant patients with ICD more often received appropriate than inappropriate ICD shock therapy. The 19% appropriate ICD shock rate suggests a high burden of ventricular arrhythmias in high-risk heart transplant patients. Thus, ICD therapy may be beneficial in a select subset of heart transplant patients, keeping in mind even with appropriate shock therapy, subsequent terminal electromechanical disassociation and arrhythmias may imply ICD are not fully protective against arrhythmic aetiologies of mortality. Abstract Figure 1 Abstract Figure 2

Lead dislodgement complicated with paroxysmal atrial fibrillation as a rare cause of inappropriate implantable cardioverter defibrillator shock: a case report.

Lead dislodgement complicated with paroxysmal atrial fibrillation as a rare cause of inappropriate implantable cardioverter defibrillator shock: a case report.

Arrhythmogenic right ventricular cardiomyopathy associated with arrhythmia-induced cardiomyopathy: A case report

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a kind of inherited cardio-myopathy, which is characterized by fibro-fatty replacement of right ventricular myocardium, leading to ventricular arrhythmia. However, rapid atrial arrhythmias are also common, including atrial fibrillation, atrial flutter and atrial tachycardia. Long term rapid atrial arrhythmia can lead to further deterioration of cardiac function. This case is a 51-year-old male. He was admitted to Department of Cardiology, Peking University Third Hospital with palpitation and fatigue after exercise. Electrocardiogram showed incessant atrial tachycardia. Echocardiography revealed dilation of all his four chambers, especially the right ventricle, with the left ventricular ejection fraction of 40% and the right ventricular hypokinesis. Cardiac magnetic resonance imaging found that the right ventricle was significantly enlarged, and the right ventricular aneurysm had formed; the right ventricular ejection fraction was as low as 8%, and the left ventricular ejection fraction was 35%. The patients met the diagnostic criteria of ARVC, and both left and right ventricles were involved. His physical activities were restricted, and metoprolol, digoxin, spironolactone and ramipril were given. Rivaroxaban was also given because atrial tachycardia could cause left atrial thrombosis and embolism. His atrial tachycardia converted spontaneously to normal sinus rhythm after these treatments. Since the patient had severe right ventricular dysfunction, frequent premature ventricular beats and non-sustained ventricular tachycardia on Holter monitoring, indicating a high risk of sudden death, implantable cardioverter defibrillator (ICD) was implanted. After discharge from hospital, physical activity restriction and the above medicines were continued. As rapid atrial arrhythmia could lead to inappropriate ICD shocks, amiodarone was added to prevent the recurrence of atrial tachycardia, and also control ventricular arrhythmia. After 6 months, echocardiography was repeated and showed that the left ventricle diameter was reduced significantly, and the left ventricular ejection fraction increased to 60%, while the size of right ventricle and right atrium decreased slightly. According to the clinical manifestations and outcomes, he was diagnosed with ARVC associated with arrhythmia induced cardiomyopathy. According to the results of his cardiac magnetic resonance imaging, the patient had left ventricular involvement caused by ARVC, and the persistent atrial tachycardia led to left ventricular systolic dysfunction.

Sudden death after inappropriate shocks of implantable cardioverter defibrillator in a catecholaminergic polymorphic ventricular tachycardia case with a novel RyR2 mutation

BackgroundCatecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic syndrome and a cause of exercise-related sudden death. CPVT has been reported to be caused by gain of function underlying a mutation of cardiac ryanodine receptor (RyR2). MethodsIn a family with a CPVT patient, genomic DNA was extracted from peripheral blood lymphocytes, and the RyR2 gene underwent target gene sequence using MiSeq. The activity of wild-type (WT) and mutant RyR2 channel were evaluated by monitoring Ca2+ signals in HEK293 cells expressing WT and mutant RyR2. We investigated a role of a RyR2 mutation in the recent tertiary structure of RyR2. ResultsThough a 17-year-old man diagnosed as CPVT had implantable cardioverter defibrillator (ICD) and was going to undergo catheter ablation for the control of paroxysmal atrial fibrillation, he suddenly died at the age of twenty-one because of ventricular fibrillation which was spontaneously developed after maximum inappropriate ICD shocks against rapid atrial fibrillation. The genetic test revealed a de novo RyR2 mutation, Gln4936Lys in mosaicism which was located at the α-helix interface between U-motif and C-terminal domain. In the functional analysis, Ca2+ release from endoplasmic reticulum via the mutant RyR2 significantly increased than that from WT. ConclusionA RyR2 mutation, Gln4936Lys, to be documented in a CPVT patient with exercise-induced ventricular tachycardias causes an excessive Ca2+ release from the sarcoplasmic reticulum which corresponded to clinical phenotypes of CPVT. The reduction of inappropriate shocks of ICD is essential to prevent unexpected sudden death in patients with CPVT.

Inappropriate shock delivery by an implantable cardioverter-defibrillator due to electrical interference with a refrigerator in a 4-year-old child.

We report a patient with long QT syndrome who received an inappropriate implantable cardioverter-defibrillator shock due to electrical interference from a refrigerator. This electrical interference was mistakenly detected as an episode of ventricular fibrillation and ended with an inappropriate delivery of shock without any warning symptoms before.

Association of Night-Time Heart Rate With Ventricular Tachyarrhythmias, Appropriate and Inappropriate Implantable Cardioverter-Defibrillator Shocks.

Background: Night-time heart rate (HR) is expected to reflect more accurately the cardiac autonomic function of modulating cardiovascular activity. Few studies have been conducted on the predictive values of night-time HR in relation to cardioverter-defibrillator therapies.Aims: To explore the associations of night-time HR with the ventricular tachyarrhythmias (VTAs), appropriate and inappropriate implantable cardioverter-defibrillator (ICD) shocks.Methods: Patients from the SUMMIT registry receiving ICD or cardiac resynchronization therapy with defibrillator (CRT-D) implantation were retrospectively analyzed using archived home monitoring data. Night-time HR was recorded from 2:00 am to 6:00 am during the first 30 to 60 days after implantation. VTA events and ICD shocks were identified using the intracardiac electrograms by two independent physicians. Restricted cubic splines and smooth curve fitting were conducted to address the non-linear associations between night-time HR and adjusted hazards for clinical outcomes.Results: Over a mean follow-up duration of 55.8 ± 22.7 months, 187 deaths were observed among 730 patients. VTAs, appropriate and inappropriate ICD shocks were observed in 422 (57.8%), 293 (40.1%), and 72 (10.0%) patients, respectively. Apparent U-shaped non-linear associations of night-time HR with VTAs (P for non-linearity = 0.007), appropriate ICD shocks (P for non-linearity = 0.003) and inappropriate ICD shocks (P for non-linearity = 0.014) were detected. When night-time HR was beyond 60 bpm, every 1 bpm increase in night-time HR could result in 3.2, 3.3, and 4.9% higher risks of VTAs and appropriate and inappropriate ICD shocks, respectively; when night-time HR was lower than 60 bpm, every 1 bpm increase in night-time HR could result in 6.0 and 10.7% lower risks of appropriate and inappropriate ICD shocks. Compared to night-time HR of ≤ 50 or ≥70 bpm, night-time HR of 50–70 bpm was associated with 24.9, 30.2, 63.5, and 31.5% reduced incidences of VTA events, appropriate ICD shocks, inappropriate ICD shocks, and all-cause mortality, respectively.Conclusion: Apparent non-linear associations of night-time HR with VTAs and ICD shocks were detected. An increasing incidence of VTAs and ICD shocks was observed at both low and high levels of night-time HR. Night-time HR of 50–70 bpm might be the optimal therapeutics target for the management of ICD/CRT-D recipients.