Analysis of implantable cardioverter defibrillator therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial

Application prospect of speckle tracking echocardiography in pacemaker implantation

More than 1 million permanent pacemakers are implanted worldwide each year, half of which are in patients with high-grade atrioventricular block. Pacemakers provide adequate frequency support in the initial stage, but traditional right ventricular (RV) pacing may lead to or aggravate left ventricular dysfunction and arrhythmia. Several potential risk factors for heart failure and arrhythmias after pacemaker surgery have been identified, but their occurrence remains difficult to predict clinically. Compared with RV pacing, His bundle pacing (HBP) and left bundle branch pacing (LBBP) activate the intrinsic His-Purkinje conduction system and provide physiological activation, but whether HBP and LBBP also cause ventricular mechanical dyssynchrony remains uncertain. The implantation of cardiac resynchronization therapy and implantable cardioverter defibrillator depends on left ventricular ejection fraction (LVEF). LVEF This depends on volume changes and is less reproducible. Speckle tracking echocardiography (STE) is a technique that can accurately quantify the degree and duration of systolic deformation. STE detects changes in myocardial function more sensitively than traditional measures of diastolic and systolic function, including LVEF. Clinicians can evaluate myocardial strain and synchrony based on strain (percent change in segmental length from baseline) and strain rate (strain per unit time). This review and case series investigate the clinical use of speckle tracking echocardiography in pacemaker implantation.

Lead Management: Device Programming and Defibrillation Threshold Testing

Implantable cardioverter-defibrillators (ICDs) reduce sudden cardiac death (SCD) and improve survival in patients with a history of life-threatening arrhythmia or sudden cardiac arrest, and in select populations at high risk of SCD due to ventricular arrhythmias. However, patients with ICDs may receive inappropriate or unnecessary shocks, which have been associated with pro-arrhythmia, psychological sequelae, poor quality of life, and increased mortality. The benefits and risks of ICD therapy are therefore directly impacted on by physician operative and programming decisions. This article aims to provide a detailed review of transvenous ICD programming as guided by clinical trials.

Excellent Outcomes After First-Line Ablation in Post-MI Patients With Tolerated VT and LVEF >35

BACKGROUND

Post-myocardial infarction (MI) patients with ventricular tachycardia (VT) are considered at risk for VT recurrence and sudden cardiac death (SCD). Recent guidelines indicate that in selected patients catheter ablation should be considered instead of an implantable cardioverter-defibrillator (ICD).

OBJECTIVES

This study aimed to analyze outcomes of patients referred for VT ablation according to left ventricular ejection fraction (LVEF), tolerance of VT, and acute ablation outcome.

METHODS

Post-MI patients without prior ICD undergoing VT ablation at a single center between 2009 and 2022 were included. Patients who presented with tolerated VT and who had an LVEF >35% were offered catheter ablation as first-line therapy. ICD implantation was offered to all patients but was subject to shared decision according to clinical presentation, LVEF, and ablation outcome.

RESULTS

Eighty-six patients (mean age 69 ± 9 years, 84% male, mean LVEF 41 ± 9%) underwent VT ablation. In 66 patients, LVEF was >35%, of whom 51 had tolerated VT. Of these 51 patients, 37 (73%) were rendered noninducible. In 5 of 37 noninducible and in 11 of 14 inducible patients, an ICD was implanted. During a median follow-up of 40 months (Q1-Q3: 24-70 months), 10 of 86 patients had VT recurrence. The overall mortality was 27%, and 1 patient with ICD died suddenly. Among the 37 patients (none on antiarrhythmic drugs) with LVEF >35%, tolerated VT, and noninducibility, no SCD or VT recurrence occurred. Among the 14 patients with LVEF >35%, tolerated VT, and inducibility after ablation, no SCD occurred, but VT recurred in 29%.

CONCLUSIONS

Post-MI patients with LVEF >35%, tolerated VT, and noninducibility after ablation have an excellent prognosis. Deferring ICD implantation seems to be safe in these patients.

Efficiency of MVP ECG Risk Score for Prediction of Long-Term Atrial Fibrillation in Patients With ICD for Heart Failure With Reduced Ejection Fraction

BACKGROUND AND OBJECTIVES

The morphology-voltage-P-wave duration (MVP) electrocardiography (ECG) risk score is a newly defined scoring system that has recently been used for atrial fibrillation (AF) prediction. The aim of this study was to evaluate the ability of the MVP ECG risk score to predict AF in patients with an implantable cardioverter defibrillator (ICD) and heart failure with reduced ejection fraction in long-term follow-up.

METHODS

The study used a single-center, and retrospective design. The study included 328 patients who underwent ICD implantation in our hospital between January 2010 and April 2021, diagnosed with heart failure. The patients were divided into low, intermediate and high-risk categories according to the MVP ECG risk scores. The long-term development of atrial fibrillation was compared among these 3 groups.

RESULTS

The low-risk group included 191 patients, the intermediate-risk group 114 patients, and the high-risk group 23 patients. The long-term AF development rate was 12.0% in the low-risk group, 21.9% in the intermediate risk group, and 78.3% in the high-risk group. Patients in the high-risk group were found to have 5.2 times higher rates of long-term AF occurrence compared to low-risk group.

CONCLUSIONS

The MVP ECG risk score, which is an inexpensive, simple and easily accessible tool, was found to be a significant predictor of the development of AF in the long-term follow-up of patients with an ICD with heart failure with reduced ejection fraction. This risk score may be used to identify patients who require close follow-up for development and management of AF.

A Case of 25 Inappropriate Automatic Implantable Cardioverter Defibrillator Shocks and 22 Episodes of Antitachycardia Pacing

An implantable cardioverter defibrillator (ICD) can save lives from fatal tachyarrhythmias. In rare cases, these devices can fail or malfunction. We present a case of a patient that suffered from 25 inappropriate shocks and 22 episodes of antitachycardia pacing (ATP), secondary to a probable non-traumatic dual lead fracture. One episode of ATP induced an R-on-T phenomenon, causing monomorphic ventricular tachycardia in the patient. The inappropriately functioning ICD also required two magnets to be placed on the patient's chest in the emergency department to convert the device to an asynchronous mode. An unexpected case of this magnitude and in such a brief timeframe has not been reported in prior ICD studies.

Does Timing of Ventricular Tachycardia Ablation Affect Prognosis in Patients With an Implantable Cardioverter Defibrillator? Results From the Multicenter Randomized PARTITA Trial

BACKGROUND

Optimal timing for catheter ablation of ventricular tachycardia is an important unresolved issue. There are no randomized trials evaluating the benefit of ablation after the first implantable cardioverter defibrillator (ICD) shock.

METHODS

We conducted a 2-phase, prospective, multicenter, randomized clinical trial. Patients with ischemic or nonischemic dilated cardiomyopathy and primary or secondary prevention indication for ICD were enrolled in an initial observational phase until first appropriate shock (phase A). After reconsenting, patients were randomly assigned 1:1 in phase B to immediate ablation (within 2 months from shock delivery) or continuation of standard therapy. The primary end point was a composite of death from any cause or hospitalization for worsening heart failure. Amiodarone intake was not allowed except for documented atrial tachyarrhythmias. On July 23, 2021, phase B of the trial was interrupted as a result of the first interim analysis on the basis of the Bayesian adaptive design.

RESULTS

Of the 517 patients enrolled in phase A, 154 (30%) had ventricular tachycardia, 56 (11%) received an appropriate shock over a median follow-up of 2.4 years (interquartile range, 1.4-4.4), and 47 of 56 (84%) agreed to participate in phase B. After 24.2 (8.5-24.4) months, the primary end point occurred in 1 of 23 (4%) patients in the ablation group and 10 of 24 (42%) patients in the control group (hazard ratio, 0.11 [95% CI, 0.01-0.85]; P=0.034). The results met the prespecified termination criterion of >99% Bayesian posterior probability of superiority of treatment over standard therapy. No deaths were observed in the ablation group versus 8 deaths (33%) in the control group (P=0.004); there was 1 worsening heart failure hospitalization in the ablation group (4%) versus 4 in the control group (17%; P=0.159). ICD shocks were less frequent in the ablation group (9%) than in the control group (42%; P=0.039).

CONCLUSIONS

Ventricular tachycardia ablation after first appropriate shock was associated with a reduced risk of the combined death or worsening heart failure hospitalization end point, lower mortality, and fewer ICD shocks. These findings provide support for considering ventricular tachycardia ablation after the first ICD shock.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01547208.

Psychosocial symptoms of ventricular arrhythmias: Integrating patient-reported outcomes into clinical care

Patient-reported outcome measures (PROMs) are a valuable metric for assessing the quality of life and overall well-being in patients with ventricular arrhythmias (VAs) and/or implantable cardioverter-defibrillators (ICDs). The incorporation of PROMs into the workflow of a VA clinic not only allows for more patient-centered care but also may improve detection and treatment of clinically relevant anxiety or depression symptoms. Awareness of the factors known to correlate with adverse PROM scores may guide PROM administration and subsequent referral to mental health services. Further, change or stability in PROM scores can be used as a gauge to guide the effectiveness of cardiac and psychological treatment in certain populations that are the focus of this manuscript: patients with ICDs (with and without shocks), cardiac arrest survivors, and those with inherited arrhythmia syndromes.

CMR-Based Risk Stratification of Sudden Cardiac Death and Use of Implantable Cardioverter-Defibrillator in Non-Ischemic Cardiomyopathy

Non-ischemic cardiomyopathy (NICM) is one of the most important entities for arrhythmias and sudden cardiac death (SCD). Previous studies suggest a lower benefit of implantable cardioverter–defibrillator (ICD) therapy in patients with NICM as compared to ischemic cardiomyopathy (ICM). Nevertheless, current guidelines do not differentiate between the two subgroups in recommending ICD implantation. Hence, risk stratification is required to determine the subgroup of patients with NICM who will likely benefit from ICD therapy. Various predictors have been proposed, among others genetic mutations, left-ventricular ejection fraction (LVEF), left-ventricular end-diastolic volume (LVEDD), and T-wave alternans (TWA). In addition to these parameters, cardiovascular magnetic resonance imaging (CMR) has the potential to further improve risk stratification. CMR allows the comprehensive analysis of cardiac function and myocardial tissue composition. A range of CMR parameters have been associated with SCD. Applicable examples include late gadolinium enhancement (LGE), T1 relaxation times, and myocardial strain. This review evaluates the epidemiological aspects of SCD in NICM, the role of CMR for risk stratification, and resulting indications for ICD implantation.

Early ICD implantation in cardiac arrest survivors with acute coronary syndrome - predictors of implantation, ICD-therapy and long-term survival

Objectives. Implantable cardioverter defibrillator (ICD) implantation in patients resuscitated from out-of-hospital cardiac arrest (OHCA) due to acute myocardial infarction (AMI) is controversial. Design. Consecutive OHCA-survivors due to AMI from two Danish tertiary heart centers from 2007 to 2011 were included. Predictors of ICD-implantation, ICD-therapy and long-term survival (5 years) were investigated. Patients with and without ICD-implantation during the index hospital admission were included (later described as early ICD-implantation). Patients with an ICD after hospital discharge were censored from further analyses at time of implantation. Results. We identified 1,457 consecutive OHCA-patients, and 292 (20%) of the cohort met the inclusion criteria. An ICD was implanted during hospital admission in 78 patients (27%). STEMI and successful revascularization were inversely and independently associated with ICD-implantation (OR_STEMI = 0.37, 95% CI: 0.14-0.94, OR_revasc = 0.11, 0.03-0.36) whereas age, sex, LVEF <35%, comorbidity burden or shockable first OHCA-rhythm were not associated with ICD-implantation. Appropriate ICD-shock therapy during the follow-up period was noted in 15% of patients (n = 12). Five-year mortality-rate was significantly lower in ICD-patients (18% vs. 28%, p_logrank = 0.02), which was persistent after adjustment for prognostic factors (HR = 0.44 (95% CI: 0.23-0.88)). This association was no longer found when using first event (death or appropriate shock whatever came first) as outcome variable (p_logrank = 0.9). Conclusions. Mortality after OHCA due to AMI was significantly lower in patients with early ICD-implantation after adjustment for prognostic factors. When using appropriate shock and death as events, ICD-patients had similar outcome as patients without an ICD, which may suggest a survival benefit due to appropriate device therapy.

Surgical Techniques, Complications, and Long-Term Health Effects of Cardiac Implantable Electronic Devices

Cardiovascular implantable electronic device (CIED) has helped with advanced technological improvement in the cardiac field and has been a long-term alternative to medical management. There are different forms of CIEDs such as pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization therapy. These devices are efficient in establishing near-normal hemodynamics and circulation that ultimately aid physicians to improve the quality of life for their patients. However, there are risk factors that can result in postoperative complications, including infection, lead and pulse generator complications, heart complications, medication-related complications, and psychosocial complications. To ensure optimal outcome of CIED placement, preprocedural measures need to be in place such as matching the right candidate and using appropriate devices. This review aims to highlight the surgical techniques for CIEDs, the associated postoperative complications, and long-term health effects.

Risk and predictors of sudden death in cardiac sarcoidosis: A systematic review and meta-analysis

BACKGROUND

To evaluate the risk for ventricular arrhythmia (VA) and sudden cardiac death (SCD) in patients with cardiac sarcoidosis (CS) and determine the prognostic factors.

METHODS AND RESULTS

PUBMED, EMBASE and SCOPUS were searched up to 14th April 2020. Studies reporting the incidence of SCD, appropriate ICD therapy in CS patients, or relevant prognostic information in patients having undergone MRI, PET, or programmed electrical stimulation (PES) were included. Nineteen studies consisting of 1247 patients, reported the risk of ICD therapies or SCD over a follow-up period of 1.7-7 years. 22.7% (n = 9; 22.7, 95%CI [16.10-29.36]) of patients in primary and 58.4% (n = 9; 58.42, 95% CI [38.61-78.22]) in secondary prevention cohorts experienced appropriate device therapy or SCD events. 18% (n = 2; 18, 95%CI [14-23]) of patients received ≥5 appropriate therapies. 9 out of 664 patients with confirmed cardiac sarcoidosis but without implanted ICDs died suddenly. 17.9% of patients (n = 4; 17.9, 95%CI [10.80-25.03]) experienced inappropriate device therapy. Positive LGE-MRI and PES were associated with an 8.6-fold (n = 6; RR = 8.60, 95%CI [3.80-19.48]) and 9-fold (n = 5; RR = 9.07, 95%CI [4.65-17.68]) increased risk of VA respectively. Positive LGE-MRI and PET with associated with a 6.8-fold (n = 12; RR = 6.82, 95%CI [4.57-10.18]) and 3.4-fold (n = 7; RR = 3.41, 95%CI [2.03-5.74]) respectively for increased risk of major adverse cardiac events.

CONCLUSIONS

The risk of appropriate ICD therapy or sudden cardiac death is high in patients with CS. The presence of LGE-MRI and positive electrophysiology study identify patients at increased risk of ventricular arrhythmias. [CRD42019124220].

Feasibility and Efficacy of His Bundle Pacing or Left Bundle Pacing Combined With Atrioventricular Node Ablation in Patients With Persistent Atrial Fibrillation and Implantable Cardioverter-Defibrillator Therapy

Background

Persistent atrial fibrillation may lead to a higher probability of inappropriate shocks in heart failure patients with an implantable cardioverter‐defibrillator (ICD). The aim of this study was to evaluate the impact of His‐Purkinje conduction system pacing combined with atrioventricular node ablation in improving heart function and preventing inappropriate shock therapy in these patients.

Methods and Results

A total of 86 consecutive patients with persistent atrial fibrillation and heart failure who had indications for ICD implantation were enrolled from January 2010 to March 2018. His‐Purkinje conduction system pacing with ICD and atrioventricular node ablation was attempted in 55 patients, and the remaining patients underwent ICD implantation only. Left ventricular (LV) ejection fraction, LV end‐systolic volume, New York Heart Association (NYHA) classification, shock therapies, and drug therapy were assessed during follow‐up. Overall, 31 patients received ICD implantation with optimal drug therapy (group 1). atrioventricular node ablation combined with His‐Purkinje conduction system pacing was successfully achieved in 52 patients (group 2). During follow‐up, patients in group 2 had lower incidence of inappropriate shock (15.6% versus 0%, P<0.01) and adverse events (P=0.011). Meanwhile, improvement in LV ejection fraction and reduction in LV end‐systolic volume were significantly higher in group 2 than in group 1 (15% versus 3%, P<0.001; and 40 versus 2 mL, P<0.01, respectively). NYHA functional class improved in both groups from a baseline 2.57±0.68 to 1.73±0.74 in group 1 and 2.73±0.59 to 1.42±0.53 in group 2 (P<0.01).

Conclusions

His‐Purkinje conduction system pacing combined with atrioventricular node ablation is feasible and safe with a high success rate in persistent atrial fibrillation patients with heart failure and ICD indication. It can significantly reduce the incidence of inappropriate shocks and improve LV function.

Utilization of implantable cardioverter-defibrillators for the prevention of sudden cardiac death in emerging countries: Improve SCA clinical trial

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) are underutilized in Asia, Latin America, Eastern Europe, the Middle East, and Africa. The Improve SCA Study is the largest prospective study to evaluate the benefit of ICD therapy in underrepresented geographies. This analysis reports the primary objective of the study.

OBJECTIVES

The objectives of this study was to determine whether patients with primary prevention (PP) indications with specific risk factors (1.5PP: syncope, nonsustained ventricular tachycardia, premature ventricular contractions >10/h, and low ventricular ejection fraction <25%) are at a similar risk of life-threatening arrhythmias as patients with secondary prevention (SP) indications and to evaluate all-cause mortality rates in 1.5PP patients with and without devices.

METHODS

A total of 3889 patients were included in the analysis to evaluate ventricular tachycardia or fibrillation therapy and mortality rates. Patients were stratified as SP (n = 1193) and patients with PP indications. The PP cohort was divided into 1.5PP patients (n = 1913) and those without any 1.5PP criteria (n = 783). The decision to undergo ICD implantation was left to the patient and/or physician. The Cox proportional hazards model was used to compute hazard ratios.

RESULTS

Patients had predominantly nonischemic cardiomyopathy. The rate of ventricular tachycardia or fibrillation in 1.5PP patients was not equivalent (within 30%) to that in patients with SP indications (hazard ratio 0.47; 95% confidence interval 0.38-0.57) but was higher than that in PP patients without any 1.5PP criteria (hazard ratio 0.67; 95% confidence interval 0.46-0.97) (P = .03). There was a 49% relative risk reduction in all-cause mortality in ICD implanted 1.5PP patients. In addition, the number needed to treat to save 1 life over 3 years was 10.0 in the 1.5PP cohort vs 40.0 in PP patients without any 1.5PP criteria.

CONCLUSION

These data corroborate the mortality benefit of ICD therapy and support extension to a selected PP population from underrepresented geographies.

Driving with cardiac devices in Australia. Does a review of recent evidence prompt a change in guidelines?

Australian Driving Guidelines for patients with pacemakers and implanted cardioverter defibrillators are in line with many around the world, with some minor differences. Some aspects of these guidelines lack contemporary evidence in key decision-making areas and make broad recommendations regarding groups with heterogeneous populations. In addition, more recent studies suggest lower rates of adverse events in some patients with these devices than previously thought. Through a systematic literature review, along with discussion of current guidelines, we combine new evidence with well established risk assessment tools to ask the following questions: (i) Given the heterogeneity of patient risk within the defibrillator population, should guidelines allow for further individualisation of risk and subsequent licensing restrictions?; and (ii) Could some patients with primary prevention automated cardioverter defibrillators be able to hold a commercial driving licence?

Reduction in depressive symptoms in primary prevention ICD scheduled patients - One year prospective study

OBJECTIVE

Implantable Cardioverter Defibrillators (ICDs), have previously been associated with the onset of depression and anxiety. The aim of this one-year prospective study was to evaluate the rate of new onset psychopathological symptoms after elective ICD implantation.

METHODS

A total of 158 consecutive outpatients who were scheduled for an elective ICD implantation were diagnosed and screened based on the Mini International Neuropsychiatric Interview (MINI). Depression and anxiety were evaluated using the Hamilton Rating Scales for Depression (HAM-D) and Anxiety (HAM-A). Patient's attitude toward the ICD device was evaluated using a Visual Analog Scale (VAS).

RESULTS

Patients' mean age was 64±12.4years; 134 (85%) were men, with the majority of patients performing the procedure for reasons of 'primary prevention'. According to the MINI diagnosis at baseline, three (2%) patients suffered from major depressive disorder and ten (6%) from dysthymia. Significant improvement in HAM-D mean scores was found between baseline, three months and one year after implantation (6.50±6.4; 4.10±5.3 and 2.7±4.6, respectively F(2100)=16.42; p<0.001). There was a significantly more positive attitude toward the device over time based on the VAS score [F(2122)=53.31, p<0.001].

CONCLUSIONS

ICD implantation significantly contributes to the reduction of depressive symptoms, while the overall mindset toward the ICD device was positive and improved during the one-year follow-up.

Inappropriate implantable cardioverter defibrillator shocks-incidence, effect, and implications for driver licensing

Purpose

Patients with implantable cardioverter defibrillators (ICDs) have an ongoing risk of sudden incapacitation that may cause traffic accidents. However, there are limited data on the magnitude of this risk after inappropriate ICD therapies. We studied the rate of syncope associated with inappropriate ICD therapies to provide a scientific basis for formulating driving restrictions.

Methods

Inappropriate ICD therapy event data between 1997 and 2014 from 50 Japanese institutions were analyzed retrospectively. The annual risk of harm (RH) to others posed by a driver with an ICD was calculated for private driving habits. We used a commonly employed annual RH to others of 5 in 100,000 (0.005%) as an acceptable risk threshold.

Results

Of the 4089 patients, 772 inappropriate ICD therapies occurred in 417 patients (age 61 ± 15 years, 74% male, and 65% secondary prevention). Patients experiencing inappropriate therapies had a mean number of 1.8 ± 1.5 therapy episodes during a median follow-up period of 3.9 years. No significant differences were found in the age, sex, or number of inappropriate therapies between patients receiving ICDs for primary or secondary prevention. Only three patients (0.7%) experienced syncope associated with inappropriate therapies. The maximum annual RH to others after the first therapy in primary and secondary prevention patients was calculated to be 0.11 in 100,000 and 0.12 in 100,000, respectively.

Conclusions

We found that the annual RH from driving was far below the commonly cited acceptable risk threshold. Our data provide useful information to supplement current recommendations on driving restrictions in ICD patients with private driving habits.

Electronic supplementary material

The online version of this article (doi:10.1007/s10840-017-0272-4) contains supplementary material, which is available to authorized users.

Driving restrictions in patients with implantable cardioverter defibrillators and pacemakers

Implantable cardioverter-defibrillators (ICDs) improve the survival in patients at risk of sudden cardiac death. However, these patients have an ongoing risk of sudden incapacitation that may cause harm to individuals and others when driving. Considerable disagreement exists about whether and when these patients should be allowed to resume driving after ICD therapies. This information is critical for the management decisions to avoid future potentially lethal incidents and unnecessary restrictions for ICD patients. The cardiac implantable device committee of the Japanese Heart Rhythm Society reassessed the risk of driving for ICD patients based on the literature and domestic data. We reviewed the driving restrictions of ICD patients in various regions and here present updated Japanese driving restrictions.

Effectiveness of Implantable Cardioverter-Defibrillator Therapy for Heart Failure Patients according to Ischemic or Non-Ischemic Etiology in Korea

Background and Objectives

This study was performed to describe clinical characteristics of patients with left ventriculars (LV) dysfunction and implantable cardioverter-defibrillator (ICD), and to evaluate the effect of ICD therapy on survival in Yeongnam province of Korea.

Subjects and Methods

From a community-based device registry (9 centers, Yeongnam province, from November 1999 to September 2012), 146 patients with LV dysfunction and an ICD implanted for primary or secondary prophylaxis, were analyzed. The patients were divided into two groups, based on the etiology (73 with ischemic cardiomyopathy and 73 with non-ischemic cardiomyopathy), and indication for the device implantation (36 for primary prevention and 110 for secondary prevention). The cumulative first shock rate, all cause death, and type and mode of death, were determined according to the etiology and indication.

Results

Over a mean follow-up of 3.5 years, the overall ICD shock rate was about 39.0%. ICD shock therapy was significantly more frequent in the secondary prevention group (46.4% vs. 16.7%, p=0.002). The cumulative probability of a first appropriate shock was higher in the secondary prevention group (p=0.015). There was no significant difference in the all-cause death, cardiac death, and mode of death between the groups according to the etiology and indication.

Conclusion

Studies from this multicenter regional registry data shows that in both ischemic and non-ischemic cardiomyopathy patients, the ICD shock therapy rate was higher in the secondary prevention group than primary prevention group.

The Significance of Shocks in Implantable Cardioverter Defibrillator Recipients

Large-scale implantable cardioverter defibrillator (ICD) trials have unequivocally shown a reduction in mortality in appropriately selected patients with heart failure and depressed left ventricular function. However, there is a strong association between shocks and increased mortality in ICD recipients. It is unclear if shocks are merely a marker of a more severe cardiovascular disease or directly contribute to the increase in mortality. The aim of this review is to examine the relationship between ICD shocks and mortality, and explore possible mechanisms. Data examining the effect of shocks in the absence of spontaneous arrhythmias as well as studies of non-shock therapy and strategies to reduce shocks are analysed to try and disentangle the shocks versus substrate debate.

Experience With the Wearable Cardioverter-Defibrillator in Patients at High Risk for Sudden Cardiac Death

Supplemental Digital Content is available in the text.

Background:

This study evaluated the wearable cardioverter-defibrillator (WCD) for use and effectiveness in preventing sudden death caused by ventricular tachyarrhythmia or fibrillation.

Methods:

From April 2010 through October 2013, 6043 German WCD patients (median age, 57 years; male, 78.5%) were recruited from 404 German centers. Deidentified German patient data were used for a retrospective, nonrandomized analysis.

Results:

Ninety-four patients (1.6%) were treated by the WCD in response to ventricular tachyarrhythmia/fibrillation. The incidence rate was 8.4 (95% confidence interval, 6.8–10.2) per 100 patient-years. Patients with implantable cardioverter-defibrillator explantation had an incidence rate of 19.3 (95% confidence interval, 12.2–29.0) per 100 patient-years. In contrast, an incidence rate of 8.2 (95% confidence interval, 6.4–10.3) was observed in the remaining cardiac diagnosis groups, including dilated cardiomyopathy, myocarditis, and ischemic and nonischemic cardiomyopathies. Among 120 shocked patients, 112 (93%) survived 24 hours after treatment, whereas asystole was observed in 2 patients (0.03%) with 1 resulting death.

ConclusionS:

This large cohort represents the first nationwide evaluation of WCD use in patients outside the US healthcare system and confirms the overall value of the WCD in German treatment pathways.

Changes in Implantation Patterns and Therapy Rates of Implantable Cardioverter Defibrillators over Time in Ischemic and Dilated Cardiomyopathy Patients

BACKGROUND

Clinical guidelines on implantable cardioverter defibrillator (ICD) therapy changed significantly in the last decades with potential inherent effects on therapy efficacy. We aimed to study therapy rates in time and the association between therapies and mortality.

METHODS

All patients receiving an ICD, primary and secondary prevention, were included in a single-center retrospective registry. Information on first appropriate and inappropriate therapies was documented. Dates of implant were divided in P1: 1996-2001, P2: 2002-2008, and P3: 2009-2014.

RESULTS

A total of 727 patients, 84.9% male-66.4% ischemic cardiomyopathy (ICM)-56% primary prevention-mean follow-up 5.2 ± 4.1 years, were included. There was a shift from secondary to primary prevention indications, from ischemic to non-ICM, and from single chamber to cardiac resynchronization therapy defibrillator devices. The annual 1- and 3-year appropriate shock (AS) rate declined from 29.4% and 15.1% in P1, over 13.3% and 9.2% in P2 to 7.8% and 5.7% in P3 (log-rank P < 0.001), while inappropriate shock (IAS) rates remained unchanged (log-rank P = 0.635). After multivariate regression analysis a higher age at implant, lower left ventricular ejection fraction, history of stroke, diabetes mellitus, intake of loop diuretics or digitalis, higher creatinine, and longer QTc were independent predictors of mortality.

CONCLUSION

These changes in clinical practice with a shift to primary prevention and rise in non-ICM implants caused a significant decrease in AS incidence, while IAS remained stable. Receiving AS or IAS was not an independent predictor of mortality in our real-life cohort.

Tachyarrhythmia Cycle Length in Appropriate versus Inappropriate Defibrillator Shocks in Brugada Syndrome, Early Repolarization Syndrome, or Idiopathic Ventricular Fibrillation

Background and Objectives

Implantable cardioverter–defibrillators (ICDs) are indicated in patients with Brugada syndrome (BS), early repolarization syndrome (ERS), or idiopathic ventricular fibrillation (IVF) who are at high risk for sudden cardiac death. The optimal ICD programming for reducing inappropriate shocks in these patients remains to be determined. We investigated the difference in the mean cycle length of tachyarrhythmias that activated either appropriate or inappropriate ICD shocks in these three patient groups to determine the optimal ventricular fibrillation (VF) zone for minimizing inappropriate ICD shocks.

Subjects and Methods

We selected 41 patients (35 men) (mean age±standard deviation=42.6±13.0 year) who received ICD shocks between April 1996 and April 2014 to treat BS (n=24), ERS (n=9), or IVF (n=8). Clinical and ICD interrogation data were retrospectively collected and analyzed for all events with ICD shocks.

Results

Of the 244 episodes, 180 (73.8%) shocks were appropriate and 64 (26.2%) were inappropriate. The mean cycle lengths of the tachyarrhythmias that activated appropriate and inappropriate shocks were 178.9±28.7 ms and 284.8±24.4 ms, respectively (p<0.001). The cutoff value with the highest sensitivity and specificity for discriminating between appropriate and inappropriate shocks was 235 ms (sensitivity, 98.4%; specificity, 95.6%). When we programmed a single VF zone of ≤270 ms, inappropriate ICD shocks were reduced by 70.5% and appropriate shocks were missed in 1.7% of these patients.

Conclusion

Programming of a single VF zone of ≤270 ms in patients with BS, ERS, or IVF could reduce inappropriate ICD shocks, with a low risk of missing appropriate shocks.

ED evaluation and management of implantable cardiac defibrillator electrical shocks

Patients with implantable cardiac defibrillators not infrequently present to the emergency department after experiencing an implantable cardiac defibrillator shock. This review considers the management of such patients in the emergency department, including appropriate, inappropriate, and phantom shocks as well as electrical storm.

Low rate of and rapid attention to inappropriate ICD shocks with remote device and rhythm monitoring: a qualitative study

Objectives

Inappropriate shocks are unpleasant and painful. We hypothesise that remote monitoring and careful attention to known and incident atrial fibrillation (AF) can reduce inappropriate shocks to a very low level in clinical praxis.

Methods

Altogether 259 patients with implantable cardioverter defibrillator implanted for secondary (S, n=113) and primary (P, n=146) prevention were followed via remote monitoring. At implant, 42S (37%) and 54P (37%) patients had known AF.

Results

Inappropriate shocks, all but five due to AF, occurred in 7S (6.2%) and 11P (7.5%), and there were only inappropriate shocks in 5/7S and in 8/11P. They occurred in four of 42S (9.5%) with and in three of 71S (4.2%) without known AF, and in seven of 54P (13%) with and in four of 92P (4.3%) without known AF. The median time from shock to action was 5 and 1 day, respectively. Actions were medication with amiodarone, β blockers, β blockers+amiodarone or β blockers+digoxin (n=5), β blockers+insertion of an atrial lead (n=1), replacement of a fractured lead (n=2), reprogramming in combination with β blockers, digoxin or amiodarone (n=4), reprogramming (n=2) and none (n=4). After action, four further inappropriate shocks occurred during more than 2 years of follow-up, all due to AF.

Conclusions

Inappropriate shocks occurred at a low rate and most often because of AF known at implant. Remote monitoring enabled rapid action, after which few inappropriate shocks occurred over more than 2 years. Attention to known and incident AF was the most important action to reduce inappropriate shocks.

Implantable cardioverter defibrillators for the treatment of arrhythmias and cardiac resynchronisation therapy for the treatment of heart failure: systematic review and economic evaluation

BACKGROUND

This assessment updates and expands on two previous technology assessments that evaluated implantable cardioverter defibrillators (ICDs) for arrhythmias and cardiac resynchronisation therapy (CRT) for heart failure (HF).

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of ICDs in addition to optimal pharmacological therapy (OPT) for people at increased risk of sudden cardiac death (SCD) as a result of ventricular arrhythmias despite receiving OPT; to assess CRT with or without a defibrillator (CRT-D or CRT-P) in addition to OPT for people with HF as a result of left ventricular systolic dysfunction (LVSD) and cardiac dyssynchrony despite receiving OPT; and to assess CRT-D in addition to OPT for people with both conditions.

DATA SOURCES

Electronic resources including MEDLINE, EMBASE and The Cochrane Library were searched from inception to November 2012. Additional studies were sought from reference lists, clinical experts and manufacturers' submissions to the National Institute for Health and Care Excellence.

REVIEW METHODS

Inclusion criteria were applied by two reviewers independently. Data extraction and quality assessment were undertaken by one reviewer and checked by a second. Data were synthesised through narrative review and meta-analyses. For the three populations above, randomised controlled trials (RCTs) comparing (1) ICD with standard therapy, (2) CRT-P or CRT-D with each other or with OPT and (3) CRT-D with OPT, CRT-P or ICD were eligible. Outcomes included mortality, adverse events and quality of life. A previously developed Markov model was adapted to estimate the cost-effectiveness of OPT, ICDs, CRT-P and CRT-D in the three populations by simulating disease progression calculated at 4-weekly cycles over a lifetime horizon.

RESULTS

A total of 4556 references were identified, of which 26 RCTs were included in the review: 13 compared ICD with medical therapy, four compared CRT-P/CRT-D with OPT and nine compared CRT-D with ICD. ICDs reduced all-cause mortality in people at increased risk of SCD, defined in trials as those with previous ventricular arrhythmias/cardiac arrest, myocardial infarction (MI) > 3 weeks previously, non-ischaemic cardiomyopathy (depending on data included) or ischaemic/non-ischaemic HF and left ventricular ejection fraction ≤ 35%. There was no benefit in people scheduled for coronary artery bypass graft. A reduction in SCD but not all-cause mortality was found in people with recent MI. Incremental cost-effectiveness ratios (ICERs) ranged from £14,231 per quality-adjusted life-year (QALY) to £29,756 per QALY for the scenarios modelled. CRT-P and CRT-D reduced mortality and HF hospitalisations, and improved other outcomes, in people with HF as a result of LVSD and cardiac dyssynchrony when compared with OPT. The rate of SCD was lower with CRT-D than with CRT-P but other outcomes were similar. CRT-P and CRT-D compared with OPT produced ICERs of £27,584 per QALY and £27,899 per QALY respectively. The ICER for CRT-D compared with CRT-P was £28,420 per QALY. In people with both conditions, CRT-D reduced the risk of all-cause mortality and HF hospitalisation, and improved other outcomes, compared with ICDs. Complications were more common with CRT-D. Initial management with OPT alone was most cost-effective (ICER £2824 per QALY compared with ICD) when health-related quality of life was kept constant over time. Costs and QALYs for CRT-D and CRT-P were similar. The ICER for CRT-D compared with ICD was £27,195 per QALY and that for CRT-D compared with OPT was £35,193 per QALY.

LIMITATIONS

Limitations of the model include the structural assumptions made about disease progression and treatment provision, the extrapolation of trial survival estimates over time and the assumptions made around parameter values when evidence was not available for specific patient groups.

CONCLUSIONS

In people at risk of SCD as a result of ventricular arrhythmias and in those with HF as a result of LVSD and cardiac dyssynchrony, the interventions modelled produced ICERs of < £30,000 per QALY gained. In people with both conditions, the ICER for CRT-D compared with ICD, but not CRT-D compared with OPT, was < £30,000 per QALY, and the costs and QALYs for CRT-D and CRT-P were similar. A RCT comparing CRT-D and CRT-P in people with HF as a result of LVSD and cardiac dyssynchrony is required, for both those with and those without an ICD indication. A RCT is also needed into the benefits of ICD in non-ischaemic cardiomyopathy in the absence of dyssynchrony.

STUDY REGISTRATION

This study is registered as PROSPERO number CRD42012002062.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Late gadolinium enhancement among survivors of sudden cardiac arrest

OBJECTIVES

The aim of this study was to describe the role of contrast-enhanced cardiac magnetic resonance (CMR) in the workup of patients with aborted sudden cardiac arrest (SCA) and in the prediction of long-term outcomes.

BACKGROUND

Myocardial fibrosis is a key substrate for SCA, and late gadolinium enhancement (LGE) on a CMR study is a robust technique for imaging of myocardial fibrosis.

METHODS

We performed a retrospective review of all survivors of SCA who were referred for CMR studies and performed follow-up for the subsequent occurrence of an adverse event (death and appropriate defibrillator therapy).

RESULTS

After a workup that included a clinical history, electrocardiogram, echocardiography, and coronary angiogram, 137 patients underwent CMR for workup of aborted SCA (66% male; mean age 56 ± 11 years; left ventricular ejection fraction 43 ± 12%). The presenting arrhythmias were ventricular fibrillation (n = 105 [77%]) and ventricular tachycardia (n = 32 [23%]). Overall, LGE was found in 98 patients (71%), with an average extent of 9.9 ± 5% of the left ventricular myocardium. CMR imaging provided a diagnosis or an arrhythmic substrate in 104 patients (76%), including the presence of an infarct-pattern LGE in 60 patients (44%), noninfarct LGE in 21 (15%), active myocarditis in 14 (10%), hypertrophic cardiomyopathy in 3 (2%), sarcoidosis in 3, and arrhythmogenic cardiomyopathy in 3. In a median follow-up of 29 months (range 18 to 43 months), there were 63 events. In a multivariable analysis, the strongest predictors of recurrent events were the presence of LGE (adjusted hazard ratio: 6.7; 95% CI: 2.38 to 18.85; p < 0.001) and the extent of LGE (hazard ratio: 1.15; 95% CI: 1.11 to 1.19; p < 0.001).

CONCLUSIONS

Among patients with SCA, CMR with contrast identified LGE in 71% and provided a potential arrhythmic substrate in 76%. In follow-up, both the presence and extent of LGE identified a group at markedly increased risk of future adverse events.

ICD programming to reduce shocks and improve outcomes

Despite the clinical benefit of implantable cardioverter defibrillator (ICD), there is a high frequency of inappropriate ICD therapy associated with impaired quality of life, unwanted health care resource utilization, and adverse clinical outcome. Alternative strategies of ICD programming are needed to reduce the risk of inappropriate and "unnecessary" ICD therapies and to improve patient outcome. In this review, we provide an overview of the rate of inappropriate and appropriate ICD therapies in clinical trials and large registries as well as a review of current trials evaluating novel ICD programming to reduce inappropriate ICD therapy to avoid unnecessary ICD therapy. Based on recent studies including a large randomized trial, we recommend a simple programming approach involving high-rate device therapy beginning at 200 bpm with a 2.5 sec delay for it reduces inappropriate therapy, unnecessary therapy, and all-cause mortality in patients receiving ICD or CRT-D devices for primary prevention indications.

State of the art of ICD programming: Lessons learned and future directions

The lifesaving benefits of implantable cardioverter defibrillator (ICD) therapy are more and more weighted against possible harm (e.g. unnecessary device therapy, procedural complications, device malfunction etc.) which might have adverse effects on patients' perceived health status and quality of life. Hence, there has been an increasing interest in the optimisation of ICD programming to prevent inappropriate and appropriate but unnecessary device therapy. The purpose of the current report is to give an overview of research into the optimisation of ICD programming and present the design of the on-going ENHANCED-ICD study. The ENHANCED-ICD study is a prospective, safety monitoring study enrolling 60 primary and secondary prophylactic ICD patients at the University Medical Center Utrecht. Patients implanted with any type of ICD with SmartShock technology(TM), and between 18-80 years of age, were eligible to participate. In all patients a prolonged detection of 60/80 intervals was programmed. The primary objective of the study is to investigate whether enhanced programming to further reduce ICD therapies is safe. The secondary objective is to examine the impact of enhanced programming on (i) antitachycardia pacing and shocks (both appropriate and inappropriate) and (ii) quality of life and distress. The first results of the ENHANCED-ICD study are expected in 2015.

Adjuvant antiarrhythmic therapy in patients with implantable cardioverter defibrillators

The risk of sudden cardiac death from ventricular fibrillation or ventricular tachycardia in patients with cardiomyopathy related to structural heart disease has been favorably impacted by the wide adaptation of implantable cardioverter defibrillators (ICDs) for both primary and secondary prevention. Unfortunately, after ICD implantation both appropriate and inappropriate ICD therapies are common. ICD shocks in particular can have significant effects on quality of life and disease-related morbidity and mortality. While not indicated for primary prevention of ICD therapies, beta-blockers and antiarrhythmic drugs are a cornerstone for secondary prevention of them. This review will summarize our current understanding of adjuvant antiarrhythmic drug therapy in ICD patients. The review will also discuss the roles of nonantiarrhythmic drug approaches that are used in isolation and in combination with antiarrhythmic drugs to reduce subsequent risk of ICD shocks.

ICD programming

BACKGROUND

Appropriate ICD programming is the key to prevent inappropriate shock delivery, that is closely associated to a negative patients' outcome.

METHODS

Review of the literature on ICD therapy to generate ICD programmings that can be applied to the broad population of ICD and CRT-D carriers.

RESULTS

Arrhythmia detection should occur with a detection time ranging 9″-12″ in the VF zone, and 15″-60″ in the VT zone. Discriminator should be applied at least up to 200 bpm. ATP therapy is applied to all VTs up to 250 bpm, with a success rate of 70%. Inappropriate shocks should occur in <3.6% of patients.

CONCLUSION

Tailored ICD programming can be achieved following evidence from large ICD trials. Pre-defined settings that are saved on the programmer and that can be uploaded at device implantation help to ensure optimal programming and to avoid random errors.

Survival after implantable cardioverter-defibrillator implantation in the elderly

BACKGROUND

The benefit of implantable cardioverter-defibrillators (ICDs) among elderly patients is controversial and may be attenuated by nonarrhythmic death. We examined the impact of age on device-delivered therapies and outcomes after primary or secondary prevention ICD.

METHODS AND RESULTS

In a prospective, inclusive registry of 5399 ICD recipients in Ontario, Canada (February 2007 to September 2010), device-delivered therapies and complications were determined at routine clinic visits. Among primary prevention ICD recipients aged 18 to 49 (n=317), 50 to 59 (n=769), 60 to 69 (n=1336), 70 to 79 (n=1242), and ≥80 (n=275) years, mortality increased with age, as follows: 2.1, 3.0, 5.4, 6.9, and 10.2 deaths per 100 person-years, respectively (P<0.001). Secondary prevention ICD recipients aged 18 to 49 (n=114), 50 to 59 (n=244), 60 to 69 (n=481), 70 to 79 (n=462), and ≥80 (n=159) years also exhibited increasing mortality, as follows: 2.2, 3.8, 6.1, 8.7, and 15.5 deaths per 100 person-years, respectively (P<0.001). However, rates of appropriate shock were similar across age groups: from 6.7 (18-49 years) to 4.2 (≥80 years) per 100 person-years after primary prevention ICDs (P=0.139) and from 11.4 (18-49 years) to 11.9 (≥80 years) per 100 person-years after secondary prevention ICDs (P=0.993). Covariate-adjusted competing risk analysis demonstrated higher risk of death (Ptrend<0.001 for both primary and secondary prevention) but no significant decline in appropriate shocks with older age after primary (P=0.130) or secondary (P=0.810) prevention ICD implantation.

CONCLUSIONS

Whereas elderly patients exhibited increased mortality after ICD implantation, rates of appropriate device shocks were similar across age groups. Decisions regarding ICD candidacy should not be based on age alone but should consider factors that predispose to mortality despite defibrillator implantation.

Protection from outpatient sudden cardiac death following ICD removal using a wearable cardioverter defibrillator

BACKGROUND

An implantable cardioverter defibrillator (ICD) is effective in preventing sudden cardiac death (SCD). Once an ICD is removed and reimplantation is not feasible, a wearable cardioverter defibrillator (WCD) may be an alternative option. We determined the effectiveness of WCD for SCD prevention in patients who were discharged after ICD removal.

METHODS

A retrospective study was conducted on all WCD (LifeVest, ZOLL, Pittsburgh, PA, USA) patients who underwent ICD removal due to cardiac device infections (CDIs) at two referral centers between January 1, 2005 and December 31, 2009. Clinical characteristics, device information, and WCD data were analyzed. Sudden cardiac arrest was defined as all sustained ventricular tachycardia (VT) and ventricular fibrillation occurring within a single 24-hour period.

RESULTS

Ninety-seven patients (mean age 62.8 ± 13.3, male 80.4%) were included in the study. The median duration of antibiotic use was 14.7 days (interquartile range [IQR] 10-30). The median daily WCD use was 20 hours/day and the median length of use was 21 days (IQR 5-47). A total of three patients were shocked by WCD. Two patients had four episodes of sustained VT, successfully terminated by the WCD. A third patient experienced two inappropriate treatments due to oversensitivity of the signal artifact. Three patients experienced sudden death outside the hospital while not wearing the device. Five patients died while hospitalized.

CONCLUSION

WCD can prevent SCD, until ICD reimplantation is feasible in patients who underwent device removals for CDI. However, patient compliance is essential for the effective use of this device.

Sudden cardiac arrest in hemodialysis patients with wearable cardioverter defibrillator

Background

The survival outcome following a sudden cardiac arrest (SCA) in hemodialysis (HD) patients is poor regardless of whether an event takes place in or out of a dialysis center. The characteristics of SCA and post‐SCA survival with HD patients using a wearable cardioverter defibrillator (WCD) are unknown.

Methods

All HD patients who were prescribed a WCD between 2004 and 2011 and experienced at least one SCA event were included in this study. Demographics, clinical background, characteristics of SCA events were identified from the manufacturer's database. An SCA event was defined as all sustained ventricular tachycardia/fibrillation (VT/VF) or asystole occurring within 24 hours of the index arrhythmia episode. The social security death index was used to determine mortality after WCD use.

Results

A total of 75 HD patients (mean age = 62.9 ± 11.7 years, female = 37.3%) experienced 84 SCA events (119 arrhythmia episodes) while wearing the WCD. Sixty six (78.6%) SCA events were due to VT/VF and 18 (21.4%) were due to asystole. Most SCA episodes occurred between 09:00 and 10:00 (RR = 2.82, 95% CI [1.05, 7.62], P < 0.0001), followed by the 13:00–14:00 time interval (RR = 2.22, 95% CI [0.79, 6.21], P = 0.006). Acute 24‐hour survival was 70.7% for all SCA events; 30‐day and 1‐year survival were 50.7% and 31.4%, respectively. Women had a better post‐SCA survival than men (HR = 2.41, 95% CI [1.09, 5.36], P = 0.03).

Conclusions

The use of WCD in HD patients was associated with improved post‐SCA survival when compared to historical data.