Inappropriate Implantable Cardioverter-defibrillator Research Articles

Analysis of electrotherapy in patients with implantable cardioverter-defibrillator for primary prevention of sudden cardiac death according to remote monitoring data

Aim: To determine the factors associated with development of justified and inappropriate implantable cardioverter-defibrillator (ICD) activations in patients at high risk of sudden cardiac death based on the remote monitoring systemMaterial and Methods. We analyzed remote monitoring data from 2014 to 2022 in 132 patients with ICD for primary prevention of sudden cardiac death (SCD). Patients were divided into 2 groups 1 – patients with persistent paroxysmal tachyarrhythmias; 2 – patients without persistent paroxysms of ventricular tachycardia (VT) / ventricular fibrillation (VF). In case of inappropriate shocks, the causes and possible predictors of their development were analyzed.Results. Of 132 patients, 62 (46.9%) patients appeared to have persistent VT/VF. It was found that the probability of detecting persistent paroxysms of VT/VF decreased with a history of revascularization (p = 0.030) and increased in the absence of amiodarone therapy (p = 0.012), with increasing age (p = 0.035), with decreasing left ventricular ejection fraction (LVEF) less than 35% (p = 0.016). 71 arrhythmic episodes (17.9%) in 27 (20.4%) patients were considered as false detection of tachyarrhythmias. Analyzing the causes of inappropriate electrotherapy, different types of supraventricular tachyarrhythmias in the zone of VT detection (85.9%), including atrial fibrillation (25.4%), in smaller percentage of cases there was discovered T-wave detection 4.2%, noise on the electrode – 2.8%, 7.1% – double counter due to the operation of the cardiac contractility modulation device. When analyzing factors associated with the development of false detection, reliable results were obtained with regard to the presence of a history of atrial fibrillation (p = 0.036), implanted single-chamber ICD (p = 0.028).Conclusion. The development of persistent ventricular tachyarrhythmias was noted in 47% of patients with ICD as a part of primary prevention of sudden cardiac death, and 20.4% had the development of inappropriate detection and electrotherapy. Predictors of their occurrence have been identified, which can be used as development of strategies for shock minimization.

Improved outcomes of cardiac resynchronization therapy with a defibrillator in systolic heart failure: Analysis of the Japan cardiac device treatment registry database

AbstractBackgroundTemporal change in outcomes of heart failure patients receiving cardiac resynchronization therapy with a defibrillator (CRT‐D) is unknown.MethodsWe assess outcomes and underlying heart diseases of patients receiving CRT‐D with analyzing database of the Japan cardiac device treatment registry (JCDTR) at the implantation year 2011–2015 and New JCDTR at the implantation year 2018–2021.ResultsProportion of nonischemic heart diseases was about 70% in both the groups (JCDTR: 69%; New JCDTR: 72%). Cardiac sarcoidosis increased with the rate of 5% in the JCDTR to 9% in the New JCDTR group. During an average follow‐up of 21 months, death from any cause occurred in 167 of 906 patients in the JCDTR group (18%) and 79 of 611 patients in the New JCDTR group (13%) (adjusted hazard ratio [aHR] in the New JCDTR group, 0.72; 95% confidence interval [CI]: 0.55–0.94; p = .017). The superiority was mainly driven by reduction in the risk of noncardiac death. With regard to appropriate and inappropriate implantable cardioverter–defibrillator (ICD) therapy, there was a significant reduction in the New JCDTR group versus the JCDTR group (aHR in the New JCDTR group, 0.76; 95% CI: 0.59–0.98; p = .032 for appropriate ICD therapy; aHR in the New JCDTR group, 0.24; 95% CI: 0.12–0.50; p < .0001 for inappropriate ICD therapy).ConclusionsAll‐cause mortality was reduced in CRT‐D patients implanted during 2018–2021 compared to those during 2011–2015, with a significant reduction in noncardiac death.

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

We aimed to develop machine learning-based predictive models for identifying inappropriate implantable cardioverter-defibrillator (ICD) therapy. Our study included 182 consecutive cases (average age 62.2 ± 4.5 years, 169 men) and employed 14 non-deep learning models for prediction (hold-out method). These models utilized selected electrocardiogram parameters and clinical features collected after ICD implantation. From the feature importance analysis of the best ML model, we established easily calculable scores. Among the patients, 25 (13.7%) experienced inappropriate therapy, and we identified 16 significant predictors. Using recursive feature elimination with cross-validation, we reduced the features to six with high feature importance: history of atrial arrhythmia (Atr-arrhythm), ischemic cardiomyopathy (ICM), absence of diabetes mellitus (DM), lack of cardiac resynchronization therapy (CRT), V3 ST level at J point (V3 STJ), and V5 R-wave amplitudes (V5R amp). The extra-trees classifier yielded the highest area under receiver operating characteristics curve (AUROC; 0.869 on test data). Thus, the Cardi35 score was defined as [+ 5.5*Atr-arrhythm − 1.5*CRT + 1.0*V3STJ + 1.0*V5R − 1.0*ICM − 0.5*DM], which demonstrated a hazard ratio of 1.62 (P < 0.001). A cut-off value of the score + 5.5 showed high AUROC (0.826). The ML approach can yield a robust prediction model, and the Cardi35 score was a convenient predictor for inappropriate therapy.

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.

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.

Effect of Novel Programming on Inappropriate Implantable Cardioverter-Defibrillator Therapy in Patients With Very Low Ejection Fraction (from A MADIT-RIT)

The Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy showed a significant reduction in the risk of inappropriate therapy in patients with a programmed high-rate cutoff ≥200 beats per minute or delayed therapy for events ≥170 beats per minute compared with conventional programming. We aimed to characterize outcomes by left ventricular ejection fraction (LVEF) ranges for patients with high-rate, delayed, or conventional implantable cardioverter-defibrillator programming. We assessed the effect of LVEF (LVEF &lt;15%, LVEF 15% to 25%, LVEF &gt;25%) on the risk of inappropriate conventional implantable cardioverter-defibrillator therapy and death in Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy. Inappropriate therapies and death were independently evaluated by the adjudication committee. Statistical methods involved Kaplan-Meier time-to-event graphs and Cox proportional hazards regression analyses. The study involved 140 patients (9%) with LVEF 15%, 585 with LVEF 15% to 25% (39%), and 774 with LVEF &gt;25% (52%). High-rate or delayed programming significantly reduced the risk of inappropriate therapy compared with conventional programming in patients with all LVEFs (p &lt;0.001 for all LVEF). Patients with LVEF &lt;15% had an exceptional 97% lower risk of inappropriate therapy, with high-rate programming than conventional programming (hazard ratio 0.028, p=0.001), without an increase in mortality. High-rate and delayed programming is superior to conventional programming in all LVEF ranges, without adverse effects.

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.

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.

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.

Risk factors for the first and second inappropriate implantable cardioverter-defibrillator therapy.

IntroductionVarious risk factors for the first inappropriate implantable cardioverter-defibrillator (ICD) therapy event have been reported, including a history of atrial fibrillation/atrial flutter (AF/AFL), younger age, and multiple zones. Nonetheless, which factors are concordant with real-world data has not been clarified, and risk factors for the second inappropriate ICD therapy event have not been well examined. This study aimed to clarify the risk factors for the first and second inappropriate ICD therapy events.MethodsWe conducted a post-hoc secondary analysis of data from a multicenter, prospective observational study (the Nippon Storm Study) designed to clarify the risk factors for electrical storm.ResultsThe analysis included data from 1549 patients who received ICD or cardiac resynchronization therapy with defibrillator (CRT-D). Over a median follow-up of 28 months, 293 inappropriate ICD therapy events occurred in 153 (10.0%) patients. On multivariate Cox regression analysis, the risk factors for the first inappropriate ICD therapy event were younger age (hazard ratio [HR], 0.986; p = 0.028), AF/AFL (HR, 2.324; p = 0.002), ICD without CRT implantation (HR, 2.377; p = 0.004), and multiple zones (HR, 1.852; p = 0.010). “No-intervention” after the first inappropriate ICD therapy event was the sole risk factor for the second inappropriate ICD therapy event.ConclusionsRisk factors for the first inappropriate ICD therapy event were similar to those previously reported. Immediate intervention after the first inappropriate ICD therapy event could reduce the risk of the second inappropriate event.

Implantable cardiac defibrillator events in patients with arrhythmogenic right ventricular cardiomyopathy

ObjectiveArrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with a risk of sudden cardiac death. Optimal risk stratification is still under debate. The main purpose of this long-term, single-centre observation was...

Temporal Incidence of Appropriate and Inappropriate Therapy and Mortality in Secondary Prevention ICD Patients by Cardiac Diagnosis.

This study sought to estimate the temporal development in rates and incidences of appropriate and inappropriate implantable cardioverter-defibrillator (ICD) therapy and shocks by cardiac diagnosis in a real-world population of patients with secondary prevention ICDs. Data on cardiac diagnoses and temporal development of ICD therapies in patients with secondary prevention ICDs are limited. Patients (N=4,587) with a secondary prevention ICD were identified from the Danish Pacemaker and ICD Register (January 1, 2007, to December 31, 2016) and linked to nationwide administrative registers. The outcome of appropriate and inappropriate ICD therapy and all-cause mortality were analyzed by annual event rates, cumulative incidence plots, and Cox regression models. During a mean follow-up of 3.6 ± 2.4 years, 1,362 patients (30%) experienced appropriate ICD therapy (16.8% shocks), and 350 patients (7.6%) experienced inappropriate ICD therapy (4.6% shocks). From 2007 to 2016, there was a significant temporal reduction in both appropriate and inappropriate ICD therapy from 28.2 (95% confidence interval [CI]: 21.6 to 37.0) to 7.9 (95% CI: 6.8 to 9.1) and 10.0 (95% CI: 6.4 to 15.5) to 1.0 (95% CI: 0.7 to 1.5) per 100 person-years (p for trends<0.001). Multivariate Cox regression analyses showed that arrhythmogenic right ventricular cardiomyopathy was associated with the highest probability of appropriate ICD therapy (hazard ratio: 2.45; 95% CI: 1.77 to 3.39; p<0.0001), whereas patients with hypertrophic cardiomyopathy had the lowest probability (hazard ratio: 0.62; 95% CI: 0.42 to 0.93; p=0.0196) when compared to patients with ischemic heart disease. In this nationwide real-life cohort of patients with secondary prevention ICDs, we observed a significant temporal decline in delivered appropriate and inappropriate shocks and ICD therapies in the last decade. A large proportion of patients still experienced ICD therapy but with significant differences by cardiac diagnosis.

Systolic Blood Pressure and Risk for Ventricular Arrhythmia in Patients With an Implantable Cardioverter Defibrillator

Low systolic blood pressure (SBP) was previously suggested to be a marker for heart failure and mortality in patients with low left ventricular ejection fraction. We aimed to explore the association of SBP on risk of ventricular tachyarrhythmias (VTA) and atrial arrhythmias as well as appropriate and inappropriate Implantable Cardioverter Defibrillator (ICD) therapy. The study population comprised 1,481 of 1,500 (99%) patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy trial. Multivariate Cox proportional hazards regression modeling was used to identify the association of baseline SBP (recorded prior to ICD implantation) with the risk of VTA > 170 beats/min during follow-up (primary end point) and atrial arrhythmia, appropriate and inappropriate ICD therapy, hospitalization and death (secondary end points). SBP was dichotomized at 120 mm Hg (approximate mean and median) and was also assessed as a continuous measure. Multivariate analysis showed that each 10 mm Hg decrement in SBP was associated with corresponding 11% increased risk for VTA (p = 0.008). Low SBP (≤120 mm Hg) was associated with a significant 58% (p = 0.002) increased risk for VTA ≥170 beats/min; 53% (p = 0.019) increased risk for VTA ≥200 beats/min; and 65% (p = 0.001) increased risk for appropriate ICD therapy, as compared with SBP >120 mm Hg. Low SBP was not associated with increased risk of atrial arrhythmias, and inappropriate ICD therapy. In conclusion, in MADIT-RIT, SBP (≤120 mm Hg) predicted higher rates of VTA. These findings suggest that SBP may be utilized for VTA risk stratification in candidates for primary ICD therapy.

Reassessing the role of antitachycardia pacing in fast ventricular arrhythmias in primary prevention implantable cardioverter-defibrillator recipients: Results from MADIT-RIT

In Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy (MADIT-RIT), high-rate cutoff (arm B) and delayed therapy (arm C) reduced the risk of inappropriate implantable cardioverter-defibrillator (ICD) interventions when compared with conventional programming (arm A); however, appropriate but unnecessary therapies were not evaluated. The purpose of this study was to assess the value of antitachycardia pacing (ATP) for fast ventricular arrhythmias (VAs) ≥ 200 beats/min in patients with primary prevention ICD. We compared ATP only, ATP and shock, and shock only rates in patients in MADIT-RIT treated for VAs ≥ 200 beats/min. The only difference between these randomized groups was the time delay between ventricular tachycardia detection and therapy (3.4 seconds vs 4.9 seconds vs 14.4 seconds). In arm A, 11.5% patients had events, the initial therapy was ATP in 10.5% and shock in 1%, and the final therapy was ATP in 8% and shock in 3.5%. In arm B, 6.6% had events, 4.2% were initially treated with ATP and 2.4% with shock, and the final therapy was ATP in 2.8% and shock in 3.8%. In arm C, 4.7% had events, 2.5% were initially treated with ATP and 2.3% with shock, and the final therapy was ATP in 1.4% and shock in 3.3%. The final shock rate was similar in arm A vs arm B (3.5% vs 3.8%; P = .800) and in arm A vs arm C (3.5% vs 3.3%; P = .855) despite the marked discrepancy in initial ATP therapy utilization. In MADIT-RIT, there was a significant reduction in ATP interventions with therapy delays due to spontaneous termination, with no difference in shock therapies, suggesting that earlier interventions for VAs ≥ 200 beats/min are likely unnecessary, leading to an overestimation of the value of ATP in primary prevention ICD recipients.

Reduction of inappropriate implantable cardioverter-defibrillator therapies using enhanced supraventricular tachycardia discriminators: the ReduceIT study.

Inappropriate implantable cardioverter-defibrillator (ICD) shocks are associated with greater healthcare resource utilization, poorer quality-of-life, and higher mortality. We aimed to investigate the performance of enhanced supraventricular tachycardia (SVT) discrimination algorithms (morphology discrimination, rate stability, and sudden or chamber onset) for reducing inappropriate ICD therapies in patients with ICD/cardiac resynchronization therapy devices. This prospective, non-randomized, multicenter study (ReduceIT) study took place at 56 sites across Germany and Estonia. Adults at risk of sudden cardiac death undergoing St. Jude Medical™ ICD or CRT-D implantation were included. The primary endpoint was freedom from inappropriate ICD shock at 12months and was analyzed in the intention to treat (ITT) and per-protocol population. Overall, 733 patients (65.9 ± 11.4years) were included, of which 40.9% and 59.1% received a single- and dual-chamber detection device, respectively. During follow-up (median 11.9 [0-21.6] months), 96.3% of patients experienced no inappropriate therapy (ITT). The sensitivity, specificity, and accuracy for VT/VF were 91.9%, 95.5%, and 94.7%, respectively. In the per-protocol population (n = 620), the proportion of patients free from inappropriate shock at 12months was 98.4% (n = 610; 95% CI 97.1-99.2%) and exceeded the expected value of 93% (p < 0.0001) which was derived from the rates in the SPICE, ATPonFastVT, and DECREASE studies. A total of 44 patients (6.0%) died during follow-up, 19 deaths were cardiac-related which is consistent with a meta-analysis of EMPIRIC, MADIT-RIT, ADVANCE III, and PROVIDE. Serious device and procedure-related adverse effects occurred in 9.8% of patients. In ICD/CRT-D devices with advanced SVT discriminators, device programming according to clinical setting and detection chamber significantly reduces the rate of inappropriate ICD shocks without compromising patient safety. The algorithms and settings described herein have particular clinical importance and their employment may be of benefit to ICD recipients.

Inappropriate implantable cardioverter-defibrillator shocks in repaired tetralogy of fallot patients: Prevalence and electrophysiological mechanisms

BackgroundPatients with Tetralogy of Fallot (TOF) are at increased risk for sudden cardiac death, often undergo implantable cardioverter defibrillator (ICD) implantation at younger ages, and are at greater risk of experiencing inappropriate shocks. We investigated occurrences of ICD shocks in TOF patients to identify prevalence, characteristics associated with inappropriate shocks, and therapeutic interventions after inappropriate shocks. MethodsRecords of patients with repaired TOF and ICD implantation who were followed at Columbia University Irving Medical Center between 1/1/2000 and 5/1/2019 were analyzed. Results44 patients with repaired TOF and ICD implantation were reviewed. Mean age at implantation was 39 ± 13 years. Eight (18%) patients received both appropriate and inappropriate shocks, 6 (14%) received only appropriate shocks, and 3 (7%) received only inappropriate shocks. Three patients received inappropriate shocks for sinus tachycardia, 7 for atrial arrhythmias, and 1 for noise artifact. Inappropriately shocked patients had lower beat per minute (bpm) cutoff values for ICD therapy (mean = 162 ± 24 bpm vs. 182 ± 16 bpm, p = 0.007). After inappropriate shocks, 1 patient underwent lead replacement, 1 had the VT cutoff increased, and 6 were treated with medications. ConclusionsOne quarter of TOF patients with ICDs experienced inappropriate shock therapy, the timing of which was most often clustered within the first two years after implant or years later. Lower shock therapy zones were associated with increased risk for inappropriate shocks, and the majority of inappropriate shocks resulted from atrial arrhythmias with rapid ventricular response. Treatments for inappropriate shocks included increasing VT therapy bpm and rhythm and/or rate control medications.

Subcutaneous implantable cardioverter-defibrillator troubleshooting in patients with a left ventricular assist device: A case series and systematic review

There are limited data on the performance of the subcutaneous implantable cardioverter-defibrillator (S-ICD) in patients with a left ventricular assist device (LVAD). The purpose of this study was to describe the clinical course and outcomes of patients with both an S-ICD and an LVAD at our institution and via a systematic review of published studies. We performed a retrospective cohort study of all patients who underwent LVAD implantation from 2009 to 2019 at Duke University Hospital. We also performed a systematic review of studies involving patients with an S-ICD and LVAD using the PubMed/Embase databases. Of 588 patients undergoing LVAD implantation with a preexisting implantable cardioverter-defibrillator, 4 had an S-ICD in situ after LVAD implantation. All 4 patients developed electromagnetic interference (EMI) in the primary/secondary vectors after LVAD implantation, resulting in inappropriate implantable cardioverter-defibrillator shocks in 2 patients. Sensing in the alternate vector was adequate immediately postoperatively in 1 patient. Postoperative undersensing was present in the alternate vector in 3 patients but improved at first outpatient follow-up in 2 patients, allowing tachy therapies to be reenabled. Eight studies involving 27 patients were identified in the systematic review. EMI was common and frequently absent in the alternate vector (6 of 7 patients). Undersensing and EMI are common after LVAD implantation in patients with an S-ICD in situ, particularly in the primary and secondary sensing vectors. Undersensing in the alternate vector may improve during follow-up, obviating the need for device revision or extraction.

Electrical Storm in Patients with Inappropriate Implantable Cardioverter-Defibrillator Therapy: Current Trends in Clinical Practice between Guidelines and Technology Progress

The term “Electrical Storm” (ES) indicates cardiac electrical instability manifested by several episodes of ventricular tachyarrhythmias within a short time. In the contemporary implantable cardioverter-defibrillator (ICD) era, ES is defined as recurrent (three or more separate episodes) of ICD discharges over 24 hours. Some ESs are due to inappropriate repetitive shock and are potentially lethal for the patient. The most common causes of inappropriate ICD shock include supraventricular tachycardia with high ventricular response and oversening of peaked T waves or R wave, myopotentials or electrical noise. Appropriate diagnosis and treatment are critical in the Emergency Department. To approach these patients systematically, it is important to understand, that there are four causes of shock. Modern ICD incorporate sophisticated tachycardia detection algorithms within their programming designed to minimize devices’ detection mistakes and ICD-related information can also be checked using remote home monitoring systems. However, these opportunities are often not utilized to their full benefit. Thus, careful attention should be paid to the programming of the device. Fine tuning of the detection and differentiation algorithms is critical, and best done by a practitioner who understands the subtle differences among the different manufacturers. The racommendations for those problems should be revised.