Clinical efficacy of a wearable defibrillator in acutely terminating episodes of ventricular fibrillation using biphasic shocks

First human safety and effectiveness study of defibrillation with a novel patch wearable cardioverter-defibrillator

AIMS

Wearable cardioverter-defibrillators (WCDs) are indicated in patients at risk of sudden cardiac arrest who are not immediate candidates for implantable defibrillator therapy. Limitations of existing WCDs include poor compliance and high false alarm rates. The Jewel is a novel patch-WCD (P-WCD) that addresses these limitations with an adhesive-based design for near-continuous wear and a machine learning algorithm designed to minimize inappropriate detections. This was a first-in-human study of the Jewel P-WCD conducted in an electrophysiology (EP) lab to determine the safety and effectiveness of the device in terminating ventricular tachycardia/ventricular fibrillation (VT/VF) with a single shock. The aim was to evaluate the safety and effectiveness of terminating VT/VF with a single shock using the Jewel P-WCD.

METHODS AND RESULTS

This was a first-in-human, prospective, single-arm, single-centre study in patients scheduled for an EP procedure in which VT/VF was expected to either spontaneously occur or be induced. The Jewel P-WCD was placed on consented patients; upon confirmation of VT/VF, a single shock (150 J) was delivered via the device. A group sequential design and Pocock alpha spending function was used to measure the observed proportion of successful VT/VF single-shock terminations. The endpoint was achieved if the lower confidence limit exceeded the performance goal of 62%, using a one-sided lower 97.4% exact confidence bound. Of 18 eligible subjects, 16 (88.9%, 97.4% confidence bound: 65.4%) were successfully defibrillated with a single shock, exceeding the primary endpoint performance goal with no adverse events.

CONCLUSION

This first-in-human evaluation of the Jewel P-WCD demonstrated the safety and effectiveness of terminating VT/VF.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov/; Unique identifier: NCT05490459.

[History of the implantable cardioverter-defibrillator in Germany]

The implantable cardioverter-defibrillator (ICD) was a breakthrough in the prevention of sudden cardiac death. After years of technical development in the USA, Michel Mirowski succeeded in proving reliable automatic defibrillation of ventricular tachyarrhythmias through initial human implantations in 1980, despite many obstacles. Nearly 4 years later, the first patients received ICDs at multiple centers in Germany. Subsequently, outside the USA, Germany became the country with highest implantation rates. The absolute number of implantations remained small as long as implantations required epicardial defibrillation electrodes and therefore thoracotomy by cardiac surgeons. Pacemaker-like implantation using a transvenous defibrillation electrode with a pectoral ICD became feasible in the early 1990s pushing implantation rates to the next level. Technical advancements were accompanied by clinical research in Germany, and often, the first-in-human studies were conducted in Germany. In 1991, the first guidelines for indications were established in the USA and Germany. Several randomized studies on indications were published between 1996 and 2009, mostly led by American teams with German participation, but also under German leadership (CASH, CAT, DINAMIT, IRIS). The DANISH study in 2016 questioned the results of these long-standing studies. Instead of providing ICDs to patients using a broad indication, future efforts aim to identify patients who, despite optimal medical therapy, cardiac resynchronization therapy (CRT), and/or catheter ablation, need protection against sudden cardiac death. Risk scores incorporating myocardial scars in magnetic resonance imaging (MRI) and genetic information are expected to contribute to more individualized and effective indications.

ANMCO position paper: guide to the appropriate use of the wearable cardioverter defibrillator in clinical practice for patients at high transient risk of sudden cardiac death

Extended risk stratification and optimal management of patients with a permanently increased risk of sudden cardiac death (SCD) are becoming increasingly important. There are several clinical conditions where the risk of arrhythmic death is present albeit only transient. As an example, patients with depressed left ventricular function have a high risk of SCD that may be only transient if there will be a significant recovery of function. It is important to protect the patients while receiving and titrating to the optimal dose the recommended drugs that may lead to an improved left ventricular function. In several other conditions, a transient risk of SCD can be observed even if the left ventricular function is not compromised. Examples are patients with acute myocarditis, during the diagnostic work-up of some arrhythmic conditions or after extraction of infected catheters while eradicating the associated infection. In all these conditions, it is important to offer a protection to these patients. The wearable cardioverter defibrillator (WCD) is of particular importance as a temporary non-invasive technology for both arrhythmia monitoring and therapy in patients with increased risk of SCD. Previous studies have shown the WCD to be an effective and safe therapy for the prevention of SCD caused by ventricular tachycardia/fibrillation. The aim of this ANMCO position paper is to provide a recommendation for clinical utilization of the WCD in Italy, based upon current data and international guidelines. In this document, we will review the WCD functionality, indications, clinical evidence, and guideline recommendations. Finally, a recommendation for the utilization of the WCD in routine clinical practice will be presented, in order to provide physicians with a practical guidance for SCD risk stratification in patients who may benefit from this device.

Defibrillation effectiveness and safety of the shock waveform used in a contemporary wearable cardioverter defibrillator: Results from animal and human studies

INTRODUCTION

The wearable cardioverter defibrillator (WCD) is used to protect patients at risk for sudden cardiac arrest. We examined defibrillation efficacy and safety of a biphasic truncated exponential waveform designed for use in a contemporary WCD in three animal studies and a human study.

METHODS

Animal (swine) studies: #1: Efficacy comparison of a 170J BTE waveform (SHOCK A) to a 150J BTE waveform (SHOCK B) that approximates another commercially available waveform. Primary endpoint first shock success rate. #2: Efficacy comparison of the two waveforms at attenuated charge voltages in swine at three prespecified impedances. Primary endpoint first shock success rate. #3: Safety comparison of SHOCK A and SHOCK B in swine. Primary endpoint cardiac biomarker level changes baseline to 6 and 24 hours post-shock. Human Study: Efficacy comparison of SHOCK A to prespecified goal and safety evaluation. Primary endpoint cumulative first and second shock success rate. Safety endpoint adverse events.

RESULTS

Animal Studies #1: 120 VF episodes in six swine. First shock success rates for SHOCK A and SHOCK B were 100%; SHOCK A non-inferior to SHOCK B (entire 95% CI of rate difference above -10% margin, p < .001). #2: 2,160 VF episodes in thirty-six swine. Attenuated SHOCK A was non-inferior to attenuated SHOCK B at each impedance (entire 95% CI of rate difference above -10% margin, p < .001). #3: Ten swine, five shocked five times each with SHOCK A, five shocked five times each with SHOCK B. No significant difference in troponin I (p = 0.658) or creatine phosphokinase (p = 0.855) changes from baseline between SHOCK A and SHOCK B. Human Study: Thirteen patients, 100% VF conversion rate. Mild skin irritation from adhesive defibrillation pads in three patients.

CONCLUSIONS

The BTE waveform effectively and safely terminated induced VF in swine and a small sample in humans.

TRIAL REGISTRATION

Human study clinical trial registration: URL: https://clinicaltrials.gov; Unique identifier: NCT04132466.

Wearable cardioverter-defibrillator (life-vest): A feasible bridging treatment in adult congenital heart disease

BACKGROUND

Wearable cardioverter-defibrillators (WCDs) are currently used in patients at temporarily heightened risk for sudden cardiac death (SCD) who are temporarily unable to receive an implantable cardioverter-defibrillator (ICD). WCD can safely record and terminate life-threatening arrhythmias through a non-invasive electrode-based system. The current clinical indications for WCD use are varied and keep evolving as experience with this technology increases.

METHODS

We reviewed and explored the data behind indications for WCD use and discuss its usefulness in congenital heart disease (CHD) patients.

RESULTS

We considered 8 consecutive patients (mean age 35.25 years, range 18-51 years, average duration of WCD use 4 months, range 3-6 months) with complex CHD, in which a WCD was used between June 2018 and January 2022. No sustained ventricular arrhythmias requiring shocks were recorded in the observation period. No inappropriate shocks were recorded. All the patients showed a good compliance and a very high mean wear time per day (21.2 ± 1 h a day). Four patients implanted a permanent device (3 CRT-D, 1 ICD), three underwent cardiac surgery at the end of the WCD period and one is still on the waiting list for the operation.

CONCLUSIONS

Larger trial could confirm the possible conceivable benefit from an extended use of the WCD in certain populations with complex CHD as in our case series, especially in patients with life-treating ventricular arrhythmias waiting for surgery for residual cardiac defects or in the early phases following the surgical/hemodynamic interventions, patients with tachycardiomyopathy expected to improve after the arrhythmias are removed and patients awaiting implantation of an ICD at high risk due to active infection.

Management of patients explanted for implantable cardioverter defibrillator infections: Bridge therapy with external temporary ICD

AIMS AND METHODS

In case of cardiacimplantable electronicdevice (CIED)-related infections, it is mandatory to completely remove the device and administer prolonged antibiotic therapy. The management of patients explanted for an implantable defibrillator (ICD) infection is complex especially in patients needing anti-bradycardia pacing or tachyarrhythmia protection. We tested the efficacy and safety of a conventional ICD externally connected to a transvenous dual-coil lead as bridging therapy before the reimplant, comparing outcomes with a historical cohort of patients (N = 113) treated with temporary transvenous pacing. We enrolled 18 patients explanted for ICD infection and needing prolonged antibiotic therapy in three high-volume Italian centers. They received an external ICD stand-by for a mean of 16.5 (4-30) days before the reimplant.

RESULTS

No patient experienced malfunction of the system, with a significant reduction of this complication versus temporary transfemoral pacing (37%, p = .004). Post-procedural occurrence of other complications (infection, relevant local bleeding, ventricular tachycardia during insertion of the lead, cardiac perforation, and venous thromboembolism) was low and not different in the two groups. One patient experienced an electrical storm, effectively recognized by the external ICD and treated with anti-tachycardia pacings (ATPs) and shocks.

CONCLUSIONS

An approach with an external ICD seems to be a safe and viable option as bridging therapy in patients requiring ICD explant for CIED infection.

Keeping up to date: a current review of wearable cardioverter defibrillator use

The introduction of wearable cardioverter defibrillators (WCD) provides a novel means of protection in select patients at high risk for sudden cardiac death. The WCD can safely record and terminate life-threatening arrhythmias. In this review, we explore the data behind indications for WCD use and discuss its limitations. We searched PubMed, Google Scholar and Cochrane Central Register of controlled trials for relevant studies. The VEST trial, the first randomised controlled trial on WCD use, did not show statistical significance in utility of the WCD in post-myocardial infarction patients with low ejection fraction. While the use of WCD in this select patient population showed no benefit, the findings of the trial merit closer inspection. Various other indications of WCD use still exist and others require exploration. Select subsets of patients who stand to benefit for other indications include severely decreased left ventricular function post-revascularization with high arrhythmic burden, severe non-ischaemic cardiomyopathy, patients awaiting heart transplant and patients who have had their implantable cardioverter device temporarily removed. The role of the WCD is also being explored in children, peripartum cardiomyopathy, haemodialysis patients, and in syncope secondary to high-risk arrhythmias.

Influence of decompensated heart failure on cardiac acoustic biomarkers: impact on early readmissions

Aims

Preventing hospitalization by detecting early evidence of heart failure (HF) decompensation in an outpatient setting can improve patient's quality of life and reduce costs of care. The purpose of this study was to assess the value of cardiac acoustic biomarkers (CABs), a combination of cardiohaemic vibrations synchronized with ECG signals, and heart rate (HR) for detecting HF decompensation during first 3 months after hospital discharge for HF.

Methods and results

Patients with an ejection fraction ≤35% (HFrEF) and hospitalized for decompensated HF were enrolled in a prospective observational study. All subjects wore a wearable cardioverter‐defibrillator (ZOLL LifeVest^®, Pittsburgh, PA, USA) that is capable of recording CABs and HR. The primary endpoint of the study was the first HF event, defined as HF readmission or HF emergency room visit. From June 2017 through August 2019, 671 patients with HFrEF were enrolled. Eighty‐one patients (12.1%) had a total of 112 HF events. The algorithm detected HF events with a median of 32 days (interquartile range = 11‐45) in advance of the first HF event. The algorithm had a sensitivity of 69%, specificity of 60%, positive predictive value of 19%, and a negative predictive value of 94%. Of note, the baseline (first 7 days post‐enrolment) algorithm using CABs and HR was superior to New York Heart Association classification in detecting patients more likely to have HF decompensation (sensitivity and specificity of 61% and 68% vs. 46% and 55%, respectively).

Conclusions

This prospective international registry showed that an algorithm incorporating CABs and HR data detected HF events 30 days in advance of the event in patients with HFrEF during first 3 months after hospital discharge. Therefore, integrating CAB technology into clinical practice may prevent HF rehospitalizations.

Cardiac Implantable Electronic Device Therapy in Heart Failure

The population of patients with heart failure continues to grow, which introduced significant challenges in clinical practice related to the management of cardiac arrhythmia and advanced heart failure syndromes. Device therapy has increasingly become essential in the management of life-threatening arrhythmia and clinical heart failure in this population. This review will discuss the use of cardiac implantable electronic devices in heart failure with primary focus on sudden cardiac death prevention and cardiac resynchronization, including published evidence and evolving technologies.

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

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

The wearable cardioverter-defibrillator vest: Indications and ongoing questions

Multiple clinical trials have demonstrated the efficacy of implantable cardioverter-defibrillators (ICDs) for the prevention of sudden cardiac death (SCD) among specific high-risk populations. However, it remains unclear how to optimally treat those patients who are at elevated risk of cardiac arrest but are not among the presently identified groups proven to benefit from an ICD, are unable to tolerate surgical device implantation, or refuse invasive therapies. The wearable cardioverter-defibrillator (WCD) is an alternative antiarrhythmic device that provides continuous cardiac monitoring and defibrillation capabilities through a noninvasive, electrode-based system. The WCD has been shown to be highly effective at restoration of sinus rhythm in patients with a ventricular tachyarrhythmia, and one randomized trial using the WCD in patients with recent myocardial infarction at elevated risk for arrhythmic death reported a decrease in overall mortality despite no SCD mortality benefit. The current clinical indications for WCD use are varied and continue to evolve as experience with this technology increases.

Misunderstood or Mistrusted? The Under-Utilization of the Wearable Cardioverter Defibrillator in Clinical Practice

Annually in the United States, sudden cardiac death (including out-of-hospital cardiac arrests) is responsible for over 300,000 deaths, comprising 40%-50% of total mortality rates from cardiovascular disease. Among the highest-risk patients are those with ischemic and nonischemic cardiomyopathy who have a reduced left ventricular ejection fraction (≤ 35%-40%). However, not everyone is a candidate for an implantable cardioverter defibrillator. In 2002, the wearable cardioverter defibrillator (WCD) gained Food and Drug Administration approval for its efficacy in the prevention of sudden cardiac arrest or death in certain at-risk populations and has been making its way into national guidelines with Class IIa to IIb strength of evidence. Despite the prevalence of sudden cardiac death and the demonstrated efficacy of the WCD, this technology remains under-prescribed. This study seeks to explicate the potential causes for under-utilization of WCDs and offer means of overcoming barriers to its use. Among these reasons include confusion about the guidelines and when to prescribe, who can prescribe the device, and debate about whether the WCD is efficacious based on recent studies. Other social barriers to prescription include cost and adherence to therapy by the patient. This study sets the stage for further research on the improvement of education about the device and opens discourse about its prescription in clinical practice.

Use of the wearable cardioverter-defibrillator (WCD) and WCD-based remote rhythm monitoring in a real-life patient cohort

The wearable cardioverter-defibrillator (WCD) was introduced to provide protection from sudden cardiac death (SCD) in patients with transiently elevated risk or during ongoing risk stratification. Benefits and clinical characteristics of routine WCD use remain to be assessed in larger patient populations. This study aims to identify determinants of WCD compliance, therapies, and inappropriate alarms in a real-life cohort. A total of 106 cases (68.9% male) were included between 11/2010 and 04/2016. WCD therapies, automatically recorded arrhythmia episodes, inappropriate WCD alarms, patient compliance, and outcome after WCD prescription were analyzed. Median duration of WCD use was 58.5 days. Average daily wearing time was 22.7 h. Compliance was reduced in patients ≤ 50 years. Three patients received WCD therapies (2.8%). In one case ventricular fibrillation (VF) was appropriately terminated with the first shock. Two patients received inappropriate WCD therapies due to WCD algorithm activation during ventricular pacemaker stimulation. One patient died of asystole while carrying a WCD (0.9%). Additional arrhythmias detected comprised self-terminating sustained ventricular tachycardia (VT; 2.8%), non-sustained VT (2.8%), and supraventricular arrhythmias (5.7%). Inappropriate WCD alarms due to over-/undersensing occurred in 77/106 patients (72.6%), of which 41 (38.7%) experienced ≥ 10 inappropriate WCD alarms during the prescription period. Thirteen patients (12.3%) displayed a mean of > 1 inappropriate alarms/day. WCD use was associated with high compliance and provided protection from VT/VF-related SCD. The majority of patients experienced inappropriate WCD alarms. Alterations in QRS morphology during pacemaker stimulation require consideration in WCD programming to prevent inappropriate alarms.

Use of the Wearable Cardioverter Defibrillator as a Bridge to Implantable Cardioverter Defibrillator

The wearable cardioverter defibrillator has been shown to be effective in terminating ventricular arrhythmias in patients at risk for sudden cardiac death. There are numerous scenarios in which implant of a permanent implantable cardioverter defibrillator is temporarily contraindicated or not advisable and a wearable cardioverter defibrillator may be beneficial. There are no prospective randomized studies published that provide conclusive guidance toward the use of the wearable cardioverter defibrillator, and thus, patient management needs to be individualized based on the available data.

The wearable cardioverter-defibrillator: current technology and evolving indications

The wearable cardioverter-defibrillator has been available for over a decade and now is frequently prescribed for patients deemed at high arrhythmic risk in whom the underlying pathology is potentially reversible or who are awaiting an implantable cardioverter-defibrillator. The use of the wearable cardioverter-defibrillator is included in the new 2015 ESC guidelines for the management of ventricular arrhythmias and prevention of sudden cardiac death. The present review provides insight into the current technology and an overview of this approach.

A real world wearable cardioverter defibrillator experience - Very high appropriate shock rate in ischemic cardiomyopathy patients at a European single-center

BACKGROUND

The wearable cardioverter defibrillator (WCD) has emerged as a valuable tool to protect patients with increased risk of sudden cardiac death (SCD). We sought to characterize WCD patients and to analyze predictors of ventricular arrhythmia (VA) occurrence and WCD shock delivery.

METHODS AND RESULTS

One hundred fourteen patients with WCD use were included in the study. Indications were mainly ischemic cardiomyopathy (ICM; 31.6%), non-ICM (45.6%) and explantation of implantable cardioverter defibrillator due to device infection (11.4%). We observed sustained VA in 9.6% of the study population and 6.1% received an appropriate shock. VA occurred in 16.7% of ICM, 3.8% of non-ICM and 15.4% of patients with device infection.

CONCLUSIONS

Our data demonstrate a very high rate of sustained VA in patients at risk for SCD during WCD use. ICM patients, including those with recent MI, bore the highest risk.

The impact of body mass index on the wearable cardioverter defibrillator shock efficacy and patient wear time

BACKGROUND

The impact of body mass index (BMI) on the shock efficacy and patient adherence among patients using a wearable cardioverter defibrillator (WCD) is unknown.

METHODS

Patients prescribed the WCD between January 1, 2008 and June 1, 2013, who experienced at least one episode of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and who received appropriate WCD therapy, were identified within a registry maintained by the manufacturer for regulatory, reimbursement, and administrative purposes. The registry contained patients' Body Mass Index (BMI) which was categorized as normal (18.0<BMI<25.0), overweight (25.0≤BMI<30.0) or obese (30.0≥BMI). Demographics, indication for WCD prescription and other clinical information were reviewed. Device-stored ECG, transthoracic impedance (TTI) and time worn were downloaded for analyses. A post-shock rhythm which was no longer VT or VF was considered a successful tachyarrhythmia conversion. Only the first-shock arrhythmia conversion and TTI were included in the analyses.

RESULTS

A total of 574 patients were included in the final analyses. Patient characteristics were similar across all groups except the obese group (60±11 years) was younger than the normal (63±16 years) and overweight (64±12 years, P=.001) groups. Mean length of use for normal, overweight and obese groups was 79±131, 82±202 and 55±97 days (P=.12), respectively; the median daily wear time was 21 hours among all groups. In a total of 623 VT/VF events, the median TTI was 44 ohms, 51 ohms and 65 ohms for normal, overweight and obese groups, respectively; TTI was positively correlated to BMI (r=0.33, P<.01). First-shock conversion rate was 92.9% in the normal group, 93.6% and 93.9% in the overweight and obese groups, respectively (P=.93). There was no difference in 24-hour survival among the three groups (91.9%, 94.1% and 92.3%, P=.66).

CONCLUSION

The WCD first-shock success rate and post-event 24-hour survival were high and independent from BMI. TTI was positively correlated with BMI but did not impact early clinical outcome. WCD was safe to all BMI groups and the patient wear time was excellent across all groups.

Safety of the Wearable Cardioverter Defibrillator (WCD) in Patients with Implanted Pacemakers

BACKGROUND

The wearable cardioverter defibrillator (WCD) is an important approach for better risk stratification, applied to patients considered to be at high risk of sudden arrhythmic death. Patients with implanted pacemakers may also become candidates for use of the WCD. However, there is a potential risk that pacemaker signals may mislead the WCD detection algorithm and cause inappropriate WCD shock delivery. The aim of the study was to test the impact of different types of pacing, various right ventricular (RV) lead positions, and pacing modes for potential misleading of the WCD detection algorithm.

METHODS

Sixty patients with implanted pacemakers received the WCD for a short time and each pacing mode (AAI, VVI, and DDD) was tested for at least 30 seconds in unipolar and bipolar pacing configuration. In case of triggering the WCD detection algorithm and starting the sequence of arrhythmia alarms, shock delivery was prevented by pushing of the response buttons.

RESULTS

In six of 60 patients (10%), continuous unipolar pacing in DDD mode triggered the WCD detection algorithm. In no patient, triggering occurred with bipolar DDD pacing, unipolar and bipolar AAI, and VVI pacing. Triggering was independent of pacing amplitude, RV pacing lead position, and pulse generator implantation site.

CONCLUSION

Unipolar DDD pacing bears a high risk of false triggering of the WCD detection algorithm. Other types of unipolar pacing and all bipolar pacing modes do not seem to mislead the WCD detection algorithm. Therefore, patients with no reprogrammable unipolar DDD pacing should not become candidates for the WCD.

The wearable cardioverter-defibrillator in a real-world clinical setting: experience in 102 consecutive patients

BACKGROUND

The wearable cardioverter-defibrillator (WCD) is used for temporary protection of patients deemed to be at high risk for sudden death (SCD) not yet meeting indications for the implantable defibrillator (ICD).

OBJECTIVES

To evaluate the efficacy, safety, and compliance of/to WCD use and subsequent medium-term outcome of patients in a single-center observational study.

METHODS

A total of 102 consecutive patients were fitted with the WCD from 2012 to 2015 and followed for a mean of 11 months (±8 months).

RESULTS

The most common clinical indication for WCD-prescription (63%) was a new diagnosis of severely impaired LV function (LVEF ≤35%). The median wear time of the WCD was 54 days with a daily use of 23 h. Appropriate WCD therapy occurred in four patients (seven shocks for VF, one shock for VT). An ICD was finally implanted in 56 patients (55%). Improvement in LV function was the most common reason not to implant an ICD (HR 0.37; 95% CI 0.19-0.73; p = 0.004). Two patients had inappropriate shocks from their WCD due to atrial fibrillation/flutter. Five patients fitted with an ICD after the end of WCD therapy suffered VT/VF episodes. After wearing the WCD, six patients died (five ICD recipients and one non-ICD recipient).

CONCLUSION

WCD therapy was well accepted by patients and provided temporary protection against ventricular tachyarrhythmias in patients at risk for SCD. The WCD may help to avoid unnecessary ICD implantations in a significant proportion of patients.

Wearable Cardioverter Defibrillators

The use of implantable cardioverter defibrillators (ICD) has favorably impacted the prevention and treatment of sudden cardiac death (SCD) associated with ventricular arrhythmias. However, there are situations where an ICD cannot be immediately implanted, even though the patient is at high risk for SCD. The wearable cardioverter defibrillator (WCD) is a unique technology that can bridge this gap for patients. The WCD has been demonstrated to terminate ventricular tachycardia/fibrillation if worn and used correctly. With proper training, it is relatively easy to put on, maintain, and use. Most patients are compliant and are able to consistently wear the device. The WCD negates the infection risk or procedural complications associated with insertion and possible extraction of leads, as with an ICD. In terms of primary prevention of ventricular tachycardia/fibrillation in patients with a left ventricular ejection fraction ≤35%, prospective, randomized studies evaluating the survival of patients utilizing the WCD will need to be performed before evidenced-based criteria for its use can be established. On the basis of current data, WCD use for those awaiting heart transplant, for those with ICD indications status post-ICD explant, and for high-risk SCD patients with possible reversible cardiomyopathy appears to be a reasonable approach on the basis of current data.

National experience with long-term use of the wearable cardioverter defibrillator in patients with cardiomyopathy

PURPOSE

The wearable cardioverter defibrillator (WCD) is generally used for short periods of sudden cardiac death (SCD) risk; circumstances may occasionally result in prolonged use (over 1 year). The aim of this study was to determine the benefits and risks of prolonged use in patients with systolic heart failure (HF).

METHODS

ZOLL's post-market US database included adult patients (≥18 years) with ischemic and/or non-ischemic cardiomyopathy (ICM, NICM) and at least 1 year of use. Cox-regression was used to identify factors associated with survival with WCD use, and reasons for stopping use were entered as time-dependent factors.

RESULTS

Among 220 patients, age (mean ± SD) 55.4 ± 14.8 years, WCD use 451.4 ± 289.9 days, and 67.3 % were male and their left ventricle ejection fraction (EF) averaged 20.9 ± 7.2 %. Eighty-nine (40.5 %) were continuing WCD use at the last follow-up. Thirty-six (16.4 %) and 56 (25.5 %) patients discontinued WCD use because of EF recovery and implantable cardioverter (ICD) implantation, respectively. Nine patients (4.1 %) received appropriate shock therapy for 13 episodes of sustained ventricular tachyarrhythmia with 12 (92.3 %) successful shocks. One patient died of refractory ventricular fibrillation. One patient died from sinus bradycardia transitioning to asystole. Eight patients (3.6 %) had nine episodes of non-fatal inappropriate shocks.

CONCLUSIONS

Long-term use of the WCD is safe and effective. Recovery of EF was seen in significant number of patients even after 1 year of WCD use.

[The wearable cardioverter/defibrillator : Temporary protection from sudden cardiac death]

In the majority of cases sudden cardiac death (SCD) is caused by ventricular tachyarrhythmia. Implantable cardioverter-defibrillators (ICD) represent an evidence-based and established method for prevention of SCD. For patients who do not fulfill the criteria for guideline-conform implantation of an ICD but still have an increased, e.g. transient risk for SCD, a wearable cardioverter-defibrillator (WCD) vest was developed to temporarily prevent SCD. Numerous studies have shown the safety and efficacy of the WCD, although there is still a gap in evidence concerning a reduction in overall mortality and improvement in prognosis. This article gives an overview on the currently available literature on WCD, the indications, potential risks and complications.

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.

The Wearable Cardioverter/Defibrillator - Toy Or Tool?

After the success story of implantable cardioverter/defibrillator systems, prevention of sudden cardiac death (SCD) remains one of the main duties in cardiology. For patients with unkown or transient risk profile for SCD, a wearable cardioverter/defibrillator (WCD) has been established for temporary and effective prevention of sudden arrhythmic death. Several studies have shown safety and efficacy of the WCD, even though randomized studies proving a mortality benefit are still lacking. This review provides an overview of actual WCD data and usage, special indications and possible risks and complications. WCD use is effective and adequate for temporary prevention of SCD in chosen populations. In particular, it provides secured time for sophisticated risk stratification to identify patients at persistent risk for SCD. Nevertheless, prospective randomized trials seem mandatory to prove a prognostic relevance and the economic value of this device.

[Mismanagement in the arrhythmia recognition algorithm of the LifeVest® with consecutive fatal outcome]

We describe for the first time the misinterpretation of a wearable cardioverter defibrillator in the arrhythmia recognition algorithm with subsequent fatal outcome of a multi-morbid patient with an ischemic cardiomyopathy and a highly reduced left ventricular pump function (30 %). The patient's death was preceded by a life-threatening shockable rhythm which was repeatedly documented, but ultimately not correctly recognized by the system and therefore not treated.

Value of The Wearable Cardioverter Defibrillator (WCD) as a Bridging-Therapy before Implantation of a Cardioverter Defibrillator (ICD)

Wearable cardioverter defibrillators (WCD), initially available in 2002, have recently experienced more routine use in many institutions as a means of preventing sudden cardiac death (SCD) prior to implantable cardioverter defibrillator (ICD) evaluation or implantation. WCD differ from ICD by their noninvasive nature, making them well suited for patient populations who have a chance for significant cardiac recovery (such as after an acute myocardial infarction). Despite their noninvasive nature, WCD treatment of sustained ventricular tachyarrhythmias is highly successful. An additional feature is the use of response buttons, which reduces the number of conscious shocks. Duration of use varies by condition but is typically several weeks to several months. Numerous studies have shown good compliance with WCD use and excellent efficacy. Although few prospective studies have been published, several are in progress including a randomized control trial of high risk patients after myocardial infarction. WCD use is rapidly gaining popularity for patients with recent myocardial infarction, recent-onset cardiomyopathies, and acute or subacute myocarditis. Surgical delays in implanting an indicated ICD or after ICD removal are also common. WCD removal occurs when the patient either qualifies for an ICD implantation or is determined to no longer have elevated SCD risk.

[The Wearable Cardioverter-Defibrillator (WCD)]

While the implantable cardioverter-defibrillator (ICD) has been proven to be the best choice for patients with long-term risk for sudden cardiac arrest/sudden cardiac death (SCA/SCD), the question is how to manage patients with only temporary risk, e.g., during the guidelines-recommended waiting period until the decision for an ICD can be made. These patient groups should be monitored around the clock to guarantee a lifesaving shock within a few minutes, if necessary.These conditions can be accomplished by the wearable cardioverter-defibrillator (WCD) in the outpatient sector. The WCD is worn on the skin and consists of four nonadhesive ECG electrodes as well as three defibrillation electrodes-two at the back and one at the front-embedded in a garment. The defibrillation unit is connected via a cord and can be worn over the shoulder or on a belt. Cardiac events can be recorded and retrospectively analyzed by the treating physician.The WCD is a safe and effective measure to terminate potentially lethal ventricular tachycardia and ventricular fibrillation. It may be used early after myocardial infarction with reduced left ventricular ejection fraction (LVEF), as well as for patients with acute heart failure in nonischemic cardiomyopathy with uncertain cause and prognosis. In addition, it may be used for patients waiting for heart transplantation, for patients who cannot be implanted an ICD due to comorbidities, and for patients after explantation of their ICD, e.g., because of infection until reimplantation.One may expect that risk stratification of patients with the WCD will lead to even better selection for ICD use.

Wearable cardioverter-defibrillator for prevention of sudden cardiac death after infected implantable cardioverter-defibrillator removal: A cost-effectiveness evaluation

BACKGROUND

Prevention of sudden cardiac arrest (SCA) after removal of an infected implantable cardioverter-defibrillator (ICD) is a challenging clinical dilemma. The cost-effectiveness of the wearable cardioverter-defibrillator (WCD) in this setting remains uncertain.

OBJECTIVE

The purpose of this study was to compare the cost-effectiveness of the WCD with discharge home, discharge to a skilled nursing facility, or inpatient monitoring for the prevention of SCA after infected ICD removal.

METHODS

A decision model was developed to compare the cost-effectiveness of use of the WCD to several different strategies for patients who undergo ICD removal. One-way and 2-way sensitivity analyses were performed to account for uncertainties.

RESULTS

In the base-case analysis, the incremental cost-effectiveness of the WCD strategy was $20,300 per life-year (LY) or $26,436 per quality-adjusted life-year (QALY) compared to discharge home without a WCD. Discharge to a skilled nursing facility and in-hospital monitoring resulted in higher costs and worse clinical outcomes. The incremental cost-effectiveness ratio was as low as $15,392/QALY if the WCD successfully terminated 95% of SCA events and exceeded the $50,000/QALY willingness-to-pay threshold if the efficacy was <69%.The WCD strategy remained cost-effective, assuming 5.6% 2-month SCA risk, as long as the time to reimplantation was at least 2 weeks.

CONCLUSION

The WCD likely is cost-effective in protecting patients against SCA after infected ICD removal while waiting for ICD reimplantation compared to keeping patients in the hospital or discharging them home or to a skilled nursing facility.

Risk for ventricular fibrillation in peripartum cardiomyopathy with severely reduced left ventricular function-value of the wearable cardioverter/defibrillator

AIMS

The true incidence of life-threatening ventricular tachyarrhythmic events and the risk of sudden cardiac death in the early stage of peripartum cardiomyopathy (PPCM) are still unknown. We aimed to assess the usefulness of the wearable cardioverter/defibrillator (WCD) to bridge a potential risk for life-threatening arrhythmic events in patients with early PPCM, severely reduced left ventricular ejection fraction (LVEF) and symptoms of heart failure.

METHODS AND RESULTS

Twelve consecutively admitted women with PPCM were included in this single-centre, prospective observational study between September 2012 and September 2013. Patients with LVEF ≤35% were considered to use the WCD for 3 months or even 6 months when considered necessary for LVEF recovery. Nine of the 12 women had a severely reduced LVEF (mean 18.3%) at the time of study enrollment; seven women received a WCD, while two patients refused to wear a WCD. During a median WCD follow-up of 81 days (range 25-345 days), we observed a total of four events of ventricular fibrillation with appropriate and successful WCD shocks in three of the seven women receiving a WCD. No syncope or sudden arrhythmic deaths occurred in women not using the WCD during a median follow-up of 12 months (range 5-15 months). All women showed impressive improvement of LVEF during follow-up.

CONCLUSION

PPCM patients with severely reduced LVEF have an elevated risk for ventricular tachyarrhythmias early after diagnosis. Therefore, use of the WCD should be considered in all women with early-stage PPCM and severely reduced LVEF during the first 6 months after initiation of heart failure therapy.

Effectiveness of wearable defibrillators: systematic review and quality of evidence

OBJECTIVES

The objectives of this systematic literature review were to identify all published literature on wearable defibrillators, assess the wearable defibrillator's efficacy and effectiveness in general and among specific patient groups, including post-myocardial infarction, post coronary artery bypass grafting or percutaneous coronary intervention, non-ischemic cardiomyopathy, and ischemic cardiomyopathy, and to evaluate the quality of evidence.

METHODS

The search and synthesis was informed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, and the quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation and the Newcastle Ottawa Scale.

RESULTS

A total of thirty-six articles and conference abstracts from thirty-three studies were included in the review. It appears that wearable defibrillator use compared with no defibrillator use reduces the chance of ventricular tachycardia and ventricular fibrillation (VT/VF) associated deaths by an absolute risk reduction of approximately 1 percent, achieved by averting approximately 4/5th of all VT/VF associated deaths. The quality of evidence was low to very low quality, such that our confidence in the reported estimates is weak.

CONCLUSIONS

To validate beneficial results, further investigation using robust study designs conducted by independent researchers is warranted.

Wearable cardioverter defibrillator: a life vest till the life boat (ICD) arrives

It is well established that implantable cardioverter defibrillator (ICD) is a life saving device ensuring protection against life threatening ventricular arrhythmias. But there are certain situations like a recent myocardial infarction where the standard guidelines do not recommend the implantation of an ICD while the patient can still be at a risk of demise due to a life threatening ventricular arrhythmia. There could also be a temporary indication for protection while explanting an infected ICD system. The wearable cardioverter defibrillator (WCD) is a device which comes to the rescue in such situations. In this brief review, we discuss the historical aspects of the development of a WCD, technical aspects as well as the clinical trial data and real world scenario of its use.

Successful use of wearable cardioverter defibrillator in a patient with dextrocardia and persistent left superior vena cava

Congenital disorders, such as dextrocardia and persistent left superior vena cava, are rare. However, their presence is often associated with other cardiac anomalies, and may lead to lethal ventricular tachyarrhythmias, which result in sudden cardiac death. Treating patients with these disorders can present a challenge to clinicians, as it may cause technical difficulties during interventional procedures, and more often, altered defibrillation techniques in a setting of prehospital sudden cardiac arrest. This report describes the first case of successful defibrillation therapy delivered by the wearable cardioverter defibrillator to a patient with dextrocardia and persistent left superior vena cava during a ventricular tachycardia arrest.

Wearable defibrillator in congenital structural heart disease and inherited arrhythmias

Patients with congenital structural heart disease (CSHD) and inherited arrhythmias (IAs) are at high risk of ventricular tachyarrhythmias and sudden cardiac death. The present study was designed to evaluate the short- and long-term outcomes of patients with CSHD and IA who received a wearable cardioverter-defibrillator (WCD) for the prevention of sudden cardiac death. The study population included 162 patients with CSHD (n = 43) and IA (n = 119) who were prospectively followed up in a nationwide registry from 2005 to 2010. The mortality rates were compared using Kaplan-Meier survival analysis. The mean age of the study patients was 38 ± 27 years. The patients with CSHD had a greater frequency of left ventricular dysfunction (ejection fraction <30%) than did the patients with IA (37% vs 5%, respectively; p = 0.002). The predominant indication for WCD was pending genetic testing in the IA group and transplant listing in the CSHD group. Compliance with the WCD was similar in the 2 groups (91%). WCD shocks successfully terminated 3 ventricular tachyarrhythmias in the patients with IA during a median follow-up of 29 days of therapy (corresponding to 23 appropriate WCD shocks per 100 patient-years). No arrhythmias occurred in the patients with CSHD during a median follow-up of 27 days. No patients died while actively wearing the WCD. At 1 year of follow-up, the survival rates were significantly lower among the patients with CSHD (87%) than among the patients with IA (97%, p = 0.02). In conclusion, our data suggest that the WCD can be safely used in high-risk adult patients with IA and CSHD. Patients with IA showed a greater rate of ventricular tachyarrhythmias during therapy but significantly lower long-term mortality rates.

Clinical characteristics of peripartum cardiomyopathy in the United States: diagnosis, prognosis, and management

Peripartum cardiomyopathy is a pregnancy-associated myocardial disease characterized by the development of heart failure due to marked left ventricular systolic dysfunction. Although the disease is relatively uncommon, its incidence is increasing, and it can be associated with important and lasting morbidity and with mortality. Peripartum cardiomyopathy seems to affect women in different parts of the world but with considerable differences in clinical presentation. The purposes of this review are to describe the clinical profile of peripartum cardiomyopathy in the United States and to provide recommendations for the diagnosis and the management of this disease.

Role of wearable and automatic external defibrillators in improving survival in patients at risk for sudden cardiac death

Cardiac arrest is a vexing public health problem. Fortunately, implantable cardioverter-defibrillators (ICDs) have been proven to decrease overall mortality in several populations at high risk for cardiac arrest. However, it is still unclear how to treat patients who have an elevated risk of cardiac arrest but are not in one of the identified high-risk groups proven to benefit from an ICD. It also is uncertain how to manage high-risk patients who have an accepted indication for an ICD but are unable or unwilling to have an ICD. In these clinical situations, the wearable defibrillator and automatic external defibrillator are options that should be considered. Both devices have been shown in small series to be highly effective at restoring sinus rhythm in patients with a ventricular tachyarrhythmia. However, there is still a lack of large-scale trials proving that these devices should be employed routinely in specific high-risk patient populations.