CAM 20215

Wearable Cardioverter-Defibrillators

Category:Medicine   Last Reviewed:March 2021
Department(s):Medical Affairs   Next Review:March 2022
Original Date:April 2003    

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 8,453 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 U.S. Food and Drug Administration (FDA) approved the Lifecor WCD® 2000 system via 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 and is now called the Zoll 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."  

Related Policies
70144 Implantable Cardioverter Defibrillator (ICD)

Policy:
The wearable cardioverter defibrillator is considered MEDICALLY NECESSARY for the following conditions: 

  • Adult patients who meet qualifications for implantation of an ICD , but because of the presence of a medical condition (e.g., localized skin/soft tissue infection at or near site of ICD implant, systemic infection),  the implantation must be temporarily postponed  [maximum benefit 90 days or less], OR
  • Adult patients who have an ICD which must be removed because of medical complication (e.g., infected ICD pocket, systemic infection), and must undergo a waiting period until the ICD can be replaced (maximum benefit 90 days or less); OR
  • Patients with Long QT syndrome who are being evaluated for effectiveness of medical therapy [maximum benefit 90 days or less]; OR
  • Patients with a recent (≤ 30 days) MI and LVEF less than or equal to 35% (by most recent ECHO):
    • If revasularization was not performed and LVEF is not expected to improve, the WCD is covered for up to 2 months (maximum benefit 60 days or less); OR
    • If revascularization (percutaneous or surgical) was performed, and there is an expectation of possible improvement in left ventricular function, the WCD is covered for up to 4 months (maximum benefit 120 days or less); OR
  • Patients with newly diagnosed dilated cardiomyopathy not due to recent MI, with LVEF less than or equal to 35%, the WCD is covered for up to 4 months (maximum benefit 120 days or less).

Wearable cardiovertor defibrillators are considered NOT MEDICALLY NECESSARY for all other indications. 

Benefit Application
BlueCard®/National Account Issues
State or federal mandates (e.g., FEP) may dictate that all FDA-approved devices may not be considered investigational and, thus, these devices may be assessed only on the basis of 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 9, 2020.

Evidence reviews assess the clinical evidence to determine whether the use of 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 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 technology, 2 domains are examined: the relevance, and quality and credibility. To be relevant, studies must represent one or more intended clinical uses 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. RCTs 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
The available evidence on the wearable cardioverter defibrillator (WCD) consists of case series describing outcomes from patients using the device. There is 1 RCT comparing WCD with standard care. RCTs 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 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 infection6. 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.8 Of these, 16% (n=13) did not wear the WCD due to refusal, discomfort, or other/unknown reasons. In the Use of a Wearable Defibrillator in Terminating Tachyarrythmias in Patients at High Risk for Sudden Death (WEARIT) and Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to four months (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

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. 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 implantable cardiodefibrillator?

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

Patients
The relevant population of interest is patients at risk of death from cardiovascular arrest with a temporary contraindication to an implantable cardiodefibrillator.

Interventions
The therapy being considered is a WCD.

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

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

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

Outcomes
The general outcomes of interest are survival over 10-year follow-up, heart attacks, 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.

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.11 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 explanation of the ICD 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 Implantable Cardioverter Defibrillator 

Trial Study Type Country Dates Participants Treatment FU
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 mo (BIROAD) WCD 3.1 mo
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 d

BIROAD: Patients at High Risk for Sudden Death after a Myocardial Infarction or Bypass Surgery not receiving an ICD for up to four months;CABG: coronary artery bypass graft; CHD: congenital heart disease; FU: follow-up; 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 Tachyarrythmias 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 four months.

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

Trial Appropriate Shocka Inappropriate Shocka 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 four months; ICD: implantable cardioverter defibrillator; WCD: wearable cardioverter defibrillator.WEARIT: Use of a Wearable Defibrillator in Terminating Tachyarrythmias 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 four months.

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 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. Myocardial infarction (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 left ventricular ejection fraction (LVEF) of 35% of less to early ICD implantation 6 to 40 days after acute MI or medical therapy alone, there was no significant improvement in overall mortality.12,13 The hazard ratio (HR) for overall survival (OS) in the DINAMIT and IRIS trial 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).

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–myocardial infarction period?

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

Patients
The relevant population of interest is patients in the immediate post–myocardial infarction period.

Interventions
The therapy being considered is a WCD.

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

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

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

Outcomes
The general outcomes of interest are survival over 10-year follow-up, heart attacks, 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 1,524 patients with acute myocardial infarction and an ejection fraction ≤35% to WCD and 778 to receive only guideline-based therapy (total N=2,302).14 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
Epstein et al. (2013) reported on the results of a postmarket registry data from 8453 post-MI patients who received WCDs for risk of sudden cardiac arrest while awaiting ICD placement.15 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.

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 soon after post-MI (≤40 days) with a LVEF of 35% or less.16 Four studies (Chung et al. (2010),5 Epstein et al. (2013),15 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–Myocardial Infarction Period

Study Study Type Country Dates Participants Treatment FU
Epstein et al (2013)15 Retrospective registry (postmarket study) United States 2005-2011 High-risk post-MI patients during the 40-d and 3-mo waiting periods WCD 3 mo

FU: follow-up; MI: myocardial infarction; WCD: wearable cardioverter defibrillator.

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

Study Outcomes
Epstein et al (2013)15 N=8453
Wearable cardioverter defibrillator
  • Number of patients receiving shock: 133
  • Shock events: 146
  • Appropriate shocksa: 309
  • Shocks successful in terminating VT or VF: 252 (82% success)
  • Shocks leading to asystole: 9
  • Unsuccessful shocks: 41 (10% failure)
  • Inappropriate shocks: 99 patients received 114 inappropriate shocks

VF: ventricular fibrillation; VT: ventricular tachycardia.

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 postacute MI period found no benefit to WCD over guideline-directed therapy. Two RCTs of ICD use 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 absence of a control group. 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.

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 surgery who are at high risk for lethal arrhythmias?

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

Patients
The relevant population of interest is patients post-coronary artery bypass graft surgery who are at high risk for lethal arrhythmias.

Interventions
The therapy being considered is a WCD.

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

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

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

Outcomes
The general outcomes of interest are survival over 10-year follow-up, heart attacks, 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.

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).17

Zishiri et al. (2013) reported on the results of a nonrandomized comparison of nearly 5,000 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 4,149 patients discharged without WCD from Cleveland Clinic CABG and percutaneous coronary intervention registries).18 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),15 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 FU
Zishiri et al (2013)18 Retrospective matched cohort United States 2002-2009 Patients with low-EF post-PCI or post-CABG WCD No WCD 3.2 y

CABG: coronary artery bypass graft; EF: ejection fraction; FU: follow-up; PCI: percutaneous coronary intervention; 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-PCI Mortality
(90 Days)
Post-CABG Mortality (Long-Term) Post-PCI Mortality (Long-Term)
Zishiri et al (2013)18        
WCD, n/N (%) (n=809) 7/26 (3.1%) 5/288 (1.7%) 19/226 (8.4%) 31/228 (11%)
No WCD, 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=.048a 0.430 (0.290 to 0.638); <.001a

CABG: coronary artery bypass graft; CI: confidence interval; HR: hazard ratio; PCI: percutaneous coronary intervention; 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
Cliical 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.

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

Interventions
The therapy being considered is a WCD.

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

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

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

Outcomes
The general outcomes of interest are survival over 10-year follow-up, heart attacks, 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.

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.19 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.20 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 FU
Opreanu et al (2015)19 Retrospective registry U.S. 2004-2011 Patients using the WCD for primary prevention of SCD in patients awaiting HT WCD 39 d
Wässnig et al (2016)20 Retrospective cohort Germany, multiple sites 2010-2013 Patients with multiple etiology WCD NR

FU: follow-up; HT: heart transplant; 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 Shocka Inappropriate Shocka Adherence
Opreanu et al (2015)19      
WCD 7/121 (6%) 2/121 (2%) Average of 20 h/d
Wässnig et al (2016)20      
WCD 1/40 (2.5%) Stratified data not reported Stratified data not reported

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.9 Rao et al. (2011) published a case series of 162 patients with congenital structural heart disease or inherited arrhythmias treated with WCD.21 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. 2 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.

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

Interventions
The therapy being considered is a WCD.

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

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

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

Outcomes
The general outcomes of interest are survival over 10-year follow-up, heart attacks, 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.

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; 955 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).22 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 VTs 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.23 Mean EF was 19.9% on presentation. Patients wore the WCD for a median of 51 days and a median of 18.0 hours a 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.20 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 separately24 from the full cohort.25

The Uyei and Braithwaite (2014) systematic review also identified 4 studies (Saltzberg et al. (2012),26 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 Cardiomyopath 

Study; Trial Study Type Country Dates Participants Treatment FU
Kutyifa et al(2015)10;WEARIT-II Registry Prospective registry United States, Germany 2011-2014 Patients withnonischemic cardiomyopathy WCD 90 d
Salehi et al (2016)23 Retrospective registry United States 2005- 2012 Patients with nonischemic cardiomyopathy who self-reported a history of excess alcohol use WCD 100 d
Duncker et al (2017)24,25; PROLONG Retrospective cohort Germany 2012- 2016 Newly diagnosed LVEF ≤35% WCD 11 mo
Wässnig et al (2016)20 Retrospective cohort Germany, multiple sites 2010- 2013 Patients with multiple etiology WCD NR

FU: follow-up; LVEF: left ventricular ejection fraction; NR: not reported; WCD: wearable cardioverter defibrillator. 

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

Study; Trial Appropriate Shocka Inappropriate Shocka Nonadherence
Kutyifa et al (2015)10; WEARIT-II Registry 927    
WCD Not reported Not reported Not reported
Salehi et al (2016)23      
WCD 7/127 (6%) 13/127 (10.2%)  
Duncker et al (2017)24,25,; PROLONG      
WCD 8/117 (7%) None Of 156 (entire cohort), 48 terminated WCD treatment before 3-mo follow-up. Of the 48, 24 (50%) discontinued due to noncompliance.
Wässnig et al (2016)20      
WCD 7/735 (1%) Stratified data not reported Stratified data not reported

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 analysis 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.

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

Interventions
The therapy being considered is a WCD.

Patients with peripartum cardiomyopathy may be jointly managed by cardiologists and obstetricians.

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

Patients at risk for SCD are actively managed by cardiologists in an outpatient clinical setting.

Outcomes
The general outcomes of interest are survival over 10-year follow-up, heart attacks, 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.

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.26 The event rate was 0 in the peripartum cardiomyopathy 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.27 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. 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 8,453 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. 

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. 

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. .

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.

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.

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 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 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.

2010 Input
In response to requests, input was received from 4 academic medical centers while this policy was under review in 2010. Most, but not all, providing comment suggested that the WCD may have a role in select high-risk patients following acute myocardial infarction or in newly diagnosed cardiomyopathy.

2008 Input
In response to requests, input from physician specialty societies and academic medical centers was not received while this policy was under review in 2008.

Practice Guidelines and Position Statements
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 arrhythias and prevention of sudden cardiac death.28 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 NICM, 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. Class IIa is moderate recommendation, and class IIb is a weak recommendation.

Table 11. Guidelines for Wearable Cardioverter Defibrillator Therapy  

Recommendation COR LOE
"In patients with an ICD and a history of SCA or sustained VA in whom removal of the ICD is required (as with infection, the wearable cardioverter-defibrillator is reasonable for the prevention of SCD." 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, NICM, revascularization within the past 90 days, myocarditis or secondary cardiomyopathy or a systemic infection, the wearable cardioverter-defibrillator may be reasonable." 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; NICM: non-ischemic cardiomyopathy; SCA: sudden cardiac arrest; SCD: sudden cardiac death; WCD: wearable cardioverter defibrillator.

In 2016, the AHA published a scientific advisory on the WCD.29 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 Wearable Cardioverter Defibrillator Therapy 

Recommendation COR LOE
"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 D 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 mo." 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.

American College of Cardiology et al
In 2018, the American College of Cardiology, AHA, and the Heart Rhythm Society jointly published guidelines on the management of adults who have ventricular arrhythmias or who are at risk for sudden cardiac death, including diseases and syndromes associated with a risk of sudden cardiac death from ventricular arrhythmias.28 Recommendations related to the use of WCDs are provided in Table 13.

Table 13. Guidelines for Wearable Cardioverter Defibrillator Therapy  

Recommendations COR LOE
In patients with an implantable cardioverter defibrillator and a history of sudden cardiac arrest or sustained ventricular arrhythmia in whom removal of the implantable cardioverter defibrillator is required (as with infection), the wearable cardioverter defibrillator is reasonable for the prevention of sudden cardiac death.a IIa B-NR
In patients at an increased risk of sudden cardiac death but who are not ineligible for an implantable cardioverter defibrillator, 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, wearable cardioverter defibrillator may be reasonable.b IIb B-NR

B-NR: data derived from ≥1 nonrandomized trials or meta-analysis of such studies; COR: class of recommendation; ICD: implantable cardioverter defibrillator; LOE: level of evidence; LVEF: left ventricular ejection fraction; MI: myocardial infarction.

a Removal of an ICD for a period of time, most commonly due to infection, exposes the patient to risk of untreated ventricular tachycardia/sudden cardiac death 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%.30 For patients with a history of sudden cardiac arrest or sustained ventricular arrhythmia, the WCD may allow the patient to be discharged from the hospital with protection from ventricular tachycardia/sudden cardiac death until the clinical situation allows reimplantation of an ICD.

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 ventricular tachycardia or sudden cardiac death. 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.

International Society for Heart and Lung Transplantation
In 2006, the International Society for Heart and Lung Transplantation issued guidelines on the care of cardiac transplant candidates that addressed use of ICDs or WCDs.31 Recommendations on the use of WCDs are provided in Table 14.

Table 14. Guidelines on Management of Cardiac Transplant Candidates With ICDs  

Recommendation COR LOE
"An implanted or wearable ICD should be provided for Status 1B patients [ie, dependent on intravenous medications or a mechanical assist device] who are discharged home given that the wait for transplantation remains significant." I C
"It is reasonable to consider placement of a defibrillator in patients with Stage D failure who are candidates for transplantation or LVAD destination therapy (see subsequent considerations for MCSD referral: bridge or destination)." IIa C

COR: class of recommendation; ICD: implantable cardioverter defibrillator; LOE: level of evidence; LVAD: left ventricular assist device; MCSD: mechanical circulatory support device.

U.S. Preventive Services Task Force Recommendations
Not applicable.

Ongoing and Unpublished Clinical Trials
Some currently unpublished trials that might influence this review are listed in Table 15.

Table 15. Summary of Key Trials  

NCT No. Trial Name Planned Enrollment Completion Date
Ongoing      
NCT02816047 Indications for and Experience With the Wearable Cardioverter Defibrillator (WCD)–Austrian WCD Registry 450 Jan 2021
  EURObservational research programme: Peripartum Cardiomyopathy (PPCM) Registrya    

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

References: 

  1. Food and Drug Administration. Summary of Safety and Effectiveness Data, P010030, Lifecor, Inc. WCD 2000 System. 2001; https://www.accessdata.fda.gov/cdrh_docs/pdf/p010030b.pdf. Accessed March 19, 2020.
  2. Beauregard LA. Personal security: Clinical applications of the wearable defibrillator. Pacing Clin Electrophysiol. Jan 2004; 27(1): 1-3. PMID 14720147
  3. Blue Cross and Blue Shield Association Technology Evaluation Center (TEC). Wearable cardioverter-defibrillator as a bridge to implantable cardioverter-defibrillator treatment. TEC Assessments. 2010;Volume 25:Tab 2.
  4. Auricchio A, Klein H, Geller CJ, et al. Clinical efficacy of the wearable cardioverter-defibrillator in acutely terminating episodes of ventricular fibrillation. Am J Cardiol. May 15 1998; 81(10): 1253-6. PMID 9604964
  5. Chung MK, Szymkiewicz SJ, Shao M, et al. Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival. J Am Coll Cardiol. Jul 13 2010; 56(3): 194-203. PMID 20620738
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. Opreanu M, Wan C, Singh V, et al. Wearable cardioverter-defibrillator as a bridge to cardiac transplantation: A national database analysis. J Heart Lung Transplant. Oct 2015; 34(10): 1305-9. PMID 26094085
  20. Wassnig NK, Gunther M, Quick S, et al. Experience With the Wearable Cardioverter-Defibrillator in Patients at High Risk for Sudden Cardiac Death. Circulation. Aug 30 2016; 134(9): 635-43. PMID 27458236
  21. Rao M, Goldenberg I, Moss AJ, et al. Wearable defibrillator in congenital structural heart disease and inherited arrhythmias. Am J Cardiol. Dec 01 2011; 108(11): 1632-8. PMID 21890075
  22. Kadish A, Schaechter A, Subacius H, et al. Patients with recently diagnosed nonischemic cardiomyopathy benefit from implantable cardioverter-defibrillators. J Am Coll Cardiol. Jun 20 2006; 47(12): 2477-82. PMID 16781376
  23. Salehi N, Nasiri M, Bianco NR, et al. The Wearable Cardioverter Defibrillator in Nonischemic Cardiomyopathy: A US National Database Analysis. Can J Cardiol. Oct 2016; 32(10): 1247.e1-1247.e6. PMID 26975224
  24. Duncker D, Konig T, Hohmann S, et al. Ventricular arrhythmias in patients with newly diagnosed nonischemic cardiomyopathy: Insights from the PROLONG study. Clin Cardiol. Aug 2017; 40(8): 586-590. PMID 28333373
  25. Duncker D, Konig T, Hohmann S, et al. Avoiding Untimely Implantable Cardioverter/Defibrillator Implantation by Intensified Heart Failure Therapy Optimization Supported by the Wearable Cardioverter/Defibrillator-The PROLONG Study. J Am Heart Assoc. Jan 17 2017; 6(1). PMID 28096098
  26. Saltzberg MT, Szymkiewicz S, Bianco NR. Characteristics and outcomes of peripartum versus nonperipartum cardiomyopathy in women using a wearable cardiac defibrillator. J Card Fail. Jan 2012; 18(1): 21-7. PMID 22196837
  27. Duncker D, Haghikia A, Konig T, et al. Risk for ventricular fibrillation in peripartum cardiomyopathy with severely reduced left ventricular function-value of the wearable cardioverter/defibrillator. Eur J Heart Fail. Dec 2014; 16(12): 1331-6. PMID 25371320
  28. Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. Sep 25 2018; 138(13): e272-e391. PMID 29084731
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  31. Gronda E, Bourge RC, Costanzo MR, et al. Heart rhythm considerations in heart transplant candidates and considerations for ventricular assist devices: International Society for Heart and Lung Transplantation guidelines for the care of cardiac transplant candidates--2006. J Heart Lung Transplant. Sep 2006; 25(9): 1043-56. PMID 16962465

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 and Blue Shield Association technology assessment program (TEC) and other non-affiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

"Current Procedural Terminology © American Medical Association. All Rights Reserved" 

History From 2013 Forward     

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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