Medical Policy

Policy Num:       02.002.023
Policy Name:     Wearable Cardioverter Defibrillators
Policy ID:            [2.002.023]  [Ac / B / M+ / P+]  [2.02.15]

Last Review:      June 06, 2024
Next Review:      June 20, 2025
 

Related Policies:

07.001.050 Implantable Cardioverter Defibrillator

Wearable Cardioverter Defibrillators

Summary

Description

A wearable cardioverter defibrillator (WCD) is a temporary, external device that is an alternative to an implantable cardioverter defibrillator (ICD). It is primarily intended for temporary conditions for which an implantable device is contraindicated, or for the period during which the need for a permanent implantable device is uncertain.

Summary of Evidence

Overview of Wearable Cardioverter Defibrillator Versus Implantable Cardioverter Defibrillator

One randomized controlled trial (RCT) has compared wearable cardioverter defibrillators (WCDs) with usual guideline-based care and found no significant benefit to WCD over usual care. No studies have directly compared the performance of a WCD with a permanent implantable cardioverter defibrillator (ICD). One small study in an electrophysiology lab demonstrated that the WCD can correctly identify and terminate most induced ventricular arrhythmias. Similarly, a study of the ASSURE WCD in patients with cardiomyopathy found that the WCD detected all events recorded by an ICD with few false-positive shock alarms in a 30-day period. A cohort study of WCD use estimated that the percentage of successful resuscitations was approximately 70%. Multiple studies have demonstrated suboptimal adherence. Device failures were largely attributed to incorrect device use and/or nonadherence. A more recent registry study has reported a high compliance rate, although these results may be biased by self-selection. Collectively, this evidence indicates that the WCD can successfully detect and terminate arrhythmias in at least some patients but that overall performance in clinical practice might be inferior to a permanent ICD.

Temporary Contraindications

For individuals who have a temporary contraindication to an ICD who receive a WCD, the evidence includes prospective cohort studies and a technology assessment that assessed ICD devices, given the absence of evidence on WCD devices. Relevant outcomes are overall survival (OS), morbid events, functional outcomes, and treatment-related morbidity. A small number of patients meet established criteria for an ICD but have a transient contraindication for an implantable device, most commonly an infectious process. The available data have established that the WCD device can detect lethal arrhythmias and successfully deliver a countershock in most cases. In patients scheduled for ICD placement, the WCD will improve outcomes as an interim treatment. The evidence is sufficient to determine that the technology results in an improvement in the net health outcome.

Immediate Post-Myocardial Infarction

For individuals who are in the immediate post-myocardial infarction (MI) period who receive a WCD, the evidence includes an RCT comparing WCD with guideline-based therapy, 2 cohort studies, and a systematic review. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. The RCT reported no benefit of WCD over guideline-based therapy. The cohort study of 8453 patients showed that 252 shocks successfully terminated ventricular fibrillation (VF) or ventricular tachycardia (VT) (82% success rate), but without a control group, interpretation is difficult. Similarly, a retrospective cohort of Medicare data found that WCD use was associated with lower 1-year mortality than no WCD use, but potential biases were noted. Evidence from the systematic review was deemed of low to very low quality, and the reviewers had weak confidence in the reported estimates. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Post-Coronary Artery Bypass Graft Surgery at High Risk for Lethal Arrhythmias

For individuals who are post-coronary artery bypass graft (CABG) surgery and are at high risk for lethal arrhythmias, the evidence includes an RCT for ICD and a registry study. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. For high-risk post-CABG patients, an RCT reported no difference in OS associated with early ICD placement. The registry study found survival benefits with WCD but had limited interpretation of data. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Awaiting Heart Transplantation at High Risk for Lethal Arrhythmias

For individuals who are awaiting heart transplantation and are at high risk for lethal arrhythmias, the evidence includes analyses of subsets of patients from the manufacturer registry, a subset from a prospective cohort study, and a case series. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. These studies do not provide sufficient evidence to determine whether a WCD is of benefit compared with usual care. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Newly Diagnosed Nonischemic Cardiomyopathy

For individuals who have newly diagnosed nonischemic cardiomyopathy, the evidence includes an RCT for ICD and several retrospective analyses of WCD registry data. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. The RCT found that prophylactic ICD placement for nonischemic cardiomyopathy did not improve mortality compared with usual care. Evidence from the retrospective analysis was not sufficient to determine whether WCD improves outcomes compared with usual care. Given the lack of evidence that ICD improves outcomes, WCD is not expected to improve outcomes under the conditions studied in these trials. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Peripartum Cardiomyopathy

For individuals who have peripartum cardiomyopathy, the evidence includes a retrospective registry data analysis and a small cohort study. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. The registry study revealed that no shocks were delivered during use over an average of 124 days. The cohort study identified 4 episodes of appropriate electric shock over 133 days. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Additional Information

**Refer to Additional Clinical Evidence on PICO 1**

OBJECTIVE

The objective of this evidence review is to assess whether the use of a wearable cardioverter defibrillator improves net health outcome in patients with a temporary contraindication to implantable cardioverter defibrillator, or as a bridge to implantable cardioverter defibrillator placement, heart transplantation, or recovery.

POLICY Statements

Use of wearable cardioverter defibrillators (WCDs) for the prevention of sudden cardiac death may be considered medically necessary as interim treatment for individuals who:

• meet the criteria for an implantable cardioverter defibrillator (ICD; see indications in evidence review 07.001.050); and

• have a temporary contraindication to receiving an ICD, such as a systemic infection, at the current time; and

• have been scheduled for an ICD placement or who had an ICD removed and have been rescheduled for placement of another ICD once the contraindication is treated.

• individuals with a permanent implantable cardioverter-defibrillator (ICD) that must be explanted, or those with a delay in implanting a newly indicated ICD (eg, due to systemic infection). 

• individuals with reduced left ventricular (LV) systolic function (LVEF ≤35 percent) who have had a myocardial infarction (MI) within the past 40 days. 

• individuals with reduced LV systolic function (LVEF ≤35 percent) who have undergone coronary revascularization with coronary artery bypass graft (CABG) surgery in the past three months. 

• individuals with newly diagnosed nonischemic cardiomyopathy with severely reduced LV systolic function (LVEF ≤35 percent) that is potentially reversible.

• individuals with severe heart failure who are awaiting heart transplantation at high risk for lethal arrhythmias. 

• women with peripartum cardiomyopathy with reduced LV systolic function (LVEF ≤35 percent)

• individuals with familial or inherited conditions with a high risk of life threatening ventricular tachyarrhythmia such as long QT syndrome or hypertrophic cardiomyopathy

Use of WCDs for the prevention of sudden cardiac death is considered investigational for the following indications when they are the sole indication for a WCD:

• Individuals in the immediate (ie, <40 days) period following an acute myocardial infarction;

• Individuals post coronary artery bypass graft surgery;

• High-risk individuals awaiting heart transplant;

• Individuals with newly diagnosed nonischemic cardiomyopathy;

• Individuals with peripartum cardiomyopathy.

Use of WCDs is considered investigational for all other indications.

POLICY GUIDELINES

It is uncommon for individuals to have a temporary contraindication to implantable cardioverter defibrillator (ICD) placement. The most common reason will be a systemic infection that requires treatment before the ICD can be implanted. The wearable cardioverter defibrillator (WCD) should only be used short-term while the temporary contraindication (eg, systemic infection) is being clinically managed. Once treatment is completed, the permanent ICD should be implanted.

Coding

See Codes table for details.

BENEFIT APPLICATION

BlueCard/National Account Issues

State or federal mandates (eg, Federal Employee Program) may dictate that certain U.S. Food and Drug Administration approved devices, drugs, or biologics may not be considered investigational, and thus these devices may be assessed only by their medical necessity.

Benefits are determined by the group contract, member benefit booklet, and/or individual subscriber certificate in effect at the time services were rendered.  Benefit products or negotiated coverages may have all or some of the services discussed in this medical policy excluded from their coverage.

BACKGROUND

Sudden Cardiac Arrest

Sudden cardiac arrest (SCA) is the most common cause of death in patients with coronary artery disease.

Treatment

The implantable cardioverter defibrillator (ICD) has proven effective in reducing mortality for survivors of SCA and for patients with documented malignant ventricular arrhythmias. More recently, use of ICDs has been broadened by studies reporting a reduction in mortality for patients at risk for ventricular arrhythmias, such as patients with prior myocardial infarction (MI) and reduced ejection fraction (EF).

Implantable cardioverter defibrillators consist of implantable leads, which are placed percutaneously in the heart, that are connected to a pulse generator placed beneath the skin of the chest or abdomen. Placement of the ICD is a minor surgical procedure. Potential adverse events of ICD placement are bleeding, infection, pneumothorax, and delivery of unnecessary counter shocks. See evidence review 7.01.44 for further information on ICDs.

The wearable cardioverter defibrillator (WCD) is an external device intended to perform the same tasks as an ICD, without invasive procedures. It consists of a vest worn continuously underneath the patient's clothing. Part of this vest is the "electrode belt" that contains the cardiac-monitoring electrodes and the therapy electrodes that deliver a counter shock. The vest is connected to a monitor with a battery pack and alarm module worn on the patient's belt. The monitor contains the electronics that interpret the cardiac rhythm and determines when a counter shock is necessary. The alarm module alerts the patient to certain conditions by lights or voice messages, during which time a conscious patient can abort or delay the shock.

U.S. Food and Drug Administration (FDA)-labeled indications for the WCD are adults at risk for SCA who either are not candidates for or refuse an implantable ICD.^1, Some experts have suggested that the indications for a WCD should be broadened to include other populations at high risk for SCA.^2, The potential indications include:

• Bridge to transplantation (ie, the Use of a Wearable Defibrillator in Terminating Tachyarrhythmias in Patients at High Risk for Sudden Death [WEARIT] study population);

• Bridge to implantable device or clinical improvement (ie, the Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to four months [BIROAD] study population):

  • Post bypass with EF less than 30%,

  • Post bypass with ventricular arrhythmias or syncope within 48 hours of surgery,

  • Post MI with EF less than 30%,

  • Post MI with ventricular arrhythmias within 48 hours;

• Drug-related arrhythmias (during drug washout or after, during evaluation of long-term risk);

• Patients awaiting revascularization;

• Patients too ill to undergo device implantation; and

• Patients who refuse device therapy.

Regulatory Status

In 2001, the Lifecor WCD® 2000 system was approved by the FDA through the premarket approval process for "adult patients who are at risk for cardiac arrest and are either not candidates for or refuse an implantable defibrillator." The vest was renamed the LifeVest®.

In 2015, the FDA approved the LifeVest for "certain children who are at risk for sudden cardiac arrest, but are not candidates for an implantable defibrillator due to certain medical conditions or lack of parental consent."

In 2021, the FDA approved the ASSURE® WCD for adult patients at risk for SCA who are not candidates for (or refuse) an ICD.

FDA product code: MVK.

RATIONALE

This evidence review was created in April 2003 and has been updated regularly with searches of the PubMed database. The most recent literature update was performed through March 27, 2024.

Evidence reviews assess the clinical evidence to determine whether the use of a technology improves the net health outcome. Broadly defined, health outcomes are the length of life, quality of life, and ability to function, including benefits and harms. Every clinical condition has specific outcomes that are important to patients and to managing the course of that condition. Validated outcome measures are necessary to ascertain whether a condition improves or worsens; and whether the magnitude of that change is clinically significant. The net health outcome is a balance of benefits and harms.

To assess whether the evidence is sufficient to draw conclusions about the net health outcome of a technology, 2 domains are examined: the relevance and the quality and credibility. To be relevant, studies must represent one or more intended clinical use of the technology in the intended population and compare an effective and appropriate alternative at a comparable intensity. For some conditions, the alternative will be supportive care or surveillance. The quality and credibility of the evidence depend on study design and conduct, minimizing bias and confounding that can generate incorrect findings. The randomized controlled trial (RCT) is preferred to assess efficacy; however, in some circumstances, nonrandomized studies may be adequate. Randomized controlled trials are rarely large enough or long enough to capture less common adverse events and long-term effects. Other types of studies can be used for these purposes and to assess generalizability to broader clinical populations and settings of clinical practice.

Promotion of greater diversity and inclusion in clinical research of historically marginalized groups (e.g., People of Color [African-American, Asian, Black, Latino and Native American]; LGBTQIA (Lesbian, Gay, Bisexual, Transgender, Queer, Intersex, Asexual); Women; and People with Disabilities [Physical and Invisible]) allows policy populations to be more reflective of and findings more applicable to our diverse members. While we also strive to use inclusive language related to these groups in our policies, use of gender-specific nouns (e.g., women, men, sisters, etc.) will continue when reflective of language used in publications describing study populations.

Overview of Wearable Cardioverter Defibrillator Versus Implantable Cardioverter Defibrillator

There is 1 RCT comparing wearable cardioverter defibrillator (WCD) with standard care. Randomized controlled trials of patients undergoing permanent implantable cardioverter defibrillator (ICD) placement can provide indirect evidence on the efficacy of the WCD if the (1) indications for a permanent ICD are similar to the indications for WCD and (2) performance of the WCD has been shown to approximate that of a permanent ICD. It was on this basis that a TEC Assessment (2010) found that the evidence was sufficient to conclude that the WCD can successfully terminate malignant ventricular arrhythmias.^3, Assessment conclusions were based on several factors. First, there is a strong physiologic rationale for the device. It is known that sensor leads placed on the skin can successfully detect and characterize arrhythmias. It is also established that a successful countershock can be delivered externally. The use of external defibrillators is extensive, ranging from in-hospital use to public access placement and home use. Its novelty is in the way that the device is packaged and utilized. Second, some evidence has suggested the device successfully terminates arrhythmias.

Two uncontrolled studies were identified that directly tested the efficacy of the WCD. Auricchio et al (1998) reported on the first case series of 15 survivors of sudden cardiac arrest (SCA) scheduled to receive an ICD.^4, During the procedure to place a permanent ICD, or to test a previously inserted ICD, patients wore the WCD while clinicians attempted to induce ventricular arrhythmias. Of the 15 patients, 10 developed ventricular tachycardia (VT) or ventricular fibrillation (VF). The WCD correctly detected the arrhythmia in 9 of 10 cases and successfully terminated the arrhythmia in all 9 cases. Chung et al (2010) published an evaluation of WCD effectiveness in preventing sudden cardiac death (SCD) based on a postmarket release registry of 3569 patients who received a WCD.^5, Investigators found an overall successful shock rate of 99% for VT or VF (79/80 cases of VT or VF among 59 patients). Fifty-two percent of patients wore the device for more than 90% of the day. Eight patients died after successful conversion of VT and VF.

Goetz et al (2023) published a systematic review of the only available RCT (n=2348) and 11 observational studies (n=5345) in patients that used a WCD to prevent SCD.^6, Data from the RCT was not pooled with data from the observational studies. Indications for WCDs varied among the observational studies and follow-up ranged from 6 weeks to 36.2 months. Compliance in the observational studies ranged form 20 to 23.5 hours per day. The rate of appropriate and inappropriate shocks was 1% to 4.8% and 1% to 2%, respectively. The analysis was limited by a high risk of bias in 8 of the 11 observational studies and a low or very low certainty of evidence among the included studies.

Multiple studies have reported that adherence with WCD may be suboptimal. Tanawuttiwat et al (2014) reported on the results of a retrospective, uncontrolled evaluation of 97 patients who received a WCD after their ICD was explanted due to device infection.^7, Subjects wore the device for a median of 21 days; during the study period, 2 patients had 4 episodes of arrhythmia appropriately terminated by the WCD, 1 patient experienced 2 inappropriate treatments, and 3 patients experienced SCD outside the hospital while not wearing their WCD device. Mitrani et al (2013) reported a dropout rate of 35% in a study of 134 consecutive, uninsured patients with cardiomyopathy and a mean ejection fraction (EF) of 22.5% who were prescribed a WCD.^8, The WCD was never used by 8 patients, and 27% patients wore the device more than 90% of the day. Patients who were followed for 72 days wore the WCD for a mean of 14.1 hours per day. Additionally, during follow-up, no arrhythmias or shock were detected. Kao et al (2012) reported on the results of a prospective registry of 82 heart failure patients eligible for WCDs.^9, Of these, 16% (n=13) did not wear the WCD due to refusal, discomfort, or other/unknown reasons. In the Wearable Defibrillator Investigative Trial (WEARIT) and Bridge to ICD in Patients at Risk of Arrhythmic Death (BIROAD) studies (later combined), the 2 unsuccessful defibrillations occurred in patients with incorrectly placed therapy electrodes (eg, defibrillating pads reversed and not directed to the skin) with 1 SCD in a patient with reversed leads.^10, These results suggested that the WCD might be inferior to an ICD, due to suboptimal adherence and difficulty with correct placement of the device. Therefore, these data corroborate the assumption that the WCD should not be used as a replacement for an ICD but only considered in those situations in which the patient does not meet criteria for a permanent ICD. However, high compliance with the WCD with a median daily use of 22.5 hours was reported in the Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients (WEARIT-II) Registry, a large prospective study with 2000 patients from a real-world setting.^11,

In a 2022 study of the ASSURE WCD device, 130 patients with ICD were fitted with the WCD and followed for 30 days.^12, The WCD was enabled for detection and shock alarms were recorded; however, shocks and shock alarms were disabled on the WCD. The study was conducted at multiple centers in the US, and enrolled patients had cardiomyopathy of various etiologies. The majority of the patients were male (≈70%) and white (≈64%). The WCD detected 163 events with 3 false-positive shock alarms (0.00075 false-positive shock alarms per patient-day). No events recorded by the ICD were missed by the WCD. Adherence was good with median wear of 31 days and median daily use of 23 hours. Although adherence in this study appears improved compared with studies of other devices, the short duration and small sample size limit applicability.

Section Summary: Wearable Cardioverter Defibrillator Versus Implantable Cardioverter Defibrillator

One RCT compared WCD with usual guideline-based care and found no significant benefit to WCD over usual care. No studies have directly compared the performance of a WCD with a permanent ICD. One small study in an electrophysiology lab demonstrated that the WCD can correctly identify and terminate most induced ventricular arrhythmias. Similarly, a study of the ASSURE WCD in patients with cardiomyopathy found the WCD to detect all events recorded by an ICD with few false-positive shock alarms in a 30-day period. A cohort study of WCD use estimated that the percentage of successful resuscitations was approximately 70%. Multiple studies have demonstrated suboptimal adherence. Device failures were largely attributed to incorrect device use and/or nonadherence. A more recent registry study has reported a high compliance rate, although these results may be biased by self-selection. Collectively, this evidence indicates that the WCD can successfully detect and terminate arrhythmias in at least some patients but that overall performance in clinical practice might be inferior to a permanent ICD.

Population Reference No. 1

Patients With a Temporary Contraindication to an Implantable Cardioverter Defibrillator

Clinical Context and Therapy Purpose

The purpose of WCDs in nindividuals who have risk of sudden death from cardiac arrest is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The following PICO was used to select literature to inform this review.

Populations

The relevant population of interest is nindividuals at risk of death from cardiovascular arrest with a temporary contraindication to an ICD.

Interventions

The therapy being considered is a WCD.

Comparators

The following therapies are currently being used: usual clinical care.

Outcomes

The general outcomes of interest are overall survival (OS), morbid events, functional outcomes, and treatment-related morbidity. Specific outcomes of interest include survival over 10-year follow-up, myocardial infarction (MI), function, and appropriate and inappropriate shocks from the WCD.

Study Selection Criteria

Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.

• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.

• To assess longer-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.

• Studies with duplicative or overlapping populations were excluded.

Review of Evidence

Contraindications to an ICD are few. According to the American College of Cardiology and American Heart Association (1998) guidelines on ICD use, the device is contraindicated in patients with terminal illness, in patients with drug-refractory class IV heart failure, in patients who are not candidates for transplantation, and in patients with a history of psychiatric disorders that interferes with the necessary care and follow-up postimplantation.^13, It is not known how many patients refuse an ICD placement after it has been recommended. A subset of patients who may otherwise meet the established criteria for an ICD (see evidence review 7.01.44) but may have a temporary contraindication for an implantable device such as infection may benefit from WCD. Similarly, a patient with an existing ICD and concurrent infection may require explantation of the ICD; a WCD may benefit this group during the time before reinsertion of ICD may be attempted.

Study characteristics and results of 2 prospective cohort studies are summarized in Tables 1 and 2, respectively. The combined WEARIT and BIROAD study evaluated a prospective cohort of 289 patients at high risk for SCD but who did not meet criteria for an ICD or who could not receive an ICD for several months.^10, The WEARIT-II Registry study reported on the results of patients with ischemic (n=805) or nonischemic cardiomyopathy (n=927) or congenital/inherited heart disease (n=268) who had been prescribed a WCD for risk assessment. At the end of the evaluation period, 42% of patients received an ICD and 40% of patients were no longer considered to need an ICD, most frequently because EF had improved.

Table 1. Key Nonrandomized Trial Characteristics Assessing Temporary Contraindications to an Implantable Cardioverter Defibrillator

BIROAD: Bridge to ICD in Patients at Risk of Arrhythmic Death; CABG: coronary artery bypass graft; CHD: congenital heart disease; ICD: implantable cardioverter defibrillator; IHD: inherited heart disease; LVEF: left ventricular ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; SCD: sudden cardiac death; WEARIT: Wearable Defibrillator Investigative Trial; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients; WCD: wearable cardioverter defibrillator.

Table 2. Key Nonrandomized Trial Results Assessing Temporary Contraindications to an Implantable Cardioverter Defibrillator

BIROAD: Bridge to ICD in Patients at Risk of Arrhythmic Death; WEARIT: Wearable Defibrillator Investigative Trial; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients; WCD: wearable cardioverter defibrillator.
^a Appropriate WCD therapy was classified as ventricular tachycardia or ventricular fibrillation episodes detected and treated by a WCD shock and inappropriate if not.

Additional Clinical Evidence

**A 2019 systematic review and meta-analysis, which included 33,242 WCD users from 28 studies (the randomized VEST trial and 27 nonrandomized studies), assessed the likelihood of WCD therapy in a broad range of patient populations, including both primary/secondary prevention and ischemic/nonischemic cardiomyopathy patients. The incidence of appropriate shocks was 5 per 100 persons over three months (1.67 percent per month) with mortality while wearing the device noted to be 0.7 per 100 persons over three months.

Bridge to indicated or interrupted ICD therapy — In some patients with an indication for ICD placement, implantation of the device may be delayed due to comorbid conditions, including:

Infection

Recovery from surgery

Lack of vascular access

In addition, patients with a preexisting ICD who develop device infection or endocarditis usually require system extraction to effectively treat the infection. Unless the patient is pacemaker dependent, reimplantation in many patients is deferred until the infection is completely cleared after an appropriate course of antibiotics. The WCD may provide protection against ventricular tachyarrhythmias during these periods until an ICD can be implanted.

In a review of 8058 patients who were prescribed the WCD after ICD removal because of infection, median time to reimplantation was 50 days, and 334 (4 percent) experienced 406 ventricular tachycardia/ventricular fibrillation (VT/VF) events, with 348 events treated by the WCD and 54 treatments averted by conscious patients [18]. The one-year cumulative event rate was 10 percent.

Early post-MI patients with LV dysfunction — Among patients with LV ejection fraction (LVEF) ≤35 percent who are less than 40 days post-MI, there are conflicting data on the benefits of a WCD for primary prevention against SCD. Following discussion of the potential benefits and risks, use of the WCD within this 40-day window could be considered among motivated patients who have LVEF ≤35 percent and in New York Heart Association (NYHA) functional class II or III, or LVEF <30 percent and in NYHA class I, as these patients would be candidates for ICD implantation after 40 days. Patients should be reminded of the importance of compliance with the WCD in order to optimize any potential benefits on prevention of arrhythmic death. Reevaluation of LVEF should occur one to three months after the MI. If LVEF remains ≤35 percent on follow-up assessment, while the patient is taking appropriate medical therapy, ICD implantation is indicated. After ICD implantation, use of the WCD would be discontinued.

Despite advances in the treatment of acute coronary syndromes with early revascularization and effective medical therapies that have reduced mortality, some residual risk of SCD remains in the early period following an MI, especially in the setting of severely reduced LVEF (2.3 percent/month for patients with LVEF ≤30 percent) [4,19]. However, there are conflicting data on the utility of an ICD in the early post-MI period.

In an analysis of 712 patients with a history of MI who were enrolled in the SCD-HeFT trial, there was no evidence of differential mortality benefit with ICDs as a function of time after MI, indicating that the potential benefit of ICD therapy is not restricted only to remote MIs.

In the DINAMIT (674 patients) and IRIS (898 patients) trials, which randomized patients with LVEF ≤35 percent to either early ICD implantation 6 to 40 days after acute MI or medical therapy alone, there was no significant improvement in overall mortality. Despite a reduction in arrhythmic deaths among patients with an ICD, there was a higher risk of nonarrhythmic deaths during this early period, resulting in similar overall mortality rates.

Professional society guidelines do not recommend ICD implantation for primary prevention of SCD within 40 days of acute MI . However, due to the risk of SCD in some patients early post-MI, the WCD has been studied in this patient population.

In the VEST trial, 2302 patients with an acute MI and LVEF ≤35 percent were randomly assigned (within seven days of hospital discharge) in a 2:1 ratio to wear the WCD in addition to usual medical treatment (1524 patients) or to receive standard medical treatment alone (778 patients) . Over an average follow-up of 84 days, patients in the WCD group had no significant improvement in the primary outcome of arrhythmic death (25 patients [1.6 percent] versus 19 patients [2.4 percent] with medical therapy alone; relative risk [RR] 0.67; 95% CI 0.37-1.21). Compliance with medical therapy was excellent in both groups, likely contributing to fewer than expected events and the trial possibly being underpowered. However, compliance with WCD usage was markedly lower than expected (median and mean daily wear times of 18 and 14 hours, respectively), with over half of patients assigned to the WCD not wearing it by the end of the 90-day study. Among 48 total deaths in the WCD group, only 12 patients (25 percent) were wearing the WCD at the time of death. Asystolic events not treated by the WCD likely also contributed to the nonsignificant primary outcome results of the trial.

The VEST study also demonstrates the challenges in trying to improve mortality in the post-MI population. Not all patients will survive despite initial appropriate and successful shocks for VT or VF. Of nine patients wearing the WCD with arrhythmic death in the VEST trial, four had been initially successfully treated but subsequently died. Of six patients who had an appropriate shock from the WCD but died during the study, two developed post-VT/VF asystole.

Similar WCD shock rates (between 1.5 and 2 percent within 90 days post-MI) have been reported in observational studies. In registry data from two large registries (involving 3569 and 8453 patients, respectively), similar rates of WCD shocks have been seen (1.7 and 1.6 percent of patients, respectively) .

Patients with LV dysfunction early after coronary revascularization — Among patients with LVEF ≤35 percent who have undergone coronary revascularization with coronary artery bypass graft (CABG) surgery or percutaneous coronary intervention (PCI) in the past three months, we offer a WCD to highly motivated patients for primary prevention against SCD [15]. LVEF should be reassessed three months following CABG or PCI. If a sustained ventricular tachyarrhythmia has occurred, or if the LVEF remains ≤35 percent three months after CABG or PCI, implantation of an ICD is usually indicated . 

While professional society guidelines do not specifically exclude ICD implantation for patients with LV dysfunction within three months of revascularization, reimbursement in some countries may be denied. As an example, in the United States the national coverage decision for the Centers for Medicare & Medicaid Service (CMS) excludes coverage for primary prevention ICDs if patients have had CABG surgery or PCI within the past three months. This is based upon the clinical profile of subjects included in the major ICD trials for primary prevention of SCD in ischemic cardiomyopathy. Despite this exclusion period, patients with LV dysfunction (eg, LVEF ≤30 percent) have been shown to have significantly higher rates of mortality early after PCI or CABG based on large National Cardiovascular Data Registry (NCDR) and Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database studies, respectively.

Patients with significant LV dysfunction have higher 30-day mortality rates after coronary artery bypass graft (CABG) surgery than patients with normal LV function. While these persons have an increased risk of SCD due to ventricular arrhythmias, they are also at risk for nonarrhythmic causes of death. There are limited data on the utility of an ICD in the early post-CABG period, as several ICD studies of primary prevention have excluded patients within one to three months after coronary revascularization . However, the CABG Patch trial did not report a survival benefit from epicardial ICD implantation at the time of CABG in patients with LVEF ≤35 percent.

Professional society guidelines do not recommend ICD implantation for primary prevention of SCD within three months of CABG. However, due to the risk of SCD in some patients early post-CABG, the WCD has been studied in this patient population, in whom wearing the WCD may provide protection from SCD during healing and potential recovery of LV function . The potential utility for a WCD in this setting is illustrated by the following studies:

In a nonrandomized comparison of nearly 5000 patients with LVEF ≤35 percent from two separate cohorts who underwent revascularization with CABG or percutaneous coronary intervention (PCI) (809 patients discharged with a WCD from a national registry and 4149 patients discharged without WCD from Cleveland Clinic CABG and PCI registries), patients discharged with the WCD had significantly lower 90-day mortality rates (3 versus 7 percent). While patients using a WCD appear to have improved outcomes, only 1.3 percent of the WCD group received an appropriate therapy while wearing the device, thereby indicating that the majority of the mortality benefit was not attributable to life-saving therapies from the WCD.

In a German cohort of 354 patients who wore the WCD, including approximately 90 patients in the early post-CABG period, 7 percent received a shock for a ventricular tachyarrhythmia during the three months of WCD use.

In a study of 3569 patients in the United States using the WCD, among which 9 percent of WCD use was early post-CABG, appropriate shocks for a ventricular tachyarrhythmia occurred in 0.8 percent of these patients over a mean follow-up of 47 days.

Newly diagnosed nonischemic cardiomyopathy — In selected patients with newly diagnosed nonischemic cardiomyopathy with severely reduced LV systolic function that is potentially reversible, such as tachycardia- or myocarditis-associated cardiomyopathy, the WCD may be useful for the prevention of SCD due to ventricular arrhythmias while awaiting improvement in LV function.

While a benefit from ICD implantation has long been recognized in patients with significant LV systolic dysfunction related to underlying ischemic heart disease, an increase in SCD risk and potential benefit from an ICD has also been demonstrated in patients with a nonischemic cardiomyopathy in several studies:

In SCD-HeFT, which compared ICD implantation with amiodarone treatment alone or placebo for primary prevention of SCD in patients with ischemic or nonischemic heart failure and LVEF ≤35 percent, patients who received an ICD had significantly improved survival. However, patients within three months of their initial heart failure diagnosis were excluded from this study.

In DEFINITE, which compared ICD implantation with standard medical therapy to standard medical therapy alone for primary prevention of SCD in patients with a nonischemic cardiomyopathy, nonsustained VT, and LVEF ≤35 percent, there was a trend toward improved mortality in patients who received an ICD, regardless of duration since diagnosis.

Following DEFINITE, another study reported similar occurrences of lethal arrhythmias irrespective of diagnosis duration in patients with a nonischemic cardiomyopathy and LVEF ≤35 percent.

Major society guidelines recommend implantation of an ICD for nonischemic cardiomyopathy with LVEF ≤35 percent, provided that a reversible cause of transient LV dysfunction has been excluded and that response to optimal medical therapy has been assessed. The guidelines do not specify a waiting period prior to reassessing LVEF. In the United States, however, the Center for Medicare Services (CMS) requires a three-month period of optimal medical therapy prior to reimbursement for ICD placement for primary prevention (if repeat LVEF assessment continues to show LVEF ≤35 percent). 

In patients felt to be at high risk of SCD while undergoing a trial of optimal medical therapy, the WCD may provide protection against SCD while awaiting improvement in LV function, although the event rates in this population appear to be lower than patients with ischemic cardiomyopathy.

In a post-approval study of the WCD, 0.7 percent of patients prescribed a WCD for recently diagnosed nonischemic cardiomyopathy required shocks for a ventricular tachyarrhythmia over a mean follow-up period of 57 days.

Among a single-center cohort of 254 patients with newly diagnosed nonischemic cardiomyopathy treated with the WCD between 2004 and 2015 (median duration of treatment 61 days, total follow-up 56.7 patient-years) who were highly compliant with using the WCD (median wear time 22 hours per day), no patients received an appropriate shock, and only three patients (1.2 percent) received an inappropriate shock [32]. This was compared with 6 of 271 patients (2.2 percent) with newly diagnosed ischemic cardiomyopathy who received an appropriate shock; in this group, two (0.7 percent) received inappropriate shocks. Of interest, 39 percent of nonischemic and 32 percent of ischemic cardiomyopathy patients experienced improvement in LVEF to >35 percent, obviating the need for an ICD.

In a prospective study of the WCD in advanced heart failure patients (SWIFT), 75 patients hospitalized with heart failure (66 percent nonischemic cardiomyopathy) were prescribed a WCD for three months. Among the nonischemic cardiomyopathy patients, one had recurrent supraventricular tachycardia and another had multiple ventricular premature beats detected, but no WCD therapies were delivered.

In the WEARIT II registry, which included 927 patients with nonischemic cardiomyopathy, over a median wear time of 90 days, the treated event rate was 1 percent, compared with 3 percent for the 805 patients with ischemic cardiomyopathy.

Special populations include those with alcoholic cardiomyopathy, postpartum cardiomyopathy, or myocarditis, all of which may or may not be associated with improvement in ventricular function with optimal medical therapy and reversal or treatment of causative factors. In a study of 127 patients with alcoholic cardiomyopathy wearing the WCD a median of 51 days, 5.5 percent had appropriate shocks for VT/VF [34]. Improved LVEF occurred in 33 percent, and 23.6 percent received an ICD.

In the PROLONG study of 156 patients (111 with nonischemic cardiomyopathy) with newly diagnosed LVEF ≤35 percent wearing a WCD for an average of 101 days, WCD shocks for VT/VF were experienced by 7.2 percent, compared with 6.7 percent in the 45 patients with ischemic cardiomyopathy [35]. The event rates were 21.1 percent in the 19 patients with postpartum cardiomyopathy, 0 percent in the six patients with myocarditis, and 4.7 percent in patients with other forms of nonischemic cardiomyopathy.

In a separate study of 107 women with peripartum cardiomyopathy, who were matched to 159 nonpregnant women with nonischemic dilated cardiomyopathy, the event rate was 0 in the peripartum cardiomyopathy over an average WCD use of 124 days, compared with two shocks in one patient with nonperipartum nonischemic cardiomyopathy.

With such low event rates, the utility of the WCD for newly-diagnosed nonischemic cardiomyopathy has been debated. However, from the WEARIT II registry, the number of VT/VF events per 100 patient-years was 1.5 for treated events versus 12 for untreated events. Presumably, some of the untreated events led to earlier ICD implantation and may represent a nontreatment yield from the WCD monitoring functions. As data remain limited for such patients, the decision on whether to use a WCD remains based on clinical judgment for patients assessed to have high-risk severe newly diagnosed nonischemic cardiomyopathy while undergoing optimization of medical therapy, awaiting improvement in LV function, ICD implantation, or if needed, cardiac transplantation. 

Bridge to heart transplant — Patients with severe heart failure awaiting heart transplantation represent a group at particularly high risk for SCD. ICD implantation is often recommended for such patients, particularly those discharged to home while awaiting transplantation. The WCD may be a reasonable noninvasive alternative approach, though data on its use in patients awaiting heart transplantation are limited:

In one study of 91 cardiac transplant candidates discharged to home (UNOS Status 1B patients receiving home inotrope infusion), among whom 25 had an ICD and 13 used a WCD, two patients died suddenly at home, one who was not wearing his WCD and another who declined use of a WCD. In the 13 patients wearing the WCD, three asymptomatic events occurred with one shock delivered for rapid atrial fibrillation.

In a German study of 354 WCD patients, 6 percent wore the WCD while awaiting heart transplantation, with an incidence of ventricular arrhythmias of 11 percent.

In the WEARIT study of WCD use in 177 patients with NYHA functional class III or IV heart failure (not listed for heart transplant but with similar functional status to patients who might be listed for heart transplant), one patient received two successful defibrillations.

In a registry of 121 patients prescribed a WCD as a bridge to heart transplantation, seven patients (6 percent) received appropriate shocks over an average use of 127 days (median 39 days).

The International Society for Heart and Lung Transplantation Guidelines state as a class I recommendation that an ICD or WCD should be provided for status 1B patients who are discharged home given that the wait for transplantation remains significant. The WCD may also be appropriate in patients whose anticipated waiting time to transplant is short (ie, blood types A and B) if an ICD is not already present.

WCD in patients with VADs — The role for ICD and WCD therapy remains unclear in patients with ventricular assist devices (VADs). With VADs, circulatory support is often adequate even in the event of a ventricular tachyarrhythmia. However, one study reported the presence of an ICD was associated with improved survival in patients undergoing VAD support. Whether the WCD could impart similar survival benefits in patients awaiting transplantation with VAD support has yet to be studied. 

WCD use in hemodialysis patients — Patients with end-stage kidney disease on hemodialysis are at high risk for SCD, but they are also at higher risk for infection, bleeding, and other complications of implantable device therapies, which may lead to underutilization of ICDs. Although the arrhythmia event rates for patients on hemodialysis wearing a WCD are not published, a study of 75 hemodialysis patients who experienced sudden cardiac arrest events while wearing a WCD reported that 78.6 percent of events were due to VT/VF and 21.4 percent were due to asystole. Survival was 71, 51, and 31 percent at 24 hours, 30 days, and one year, respectively, which was reported to be improved compared with historical controls. **

Section Summary: Patients With a Temporary Contraindication to an Implantable Cardioverter Defibrillator

A small number of patients meet established criteria for an ICD but have a transient contraindication for an implantable device, most commonly an infectious process. Prospective cohort studies have established that the WCD device can detect lethal arrhythmias and can successfully deliver a countershock in most cases. In patients scheduled for ICD placement, the WCD will improve outcomes as an interim treatment. These patients are expected to benefit from an ICD, and use of a WCD is a reasonable alternative because there are no other options for automatic detection and termination of ventricular arrhythmias.

Temporary Contraindications

For individuals who have a temporary contraindication to an ICD who receive a WCD, the evidence includes prospective cohort studies and a technology assessment that assessed ICD devices, given the absence of evidence on WCD devices. Relevant outcomes are overall survival (OS), morbid events, functional outcomes, and treatment-related morbidity. A small number of patients meet established criteria for an ICD but have a transient contraindication for an implantable device, most commonly an infectious process. The available data have established that the WCD device can detect lethal arrhythmias and successfully deliver a countershock in most cases. In patients scheduled for ICD placement, the WCD will improve outcomes as an interim treatment. The evidence is sufficient to determine that the technology results in an improvement in the net health outcome.

Population Reference No. 2

Patients in Immediate Post-Myocardial Infarction Period

Clinical Context and Therapy Purpose

The purpose of WCDs in nindividuals who have risk of sudden death from cardiac arrest is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The following PICO was used to select literature to inform this review.

Populations

The relevant population of interest is nindividuals in the immediate post-MI period.

Interventions

The therapy being considered is a WCD.

Comparators

The following therapies are currently being used: usual clinical care.

Outcomes

The general outcomes of interest are OS, morbid events, functional outcomes, and treatment-related morbidity. Specific outcomes of interest include survival over 10-year follow-up, MI, function, and appropriate and inappropriate shocks from the WCD.

Study Selection Criteria

Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.

• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.

• To assess longer-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.

• Studies with duplicative or overlapping populations were excluded.

Review of Evidence

Randomized Trial

Use of WCD in the immediate post-MI period as a bridge to permanent ICD placement was reviewed in a TEC Assessment (2010).^3, For these patients, indications for a permanent ICD cannot be reliably assessed immediately post-MI because it is not possible to determine the final EF until at least 30 days after the event. Because the first 30 days after an acute MI represent a high-risk period for lethal ventricular arrhythmias, there is a potential to reduce mortality using other treatments. Despite the rationale for this potential indication, the TEC Assessment concluded that the available evidence does not support the contention that any cardioverter defibrillator improves mortality in patients in the immediate post-MI period. Two RCTs (Defibrillator in Acute Myocardial Infarction Trial [DINAMIT] and Immediate Risk Stratification Improves Survival [IRIS]) and a post hoc analysis of an RCT, the Prophylactic Implantation of a Defibrillator in Patients with Myocardial Infarction and Reduced Ejection Fraction (MADIT-II) led to this conclusion. In the DINAMIT (674 patients) and IRIS (898 patients) trials, which randomized patients with LVEF of 35% or less to early ICD implantation 6 to 40 days after acute MI or medical therapy alone, there was no significant improvement in overall mortality.^14,15, The hazard ratios (HR) for OS in the DINAMIT and IRIS trials were 1.08 (95% confidence interval [CI], 0.76 to 1.55; p=.66) and 1.04 (95% CI, 0.81 to 1.35; p=.78), respectively. Despite a reduction in arrhythmic deaths among patients with an ICD, there was a higher risk of nonarrhythmic deaths during this early period, resulting in similar overall mortality rates in the 2 trials. Secondary analysis of data from the MADIT-II trial showed that the survival benefit associated with ICDs appeared to be greater for remote MI and remained substantial for up to 15 or more years after MI. Within the first 18 months post-MI, there was no benefit found for ICD placement (HR, 0.97; 95% CI, 0.51 to 1.81; p=.92). In contrast, there was a significant mortality benefit when the length of time since MI was greater than 18 months (HR, 0.55; 95% CI, 0.39 to 0.78; p=.001).

Olgin et al (2018) randomly allocated patients with an acute MI and an EF of 35% or less to either WCD (n=1524) or to receive only guideline-based therapy (n=778).^16, Patients in the treatment group wore the device a median of 18.0 hours per day (interquartile range, 3.8 to 22.7). Within 90 days, 1.6% of participants in the WCD group and 2.4% of those in the control group had died of arrhythmia (relative risk [RR], 0.67; 95% CI, 0.37 to 1.21; p=.18). In the WCD group, death from any cause was seen in 3.1% of participants; in the control group, the death rate was 4.9% (RR, 0.64; 95% CI, 0.43 to 0.98; uncorrected p=.04). In the WCD group, of the 48 patients who died, 12 were wearing the WCD at time of death. Twenty participants in the WCD (1.3%) group received appropriate shock, and 9 (0.6%) an inappropriate shock. The results of this trial show that for patients with these specific conditions, the WCD did not improve the rate of arrhythmic death compared with usual care.

Nonrandomized Trial

Uyei and Braithwaite (2014) reported on the results of a systematic review conducted to evaluate the effectiveness of WCD use in several clinical situations, including individuals post-MI (≤40 days) with a left ventricular ejection fraction (LVEF) of 35% or less.^17, Four studies (Chung et al [2010];^5, Epstein et al [2013], described in detail below;^18, and 2 conference abstracts) assessed the effectiveness of WCD use in post-MI patients. Outcomes reported were heterogeneous. For 2 studies that reported VF- and VT-related mortality, on average, 0.52% (2/384) of the study population died of VF or VT over a mean of 58.3 days of WCD use. For 2 studies that reported on VT and VF incidence, on average, 2.8% (11/384) of WCD users experienced a VT and/or VF event over a mean of 58.3 days of WCD use (range, 3 to 146 days). Among those who experienced a VT or VF event, on average, 82% (9/11) had successful termination of 1 or more arrhythmic events. Reviewers concluded that the quality of evidence was low to very low quality and confidence in the reported estimates was weak.

Epstein et al (2013) reported on the results of postmarket registry data from 8453 post-MI patients who received WCDs for risk of SCA while awaiting ICD placement.^18, The WCD was worn a median of 57 days (mean, 69 days), with a median daily use of 21.8 hours. Study characteristics and results are summarized in Tables 3 and 4, respectively. While 1.4% of this registry population was successfully treated with WCDs, interpretation of registry data is limited. It is not possible to determine whether outcomes were improved without a control group, and the registry contained limited patient and medical information, making interpretation of results difficult.

Clark et al (2019) reported on the results of a retrospective cohort analysis of Medicare claims data of 16,935 patients who were post-MI and received WCDs.^19, The analysis utilized a 5% sample of Medicare’s Standard Analytical Files (2010 to 2012) and included patients with an inpatient admission for acute MI. One-year adjusted mortality rates were compared between patients who received a WCD within 15 days of discharge and those who did not receive a WCD (Tables 3 and 4). The 30-day mortality rate in the WCD group was not reported due to Medicare restrictions on reporting that represents less than 11 beneficiaries, but was stated to be lower than that in the no WCD group (10.4%; p=.18). While these results favored WCD, interpretation of these findings is limited; for example, the authors noted the potential for confounding by indication and performance bias, and the WCD group was significantly younger and had more frequent congestive heart failure, unstable angina, and other acute ischemic heart disease.

Table 3. Key Nonrandomized Trial Characteristics in Immediate Post- Myocardial Infarction Period

 MI: myocardial infarction; WCD: wearable cardioverter defibrillator.

Table 4. Key Nonrandomized Trial Results in Immediate Post- Myocardial Infarction Period

CI: confidence interval; HR: hazard ratio; NR: not reported; VF: ventricular fibrillation; VT: ventricular tachycardia; WCD: wearable cardioverter defibrillator.
^a Shocks deemed appropriate if they occurred during sustained (>30 seconds) VT or VF and inappropriate if not.

Section Summary: Patients in Immediate Post-Myocardial Infarction Period

One RCT of WCD in the early post-acute MI period found no benefit to WCD over guideline-directed therapy. Two RCTs of ICD use in this period concluded that mortality rates did not improve compared with usual care. In both trials, SCD was reduced in the ICD group, but non-SCD events increased, resulting in no difference in overall mortality. Analysis of data from a retrospective postmarket registry reported a success rate of 82% but interpretation of registry data was limited in the absence of a control group. Similarly, a retrospective cohort of Medicare data found that WCD use was associated with lower 1-year mortality than no WCD use, but potential biases were noted. Because a permanent ICD does not appear to be beneficial in the early post-MI period, a WCD would also not be beneficial for these patient populations.

Immediate Post-Myocardial Infarction

For individuals who are in the immediate post-myocardial infarction (MI) period who receive a WCD, the evidence includes an RCT comparing WCD with guideline-based therapy, 2 cohort studies, and a systematic review. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. The RCT reported no benefit of WCD over guideline-based therapy. The cohort study of 8453 patients showed that 252 shocks successfully terminated ventricular fibrillation (VF) or ventricular tachycardia (VT) (82% success rate), but without a control group, interpretation is difficult. Similarly, a retrospective cohort of Medicare data found that WCD use was associated with lower 1-year mortality than no WCD use, but potential biases were noted. Evidence from the systematic review was deemed of low to very low quality, and the reviewers had weak confidence in the reported estimates. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Population Reference No. 3

Patients Post-Coronary Artery Bypass Graft Surgery at High Risk for Lethal Arrhythmias

Clinical Context and Therapy Purpose

The purpose of WCDs in nindividuals who have risk of sudden death from cardiac arrest is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The following PICO was used to select literature to inform this review.

Populations

The relevant population of interest is nindividuals post-coronary artery bypass graft (CABG) surgery who are at high risk for lethal arrhythmias.

Interventions

The therapy being considered is a WCD.

Comparators

The following therapies are currently being used: usual clinical care.

Outcomes

The general outcomes of interest are OS, morbid events, functional outcomes, and treatment-related morbidity. Specific outcomes of interest include survival over 10-year follow-up, MI, function, and appropriate and inappropriate shocks from the WCD.

Study Selection Criteria

Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.

• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.

• To assess longer-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.

• Studies with duplicative or overlapping populations were excluded.

Review of Evidence

Randomized Trial

Evidence on use of early ICD placement in high-risk post-CABG patients with a low LVEF and abnormalities on signal-averaged electrocardiography consists of an RCT (CABG Patch) that reported no difference in overall mortality between the ICD and the control groups (HR, 1.07; 95% CI, 0.81 to 1.42).^20,

Nonrandomized Trial

Zishiri et al (2013) reported on the results of a nonrandomized comparison of nearly 5000 patients with LVEF of 35% or less from 2 separate cohorts who underwent revascularization with CABG or percutaneous coronary intervention (809 patients discharged with a WCD from a national registry and 4149 patients discharged without WCD from Cleveland Clinic CABG and percutaneous coronary intervention registries).^21, Study characteristics and results are summarized in Tables 5 and 6, respectively. Results show significant reduction in the mortality rates between the WCD group and the no WCD group. In this nonrandomized comparison, WCD use might have been associated with other confounding factors, including potential triggering of closer follow-up and reassessment for ICD implantation at subsequent follow-up. Therefore, use of WCD during this early period post-CABG should be evaluated in an RCT.

In the Uyei and Braithwaite (2014) systematic review (previously described), 3 studies (Chung et al (2010),^5, Epstein et al (2014),^18, and 1 conference abstract) were identified; they reported outcomes for WCDs after coronary revascularization for patients with a LVEF of 35% or less.^17, Reported outcomes were heterogeneous across studies. In 1 study that reported on VT- and VF-related mortality, 0.41% (1/243) of the study population died of VT or VF over 59.8 days (mean or median not specified). Of those who experienced a VT or VF event, 7% of patients died during "approximately 2 months" of WCD use. In another study, 50% of those with VT or VF events died over 59.8 days. Reviewers concluded that the quality of evidence was low to very low quality and confidence in the reported estimates was weak.

Table 5. Key Nonrandomized Trial Characteristics in Patients Post- Coronary Artery Bypass Graft Surgery at High-Risk for Lethal Arrhythmias

CABG: coronary artery bypass graft; EF: ejection fraction; WCD: wearable cardioverter defibrillator.

Table 6. Key Nonrandomized Trial Results in Patients Post- Coronary Artery Bypass Graft Surgery at High-Risk for Lethal Arrhythmias

CABG: coronary artery bypass graft; CI: confidence interval; HR: hazard ratio; WCD: wearable cardioverter defibrillator.
^a Multivariable Cox proportional hazards analyses.

Section Summary: Patients Post–Coronary Artery Bypass Graft Surgery at High Risk for Lethal Arrhythmias

For high-risk post-CABG patients, the evidence includes an RCT for ICD and a registry study for WCD. The RCT reported no difference in OS associated with early ICD placement. Analysis of data from the nonrandomized comparison using registry data found survival benefit with WCD but interpretation of registry data was limited. Because a permanent ICD does not appear to be beneficial in the early post-CABG period, a WCD would also not be beneficial for these patient populations.

Post-Coronary Artery Bypass Graft Surgery at High Risk for Lethal Arrhythmias

For individuals who are post-coronary artery bypass graft (CABG) surgery and are at high risk for lethal arrhythmias, the evidence includes an RCT for ICD and a registry study. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. For high-risk post-CABG patients, an RCT reported no difference in OS associated with early ICD placement. The registry study found survival benefits with WCD but had limited interpretation of data. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Population Reference No. 4

Patients Awaiting Heart Transplantation at High Risk for Lethal Arrhythmias

Clinical Context and Therapy Purpose

The purpose of WCDs in nindividuals who have risk of sudden death from cardiac arrest is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The following PICO was used to select literature to inform this review.

Populations

The relevant population of interest is nindividuals awaiting heart transplantation at high risk for lethal arrhythmias.

Interventions

The therapy being considered is a WCD.

Comparators

The following therapies are currently being used: usual clinical care.

Outcomes

The general outcomes of interest are OS, morbid events, functional outcomes, and treatment-related morbidity. Specific outcomes of interest include survival over 10-year follow-up, MI, function, and appropriate and inappropriate shocks from the WCD.

Study Selection Criteria

Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.

• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.

• To assess longer-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.

• Studies with duplicative or overlapping populations were excluded.

Review of Evidence

Many patients awaiting heart transplantation are at high risk for lethal arrhythmias, and therefore ICD implantation is often recommended for such patients, particularly those discharged to home while awaiting transplantation. A WCD can be used to reduce risks associated with ICD placement or when ICD placement is contraindicated.

Opreanu et al (2015) analyzed a subset of patients prescribed a WCD as a bridge therapy to heart transplant from a retrospective analysis of a manufacturer's registry.^22, Study characteristics and results are summarized in Tables 7 and 8, respectively. Thirteen (11%) patients ended WCD use after heart transplantation, 42% ended WCD use after ICD placement, and 15% ended WCD use after EF improved. There were 11 (9%) deaths; 9 of them were not wearing a WCD at the time of death. The 2 patients who died while wearing the WCD had an asystole.

Wässnig et al (2016) reported on the results of a national German registry of 6043 patients with multiple etiologies including dilated cardiomyopathy, myocarditis, and ischemic and nonischemic cardiomyopathies who were prescribed WCD.^23, Study characteristics and results are summarized in Tables 7 and 8, respectively. Overall, 1 (2.5%) of 40 patients awaiting heart transplantation was appropriately shocked for sustained VT or VF.

Table 7. Key Nonrandomized Trial Characteristics in Patients Awaiting Heart Transplant at High Risk for Lethal Arrhythmias

 NR: not reported; SCD: sudden cardiac death; WCD: wearable cardioverter defibrillator.

Table 8. Key Nonrandomized Trial Results in Patients Awaiting Heart Transplantation at High Risk for Lethal Arrhythmias

WCD: wearable cardioverter defibrillator.
^a A WCD shock was considered appropriate if delivered for sustained ventricular arrhythmias and inappropriate if occurring for arrhythmias other than sustained ventricular arrhythmia.

Patients awaiting transplantation have also participated in studies with mixed populations. The combined WEARIT and BIROAD study (discussed previously) assessed a prospective cohort that included patients awaiting transplant and other high-risk patients; it did not report data separately for the population awaiting transplant.^10, Rao et al (2011) published a case series of 162 patients with congenital structural heart disease or inherited arrhythmias treated with WCD.^24, Approximately one-third of these patients had a permanent ICD, which was explanted due to infection or malfunction. The remaining patients used the WCD either as a bridge to heart transplantation, during an ongoing cardiac evaluation, or in the setting of surgical or invasive procedures that increased the risk of arrhythmias. Four patients died during a mean WCD treatment duration of approximately 1 month, but none was related to cardiac causes. Two patients received 3 appropriate shocks for VT or VF, and 4 patients received 7 inappropriate shocks. The results of this series suggested that the WCD can be worn safely and can detect arrhythmias in this population, but the rate of inappropriate shocks was relatively high.

Section Summary: Patients Awaiting Heart Transplantation at High Risk for Lethal Arrhythmias

For patients awaiting heart transplantation who are at high risk for lethal arrhythmias, evidence includes analyses of subsets of patients from the manufacturer registry, a subset from a prospective cohort, and a case series. These studies do not provide sufficient evidence to determine whether a WCD improves outcomes compared with usual care.

Awaiting Heart Transplantation at High Risk for Lethal Arrhythmias

For individuals who are awaiting heart transplantation and are at high risk for lethal arrhythmias, the evidence includes analyses of subsets of patients from the manufacturer registry, a subset from a prospective cohort study, and a case series. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. These studies do not provide sufficient evidence to determine whether a WCD is of benefit compared with usual care. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Population Reference No. 5

Patients With Newly Diagnosed Nonischemic Cardiomyopathy

Clinical Context and Therapy Purpose

The purpose of WCDs in nindividuals who have risk of sudden death from cardiac arrest is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The following PICO was used to select literature to inform this review.

Populations

The relevant population of interest is nindividuals with newly diagnosed nonischemic cardiomyopathy.

Interventions

The therapy being considered is a WCD.

Comparators

The following therapies are currently being used: usual clinical care.

Outcomes

The general outcomes of interest are OS, morbid events, functional outcomes, and treatment-related morbidity. Specific outcomes of interest include survival over 10-year follow-up, MI, function, and appropriate and inappropriate shocks from the WCD.

Study Selection Criteria

Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.

• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.

• To assess longer-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.

• Studies with duplicative or overlapping populations were excluded.

Review of Evidence

Randomized Trial

In patients with newly diagnosed nonischemic cardiomyopathy, final EF is uncertain because some patients show an improvement in EF over time. The Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation RCT compared ICD implantation plus standard medical therapy with standard medical therapy alone for primary prevention of SCD in patients who had nonischemic cardiomyopathy, nonsustained VT, and a LVEF of 35% or less. Results of this trial did not show a significant reduction in mortality with ICD regardless of duration since diagnosis (HR, 0.65; 95% CI, 0.40 to 1.06; p=.08). Kadish et al (2006) conducted a post hoc analysis of the same trial that evaluated use of an ICD in patients with nonischemic dilated cardiomyopathy and examined the benefit of ICD use by time since diagnosis (<3 months and >9 months).^25, This trial excluded patients with a clinical picture consistent with a reversible cause of cardiomyopathy and thus may differ from the population considered for a WCD. The difference in survival was of borderline significance for the ICD group compared with controls, both for the recently diagnosed subgroup (HR, 0.38; 95% CI, 0.14 to 1.00; p=.05) and the remotely diagnosed subgroup (HR, 0.43; 95% CI, 0.22 to 0.99; p=.046). Study characteristics and results are summarized in Tables 9 and 10, respectively.

Nonrandomized Trial

In the WEARIT-II Registry study (discussed previously), 46% (n=927) of patients were prescribed WCD for nonischemic cardiomyopathy.^11, After 3 months of follow-up, the rate of sustained VT was 1% among those with nonischemic cardiomyopathy. However, outcomes data (appropriate and inappropriate shocks) were not reported separately for patients with nonischemic cardiomyopathy.

Another potential indication for the WCD is alcoholic cardiomyopathy where cardiomyopathy is reversible but temporary protection against arrhythmias is needed. Salehi et al (2016) reported on the results of analysis of a subset of patients identified from manufacturer registry.^26, Mean EF was 19.9% on presentation. Patients wore the WCD for a median of 51 days and a median of 18.0 hours per day. At the end of WCD use, 33% of patients had improved EF and did not require ICD placement; 24% received an ICD. Four deaths occurred during this period, with 1 death in a patient wearing WCD (due to ventricular asystole).

Wässnig et al (2016) reported on the results of a national German registry of 6043 patients with multiple etiologies including dilated cardiomyopathy, myocarditis, and ischemic and nonischemic cardiomyopathies who were prescribed WCD.^23, Overall 7 (1%) of 735 patients with nonischemic cardiomyopathy were appropriately shocked for sustained VT or VF.

Duncker et al (2017) reported on the results of the Avoiding Untimely Implantable Cardioverter/Defibrillator Implantation by Intensified Heart Failure Therapy Optimization Supported by the Wearable Cardioverter/Defibrillator (PROLONG) study of 156 patients of whom 111 with nonischemic cardiomyopathy with a newly diagnosed LVEF of 35% or less were prescribed WCD and analyzed separately^27, from the full cohort.^28,

The Uyei and Braithwaite (2014) systematic review also identified 4 studies (Saltzberg et al [2012],^29, Chung et al [2010],^5, and 2 conference abstracts) that assessed WCD use in newly diagnosed nonischemic cardiomyopathy.^17, In the 3 studies that reported VT and VF incidences, on average, 0.57% (5/871) subjects experienced VT and/or VF over a mean duration of 52.6 days. Among those who experienced a VT or VF event, on average, 80% had successful event termination.

Table 9. Key Nonrandomized Trial Characteristics for Newly Diagnosed Nonischemic Cardiomyopathy

LVEF: left ventricular ejection fraction; NR: not reported; PROLONG: Avoiding Untimely Implantable Cardioverter/Defibrillator Implantation by Intensified Heart Failure Therapy Optimization Supported by the Wearable Cardioverter/Defibrillator; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients; WCD: wearable cardioverter defibrillator.

Table 10. Key Nonrandomized Trial Results for Newly Diagnosed Nonischemic Cardiomyopathy

PROLONG: Avoiding Untimely Implantable Cardioverter/Defibrillator Implantation by Intensified Heart Failure Therapy Optimization Supported by the Wearable Cardioverter/Defibrillator; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients; WCD: wearable cardioverter defibrillator.
^a Appropriate WCD therapy was classified as ventricular tachycardia or ventricular fibrillation episodes detected and treated by a WCD shock and inappropriate if not.

Section Summary: Patients With Newly Diagnosed Nonischemic Cardiomyopathy

For patients with newly diagnosed nonischemic cardiomyopathy, the evidence includes an RCT for ICD and multiple retrospective analyses of registry data for WCD. The RCT found that prophylactic ICD placement in nonischemic cardiomyopathy did not improve mortality compared with usual clinical care. The retrospective analyses did not provide sufficient evidence to determine whether a WCD improves outcomes compared with usual care. Thus, given the lack of evidence that a permanent ICD improves outcomes, a WCD is not expected to improve outcomes under the conditions studied in this trial.

Newly Diagnosed Nonischemic Cardiomyopathy

For individuals who have newly diagnosed nonischemic cardiomyopathy, the evidence includes an RCT for ICD and several retrospective analyses of WCD registry data. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. The RCT found that prophylactic ICD placement for nonischemic cardiomyopathy did not improve mortality compared with usual care. Evidence from the retrospective analysis was not sufficient to determine whether WCD improves outcomes compared with usual care. Given the lack of evidence that ICD improves outcomes, WCD is not expected to improve outcomes under the conditions studied in these trials. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Population Reference No. 6

Patients With Peripartum Cardiomyopathy

Clinical Context and Therapy Purpose

The purpose of WCDs in nindividuals who have risk of sudden death from cardiac arrest is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The following PICO was used to select literature to inform this review.

Populations

The relevant population of interest is nindividuals with peripartum cardiomyopathy.

Interventions

The therapy being considered is a WCD.

Comparators

The following therapies are currently being used: usual clinical care.

Outcomes

The general outcomes of interest are OS, morbid events, functional outcomes, and treatment-related morbidity. Specific outcomes of interest include survival over 10-year follow-up, MI, function, and appropriate and inappropriate shocks from the WCD.

Study Selection Criteria

Methodologically credible studies were selected using the following principles:

• To assess efficacy outcomes, comparative controlled prospective trials were sought, with a preference for RCTs.

• In the absence of such trials, comparative observational studies were sought, with a preference for prospective studies.

• To assess longer-term outcomes and adverse events, single-arm studies that capture longer periods of follow-up and/or larger populations were sought.

• Studies with duplicative or overlapping populations were excluded.

Review of Evidence

Saltzberg et al (2012) retrospectively analyzed a subset of 107 women with peripartum cardiomyopathy treated with a WCD device and compared with a matched sample of 159 nonpregnant women who had nonischemic dilated cardiomyopathy.^29, The event rate was 0 in the peripartum cardiomyopathy group over an average WCD use of 124 days, compared with 2 shocks in 1 patient who had nonperipartum nonischemic cardiomyopathy over an average WCD use of 96 days.

Dunker et al (2014) reported on outcomes for 12 prospectively enrolled women with peripartum cardiomyopathy treated at a single center and followed for a median of 12 months.^30, A WCD was recommended for 9 patients with a LVEF of 35% or less and 7 of them consented to wear the WCD. For these 7 patients, median WCD wearing time was 81 days (mean, 133 days). In 3 patients, 4 episodes of VF were detected that led to delivery of a shock, which successfully terminated the arrhythmia in all cases. No inappropriate shocks were delivered. Among the 5 patients without WCD, no episodes of syncope or ventricular arrhythmia or deaths occurred.

Section Summary: Patients With Peripartum Cardiomyopathy

For peripartum cardiomyopathy, evidence includes a retrospective analysis of registry data and a small case series (N=7). In the registry study of 107 patients, no shocks were delivered during use over an average of 124 days. The prospective cohort identified 4 episodes of appropriate electric shock during a mean 133 days. Thus, given the lack of evidence that a permanent ICD improves outcomes, a WCD is not expected to improve outcomes under the conditions studied in this trial.

Peripartum Cardiomyopathy

For individuals who have peripartum cardiomyopathy, the evidence includes a retrospective registry data analysis and a small cohort study. Relevant outcomes are OS, morbid events, functional outcomes, and treatment-related morbidity. The registry study revealed that no shocks were delivered during use over an average of 124 days. The cohort study identified 4 episodes of appropriate electric shock over 133 days. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

SUPPLEMENTAL INFORMATION

The purpose of the following information is to provide reference material. Inclusion does not imply endorsement or alignment with the evidence review conclusions.

Clinical Input From Physician Specialty Societies and Academic Medical Centers

While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.

2014 Input

In response to requests, further input was received from 2 physician specialty societies and 7 academic medical centers while this policy was under review in 2014. Input related to the role of wearable cardioverter defibrillators (WCDs) in preventing sudden cardiac death (SCD) among high-risk patients awaiting a heart transplant. Overall, input on the use of WCDs in this patient population was mixed. Some reviewers indicated that it may have a role among certain patients awaiting heart transplant, but there was no consensus on specific patient indications for use.

2013 Input

In response to requests, input was received from 3 physician specialty societies and 8 academic medical centers while this policy was under review in 2013. Overall, the input was mixed. Most, but not all, providing comments suggested that the WCD may have a role in select high-risk patients following acute myocardial infarction (MI) or in newly diagnosed cardiomyopathy. However, reviewers acknowledged the lack of evidence for benefit and consistency in the evidence in defining high-risk subgroups that may benefit.

Practice Guidelines and Position Statements

Guidelines or position statements will be considered for inclusion in ‘Supplemental Information’ if they were issued by, or jointly by, a US professional society, an international society with US representation, or National Institute for Health and Care Excellence (NICE). Priority will be given to guidelines that are informed by a systematic review, include strength of evidence ratings, and include a description of management of conflict of interest.

American Heart Association et al

In 2018, the American Heart Association (AHA), the American College of Cardiology, and the Heart Rhythm Society published a guideline on the management of patients with ventricular arrhythmias and prevention of SCD.^31, The guidelines note that "the patients listed in this recommendation are represented in clinical series and registries that demonstrate the safety and effectiveness of the wearable cardioverter-defibrillator. Patients with recent MI, newly diagnosed nonischemic cardiomyopathy, recent revascularization, myocarditis, and secondary cardiomyopathy are at increased risk of VT/SCA [ventricular tachycardia/sudden cardiac arrest]. However, the wearable cardioverter-defibrillator is of unproven benefit in these settings, in part because the clinical situation may improve with therapy and time." The specific recommendations are summarized in Table 11.

Level of evidence class IIa is moderate recommendation, class IIb is a weak recommendation, and class III is a moderate recommendation for no benefit or a strong recommendation for harm.

Table 11. Guidelines for Wearable Cardioverter Defibrillator Therapy

B-NR: Level B - nonrandomized; COR: class of recommendation; ICD: implantable cardioverter defibrillator; LOE: level of evidence; LVEF: left ventricular ejection fraction; MI: myocardial infarction; SCA: sudden cardiac arrest; SCD: sudden cardiac death; VT: ventricular tachycardia; WCD: wearable cardioverter defibrillator.
^a Removal of an ICD for a period of time, most commonly due to infection, exposes the patient to risk of untreated VT/SCD unless monitoring and access to emergency external defibrillation is maintained. In 1 series of 354 patients who received the WCD, the indication was infection in 10%.^32, For patients with a history of SCA or sustained ventricular arrhythmia, the WCD may allow the patient to be discharged from the hospital with protection from VT/SCD until the clinical situation allows reimplantation of an ICD.
^b The patients listed in this recommendation are represented in clinical series and registries that demonstrate the safety and effectiveness of the WCD. Patients with recent MI, newly diagnosed nonischemic cardiomyopathy, recent revascularization, myocarditis, and secondary cardiomyopathy are at increased risk of VT or SCD. However, the WCD is of unproven benefit in these settings, in part because the clinical situation may improve with therapy and time. In patients awaiting transplant, even with anticipated survival <1 year without transplant, and depending on clinical factors such as use of intravenous inotropes and ambient ventricular arrhythmia, a WCD may be an alternative to an ICD.
^c B-NR: data derived from ≥1 nonrandomized trials or meta-analysis of such studies.

In 2016, the AHA published a scientific advisory on the WCD.^33, The AHA stated that "because there is a paucity of prospective data supporting the use of the WCD, particularly in the absence of any published, randomized, clinical trials, the recommendations provided in this advisory are not intended to be prescriptive or to suggest an evidence-based approach to the management of patients with FDA [U.S. Food and Drug Administration]-approved indications for use." The specific recommendations are summarized in Table 12.

Table 12. Guidelines for Wearable Cardioverter Defibrillator Therapy

COR: class of recommendation; ICD: implantable cardioverter defibrillator; LOE: level of evidence; MI: myocardial infarction; SCD: sudden cardiac death; WCD: wearable cardioverter defibrillator.
^a Level C evidence is based on limited data or expert opinion.

U.S. Preventive Services Task Force Recommendations

Not applicable.

Medicare National Coverage

There is no national coverage determination. In the absence of a national coverage determination, coverage decisions are left to the discretion of local Medicare carriers.

Ongoing and Unpublished Clinical Trials

Some currently ongoing and unpublished trials that might influence this review are listed in Table 13.

Table 13. Summary of Key Trials

NCT: national clinical trial.
^a Denotes industry sponsored or co-sponsored study.
^b Available at: https://www.escardio.org/Research/registries/global-registries-and-surveys-programme/PeriPartum-CardioMyopathy-PPCM-Registry.

References

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Codes

Policy History