Wearable Cardioverter-Defibrillators - CAM 20215

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.

Overview of Wearable Cardioverter Defibrillator Versus Implantable Cardioverter Defibrillator
One RCT has 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. 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 can 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 a meaningful improvement in the net health outcome.

Immediate Post Myocardial Infarction
For individuals who are in the immediate post myocardial infarction period who receive a WCD, the evidence includes a randomized controlled trial (RCT) comparing WCD with guideline-based therapy, a cohort study, 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 or ventricular tachycardia (82% success rate), but without a control group, interpretation is difficult. 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 the effects of the technology on health outcomes.

Post-Coronary Artery Bypass Graft Surgery at High Risk for Lethal Arrhythmias
For individuals who are post-coronary artery bypass graft 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 coronary artery bypass graft 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 the effects of the technology on health outcomes.

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 the effects of the technology on health outcomes.

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 the effects of the technology on health outcomes.

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 the effects of the technology on health outcomes.

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 and reduced ejection fraction.

ICDs 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. ICD placement 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 and 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 (i.e., the WEARIT study population)
Bridge to implantable device or clinical improvement (i.e., the BIROAD study population)
- Post bypass with ejection fraction less than 30%
- Post bypass with ventricular arrhythmias or syncope within 48 hours of surgery
- Post myocardial infarction with ejection fraction less than 30%
- Post myocardial infarction 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
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.

Related Policies
70144 Implantable Cardioverter Defibrillator (ICD)

Policy:
Use of a wearable cardioverter defibrillator (WCD) for the prevention of sudden cardiac death is considered MEDICALLY NECESSARY as an interim treatment for the following:

Meet the criteria for an implantable cardioverter defibrillator (see CMP Implantable Cardioverter Defibrillator); AND Either a or b
1. Patient has a temporary contraindication to receiving an implantable cardioverter defibrillator (ICD) or has had an ICD removed for a temporary contraindication (e.g. systemic infection), and has been scheduled for placement of an ICD once the temporary indication has been resolved, OR
2. Patient is awaiting heart transplantation (defined as on a waiting list) OR
Patient has an ejection fraction less than or equal to 35% AND
1. Is within 40 days of a myocardial infarction*; OR
2. Has newly diagnosed non-ischemic dilated cardiomyopathy*; OR
3. Has secondary cardiomyopathy that is potentially reversible*; OR
4. Has had revascularization, i.e., coronary artery bypass grafting, percutaneous coronary angioplasty and/or stenting within the past 90 days*.

*
- Use of a WCD after a myocardial infarction (MI) without revascularization will be covered for 40 days from the initial diagnosis.
- Use of a WCD for newly diagnosed non-ischemic dilated cardiomyopathy or for secondary cardiomyopathy that is potentially reversible will be covered for 90 days from the time of diagnosis during guideline-directed medical therapy.
- Use of a WCD after revascularization, to include after an MI, will be covered for 90 days after the procedure.

Policy Guidelines
It is uncommon for patients 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 (e.g., 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 (e.g., 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.

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 16, 2022.

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.

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.

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.⁶ 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.⁷ 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.⁸Of these, 16% (n = 13) did not wear the WCD due to refusal, discomfort, or other/unknown reasons. In the WEARIT and BIROAD studies (later combined), the 2 unsuccessful defibrillations occurred in patients with incorrectly placed therapy electrodes (e.g., defibrillating pads reversed and not directed to the skin) with one SCD in a patient with reversed leads.⁹ 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.¹⁰

In a study of the ASSURE WCD device, 130 patients with ICD were fitted with the WCD and followed for 30 days.¹¹ 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.

Patients With Temporary Contraindication to an Implantable Cardioverter Defibrillator
Clinical Context and Therapy Purpose
The purpose of WCDs in patients 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 question addressed in this evidence review is: Does a WCD improve the net health outcome in patients with a temporary contraindication to an ICD?

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

Populations
The relevant population of interest is patients 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.¹² 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.⁹ 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 ICD

Trial	Study Type	Country	Dates	Participants	Treatment	Follow-up
Feldman et al. (2004)⁹; WEARIT and BIROAD	Single-arm cohort	U.S.	2011 – 2014	Symptomatic NYHA functional class III or IV heart failure with LVEF < 30% (WEARIT) or at high risk for SCD after MI or CABG surgery not receiving an ICD for up to 4 months (BIROAD)	WCD	3.1 months
Kutyifa et al. (2015)¹⁰; WEARIT-II Registry	Prospective registry	U.S., Germany	2011 – 2014	Post-MI with or without revascularization, new-onset dilated nonischemic cardiomyopathy or IHD or CHD	WCD	90 days

BIROAD: Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to 4 months; 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; WCD: wearable cardioverter defibrillator. WEARIT: Use of a Wearable Defibrillator in Terminating Tachyarrhythmias in Patients at High Risk for Sudden Death Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to 4 months; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients.

Table 2. Key Nonrandomized Trial Results Assessing Temporary Contraindications to an ICD

Trial	Appropriate Shock^a	Inappropriate Shock^a	Nonadherence
Feldman et al. (2004)⁹; WEARIT and BIROAD	289	289	289
WCD, n/N (%)	6/8 (75%)	0.67 per month of use	6 sudden deaths: 5 not wearing; 1 incorrectly wearing the device
Kutyifa et al. (2015)¹⁰; WEARIT-II Registry	2000
WCD, n/N (%)	22/41 (54%)	10 (0.5%) patients	Not reported

BIROAD: Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to 4 months; ICD: implantable cardioverter defibrillator; VF: ventricular fibrillation; VT: ventricular tachycardia; WCD: wearable cardioverter defibrillator; WEARIT: Use of a Wearable Defibrillator in Terminating Tachyarrhythmias in Patients at High Risk for Sudden Death Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to 4 months; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients.
^a Appropriate WCD therapy was classified as VT or VF episodes detected and treated by a WCD shock and inappropriate if not.

Section Summary: Patients With 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.

Patients in Immediate Post-Myocardial Infarction Period
Clinical Context and Therapy Purpose
The purpose of WCDs in patients 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 question addressed in this evidence review is: Does a WCD improve the net health outcome in patients in the immediate post-MI period?

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

Populations
The relevant population of interest is patients 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
Olgin et al (2018) randomly allocated 1524 patients with acute MI and an EF ≤ 35% to WCD and 778 to receive only guideline-based therapy ( N = 2302).¹³ 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% confidence interval [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
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.¹⁴ 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.¹⁵ The analysis utilized a 5% sample of Medicare’s Standard Analytical Files (2010 – 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 < 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.

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.16, Four studies (Chung et al [2010],5, Epstein et al. [2013],¹⁴ 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 WD use (range, 3 – 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.

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

Study	Study Type	Country	Dates	Participants	Treatment	Follow-up
Epstein et al. (2013)¹⁴	Retrospective registry (postmarket study)	United States	2005 – 2011	High-risk post-MI patients during the 40-day and 3-month waiting periods	WCD	3 months
Clark et al. (2019)¹⁵	Retrospective cohort	United States	2010 – 2012	Medicare patients hospitalized for MI	WCD	1 year

MI: myocardial infarction; WCD: wearable cardioverter defibrillator.

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

Study	Outcomes
Epstein et al. (2013)¹⁴	N = 8453
WCD	Number of patients receiving shock: n = 133 Shock events: n = 146 Appropriate shocks^a: n = 309 Shocks successful in terminating VT or VF: n = 252 (82% success) Shocks leading to asystole: n = 9 Unsuccessful shocks: n = 41 (10% failure) Inappropriate shocks: n = 99 patients received 114 inappropriate shocks
Clark et al. (2019)¹⁵	N = 16,935
WCD, n/N (%) (n = 89)	1-year mortality: NR (11.5%)
No WCD, n/N (%) (n = 16,846)	1-year mortality: NR (19.8%)
HR (95% CI)	1-year mortality 0.46 (NR)

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. 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], 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.^17,18 The hazard ratios (HR) for OS in the DINAMIT and IRIS trials were 1.08 (95% 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).

Patients Post-Coronary Artery Bypass Graft Surgery at High Risk for Lethal Arrhythmias
Clinical Context and Therapy Purpose
The purpose of WCDs in patients 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 question addressed in this evidence review is: Does a WCD improve the net health outcome in patients post-coronary artery bypass graft (CABG) surgery who are at high risk for lethal arrhythmias?

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

Populations
The relevant population of interest is patients post-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.

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
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).¹⁹

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).²⁰ 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),¹⁴ 1 conference abstract) were identified; they reported outcomes for WCDs after coronary revascularization for patients with a LVEF of 35% or less.¹⁶ 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-CABG Surgery at High-Risk for Lethal Arrhythmias

Study	Study Type	Country	Dates	Participants	Treatment	Comparator	Follow-up
Zishiri et al. (2013)²⁰	Retrospective matched cohort	United States	2002 – 2009	Patients with low EF post-percutaneous coronary intervention or post-CABG	WCD	No WCD	3.2 years

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

Table 6. Key Nonrandomized Trial Results in Patients Post-CABG Surgery at High-Risk for Lethal Arrhythmias

Study	Post-CABG Mortality (90 Days)	Post-Percutaneous Coronary Intervention Mortality (90 Days)	Post-CABG Mortality (Long-Term)	Post-Percutaneous Coronary Intervention Mortality (Long-Term)
Zishiri et al. (2013)²⁰
WCD, n/N (%) ( N = 809)	7/26 (3.1%)	5/288 (1.7%)	19/226 (8.4%)	31/228 (11%)
No WCD, n/N (%) (N = 4149)	135/2198 (6.1%)	189/1951 (9.7%)	636/2198 (29%)	763/1951 (39%)
HR (95% CI); p			0.619 (0.385 to 0.997); adjusted p = .048^a	0.430 (0.290 to 0.638); <.001^a

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.

Patients Awaiting Heart Transplantation at High Risk for Lethal Arrhythmias
Clinical Context and Therapy Purpose
The purpose of WCDs in patients 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 question addressed in this evidence review is: Does a WCD improve the net health outcome in patients awaiting heart transplantation at high risk for lethal arrhythmias?

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

Populations
The relevant population of interest is patients 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.

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.²¹ 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.²² 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

Study	Study Type	Country	Dates	Participants	Treatment	Follow-up
Opreanu et al. (2015)²¹	Retrospective registry	U.S.	2004 – 2011	Patients using the WCD for primary prevention of SCD in patients awaiting heart transplantation	WCD	39 days
Wässnig et al. (2016)²²	Retrospective cohort	Germany, multiple sites	2010 – 2013	Patients with multiple etiology	WCD	NR

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

Study	Appropriate Shock^a	Inappropriate Shock^a	Adherence
Opreanu et al. (2015)²¹
WCD	7/121 (6%)	2/121 (2%)	Average of 20 hours/day
Wässnig et al. (2016)²²
WCD	1/40 (2.5%)	Stratified data not reported	Stratified data not reported

WCD: wearable cardioverter defibrillator.
^aA 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.⁹ Rao et al. (2011) published a case series of 162 patients with congenital structural heart disease or inherited arrhythmias treated with WCD.²³ 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.

Patients With Newly Diagnosed Nonischemic Cardiomyopathy
Clinical Context and Therapy Purpose
The purpose of WCDs in patients 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 question addressed in this evidence review is: Does a WCD improve the net health outcome in patients with newly diagnosed nonischemic cardiomyopathy?

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

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

Interventions
The therapy being considered is a WCD.

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

Study Selection Criteria
Methodologically credible studies were selected using the following principles:

Review of Evidence
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).²⁴ 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. In the WEARIT-II Registry study (discussed previously), 46% (n = 927) of patients were prescribed WCD for nonischemic cardiomyopathy.¹⁰ 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.²⁵ 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.²² 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 separately²⁶ from the full cohort.²⁷

The Uyei and Braithwaite (2014) systematic review also identified 4 studies (Saltzberg et al. [2012],²⁸ Chung et al. [2010],⁵ 2 conference abstracts) that assessed WCD use in newly diagnosed nonischemic cardiomyopathy.¹⁶ 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

Study; Trial	Study Type	Country	Dates	Participants	Treatment	Follow-up
Kutyifa et al. (2015)¹⁰; WEARIT-II Registry	Prospective registry	United States, Germany	2011 – 2014	Patients with nonischemic cardiomyopathy	WCD	90 days
Salehi et al. (2016)²⁵	Retrospective registry	United States	2005 – 2012	Patients with nonischemic cardiomyopathy who self-reported a history of excess alcohol use	WCD	100 days
Duncker et al. (2017)^26,²⁷; PROLONG	Retrospective cohort	Germany	2012 – 2016	Newly diagnosed LVEF ≤ 35%	WCD	11 months
Wässnig et al. (2016)²²	Retrospective cohort	Germany, multiple sites	2010 – 2013	Patients with multiple etiology	WCD	NR

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; WCD: wearable cardioverter defibrillator; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients.

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

Study; Trial	Appropriate Shock^a	Inappropriate Shock^a	Nonadherence
Kutyifa et al. (2015)¹⁰; WEARIT-II Registry	927
WCD	Not reported	Not reported	Not reported
Salehi et al. (2016)²⁵
WCD	7/127 (6%)	13/127 (10.2%)
Duncker et al. (2017)^26,²⁷; PROLONG
WCD	8/117 (7%)	None	Of 156 (entire cohort), 48 terminated WCD treatment before 3-month follow-up. Of the 48, 24 (50%) discontinued due to noncompliance.
Wässnig et al. (2016)²²
WCD	7/735 (1%)	Stratified data not reported	Stratified data not reported

PROLONG: Avoiding Untimely Implantable Cardioverter/Defibrillator Implantation by Intensified Heart Failure Therapy Optimization Supported by the Wearable Cardioverter/Defibrillator; VF: ventricular fibrillation; VT: ventricular tachycardia; WCD: wearable cardioverter defibrillator; WEARIT-II: Use of the Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients.
^a Appropriate WCD therapy was classified as VT or VF 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 analyse s 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.

Patients With Peripartum Cardiomyopathy
Clinical Context and Therapy Purpose
The purpose of WCDs in patients 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 question addressed in this evidence review is: Does a WCD improve the net health outcome in patients with peripartum cardiomyopathy?

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

Populations
The relevant population of interest is patients with peripartum cardiomyopathy.

Interventions
The therapy being considered is a WCD.

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

Study Selection Criteria
Methodologically credible studies were selected using the following principles:

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.28, 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.²⁹ 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.

Summary of Evidence
Overview of Wearable Cardioverter Defibrillator Versus Implantable Cardioverter Defibrillator
One RCT has 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.

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 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-MI period who receive a WCD, the evidence includes a 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 VF or 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-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.

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 U.S. professional society, an international society with U.S. 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.³⁰ 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. 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 WCD Therapy

Recommendation	COR	LOE^c
"In patients with an ICD and a history of SCA or sustained ventricular arrhythmia in whom removal of the ICD is required (as with infection), the WCD is reasonable for the prevention of SCD."^a	IIa	B-NR
"In patients at an increased risk of SCD but who are not ineligible for an ICD, such as awaiting cardiac transplant, having an LVEF of 35% or less and are within 40 days from an MI, or have newly diagnosed nonischemic cardiomyopathy, revascularization within the past 90 days, myocarditis or secondary cardiomyopathy or a systemic infection, the WCD may be reasonable."^b	IIb	B-NR

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%.³¹ 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.³² 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-approved indications for use." The specific recommendations are summarized in Table 12.

Table 12. Guidelines for WCD Therapy

Recommendation	COR	LOE^a
"Use of WCDs is reasonable when there is a clear indication for an implanted/permanent device accompanied by a transient contraindication or interruption in ICD care such as infection."	IIa	C
"Use of WCDs is reasonable as a bridge to more definitive therapy such as cardiac transplantation."	IIa	C
"Use of WCDs may be reasonable when there is concern about a heightened risk of SCD that may resolve over time or with treatment of left ventricular dysfunction/ for example, in ischemic heart disease with recent revascularization, newly diagnosed nonischemic dilated cardiomyopathy in patients starting guideline-directed medical therapy, or secondary cardiomyopathy (tachycardia mediated, thyroid mediated, etc) in which the underlying cause is potentially treatable."	IIb	C
"WCDs may be appropriate as bridging therapy in situations associated with increased risk of death in which ICDs have been shown to reduce SCD but not overall survival such as within 40 days of MI."	IIb	C
"WCDs should not be used when nonarrhythmic risk is expected to significantly exceed arrhythmic risk, particularly in patients who are not expected to survive > 6 months."	III	C

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.

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 No.	Trial Name	Planned Enrollment	Completion Date
Ongoing
NCT05201495	A Clinical Evaluation of the Jewel P-WCD in Subjects at High Risk for Sudden Cardiac Arrest	290	Jun 2023
NCT02816047	Indications for and Experience With the Wearable Cardioverter Defibrillator (WCD) — Austrian WCD Registry	450	Dec 2021
	EURObservational research programme: Peripartum Cardiomyopathy (PPCM) Registry^a

NCT: national clinical trial.
^a Available at: https://www.escardio.org/Research/Registries-&-surveys/Observational-research-programme/PeriPartum-CardioMyopathy-PPCM-Registry.

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Tanawuttiwat T, Garisto JD, Salow A, et al. Protection from outpatient sudden cardiac death following ICD removal using a wearable cardioverter defibrillator. Pacing Clin Electrophysiol. May 2014; 37(5): 562-8. PMID 24762055
Mitrani RD, McArdle A, Slane M, et al. Wearable defibrillators in uninsured patients with newly diagnosed cardiomyopathy or recent revascularization in a community medical center. Am Heart J. Mar 2013; 165(3): 386-92. PMID 23453108
Kao AC, Krause SW, Handa R, et al. Wearable defibrillator use in heart failure (WIF): results of a prospective registry. BMC Cardiovasc Disord. Dec 12 2012; 12: 123. PMID 23234574
Feldman AM, Klein H, Tchou P, et al. Use of a wearable defibrillator in terminating tachyarrhythmias in patients at high risk for sudden death: results of the WEARIT/BIROAD. Pacing Clin Electrophysiol. Jan 2004; 27(1): 4-9. PMID 14720148
Kutyifa V, Moss AJ, Klein H, et al. Use of the wearable cardioverter defibrillator in high-risk cardiac patients: data from the Prospective Registry of Patients Using the Wearable Cardioverter Defibrillator (WEARIT-II Registry). Circulation. Oct 27 2015; 132(17): 1613-9. PMID 26316618
Poole JE, Gleva MJ, Birgersdotter-Green U, et al. A wearable cardioverter defibrillator with a low false alarm rate. J Cardiovasc Electrophysiol. Feb 16 2022. PMID 35174572
Gregoratos G, Cheitlin MD, Conill A, et al. ACC/AHA guidelines for implantation of cardiac pacemakers and antiarrhythmia devices: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol. Apr 1998; 31(5): 1175-209. PMID 9562026
Olgin JE, Pletcher MJ, Vittinghoff E, et al. Wearable Cardioverter-Defibrillator after Myocardial Infarction. N Engl J Med. Sep 27 2018; 379(13): 1205-1215. PMID 30280654
Epstein AE, Abraham WT, Bianco NR, et al. Wearable cardioverter-defibrillator use in patients perceived to be at high risk early post-myocardial infarction. J Am Coll Cardiol. Nov 19 2013; 62(21): 2000-2007. PMID 23916930
Clark MA, Szymkiewicz SJ, Volosin K. Mortality and Costs Associated with Wearable Cardioverter-defibrillators after Acute Myocardial Infarction: A Retrospective Cohort Analysis of Medicare Claims Data. J Innov Card Rhythm Manag. Oct 2019; 10(10): 3866-3873. PMID 32477706
Uyei J, Braithwaite RS. Effectiveness of wearable defibrillators: systematic review and quality of evidence. Int J Technol Assess Health Care. Apr 2014; 30(2): 194-202. PMID 24893969
Hohnloser SH, Kuck KH, Dorian P, et al. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction. N Engl J Med. Dec 09 2004; 351(24): 2481-8. PMID 15590950
Steinbeck G, Andresen D, Seidl K, et al. Defibrillator implantation early after myocardial infarction. N Engl J Med. Oct 08 2009; 361(15): 1427-36. PMID 19812399
Bigger JT. Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery. Coronary Artery Bypass Graft (CABG) Patch Trial Investigators. N Engl J Med. Nov 27 1997; 337(22): 1569-75. PMID 9371853
Zishiri ET, Williams S, Cronin EM, et al. Early risk of mortality after coronary artery revascularization in patients with left ventricular dysfunction and potential role of the wearable cardioverter defibrillator. Circ Arrhythm Electrophysiol. Feb 2013; 6(1): 117-28. PMID 23275233
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Coding Section

Codes	Number	Description
CPT	93292	Interrogation device evaluation (in person) with physician analysis, review and report, includes connection, recording and disconnection per patient encounter; wearable defibrillator system
	93745	Initial setup and programming by a physician of wearable cardioverter-defibrillator includes initial programming of system, establishing baseline electronic electrocardiogram, transmission of data to data repository, patient instruction in wearing system, and patient reporting of problems or events
HCPCS	E0617	External defibriallator with integrated electrocardiogram analysis
	K0606	Automatic external defibrillator, with integrated electrocardiogram analysis, garment type
	K0607	Replacement battery for automated external defibrillator, each
	K0608	Replacement garment for use with automated external defibrillator, each
	K0609	Replacement electrodes for use with automated external defibrillator, each
ICD-10-CM (effective 10/01/15)	I42.0-I43	Cardiomyopathy code range
	I47.0-I47.9	Paroxysmal tachycardia code range
	I49.01-I49.02	Ventricular fibrillation and flutter code range
	I50.1-I50.9	Heart failure code range
	Z86.74	Personal history of sudden cardiac arrest
ICD-10-PCS (effective 10/01/15)		ICD-10-PCS codes are only used for inpatient services. There is no specific ICD-10-PCS code for the initiation or application of this therapy. They might use the following code:
	5A2204Z	Extracorporeal assistance and performance, physiological systems, restoration, cardiac, rhythm
Type of Service
Place of Service

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross Blue Shield Association technology assessment program (TEC) and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies and accredited national guidelines.

History From 2013 Forward

03/02/2023	Annual review, updating policy criteria for clarity and specificity. Updating coverage dates for various diagnoses. Also updating regulatory status, rationale and references.
03/01/2022	Annual review, no change to policy intent. Updating rationale and references.
03/02/2021	Annual review, no change to policy intent. Updating description, background, rationale and references.
03/02/2020	Annual review, no change to policy intent. Updating rationale and references.
08/14/2019	Corrected formatting in policy section. No other changes made.
07/24/2019	Updating policy verbiage with medical necessity criteria.
03/01/2019	Annual review with major revision including positive coverage statement for wearable cardioverter defibrillators within 40 days post myocardial infarction if criteria is met. Also updating: description, regulatory status, guidelines, policy, rationale, references and coding.
03/22/2018	Annual review, no change to policy intent. Updating rationale and references.
03/01/2017	Annual review, no change to policy intent. Updating background, description, regulatory status, rationale and references.
03/15/2016	Annual review, no change to policy intent.
3/12/2015	Annual review, no change to policy intent. Updated background, description, guidelines, rationale and references. Added coding.
2/25/2014	Updated policy to reflect BCA update. Added guidelines. Updated rationale and references. Updated policy verbiage to include that this technology is investigational for "high-risk patients awaiting heart transplant" and for "all other indications." Does not change the intent of the policy.
12/3/2013	Updated policy, rationale and references. Title changed. Three new diagnoses added as investigational. Added related policy.

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Wearable Cardioverter-Defibrillators - CAM 20215